Honda's VTEC.
kris
12-08-2002, 11:57 PM
Since we have an abundance of Honda owners. The following info may be of some use. :)
Temple of VTEC Asia Special Feature
VTEC
VTEC is one of Honda's greatest invention. Though an undisputed expert in turbocharging as evidenced by years of Formula-1 domination while Honda was active in the sport, Honda's engineers feels that turbocharging has disadvantages, primarily bad fuel economy, that made it not totally suitable for street use. At the same time, the advantages of working with smaller engines meant that smaller capacity engines with as high power output as possible (ie very high specific-output engines) are desirable for street engines.
Thus Honda invented VTEC which allows it to extract turbo level specific output from its engines without having to suffer from the disadvantages of turbocharging (though VTEC introduces disadvantages of its own).
The Temple of VTEC is specifically created by Jeff Palmer as a dedication to this great technology and the Temple of VTEC Asia is dedicated to the home of VTEC -and of Honda, Japan and the region of Asia.
In this permanent feature, we will examine the basic mechanism that make up the VTEC technology as well as the various implementations of VTEC.
The Basic VTEC Mechanism
The basic mechanism used by the VTEC technology is a simple hydraulically actuated pin. This pin is hydraulically pushed horizontally to link up adjacent rocker arms. A spring mechanism is used to return the pin back to its original position.
The VTEC mechanism is covered in great detail elsewhere so it is redundant to go through the entire mechanism here. Instead we will look at the basic operating principles which can be used in later sectionse to explain the various implementations VTEC by Honda.
To start on the basic principle, examine the simple diagram below. It comprises a camshaft with two cam-lobes side-by-side. These lobes drives two side-by-side valve rocker arms. The two cam/rocker pairs operates independently of each other. One of the two cam-lobes are intentionally drawn to be different. The one on the left has a "wilder" profile, it will open its valve earlier, open it more, and close it later, compared to the one on the right. Under normal operation, each pair of cam-lobe/rocker-arm assembly will work independently of each other.
VTEC uses the pin actuation mechanism to link the mild-cam rocker arm to the wild-cam rocker arm. This effectively makes the two rocker arms operate as one. This "composite" rocker arm(s) now clearly follows the wild-cam profile of the left rocker arm. This in essence is the basic working principle of all of Honda's VTEC engines.
Currently, Honda have implemented VTEC in four different configurations. For the rest of this feature, we will examine these four different implementations of VTEC.
DOHC VTEC
The pinacle of VTEC implementation is the DOHC VTEC engine. The first engine to benefit from VTEC is the legendary B16A, a 1595cc inline-4 16Valve DOHC engine with VTEC producing 160ps and first appearing in 1989 in the JDM Honda Integra XSi and RSi.
Examine the diagram of a typical Honda DOHC PGM-Fi non-VTEC engine on the left, in this case the 1590cc ZC DOHC engine. Note that each pair of cam-lobe and their corresponding rocker arms though adjacent, are spaced apart from each other.
In the DOHC VTEC implementation, Honda put an extra cam/rocker in between each pair of intake and exhaust lobes/rockers. The three cam/rocker assemblies are now next to each other. The new middle lobe is the "wild" race-tuned cam-lobe. Using VTEC to link up all three rocker arms together, Honda is able to use either the mild or the wild cam-lobes at will.
Note : Though the ZC and B16A are well-suited to illustrate the difference between plain-DOHC and DOHC-VTEC, the B16A engine is not derived from ZC. In fact, ZC and B16A have different bore and stroke. The same applies for the B18A and B18C engines used in the JDM Integra series.
DOHC VTEC implementations can produce extremely high specific outputs. The B16A for standard street use first produced 160ps and now 170ps. In the super-tuned B16B implementation used for the new JDM EK-series Honda Civic Type-R, 185ps was produced from the same 1595cc.
DOHC VTEC can also easily offer competitive power outputs to turbocharged engines for normal street use. For eg, the E-DC2 Integra Si-VTEC produces 180ps from the 1797cc DOHC VTEC B18C engine. This compares favourably to the 1.8l version of the RPS-13 Nissan 180SX which uses a 1.8l DOHC Turbo-Intercooled engine which produced 175ps.
SOHC VTEC
An alternative implementation of VTEC for high (versus very high) specific output is used in Honda's SOHC engines. SOHC VTEC engines have often been mistakenly taken as a 'poor' second-rate derivative of DOHC VTEC but this is not the true case. An SOHC engine head has advantages of a DOHC head mostly in terms of size (it is narrower) and weight. For more sedate requirements, an SOHC engine is preferable to the DOHC engine. SOHC VTEC is a power implementation of VTEC for SOHC engines with the express intention of extracting high specific output. Examine the diagram of a standard SOHC cam assembly on the right. Note that the pair of intake rocker arms are separated but adjacent to each other.
In the SOHC VTEC implementation (diagram on the right), Honda put a wild-cam lobe for the intake valves in the space between the two rocker arms.
Note that the two exhaust rocker arms are separated by the two intake rocker arms and the "tunnel" for the sparkplug cable connector. This is the reason why Honda implemented VTEC on the intake valves only.
SOHC VTEC engines are high specific output forms of the standard SOHC engines. The D15B engine used in the Civic/Civic Ferio VTi models (EG-series 1991 to 1995) gives 130ps from a 1493cc capacity. Bear in mind this kind of power levels are normally associated with 1.6l DOHC or even milder-tuned 1.8l DOHC fuel-injected engines !
VTEC-E
A novel implementation of VTEC in SOHC engines is the VTEC-E implementation (E for Economy). VTEC-E uses the principle of swirling to promote more efficient air-and-fuel mixing in the engine chambers. VTEC-E works by deactivating one intake valve. Examine the diagram below.
In the SOHC VTEC-E implementation, only one intake cam-lobe is implemented on the camshaft. Actually it is really a flat "ring". In operation this means the relevant rocker arm will not be activated causing the engine to effectively work in 12-valve mode. This promotes a swirl action during the intake cycle. VTEC is used to activate the inactive valve, making the engine work in 16-valve mode in more demanding and higher rpm conditions. Honda was able to implement air-fuel mixture ratios of more than 20:1 in VTEC-E during the 12-valve operating mode. The SOHC VTEC-E engined EG-series Civic ETi is able to return fuel consumptions of as good as 20km/litre or better!!
SOHC VTEC implemented for power is often mistaken as SOHC VTEC-E which is implemented for economy. It is worthwhile to note that the 1.5l SOHC VTEC-E used in the JDM Honda Civic ETi produces 92ps. This is in fact less than that produced by the standard 1.5l SOHC engine's 100ps which uses dual Keihin side-draft carburettors. SOHC VTEC in the D15B produces 130ps. This is 30% more than the standard SOHC implementation !
3-stage VTEC
Examine the SOHC VTEC and SOHC VTEC-E implementations. The clever Honda engineers saw that it is a logical step to merge the two implementations into one. This is in essence the 3-stage VTEC implementation. 3-stage VTEC is implemented on the D15B 1.5l SOHC engine in which the VTEC-E mechanism is combined with the power VTEC mechanism.
Many of us probably has laughed at the poor ignorant layman who said "I want power AND economy from my Honda". We know of course that power and economy are mutually exclusive implementations. Honda decided not to abide by this rule. Now, with 3-stage VTEC, we get BOTH power and economy !.
The diagram below illustrates the 3-stage VTEC implementation. The intake rocker arms have two VTEC pin actuation mechanisms. The VTEC-E actuation assembly is located above the camshaft while the VTEC (power) actuation assembly is the standard wild-cam lobe and rocker assembly.
Below 2500rpm and with gentle accelerator pressure, neither pin gets actuated. The engine operates in 12V mode with very good fuel combustion efficiency. When the right foot gets more urgent and/or above 2500rpm, the upper pin gets actuated. This is the VTEC-E mechanism at work and the engine effectively enters into the '2nd stage'. Now D15B 3-stage works in 16V mode (both intake valves works from the same mild cam-lobe).
Stage 2 operates from around 2500rpm to 6000rpm. When the rpm exceeds 6000rpm, the VTEC mechanism activates the wild cam-lobe pushing the engine into the '3rd stage', the power stage. Now the engine gives us the full benefit of its 130ps potential !
The 3-stage VTEC D15B engine is used on the current EK-series JDM Civic/Civic Ferio VTi/Vi together with Honda's new Multimatic CVT transmission. Stage-1 12V or "lean-burn" operation mode is indicated to the driver by an LED on the dashboard. The 2500rpm cutover from lean-burn to normal 16V operation in fact varies according to load and driver requirements. With gentle driving, lean-burn can operate up to 3000rpm or higher. Stage-3 may not always be activated. The Multimatic transmission has a selector for Economy, Drive, and Sports mode. In Economy mode for eg, the ECU operates with a max rpm of around 4800rpm even at Wide-Open-Throttle positions.
The essence of 3-stage VTEC is power AND economy implemented on a 1.5l SOHC PGM-Fi engine. Many people mistakes 3-stage VTEC as a "superior" evolution of the power oriented DOHC VTEC implementation, describing DOHC VTEC as "the older 2-stage VTEC" and implying an inferior relationship. This is totally wrong because DOHC VTEC is tuned purely for high specific output and sports/racing requirements. 3-stage VTEC is in truth an evolution of SOHC VTEC and VTEC-E, merging the two implementations into one.
Implementations of VTEC in Honda models
DOHC VTEC is the implementation producing the highest-powered engines and used in the highest performing models in the Honda line-up. The smallest DOHC VTEC engine is the legendary B16A. A 1595cc 160-170ps engine that first appeared in the 1989 Honda Integra XSi and RSi, it now powers the famous Civic SiR models. The B16B is a special hand-tuned super high output derivative of the B16A giving 185ps and used in the Civic Type-R.
The B18C is a 180ps 1797cc engine that appears in the high performance Integra line-up. The B18CSpec96 is a special hand-tuned super high output version of the B18C giving 200ps and used in the legendary Integra Type-R.
DOHC VTEC implementations now appear in most of Honda's great line-up. The Accord SiR used to have a detuned 190s H22A 2.2l DOHC VTEC which was also used on the same period Prelude Si-VTEC in which it gave 200ps. The current Accord line now has a 2.0l DOHC VTEC engine that gives 180ps and 200ps in the Accord SiR and SiR-T models respectively while the current Prelude SiR still uses the H22A 2.2l DOHC VTEC engine giving 200ps. A special hand-tuned version of H22A is used in the Prelude Type-S and gives 220ps.
The highest level of DOHC VTEC implementation is of course in the NSX. Implemented V6 DOHC VTEC, originally in 3.0l and now in a larger 3.2l form, it tops the 280ps "legal" limit imposed by the Japanese government for stock street cars.
SOHC VTEC appears in more guises in the Honda line-up. The smallest SOHC VTEC engine is the D15B, used on Civic and Civic Ferio VTi/Vi models in Japan. The D16A 1590cc SOHC VTEC (power) engine giving 130ps is also used on the Civic Coupe and the Civic Ferio EXi (a 4WD model). SOHC VTEC also appears on the Accord models but not the Integra or Prelude line-up. In fact in markets which Honda considers not sufficiently advanced to warrant the DOHC VTEC engines (Malaysia being one of them), Honda markets SOHC VTEC as the top engine for their line-up.
Conclusion
In this permanent feature, we have examined the basic principle on which VTEC works as well as the various implementations of VTEC. In a follow-up feature, we will look at alternative variable valve timing mechanisms which are implemented by other manufacturers.
Author : Wong, Kong-Ngai
Copyright : Temple of VTEC and Temple of VTEC ASIA
Notice : Most of the illustrations used in this feature are taken without permission from magazines and the Honda Japan's homepage. They may be withdrawn or replaced without notice.
http://asia.vtec.net/spfeature/vtecimpl/img1.jpg
http://asia.vtec.net/spfeature/vtecimpl/img2.jpg
http://asia.vtec.net/spfeature/vtecimpl/img3.jpg
http://asia.vtec.net/spfeature/vtecimpl/img4.jpg
http://asia.vtec.net/spfeature/vtecimpl/img5.jpg
http://asia.vtec.net/spfeature/vtecimpl/img6.jpg
http://asia.vtec.net/spfeature/vtecimpl/img7.jpg
http://asia.vtec.net/spfeature/vtecimpl/img8.jpg
http://asia.vtec.net/spfeature/vtecimpl/img9.jpg
Temple of VTEC Asia Special Feature
VTEC
VTEC is one of Honda's greatest invention. Though an undisputed expert in turbocharging as evidenced by years of Formula-1 domination while Honda was active in the sport, Honda's engineers feels that turbocharging has disadvantages, primarily bad fuel economy, that made it not totally suitable for street use. At the same time, the advantages of working with smaller engines meant that smaller capacity engines with as high power output as possible (ie very high specific-output engines) are desirable for street engines.
Thus Honda invented VTEC which allows it to extract turbo level specific output from its engines without having to suffer from the disadvantages of turbocharging (though VTEC introduces disadvantages of its own).
The Temple of VTEC is specifically created by Jeff Palmer as a dedication to this great technology and the Temple of VTEC Asia is dedicated to the home of VTEC -and of Honda, Japan and the region of Asia.
In this permanent feature, we will examine the basic mechanism that make up the VTEC technology as well as the various implementations of VTEC.
The Basic VTEC Mechanism
The basic mechanism used by the VTEC technology is a simple hydraulically actuated pin. This pin is hydraulically pushed horizontally to link up adjacent rocker arms. A spring mechanism is used to return the pin back to its original position.
The VTEC mechanism is covered in great detail elsewhere so it is redundant to go through the entire mechanism here. Instead we will look at the basic operating principles which can be used in later sectionse to explain the various implementations VTEC by Honda.
To start on the basic principle, examine the simple diagram below. It comprises a camshaft with two cam-lobes side-by-side. These lobes drives two side-by-side valve rocker arms. The two cam/rocker pairs operates independently of each other. One of the two cam-lobes are intentionally drawn to be different. The one on the left has a "wilder" profile, it will open its valve earlier, open it more, and close it later, compared to the one on the right. Under normal operation, each pair of cam-lobe/rocker-arm assembly will work independently of each other.
VTEC uses the pin actuation mechanism to link the mild-cam rocker arm to the wild-cam rocker arm. This effectively makes the two rocker arms operate as one. This "composite" rocker arm(s) now clearly follows the wild-cam profile of the left rocker arm. This in essence is the basic working principle of all of Honda's VTEC engines.
Currently, Honda have implemented VTEC in four different configurations. For the rest of this feature, we will examine these four different implementations of VTEC.
DOHC VTEC
The pinacle of VTEC implementation is the DOHC VTEC engine. The first engine to benefit from VTEC is the legendary B16A, a 1595cc inline-4 16Valve DOHC engine with VTEC producing 160ps and first appearing in 1989 in the JDM Honda Integra XSi and RSi.
Examine the diagram of a typical Honda DOHC PGM-Fi non-VTEC engine on the left, in this case the 1590cc ZC DOHC engine. Note that each pair of cam-lobe and their corresponding rocker arms though adjacent, are spaced apart from each other.
In the DOHC VTEC implementation, Honda put an extra cam/rocker in between each pair of intake and exhaust lobes/rockers. The three cam/rocker assemblies are now next to each other. The new middle lobe is the "wild" race-tuned cam-lobe. Using VTEC to link up all three rocker arms together, Honda is able to use either the mild or the wild cam-lobes at will.
Note : Though the ZC and B16A are well-suited to illustrate the difference between plain-DOHC and DOHC-VTEC, the B16A engine is not derived from ZC. In fact, ZC and B16A have different bore and stroke. The same applies for the B18A and B18C engines used in the JDM Integra series.
DOHC VTEC implementations can produce extremely high specific outputs. The B16A for standard street use first produced 160ps and now 170ps. In the super-tuned B16B implementation used for the new JDM EK-series Honda Civic Type-R, 185ps was produced from the same 1595cc.
DOHC VTEC can also easily offer competitive power outputs to turbocharged engines for normal street use. For eg, the E-DC2 Integra Si-VTEC produces 180ps from the 1797cc DOHC VTEC B18C engine. This compares favourably to the 1.8l version of the RPS-13 Nissan 180SX which uses a 1.8l DOHC Turbo-Intercooled engine which produced 175ps.
SOHC VTEC
An alternative implementation of VTEC for high (versus very high) specific output is used in Honda's SOHC engines. SOHC VTEC engines have often been mistakenly taken as a 'poor' second-rate derivative of DOHC VTEC but this is not the true case. An SOHC engine head has advantages of a DOHC head mostly in terms of size (it is narrower) and weight. For more sedate requirements, an SOHC engine is preferable to the DOHC engine. SOHC VTEC is a power implementation of VTEC for SOHC engines with the express intention of extracting high specific output. Examine the diagram of a standard SOHC cam assembly on the right. Note that the pair of intake rocker arms are separated but adjacent to each other.
In the SOHC VTEC implementation (diagram on the right), Honda put a wild-cam lobe for the intake valves in the space between the two rocker arms.
Note that the two exhaust rocker arms are separated by the two intake rocker arms and the "tunnel" for the sparkplug cable connector. This is the reason why Honda implemented VTEC on the intake valves only.
SOHC VTEC engines are high specific output forms of the standard SOHC engines. The D15B engine used in the Civic/Civic Ferio VTi models (EG-series 1991 to 1995) gives 130ps from a 1493cc capacity. Bear in mind this kind of power levels are normally associated with 1.6l DOHC or even milder-tuned 1.8l DOHC fuel-injected engines !
VTEC-E
A novel implementation of VTEC in SOHC engines is the VTEC-E implementation (E for Economy). VTEC-E uses the principle of swirling to promote more efficient air-and-fuel mixing in the engine chambers. VTEC-E works by deactivating one intake valve. Examine the diagram below.
In the SOHC VTEC-E implementation, only one intake cam-lobe is implemented on the camshaft. Actually it is really a flat "ring". In operation this means the relevant rocker arm will not be activated causing the engine to effectively work in 12-valve mode. This promotes a swirl action during the intake cycle. VTEC is used to activate the inactive valve, making the engine work in 16-valve mode in more demanding and higher rpm conditions. Honda was able to implement air-fuel mixture ratios of more than 20:1 in VTEC-E during the 12-valve operating mode. The SOHC VTEC-E engined EG-series Civic ETi is able to return fuel consumptions of as good as 20km/litre or better!!
SOHC VTEC implemented for power is often mistaken as SOHC VTEC-E which is implemented for economy. It is worthwhile to note that the 1.5l SOHC VTEC-E used in the JDM Honda Civic ETi produces 92ps. This is in fact less than that produced by the standard 1.5l SOHC engine's 100ps which uses dual Keihin side-draft carburettors. SOHC VTEC in the D15B produces 130ps. This is 30% more than the standard SOHC implementation !
3-stage VTEC
Examine the SOHC VTEC and SOHC VTEC-E implementations. The clever Honda engineers saw that it is a logical step to merge the two implementations into one. This is in essence the 3-stage VTEC implementation. 3-stage VTEC is implemented on the D15B 1.5l SOHC engine in which the VTEC-E mechanism is combined with the power VTEC mechanism.
Many of us probably has laughed at the poor ignorant layman who said "I want power AND economy from my Honda". We know of course that power and economy are mutually exclusive implementations. Honda decided not to abide by this rule. Now, with 3-stage VTEC, we get BOTH power and economy !.
The diagram below illustrates the 3-stage VTEC implementation. The intake rocker arms have two VTEC pin actuation mechanisms. The VTEC-E actuation assembly is located above the camshaft while the VTEC (power) actuation assembly is the standard wild-cam lobe and rocker assembly.
Below 2500rpm and with gentle accelerator pressure, neither pin gets actuated. The engine operates in 12V mode with very good fuel combustion efficiency. When the right foot gets more urgent and/or above 2500rpm, the upper pin gets actuated. This is the VTEC-E mechanism at work and the engine effectively enters into the '2nd stage'. Now D15B 3-stage works in 16V mode (both intake valves works from the same mild cam-lobe).
Stage 2 operates from around 2500rpm to 6000rpm. When the rpm exceeds 6000rpm, the VTEC mechanism activates the wild cam-lobe pushing the engine into the '3rd stage', the power stage. Now the engine gives us the full benefit of its 130ps potential !
The 3-stage VTEC D15B engine is used on the current EK-series JDM Civic/Civic Ferio VTi/Vi together with Honda's new Multimatic CVT transmission. Stage-1 12V or "lean-burn" operation mode is indicated to the driver by an LED on the dashboard. The 2500rpm cutover from lean-burn to normal 16V operation in fact varies according to load and driver requirements. With gentle driving, lean-burn can operate up to 3000rpm or higher. Stage-3 may not always be activated. The Multimatic transmission has a selector for Economy, Drive, and Sports mode. In Economy mode for eg, the ECU operates with a max rpm of around 4800rpm even at Wide-Open-Throttle positions.
The essence of 3-stage VTEC is power AND economy implemented on a 1.5l SOHC PGM-Fi engine. Many people mistakes 3-stage VTEC as a "superior" evolution of the power oriented DOHC VTEC implementation, describing DOHC VTEC as "the older 2-stage VTEC" and implying an inferior relationship. This is totally wrong because DOHC VTEC is tuned purely for high specific output and sports/racing requirements. 3-stage VTEC is in truth an evolution of SOHC VTEC and VTEC-E, merging the two implementations into one.
Implementations of VTEC in Honda models
DOHC VTEC is the implementation producing the highest-powered engines and used in the highest performing models in the Honda line-up. The smallest DOHC VTEC engine is the legendary B16A. A 1595cc 160-170ps engine that first appeared in the 1989 Honda Integra XSi and RSi, it now powers the famous Civic SiR models. The B16B is a special hand-tuned super high output derivative of the B16A giving 185ps and used in the Civic Type-R.
The B18C is a 180ps 1797cc engine that appears in the high performance Integra line-up. The B18CSpec96 is a special hand-tuned super high output version of the B18C giving 200ps and used in the legendary Integra Type-R.
DOHC VTEC implementations now appear in most of Honda's great line-up. The Accord SiR used to have a detuned 190s H22A 2.2l DOHC VTEC which was also used on the same period Prelude Si-VTEC in which it gave 200ps. The current Accord line now has a 2.0l DOHC VTEC engine that gives 180ps and 200ps in the Accord SiR and SiR-T models respectively while the current Prelude SiR still uses the H22A 2.2l DOHC VTEC engine giving 200ps. A special hand-tuned version of H22A is used in the Prelude Type-S and gives 220ps.
The highest level of DOHC VTEC implementation is of course in the NSX. Implemented V6 DOHC VTEC, originally in 3.0l and now in a larger 3.2l form, it tops the 280ps "legal" limit imposed by the Japanese government for stock street cars.
SOHC VTEC appears in more guises in the Honda line-up. The smallest SOHC VTEC engine is the D15B, used on Civic and Civic Ferio VTi/Vi models in Japan. The D16A 1590cc SOHC VTEC (power) engine giving 130ps is also used on the Civic Coupe and the Civic Ferio EXi (a 4WD model). SOHC VTEC also appears on the Accord models but not the Integra or Prelude line-up. In fact in markets which Honda considers not sufficiently advanced to warrant the DOHC VTEC engines (Malaysia being one of them), Honda markets SOHC VTEC as the top engine for their line-up.
Conclusion
In this permanent feature, we have examined the basic principle on which VTEC works as well as the various implementations of VTEC. In a follow-up feature, we will look at alternative variable valve timing mechanisms which are implemented by other manufacturers.
Author : Wong, Kong-Ngai
Copyright : Temple of VTEC and Temple of VTEC ASIA
Notice : Most of the illustrations used in this feature are taken without permission from magazines and the Honda Japan's homepage. They may be withdrawn or replaced without notice.
http://asia.vtec.net/spfeature/vtecimpl/img1.jpg
http://asia.vtec.net/spfeature/vtecimpl/img2.jpg
http://asia.vtec.net/spfeature/vtecimpl/img3.jpg
http://asia.vtec.net/spfeature/vtecimpl/img4.jpg
http://asia.vtec.net/spfeature/vtecimpl/img5.jpg
http://asia.vtec.net/spfeature/vtecimpl/img6.jpg
http://asia.vtec.net/spfeature/vtecimpl/img7.jpg
http://asia.vtec.net/spfeature/vtecimpl/img8.jpg
http://asia.vtec.net/spfeature/vtecimpl/img9.jpg
Polygon
12-19-2002, 07:06 PM
Though an undisputed expert in turbocharging as evidenced by years of Formula-1 domination while Honda was active in the sport, Honda's engineers feels that turbocharging has disadvantages, primarily bad fuel economy, that made it not totally suitable for street use. At the same time, the advantages of working with smaller engines meant that smaller capacity engines with as high power output as possible (ie very high specific-output engines) are desirable for street engines.
Thus Honda invented VTEC which allows it to extract turbo level specific output from its engines without having to suffer from the disadvantages of turbocharging (though VTEC introduces disadvantages of its own).
I just have to say a few things about this guys statements that are misleading.
1. Honda is not the undisputed turbo expert. That would belong to companies like Saab, Volovo, or Chrysler that put A LOT of turbos on A LOT of cars.
2. Honda was never that great in Formula 1. They seem to have a problem with exploding engines these days.
3. Turbos don't cause poor fuel economy. While your gas mileage will drop slightly, it is quite minimal unless you have you foot in the gas all the time. I have owned turbocharged cars and I am able to accelerate without boosting at all. My last turbo car got an average of just over 30MPG and could go 0-60 in the 6s. Eat that Honda, I would say there is NO disadvantage to having a turbo.
Thus Honda invented VTEC which allows it to extract turbo level specific output from its engines without having to suffer from the disadvantages of turbocharging (though VTEC introduces disadvantages of its own).
I just have to say a few things about this guys statements that are misleading.
1. Honda is not the undisputed turbo expert. That would belong to companies like Saab, Volovo, or Chrysler that put A LOT of turbos on A LOT of cars.
2. Honda was never that great in Formula 1. They seem to have a problem with exploding engines these days.
3. Turbos don't cause poor fuel economy. While your gas mileage will drop slightly, it is quite minimal unless you have you foot in the gas all the time. I have owned turbocharged cars and I am able to accelerate without boosting at all. My last turbo car got an average of just over 30MPG and could go 0-60 in the 6s. Eat that Honda, I would say there is NO disadvantage to having a turbo.
SkunkSI
12-19-2002, 07:27 PM
Originally posted by Polygon
I just have to say a few things about this guys statements that are misleading.
1. Honda is not the undisputed torbo expert.
I agree infact Ive never even heard of a torbo, although honda's do well with turbo's. :D
I just have to say a few things about this guys statements that are misleading.
1. Honda is not the undisputed torbo expert.
I agree infact Ive never even heard of a torbo, although honda's do well with turbo's. :D
kris
12-21-2002, 05:51 PM
Well for one, this was written in Japan, I think. I doubt they have many lebarons over there. :p
Anyways, it was not posted for the turbo issue, but for info on how vtec works. I have just had a few pm's about it, so I figured this would help.
Anyways, it was not posted for the turbo issue, but for info on how vtec works. I have just had a few pm's about it, so I figured this would help.
Steel
12-21-2002, 08:59 PM
bah! fuel economy schmuel economy!!
then again, i guess you can't really get much worse than a rotary or a stupidly large V8.......so I say "BOOST IT!"
then again, i guess you can't really get much worse than a rotary or a stupidly large V8.......so I say "BOOST IT!"
911GT2
12-22-2002, 11:40 AM
Although variable valve timing has definite benefits, there's no comparing it to a turbo charger. That's just kinda retarded.
NSX
01-08-2003, 04:16 PM
Originally posted by Polygon
1. Honda is not the undisputed turbo expert. That would belong to companies like Saab, Volovo, or Chrysler that put A LOT of turbos on A LOT of cars.
2. Honda was never that great in Formula 1. They seem to have a problem with exploding engines these days.
From http://www.hondaf1.com/english/info/honda.htm
This again forced Honda's technicians to seek new solutions... which they did successfully. With engines now being supplied to Lotus as well as Williams, Honda-powered cars took victory in 11 of the year's 16 races. The high point came at Silverstone where the Honda-powered cars of Mansell, Piquet, Ayrton Senna and Satoru Nakajima completed a 1-2-3-4 clean-sweep.
Piquet finally clinched the Drivers' Championship at the penultimate round at Suzuka, the first Japanese Grand Prix in a decade. The Brazilian's title was the first for a driver powered by a Honda engine and, at the same time, Honda had achieved its long-held ambition of victory in both the Drivers' and Constructors' World Championships.
Restrictions on turbocharged engines were further tightened for the 1988 season with boost pressure cut from 4 to 2.5 bar and fuel tank capacity reduced from 195 to 150 litres. With a new 3.5-litre normally aspirated formula due for introduction in 1989, Honda set-up a separate project to concentrate on the creation of a new 'atmo' engine. However, for 1988, Honda's engineers were determined to end the turbo era on a high note by competing with a new RA168E turbo engine designed to overcome the latest fuel-efficiency constraints.
Having ended its relationship with Williams at the end of 1987, Honda joined forces with McLaren as well as remaining with Lotus for 1988. The first ever McLaren-Honda - the MP4/4 - was an innovative machine and the new combination's dominance was total. An almost perfect record established the MP4/4 as the most successful car in F1 history.
Between them, Alain Prost and Ayrton Senna won 15 of 16 rounds with the Brazilian finally clinching his first world title after an heroic season-long duel with his French team-mate. The McLaren-Honda team broke many records during the final season of the turbocharged era, scoring an unprecedented 199 points and recording no fewer than ten 1-2 finishes.
Ever hear of Alain Prost and Ayrton Senna?
Originally posted by 911GT2
there's no comparing it to a turbo charger.
How much power did the 2.0L S15 Silvia make with turbo? How much power did '98 Integra Type R make?
1. Honda is not the undisputed turbo expert. That would belong to companies like Saab, Volovo, or Chrysler that put A LOT of turbos on A LOT of cars.
2. Honda was never that great in Formula 1. They seem to have a problem with exploding engines these days.
From http://www.hondaf1.com/english/info/honda.htm
This again forced Honda's technicians to seek new solutions... which they did successfully. With engines now being supplied to Lotus as well as Williams, Honda-powered cars took victory in 11 of the year's 16 races. The high point came at Silverstone where the Honda-powered cars of Mansell, Piquet, Ayrton Senna and Satoru Nakajima completed a 1-2-3-4 clean-sweep.
Piquet finally clinched the Drivers' Championship at the penultimate round at Suzuka, the first Japanese Grand Prix in a decade. The Brazilian's title was the first for a driver powered by a Honda engine and, at the same time, Honda had achieved its long-held ambition of victory in both the Drivers' and Constructors' World Championships.
Restrictions on turbocharged engines were further tightened for the 1988 season with boost pressure cut from 4 to 2.5 bar and fuel tank capacity reduced from 195 to 150 litres. With a new 3.5-litre normally aspirated formula due for introduction in 1989, Honda set-up a separate project to concentrate on the creation of a new 'atmo' engine. However, for 1988, Honda's engineers were determined to end the turbo era on a high note by competing with a new RA168E turbo engine designed to overcome the latest fuel-efficiency constraints.
Having ended its relationship with Williams at the end of 1987, Honda joined forces with McLaren as well as remaining with Lotus for 1988. The first ever McLaren-Honda - the MP4/4 - was an innovative machine and the new combination's dominance was total. An almost perfect record established the MP4/4 as the most successful car in F1 history.
Between them, Alain Prost and Ayrton Senna won 15 of 16 rounds with the Brazilian finally clinching his first world title after an heroic season-long duel with his French team-mate. The McLaren-Honda team broke many records during the final season of the turbocharged era, scoring an unprecedented 199 points and recording no fewer than ten 1-2 finishes.
Ever hear of Alain Prost and Ayrton Senna?
Originally posted by 911GT2
there's no comparing it to a turbo charger.
How much power did the 2.0L S15 Silvia make with turbo? How much power did '98 Integra Type R make?
Polygon
01-08-2003, 05:45 PM
Originally posted by kris
Well for one, this was written in Japan, I think. I doubt they have many lebarons over there. :p
Anyways, it was not posted for the turbo issue, but for info on how vtec works. I have just had a few pm's about it, so I figured this would help.
Well, I'll just have to show them one!!!! :D
It was a great vtec guide, very informative.
The only gas hog turbo engine I know of was the RX7 because of too much valve overlap, but good news, they fixed that in the new rotary, bad new is, its N/A.
Also, I have heard those names, but there have been MUCH bigger names in F1 history, not just recent either. Neutrino would know better than I though.
Anyhow, back on topic.
Well for one, this was written in Japan, I think. I doubt they have many lebarons over there. :p
Anyways, it was not posted for the turbo issue, but for info on how vtec works. I have just had a few pm's about it, so I figured this would help.
Well, I'll just have to show them one!!!! :D
It was a great vtec guide, very informative.
The only gas hog turbo engine I know of was the RX7 because of too much valve overlap, but good news, they fixed that in the new rotary, bad new is, its N/A.
Also, I have heard those names, but there have been MUCH bigger names in F1 history, not just recent either. Neutrino would know better than I though.
Anyhow, back on topic.
Jay!
01-08-2003, 05:49 PM
Originally posted by Polygon
The only gas hog turbo engine I know of was the RX7 because of too much valve overlap...;) No valves in a rotary engine. ;)
The only gas hog turbo engine I know of was the RX7 because of too much valve overlap...;) No valves in a rotary engine. ;)
matraca280_112
01-10-2003, 09:24 PM
quote:
--------------------------------------------------------------------------------
Originally posted by Polygon
The only gas hog turbo engine I know of was the RX7 because of too much valve overlap...
--------------------------------------------------------------------------------
No valves in a rotary engine.
the rotary engine has over lap on the rotor that turns.and that gases lick thure there. that is what he/she ment ok. and this is about vtecs not rotorys ok.
--------------------------------------------------------------------------------
Originally posted by Polygon
The only gas hog turbo engine I know of was the RX7 because of too much valve overlap...
--------------------------------------------------------------------------------
No valves in a rotary engine.
the rotary engine has over lap on the rotor that turns.and that gases lick thure there. that is what he/she ment ok. and this is about vtecs not rotorys ok.
Rich
01-11-2003, 07:08 PM
I found this kind of confusing, so I did my own search and came up with this site
Honda - VTEC (http://www.leecao.com/honda/vtec/index.html)
Was a bit easier for me to understand anyways. Just thought Id throw the link out there for others.
Honda - VTEC (http://www.leecao.com/honda/vtec/index.html)
Was a bit easier for me to understand anyways. Just thought Id throw the link out there for others.
Polygon
01-13-2003, 01:55 PM
Originally posted by jay@af
;) No valves in a rotary engine. ;)
There are two, one for intake and one for exhaust. Granted they aren't valves in the sense of most combustion engines more that they are two holes and are both open, or uncovered for a very short period of time allowing exhaust gas to be mixed in with the fuel and clean air causing stinky exhaust and poor gas mileage.
That is what I meant, and yes this is a vtec guide but it is also talking about turbos, I was out to correct some misconceptions about turbos stated in the guide, that is all.
;) No valves in a rotary engine. ;)
There are two, one for intake and one for exhaust. Granted they aren't valves in the sense of most combustion engines more that they are two holes and are both open, or uncovered for a very short period of time allowing exhaust gas to be mixed in with the fuel and clean air causing stinky exhaust and poor gas mileage.
That is what I meant, and yes this is a vtec guide but it is also talking about turbos, I was out to correct some misconceptions about turbos stated in the guide, that is all.
Chris V
01-16-2003, 02:47 PM
The basic thrust of this, and of VTEC, was to overcome what engine builders had had to deal with since the dawn of automobile engines:
Compromise.
Up until then, regardless of engine, if you wanted performance, you needed to have a more aggressive cam profile. Even in a V8 car, this meant lumpy idle and poor driveability when not on the track. This was worse in small bore sports cars and sport sedans, from BMW 2002s, to Alfa Guiliettas
So you decided how far towards a race car you wanted to go, and built around that cam profile, always compromising in some way: retinaing a bit of drivebility sacrificed ultimate power. More power, and maybe it was harder to drive around "off the cam."
Enter the VTEC system. A way to have that race/performance cam in the engine, without losing the daily driver cam and all the driveability that meant. More than just adjusting cam timing for a bit more power, this was like driving down the road with your stock cam, then having someone install a race cam automatically when you wanted more performance, and swapping back when you didn't. All while you drove!
This is more important than mere turbocharging. It doesn't add the plumbing, weight, and heat of a turbo setup. And it can be adapted to turbo enignes as well, which is important.
Compromise.
Up until then, regardless of engine, if you wanted performance, you needed to have a more aggressive cam profile. Even in a V8 car, this meant lumpy idle and poor driveability when not on the track. This was worse in small bore sports cars and sport sedans, from BMW 2002s, to Alfa Guiliettas
So you decided how far towards a race car you wanted to go, and built around that cam profile, always compromising in some way: retinaing a bit of drivebility sacrificed ultimate power. More power, and maybe it was harder to drive around "off the cam."
Enter the VTEC system. A way to have that race/performance cam in the engine, without losing the daily driver cam and all the driveability that meant. More than just adjusting cam timing for a bit more power, this was like driving down the road with your stock cam, then having someone install a race cam automatically when you wanted more performance, and swapping back when you didn't. All while you drove!
This is more important than mere turbocharging. It doesn't add the plumbing, weight, and heat of a turbo setup. And it can be adapted to turbo enignes as well, which is important.
89B18C1CRX
02-07-2003, 07:51 PM
Yes there is no comparision between VTEC and a Turbo. Yet if you put the two together it can make one hell of a ride. If you race a turbo non vtec car vs a vtec motor you will come up with that fact that off the line the turbo will pull on the car but at the top end of the gears once the engine has reached VTEC is when the Honda motor will begin to gains its ground back. Therefore if you turbo charge a VTEC motor you are talking about the ultimate ride. You can tune the car for the turbo to spoll hard in the low rpms then have your VTEC programed to kick in as the spoll is running low. Therefore optimizing your power. As for the turbo being bad fuel economy. WHO THE HELL CARES. This is supposed to be about makign a car go fast. If you are worried about fuel economy buy on of those ugly ass odessys or what ever they are. If you want power then turbo those vtec motors and run the hell out of htem and have fun doing it. TO me VTEC is great, I love it and I wont trade it but if you add a turbo charger to a VTEC motor your just talkign abotu raw hp and I love that even more!!:D
civic1784
02-23-2003, 01:46 AM
Originally posted by NSX
How much power did the 2.0L S15 Silvia make with turbo? How much power did '98 Integra Type R make?
You are comparing a 1.998L to a 1.797L, and at that, you are not factoring in the efficiency of the engines in terms of gas mileage. That is 52cc more, so that also plays a role.
Personally, I disagree with the comment that VTEC makes up for a turbo charger. All it does is allow more air into the chambers at high RPMs, like having a racecar's cam profile, but also having the ability to idle. Unfortunately, even though it will allow more air into the engine, that air is still the same density. A turbocharger increases that density, so the even though the intake valves are depressed for the same amount of time all the time, and they are depressed the same distance, more air molecules get into the engine at higher RPMs because the air is denser.
With VTEC, it is still just a more aggressive cam on a naturally aspirated engine, and the maximum airflow during VTEC engagement is always the same (ignoring temperature of course). On a turbo engine, there is no need for that aggressive cam lobe, because at higher RPMs, more air is getting in anyway, and since the cam is not aggressive, it still has a normal idle. The turbocharged engine does have a benefit also, by lacking VTEC, it lacks the chance of mechanical failure of that part. VTEC is a wonderful invention, though, because it is a way for a NA engine to perform better at the top end, while still getting excelent gas mileage.
How much power did the 2.0L S15 Silvia make with turbo? How much power did '98 Integra Type R make?
You are comparing a 1.998L to a 1.797L, and at that, you are not factoring in the efficiency of the engines in terms of gas mileage. That is 52cc more, so that also plays a role.
Personally, I disagree with the comment that VTEC makes up for a turbo charger. All it does is allow more air into the chambers at high RPMs, like having a racecar's cam profile, but also having the ability to idle. Unfortunately, even though it will allow more air into the engine, that air is still the same density. A turbocharger increases that density, so the even though the intake valves are depressed for the same amount of time all the time, and they are depressed the same distance, more air molecules get into the engine at higher RPMs because the air is denser.
With VTEC, it is still just a more aggressive cam on a naturally aspirated engine, and the maximum airflow during VTEC engagement is always the same (ignoring temperature of course). On a turbo engine, there is no need for that aggressive cam lobe, because at higher RPMs, more air is getting in anyway, and since the cam is not aggressive, it still has a normal idle. The turbocharged engine does have a benefit also, by lacking VTEC, it lacks the chance of mechanical failure of that part. VTEC is a wonderful invention, though, because it is a way for a NA engine to perform better at the top end, while still getting excelent gas mileage.
civic1784
02-23-2003, 02:05 AM
Another thing to consider:
247hp / 2L = 123.5hp/L
195hp / 1.8L = 108.33
Basically by having a larger engine, even more air can be packed into the cylinder as it is, simply due to more space. If you chose a 1.8 L turbo engine that was a factory turbo that got equal gas mileage, you could assume that the numbers would be closer together, although the turbo numbers will still be higher.
247hp / 2L = 123.5hp/L
195hp / 1.8L = 108.33
Basically by having a larger engine, even more air can be packed into the cylinder as it is, simply due to more space. If you chose a 1.8 L turbo engine that was a factory turbo that got equal gas mileage, you could assume that the numbers would be closer together, although the turbo numbers will still be higher.
Moppie
02-23-2003, 02:31 AM
The temple of VTEC article is pretty good, and does a good job of explianing how VTEC works.
Its a little biased, and its comparison with a Turbo powered engine a little incorrect, however given the age of the article is quite accpetable.
I would just like to add a few things.
Honda has had a history in formula one that is 2nd only to that of Ferrari.
Honda has produced several Turbo models during the 80s, all of which were only sold in Japan, but were all very reliable very fast, and several years ahead of what other Japanese manufactors were able to do at the time.
They included turbo versions of the: CRX, the City (the most famous) and V6 Accord. However when Turbo Charging was dropped from F1, Honda also dropped it from its road cars.
Crysler has been putting Turbos on plenty of engines, but always with the help of Mitsubishi, who are currently considered world leaders in the field, along with Porsche.
SAAB used to be a world leader, but has developed very little new turbo related technology in the last 15 years, and now only produces very low pressure Turbo engines.
Fuel economy is a measure of how much fuel a car or engine uses.
This is dependant on a very large number of variables, including the driver, weight and areodynamic efficancy of the car.
If you removed these variables then you are left with the cubic capcity of the engine, and how efficantly the combustion chamber is which effects how much fuel is needed to burn in a given amount of air.
But essentialy the more air you have the more fuel you will need to add to it to make it burn. Since a turbo charged engine by its very design forces more air into the combustion chamber all other things being equal it will require more fuel to burn the air, and so be less fuel efficant.
In real life this means a smaller engine can be used to create as much power and move a given car just as fast a larger less efficant engine. The result maybe a car that is actualy more fuel efficant, depsite the inefficany of the engine.
And the most important part.
The great design inovation in VTEC is not the ablity to use more than once cam profile to provide power and torque at both high and low RPM, and thus have an egine with a very high spefic output that is also friendly and easy to drive at low rpm.
The technology required to change the cam profile has been around almost since the invention of the camshaft, what was lacking was a cylinder head design and engine management system capable of dealing with it.
Air flows at differnt rates through differnt sized holes (inlet and exhaust ports) meaning an engines power curve is dictated by its cam profile and cylinder head and manifold design, as well as the ablity of the engine managment system to deliver fuel and alter ignition timing.
Its no good altering the cam profile if the cylinder head and manifolds are unable to deliver and remove air efficantly at both high and low rpm, and the carbs or fuel injection system are unable to deal with the radical change in fuel requirments etc etc.
What Honda did that is so brilliant, and has yet to be copyed succefuly by any other manufactor (except maybe Porsche and Ferrari) was to design a cylinder head and engine mangement that was able to cope with a radical change in cam profile, and so create an engine that was capable of a high spefic hp, but also have a long flat power curve, and make useable amounts of power and torque at both high and low rpm.
This technology came almost directly from F1 where the problem has alway been designing an engine with as much hp as possible, but also as flater torque curve as possible.
The cylinder head and ECU technology devloped by honda and tested on thier F1 engines was then applied to an existing variable cam profile technology that Honda had been useing on thier bike engines since the mid 80s to create the now famous B16a DOHC VTEC engine in the SiR Civic/CRX and XSi/RSi integra, and the 3.0 V6 engine in the NSX.
Mitsubishi were the first to copy Honda VTEC, and developed MIVEC(sp) appling to both 4cyl and 6cyl engines. However they lacked Hondas ablity to design cylinder heads, and the Mitsi engines are very peaky and inefficant when compared to the Honda engines. They were also made in much smaller numbers, and only used on low production performance models, which always had a non MIVEC variant avliable.
(in 92 Honda made VTEC avliable accross thier intier model range, and used non VTEC engines only in base model cars.)
Nissan were the next to copy VTEC with thier SR20/16 based VVTL engines. Although they made as much or more spefic hp than the equivlant B series Honda engines, they like the Mitsi engines were very peaky and lacked the smooth power delivery of the Honda engines. All becasue they lacked the cylinder head design developed by honda.
(the top VVTL engine, the SR16ve makes a claimed 200ps at about 8,000rpm. thats 15ps more than the B16b. However the SR16ve has an idle speed of 2,000rpm which is far to high for a road car. The B16b however still idles at 700rpm and even when tweaked with a set of cams to 200+hp still maintians a 700prm idle and a nice flat power curve)
And like the Mitsi MIVEC engines, the VVTL engines only sold in Japan, and only fitted to low production models, which all have an alternative non VVTL engine avliable. (except a version of the Primera Wgaon which also had a CVT g/box, a rather odd combination as its a sort of automotive contridiction)
Toyota have been latest to develop a variable cam profile system, called VVTi-L it is so far only avliable on the Celica GTS, and the Corrola GT sold in Japan. The engine has been heavily critised for being to peaky, with the change in profile occuring so high up in the RPM range that the car drops out of its limited power curve far to easily.
Again it misses out on the advanced cylinder design used by Honda.
But this will of course change, and some form of variable cam timing, or more than one profile is becoming more and more popular on new car models. Its is only a matter of time before the above listed manufactors and others develop cylinder head designs that allow them to exploit it as well as Honda does.
Its a little biased, and its comparison with a Turbo powered engine a little incorrect, however given the age of the article is quite accpetable.
I would just like to add a few things.
Honda has had a history in formula one that is 2nd only to that of Ferrari.
Honda has produced several Turbo models during the 80s, all of which were only sold in Japan, but were all very reliable very fast, and several years ahead of what other Japanese manufactors were able to do at the time.
They included turbo versions of the: CRX, the City (the most famous) and V6 Accord. However when Turbo Charging was dropped from F1, Honda also dropped it from its road cars.
Crysler has been putting Turbos on plenty of engines, but always with the help of Mitsubishi, who are currently considered world leaders in the field, along with Porsche.
SAAB used to be a world leader, but has developed very little new turbo related technology in the last 15 years, and now only produces very low pressure Turbo engines.
Fuel economy is a measure of how much fuel a car or engine uses.
This is dependant on a very large number of variables, including the driver, weight and areodynamic efficancy of the car.
If you removed these variables then you are left with the cubic capcity of the engine, and how efficantly the combustion chamber is which effects how much fuel is needed to burn in a given amount of air.
But essentialy the more air you have the more fuel you will need to add to it to make it burn. Since a turbo charged engine by its very design forces more air into the combustion chamber all other things being equal it will require more fuel to burn the air, and so be less fuel efficant.
In real life this means a smaller engine can be used to create as much power and move a given car just as fast a larger less efficant engine. The result maybe a car that is actualy more fuel efficant, depsite the inefficany of the engine.
And the most important part.
The great design inovation in VTEC is not the ablity to use more than once cam profile to provide power and torque at both high and low RPM, and thus have an egine with a very high spefic output that is also friendly and easy to drive at low rpm.
The technology required to change the cam profile has been around almost since the invention of the camshaft, what was lacking was a cylinder head design and engine management system capable of dealing with it.
Air flows at differnt rates through differnt sized holes (inlet and exhaust ports) meaning an engines power curve is dictated by its cam profile and cylinder head and manifold design, as well as the ablity of the engine managment system to deliver fuel and alter ignition timing.
Its no good altering the cam profile if the cylinder head and manifolds are unable to deliver and remove air efficantly at both high and low rpm, and the carbs or fuel injection system are unable to deal with the radical change in fuel requirments etc etc.
What Honda did that is so brilliant, and has yet to be copyed succefuly by any other manufactor (except maybe Porsche and Ferrari) was to design a cylinder head and engine mangement that was able to cope with a radical change in cam profile, and so create an engine that was capable of a high spefic hp, but also have a long flat power curve, and make useable amounts of power and torque at both high and low rpm.
This technology came almost directly from F1 where the problem has alway been designing an engine with as much hp as possible, but also as flater torque curve as possible.
The cylinder head and ECU technology devloped by honda and tested on thier F1 engines was then applied to an existing variable cam profile technology that Honda had been useing on thier bike engines since the mid 80s to create the now famous B16a DOHC VTEC engine in the SiR Civic/CRX and XSi/RSi integra, and the 3.0 V6 engine in the NSX.
Mitsubishi were the first to copy Honda VTEC, and developed MIVEC(sp) appling to both 4cyl and 6cyl engines. However they lacked Hondas ablity to design cylinder heads, and the Mitsi engines are very peaky and inefficant when compared to the Honda engines. They were also made in much smaller numbers, and only used on low production performance models, which always had a non MIVEC variant avliable.
(in 92 Honda made VTEC avliable accross thier intier model range, and used non VTEC engines only in base model cars.)
Nissan were the next to copy VTEC with thier SR20/16 based VVTL engines. Although they made as much or more spefic hp than the equivlant B series Honda engines, they like the Mitsi engines were very peaky and lacked the smooth power delivery of the Honda engines. All becasue they lacked the cylinder head design developed by honda.
(the top VVTL engine, the SR16ve makes a claimed 200ps at about 8,000rpm. thats 15ps more than the B16b. However the SR16ve has an idle speed of 2,000rpm which is far to high for a road car. The B16b however still idles at 700rpm and even when tweaked with a set of cams to 200+hp still maintians a 700prm idle and a nice flat power curve)
And like the Mitsi MIVEC engines, the VVTL engines only sold in Japan, and only fitted to low production models, which all have an alternative non VVTL engine avliable. (except a version of the Primera Wgaon which also had a CVT g/box, a rather odd combination as its a sort of automotive contridiction)
Toyota have been latest to develop a variable cam profile system, called VVTi-L it is so far only avliable on the Celica GTS, and the Corrola GT sold in Japan. The engine has been heavily critised for being to peaky, with the change in profile occuring so high up in the RPM range that the car drops out of its limited power curve far to easily.
Again it misses out on the advanced cylinder design used by Honda.
But this will of course change, and some form of variable cam timing, or more than one profile is becoming more and more popular on new car models. Its is only a matter of time before the above listed manufactors and others develop cylinder head designs that allow them to exploit it as well as Honda does.
BigJustinZ28
04-13-2003, 11:57 AM
wow , i didnt understand vtech until now . It seems like a rather smart way to add economy without much or any cost in performance. But... i think ill stick with v8's (cept maybe a buick turbocharged 6 cylinder for my trans am muahaha that would be sick !!!). Now if only you could get people to stop putting vtech stickers on pre 89 cars lol Ive seen alot of like 87 honda's with vtech stickers and the motors were not vtech. (I kid you not Ive seen a Mustang Type R (not cobra r but "Type R") before as well LOL !!! all it needed was a vtech sticker!!!) . This article was good however as now I understand why if I had an accord or integra , why I'd get the vtech one .
manolis8
05-10-2003, 06:49 AM
At www.pattakon.com a new Continuously Variable Valve Actuation system is presented, with working prototype photos, plots and animations (even stereoscopic ones).
Any engine, racing or normal, can be improved as the torque can be about constant from very low revs to the top allowable revs of the engine.
Comments? Objections?
Any engine, racing or normal, can be improved as the torque can be about constant from very low revs to the top allowable revs of the engine.
Comments? Objections?
Holyterror
05-27-2003, 03:43 PM
I think the VVA system referred to above deserves its own thread, so I'll try to keep to the original topic. It's an interesting idea, and I'd love to see what some of the tech guys around here think of it. Anyway, back to VTEC:
The advantages are obvious. I don't think we really need to try to list them because Honda and every "specific output freak" in the world has already written a dissertation on it. And yes, any presumed slight against turbocharging (unfair comparisons apply) is going to get my immediate attention. So here I go.
It's been said several times in this thread that speed is all we care about. Mileage and driveability mean nothing. Well, I'm continuing down that path. Disadvantages of VTEC for maximum performance:
Extra valvetrain mass (weight)
This is pretty self-explanatory. Lightening the valvetrain generally makes it last longer, frees up power, heightens the redline, and extends the power curve (allowing you to shift later and stay in the fattest part of the power band).
Added complexity and opportunities for breakdown
Why do many people abhor the FD3S RX-7? Over-complexity and poor reliability kill an otherwise excellent automobile. In racing, stuff breaks all the time. In short, nobody wants another expensive part that is more likely to break than one of those skinny Honda con rods. This added complexity alss makes the engines more expensive to produce. And though VTEC has been used mainly on four-cylinders, Honda will have to branch out if this technology is actually supposed to replace turbocharging. The NSX, for example, uses a V6. That means double the VTEC components. Since the search for ultimare power almost always leads to bigger engines, the first two VTEC disadvantages are going to get twice as big as larger engines use it in place of turbocharging.
The absolutely useless low RPM profile
Lert's face it: if you're drag racing, a low-RPM cam profile is pointless. Yes, you can drive it to the track. Yes, it will idle smoothly. But, after that, all you have is a normal drag car with a typical lumpy cam profile, plus the two disadvantages listed above. And so VTEC is much more at home on a daily driver than a high performance machine.
The difficulty of finding aftermarket cams
This used to be a much bigger deal than it is now, but it still factors in. Initially, aftermarket VTEC cams that worked were impossible to find. Thanks to precision CNC-machining, that has changed. Quality manufacturers can and do make good VTEC cams now, but the selection is still much thinner than for other engines.
That's just off the top of my head. In my opinion, VTEC is not for high-performance automobiles. The same applies to MIVEC, VVL, VVT-i, and any other approximations. And in any realm, it seems to me that there are some easy alternatives. Variable length intake runners and variable backpressure exahust are good examples. Harmonic optimization can give a lot of the same benefits as optimized cam timing. Variable intake manifolds seem to have been thrown to the side, but I still like them. And as far as exhaust, Nissan seems to be ditching variable capacity mufflers; they weren't that impressive anyway. Suzuki has exployed a simple system comprised of a computer-controlled butterfly valve in the exhaust stream to change the effective diameter of the pipe. I have long wanted to see this on a larger engine. My point is, I think there are several viable alternatives to VTEC that do not share in all of its disadvantages and also prove that it is not the greatest thing ever invented.
And the brief on turbochargers: modern ball-bearing turbos coupled with electronic boost control can offer much more flexibility than in the past. But this is not even important if we're still talking maximum performance. At the drag strip, you can simply have a radical cam and a huge turbo, and hiding behind a VTEC sticker will not save anyone.
As usual, I apologize for being long-winded. The good news is: you'll get over it. :smokin:
The advantages are obvious. I don't think we really need to try to list them because Honda and every "specific output freak" in the world has already written a dissertation on it. And yes, any presumed slight against turbocharging (unfair comparisons apply) is going to get my immediate attention. So here I go.
It's been said several times in this thread that speed is all we care about. Mileage and driveability mean nothing. Well, I'm continuing down that path. Disadvantages of VTEC for maximum performance:
Extra valvetrain mass (weight)
This is pretty self-explanatory. Lightening the valvetrain generally makes it last longer, frees up power, heightens the redline, and extends the power curve (allowing you to shift later and stay in the fattest part of the power band).
Added complexity and opportunities for breakdown
Why do many people abhor the FD3S RX-7? Over-complexity and poor reliability kill an otherwise excellent automobile. In racing, stuff breaks all the time. In short, nobody wants another expensive part that is more likely to break than one of those skinny Honda con rods. This added complexity alss makes the engines more expensive to produce. And though VTEC has been used mainly on four-cylinders, Honda will have to branch out if this technology is actually supposed to replace turbocharging. The NSX, for example, uses a V6. That means double the VTEC components. Since the search for ultimare power almost always leads to bigger engines, the first two VTEC disadvantages are going to get twice as big as larger engines use it in place of turbocharging.
The absolutely useless low RPM profile
Lert's face it: if you're drag racing, a low-RPM cam profile is pointless. Yes, you can drive it to the track. Yes, it will idle smoothly. But, after that, all you have is a normal drag car with a typical lumpy cam profile, plus the two disadvantages listed above. And so VTEC is much more at home on a daily driver than a high performance machine.
The difficulty of finding aftermarket cams
This used to be a much bigger deal than it is now, but it still factors in. Initially, aftermarket VTEC cams that worked were impossible to find. Thanks to precision CNC-machining, that has changed. Quality manufacturers can and do make good VTEC cams now, but the selection is still much thinner than for other engines.
That's just off the top of my head. In my opinion, VTEC is not for high-performance automobiles. The same applies to MIVEC, VVL, VVT-i, and any other approximations. And in any realm, it seems to me that there are some easy alternatives. Variable length intake runners and variable backpressure exahust are good examples. Harmonic optimization can give a lot of the same benefits as optimized cam timing. Variable intake manifolds seem to have been thrown to the side, but I still like them. And as far as exhaust, Nissan seems to be ditching variable capacity mufflers; they weren't that impressive anyway. Suzuki has exployed a simple system comprised of a computer-controlled butterfly valve in the exhaust stream to change the effective diameter of the pipe. I have long wanted to see this on a larger engine. My point is, I think there are several viable alternatives to VTEC that do not share in all of its disadvantages and also prove that it is not the greatest thing ever invented.
And the brief on turbochargers: modern ball-bearing turbos coupled with electronic boost control can offer much more flexibility than in the past. But this is not even important if we're still talking maximum performance. At the drag strip, you can simply have a radical cam and a huge turbo, and hiding behind a VTEC sticker will not save anyone.
As usual, I apologize for being long-winded. The good news is: you'll get over it. :smokin:
Moppie
05-28-2003, 09:23 PM
Some nice points Holyterror, unforunatly I think you missed a major one.
When it comes to track raceing, of any kind, then VTEC as you mentioned is an almost complete waste of time. If you really want to go fast, and class rules are not a problem then you simply use the wildest, head, cam, and forced induction set up you can manage to squeeze into the car.
Things like VTEC simply get in the way. In a race car you simply want as much hp and torque as possible over not more than 2-3,000rpm. (maybe 3-4,000 if its a rally car)
Its nice to have a wider power band, but you simply dont need it, and it can be sacrificed in the name of more power.
But:
That's just off the top of my head. In my opinion, VTEC is not for high-performance automobiles. The same applies to MIVEC, VVL, VVT-i, and any other approximations.
You seem to think that Variable valve timeing systems have no place in performance cars, this unforunatly is a clearly false claim, based on lack of knowledge.
Porsche, Ferrari and BMW now all use some kind of system that adjusts timing, lift and duration on all thier models. You can not tell me that an M3, or the new Ferrari Enzo is not a performance car.
And of course you seem to not realise that when VTEC was first released on the Market it was in the SiR Civic/CRX, the XSi/RSi Integra, and of course the NSX. All of which are performance cars in thier respective classes. (in 1989-91 the SiR CRX would have been the worlds fastest FWD production car.)
VTEC was devloped from a similar system used on Performance Honda bikes, its application to more family orintated vechiles came much later, and in the case of Mitsi's MIVEC and Nissans Neo VVTL it has only ever been used on performance models.
Added complexity and opportunities for breakdown
Relevent only to race cars, and even then doubtful.
Honda has never ever had a warrenty claim based on a failure of the Valve train, or assicaated VTEC compentents. I thrashed the crap out of my SiR Civic for 4 years and it never had a problem with it. I know more ppl than I can count who own or have owned VTEC, MIVEC, or NEO VVTL powered cars, and have driven them hard, and never had a problem.
I also know of an EX Honda Works Group N SiR Civic rally car, that for that past 13 years has run 2-5 full length really events every year, and has never had the engine apart. It's as it was assembled in 1990. The car is making well over 180hp from a B16a (1600cc DOHC VTEC).
You have to remember that the valve train is only running at half the speed of the crank and pistons, and that the parts in it are much smaller and lighter than the engines bottom end. Failures in the valve train are just as rare for a VTEC/MIVEC et al engine as any other.
The absolutely useless low RPM profile
As I said above yes, on a race car its not needed, but if your running in a class that limits engine mods, then it is nice to have a race car you can drive home and use during the week. Its the designed purpose of cars like the Type R Civic/Integra, or the N1 Pulsar, or MIVEC Mirage.
And in the case of SOHC VTEC engines, and the new BMW's then it is very useful. Anything that extends an engines power curve makes it easier to drive. Gear changes are minimised, as is response time to throttle imputs. And of course there are huge benifits to efficancy and economy, all of which have been explained in this thread.
And in any realm, it seems to me that there are some easy alternatives. Variable length intake runners and variable backpressure exahust are good examples.
These have been proven not to work as a complete alternative to actualy being able to alter the cams profile, and most of them only really work best when they are used in conjunction with some kind of VTEC type system.
Honda Toyota and BMW both use a Variable length inlets combined with altering the cam profile, as do Ferrari and Porsche. It actualy works to increase any gains from altering the cam profile, and I can not think of a single application where only a variable length inlet has been used with out at least altering the cam timing.
Quite simply the gains you can get from useing variable cam profile are signifcantly greater than all the gains from all the alternative systems you mentioned combined.
A Turbo is nice, I drive a Turbo charged vechile on a regular basis, and the increase in torque provided is something that no variable cam profile system could replicate. Unforunatly Turbo charging like variable cam profile systems also its down sides.
The two are simply just differnt ways of altering an engines power curve, and both have differnt applications, depending on what benifits you want, and what disadvantages you can life with.
When it comes to track raceing, of any kind, then VTEC as you mentioned is an almost complete waste of time. If you really want to go fast, and class rules are not a problem then you simply use the wildest, head, cam, and forced induction set up you can manage to squeeze into the car.
Things like VTEC simply get in the way. In a race car you simply want as much hp and torque as possible over not more than 2-3,000rpm. (maybe 3-4,000 if its a rally car)
Its nice to have a wider power band, but you simply dont need it, and it can be sacrificed in the name of more power.
But:
That's just off the top of my head. In my opinion, VTEC is not for high-performance automobiles. The same applies to MIVEC, VVL, VVT-i, and any other approximations.
You seem to think that Variable valve timeing systems have no place in performance cars, this unforunatly is a clearly false claim, based on lack of knowledge.
Porsche, Ferrari and BMW now all use some kind of system that adjusts timing, lift and duration on all thier models. You can not tell me that an M3, or the new Ferrari Enzo is not a performance car.
And of course you seem to not realise that when VTEC was first released on the Market it was in the SiR Civic/CRX, the XSi/RSi Integra, and of course the NSX. All of which are performance cars in thier respective classes. (in 1989-91 the SiR CRX would have been the worlds fastest FWD production car.)
VTEC was devloped from a similar system used on Performance Honda bikes, its application to more family orintated vechiles came much later, and in the case of Mitsi's MIVEC and Nissans Neo VVTL it has only ever been used on performance models.
Added complexity and opportunities for breakdown
Relevent only to race cars, and even then doubtful.
Honda has never ever had a warrenty claim based on a failure of the Valve train, or assicaated VTEC compentents. I thrashed the crap out of my SiR Civic for 4 years and it never had a problem with it. I know more ppl than I can count who own or have owned VTEC, MIVEC, or NEO VVTL powered cars, and have driven them hard, and never had a problem.
I also know of an EX Honda Works Group N SiR Civic rally car, that for that past 13 years has run 2-5 full length really events every year, and has never had the engine apart. It's as it was assembled in 1990. The car is making well over 180hp from a B16a (1600cc DOHC VTEC).
You have to remember that the valve train is only running at half the speed of the crank and pistons, and that the parts in it are much smaller and lighter than the engines bottom end. Failures in the valve train are just as rare for a VTEC/MIVEC et al engine as any other.
The absolutely useless low RPM profile
As I said above yes, on a race car its not needed, but if your running in a class that limits engine mods, then it is nice to have a race car you can drive home and use during the week. Its the designed purpose of cars like the Type R Civic/Integra, or the N1 Pulsar, or MIVEC Mirage.
And in the case of SOHC VTEC engines, and the new BMW's then it is very useful. Anything that extends an engines power curve makes it easier to drive. Gear changes are minimised, as is response time to throttle imputs. And of course there are huge benifits to efficancy and economy, all of which have been explained in this thread.
And in any realm, it seems to me that there are some easy alternatives. Variable length intake runners and variable backpressure exahust are good examples.
These have been proven not to work as a complete alternative to actualy being able to alter the cams profile, and most of them only really work best when they are used in conjunction with some kind of VTEC type system.
Honda Toyota and BMW both use a Variable length inlets combined with altering the cam profile, as do Ferrari and Porsche. It actualy works to increase any gains from altering the cam profile, and I can not think of a single application where only a variable length inlet has been used with out at least altering the cam timing.
Quite simply the gains you can get from useing variable cam profile are signifcantly greater than all the gains from all the alternative systems you mentioned combined.
A Turbo is nice, I drive a Turbo charged vechile on a regular basis, and the increase in torque provided is something that no variable cam profile system could replicate. Unforunatly Turbo charging like variable cam profile systems also its down sides.
The two are simply just differnt ways of altering an engines power curve, and both have differnt applications, depending on what benifits you want, and what disadvantages you can life with.
Chris V
07-09-2003, 01:37 PM
Brilliantly stated, Moppie.
Holyterror has a point, in that a VTEC car with a performance cam grind is no different than a "normal" race 4 cyl with a performance grind, and VTEC itself is no use in a drag race. The car doen'rt win a drag race becasue it has VTEC, but because the particular cam grind used for the high end makes the most power... I mean, a race car shifted p[roperly wouldn't ever be revving low enough to be runing on the lowr rpm cam profile of a VTEc car, any more than a typical old school drag car would be running "off the cam."
But, VTEC ended up being a way of haivng a street car remain driveable when not racing or when not being pushed hard. Those of us who built dual purpose sports cars and drag cars for decades would have loved to have that technology...
Holyterror has a point, in that a VTEC car with a performance cam grind is no different than a "normal" race 4 cyl with a performance grind, and VTEC itself is no use in a drag race. The car doen'rt win a drag race becasue it has VTEC, but because the particular cam grind used for the high end makes the most power... I mean, a race car shifted p[roperly wouldn't ever be revving low enough to be runing on the lowr rpm cam profile of a VTEc car, any more than a typical old school drag car would be running "off the cam."
But, VTEC ended up being a way of haivng a street car remain driveable when not racing or when not being pushed hard. Those of us who built dual purpose sports cars and drag cars for decades would have loved to have that technology...
jeffescortlx
07-24-2003, 04:39 PM
You can't make power with out gas. (unless your ride is electric).
So I'm with the "who cares about milage group" but a turbo car can be good on gas, as long as you stay off boost, but than again, if you want to go fast you use gas.
So I'm with the "who cares about milage group" but a turbo car can be good on gas, as long as you stay off boost, but than again, if you want to go fast you use gas.
V-8Fan
08-03-2003, 11:13 AM
To say that V-TEC is or is not as effective as a turbo is being too broad and general.
A turbo can overcome design limitations in heads, ports, and combustion chambers and the like. It does what it does.
To say that V-TEC "just lets more air in" in contrast to a turbo which "increases air density" is to be in error. More air = higher air density.
The subject of filling the combustion chamber with air needs to be approached with the concept of fluid dynamics in mind. When air/fuel begins to be sucked into a cylinder, it acquires MOMENTUM. That is why camshaft profiles can allow the intake valve to remain open long after BDC. The piston may be coming back up on the compression stroke, but the air/fuel charge is still rushing into the cylinder because of the momentum it has. In fact, the intake valve can open before the exhaust valve closes to take advantage of the momentum of the burned mixture exiting through the exhaust valve---in this way, the exhaust's momentum is assisting the fuel/air charge on its way in, and this also helps to expel more exhaust gases. There is a lot to consider when it comes to camshafts and valve timing.
I won't deny that turbos are very effective and do the job they are intended to do very well. But, I don't consider it to be a panacea. Turbos are expensive and do not contribute to engine reliability. They are another obstacle under the hood that makes working on an engine more difficult.
The V-TEC concept makes a lot of sense to me!
A turbo can overcome design limitations in heads, ports, and combustion chambers and the like. It does what it does.
To say that V-TEC "just lets more air in" in contrast to a turbo which "increases air density" is to be in error. More air = higher air density.
The subject of filling the combustion chamber with air needs to be approached with the concept of fluid dynamics in mind. When air/fuel begins to be sucked into a cylinder, it acquires MOMENTUM. That is why camshaft profiles can allow the intake valve to remain open long after BDC. The piston may be coming back up on the compression stroke, but the air/fuel charge is still rushing into the cylinder because of the momentum it has. In fact, the intake valve can open before the exhaust valve closes to take advantage of the momentum of the burned mixture exiting through the exhaust valve---in this way, the exhaust's momentum is assisting the fuel/air charge on its way in, and this also helps to expel more exhaust gases. There is a lot to consider when it comes to camshafts and valve timing.
I won't deny that turbos are very effective and do the job they are intended to do very well. But, I don't consider it to be a panacea. Turbos are expensive and do not contribute to engine reliability. They are another obstacle under the hood that makes working on an engine more difficult.
The V-TEC concept makes a lot of sense to me!
peeface
10-02-2003, 04:30 PM
I know this is late, but Polygon, please refrain from further references to Formula 1 as you obviously know nothing about it.
titutus
11-17-2003, 04:43 AM
thank you !
JohnnyWash1
11-19-2003, 04:27 AM
This all matches my thoughts on the situation, but leaves me with a question. With increasing power levels expected by consumers, Honda seems to be upping displacement with each new engine. However, for a production car, that I know of, they have never introduced a V8, Vtec or otherwise. Why is this? I understand simplicity of build and valvetrain mass, but with a V6 displacing almost as much as a Ferrari V8 (360 Modena vs. Acura 3.2TL,CL), I wonder what is truly keeping Honda back. They have displayed the financial ability to bring the hi-po V6 to the masses via the Accord (best selling car in America); why not introduce a sweet alternative to Ferrari's exclusive small displacement, hi rev V8? I have fallen in love with Honda engines, but still lust for V8s...this would wind me up beyond reason, and I know I am not alone.
Jon
Jon
jhillyer
11-28-2003, 07:35 PM
This all matches my thoughts on the situation, but leaves me with a question. With increasing power levels expected by consumers, Honda seems to be upping displacement with each new engine. However, for a production car, that I know of, they have never introduced a V8, Vtec or otherwise. Why is this? I understand simplicity of build and valvetrain mass, but with a V6 displacing almost as much as a Ferrari V8 (360 Modena vs. Acura 3.2TL,CL), I wonder what is truly keeping Honda back. They have displayed the financial ability to bring the hi-po V6 to the masses via the Accord (best selling car in America); why not introduce a sweet alternative to Ferrari's exclusive small displacement, hi rev V8? I have fallen in love with Honda engines, but still lust for V8s...this would wind me up beyond reason, and I know I am not alone.
Jon
Right, I'd be tempted by a whirring 8, 9, 10 cylinder (yeah, 9 cylinder) from Honda in displacements above 3.5 liters. I'd be swapping out German engines for these. Once favoring thrifty economy, I think foreign investors are part of the influence keeping Honda small today.
Jon
Right, I'd be tempted by a whirring 8, 9, 10 cylinder (yeah, 9 cylinder) from Honda in displacements above 3.5 liters. I'd be swapping out German engines for these. Once favoring thrifty economy, I think foreign investors are part of the influence keeping Honda small today.
Holyterror
11-28-2003, 08:40 PM
Yeah, a 9 cylinder. That would be awe... wait, we want Honda to make a WWII fighter aircraft???
For Honda, hi-po = V-TEC. So, if they were going to make a V-8, it'd be for a hi-po model, so you could reasonably expect it to be V-TEC equipped. This adds up to an expensive engine. Of course, a large-cylinder I-6 might be feasible. Fewer frictional losses (a very Honda trait) and fewer components (especially the expensive valvetrain). You trade smaller cylinders and more firings for perfect balance and lighter compensators. But then, I just like the I-6.
If we see a V-8 Accord, it will probably be a less-than-thrilling Lexus type. That's my take, anyway.
For Honda, hi-po = V-TEC. So, if they were going to make a V-8, it'd be for a hi-po model, so you could reasonably expect it to be V-TEC equipped. This adds up to an expensive engine. Of course, a large-cylinder I-6 might be feasible. Fewer frictional losses (a very Honda trait) and fewer components (especially the expensive valvetrain). You trade smaller cylinders and more firings for perfect balance and lighter compensators. But then, I just like the I-6.
If we see a V-8 Accord, it will probably be a less-than-thrilling Lexus type. That's my take, anyway.
burly
12-19-2003, 12:13 AM
Variable valve timing in any form really only saves gas in one manner. A turbo or supercharged engine puts parasitic losses on an engine at all speeds, albiet in varying amounts. Variable valve timing allows the computer to turn on the "lift" so to speak, only when certain conditions are met. This can allow for a slight boost in fuel economy as long as the engine is kept in sub-lift operating ranges. Power increases however, are not free. Once lift does come on, fuel efficiency as far as MPG is concerned will drop significantly, in favor of fuel efficiency in terms of power output. So while the article may be true, it could be misleading. Either way, variable valve timing is a great engineering feat imho (biased, as I am an engineer myself). But people do need to recognize it for what it is.
beef_bourito
03-27-2004, 11:07 AM
oh, i saw a picture of one and i only noticed 3, it was a picture from the side :banghead:
ChEvYgRuNt
04-15-2004, 07:45 PM
Good work Kris nice article
Although i already new the basic operation of vtec it was nice for someone to be able to decipher and explain all the various types of vtec applications and their differences.
As for everone arguing about the comparison between vtec and turbos. Think of this "A Sequential Twin Turbo setup mounted onto a Vtec motor". :smokin: With the second turbo staged at the point just before the wild lobe cuts in. This as i see it would be the ultimate setup!! Economy down low, and BULK AMOUNTS OF TOP END!!!!!!!
Although i already new the basic operation of vtec it was nice for someone to be able to decipher and explain all the various types of vtec applications and their differences.
As for everone arguing about the comparison between vtec and turbos. Think of this "A Sequential Twin Turbo setup mounted onto a Vtec motor". :smokin: With the second turbo staged at the point just before the wild lobe cuts in. This as i see it would be the ultimate setup!! Economy down low, and BULK AMOUNTS OF TOP END!!!!!!!
TRD2000
07-13-2004, 08:22 PM
DAMN THATS A LOT OF READING... BUT INFORMATIVE...
1. I'M GLAD SOMEONE CORRECTED THE HONDA F1 RECORD CAUSE THEY HAVE TRADITIONALLY KICKED ASS.
2. I'D SAY RENAULT SHOULD BE ON THE LIST FOR TURBO EXPERTS.. AFTER ALL IT WAS THEM WHO MADE THE DAMN THINGS EFFECTIVE IN F1.
3. OK MAYBE I'M MISSING SOMETHING, CHRYSLER TURBO? "EXPERT???" HUH?
VALVE OVERLAP... I CAN UNDERSTAND WHY IT STUFFS FUEL ECONOMY, AND WHY YOU NEED IT FOR NA CARS, AND WHY ROTORS HAVE THE SAME EFFECT. WHAT I WANT TO KNOW IS IF I TAKE A BEAMS 3S-GE VVTL-i ENGINE AND WHACK A TURBO ON IT SHOULD I CHANGE THE CAM? OR CAN THE ADVANCE/RETARD ON THE VVT SYSTEM ADJUST TO REDUCE OVERLAP? WHAT ELSE WOULD NEED TO BE CHANGED TO MAKE THE TURBO WORK EFFECTIVELY?
1. I'M GLAD SOMEONE CORRECTED THE HONDA F1 RECORD CAUSE THEY HAVE TRADITIONALLY KICKED ASS.
2. I'D SAY RENAULT SHOULD BE ON THE LIST FOR TURBO EXPERTS.. AFTER ALL IT WAS THEM WHO MADE THE DAMN THINGS EFFECTIVE IN F1.
3. OK MAYBE I'M MISSING SOMETHING, CHRYSLER TURBO? "EXPERT???" HUH?
VALVE OVERLAP... I CAN UNDERSTAND WHY IT STUFFS FUEL ECONOMY, AND WHY YOU NEED IT FOR NA CARS, AND WHY ROTORS HAVE THE SAME EFFECT. WHAT I WANT TO KNOW IS IF I TAKE A BEAMS 3S-GE VVTL-i ENGINE AND WHACK A TURBO ON IT SHOULD I CHANGE THE CAM? OR CAN THE ADVANCE/RETARD ON THE VVT SYSTEM ADJUST TO REDUCE OVERLAP? WHAT ELSE WOULD NEED TO BE CHANGED TO MAKE THE TURBO WORK EFFECTIVELY?
TRD2000
07-13-2004, 08:25 PM
The Advantage Is The Engine Length.
TRD2000
07-13-2004, 08:42 PM
I'M GLAD SOMEONE MANAGED TO ACKNOWLEGE BMW HERE.
The VANOS and double vanos systems have been used on BMW's for quite a while now and were barely mentioned... the fact mitsubishi's mivec was a copyright thing from vtec... toyota had vvt and vvtl-i.. vvt being purely duration and vvtl-i being lift and duration CONTINUOUS!!! VVTL-I is the most advanced system in use at the moment! and vvt has been fitted to more than just a celica and a corolla! its been on the supra, SW20 mr2, MRS (MR2 spyder) two celica generations, corolla, caldina, the ALTEZZA, and a bunch of others!
saab used to be up there on turbos, but have been baught out by GM and have been working on things like variable compression engines, Volvo used to be up there on turbos but they got baught out by ford, chrysler had their stuff done by mitsubishi.... Japanese company's are where its at with turbos and they are moving away from them cause of the US market! so unless you can afford something like a porsche or ferrari forget it...
vtec's nice... my girlfriends FTO really gets moving round 5000rpm... but my turbos already got me up the road!! anyway thats enough bitching for now, i still want to know about the turbo and VVTL-i!
The VANOS and double vanos systems have been used on BMW's for quite a while now and were barely mentioned... the fact mitsubishi's mivec was a copyright thing from vtec... toyota had vvt and vvtl-i.. vvt being purely duration and vvtl-i being lift and duration CONTINUOUS!!! VVTL-I is the most advanced system in use at the moment! and vvt has been fitted to more than just a celica and a corolla! its been on the supra, SW20 mr2, MRS (MR2 spyder) two celica generations, corolla, caldina, the ALTEZZA, and a bunch of others!
saab used to be up there on turbos, but have been baught out by GM and have been working on things like variable compression engines, Volvo used to be up there on turbos but they got baught out by ford, chrysler had their stuff done by mitsubishi.... Japanese company's are where its at with turbos and they are moving away from them cause of the US market! so unless you can afford something like a porsche or ferrari forget it...
vtec's nice... my girlfriends FTO really gets moving round 5000rpm... but my turbos already got me up the road!! anyway thats enough bitching for now, i still want to know about the turbo and VVTL-i!
Moppie
07-14-2004, 12:30 AM
i still want to know about the turbo and VVTL-i!
Then start another thread about it, preferably in your car models forum, or the forced induction forum.
This thread is about VTEC, it dosn't need to be filled with advice on how to turbo your car.
Then start another thread about it, preferably in your car models forum, or the forced induction forum.
This thread is about VTEC, it dosn't need to be filled with advice on how to turbo your car.
Moppie
07-21-2004, 12:23 AM
I have removed several off topic posts.
This thread is about VTEC and related or similar systems used by Honda and other manufactors.
If you want to discuss W engines, or Turbos, or phased cam timing systems with out relation to altering valve lift and duration then please start a new thread, after useing the search feature to make sure it hasn't already been covered.
Any further off topic posts will also be deleted, including any refering to the deletion of posts.
This thread is about VTEC and related or similar systems used by Honda and other manufactors.
If you want to discuss W engines, or Turbos, or phased cam timing systems with out relation to altering valve lift and duration then please start a new thread, after useing the search feature to make sure it hasn't already been covered.
Any further off topic posts will also be deleted, including any refering to the deletion of posts.
jinz_s
09-01-2004, 11:58 PM
can i ask, isn't a v-tec engine same as vvt-I engine used in toyota?
TRD2000
09-02-2004, 02:15 PM
nope...IVTEC and VVTL are very close...
V-tec basically adjusts the lift of the valves... at a certain point in the rev's it will swap to a different cam labe.. meaning more lift and possibly different duration.
VVT uses one cam lobe, and a hydraulic actuator where the cam gear is (on the end of the camshaft). the actuator actually rotates the cam forwards or backwards by a certain amount to change the timing of the engine throughout the rev range.
IVTEC and VVTL are the next generation, combining both these functions. so they are pretty similar.
V-tec basically adjusts the lift of the valves... at a certain point in the rev's it will swap to a different cam labe.. meaning more lift and possibly different duration.
VVT uses one cam lobe, and a hydraulic actuator where the cam gear is (on the end of the camshaft). the actuator actually rotates the cam forwards or backwards by a certain amount to change the timing of the engine throughout the rev range.
IVTEC and VVTL are the next generation, combining both these functions. so they are pretty similar.
crazzysol
09-02-2004, 05:17 PM
Not to bad of a forum
jinz_s
09-04-2004, 11:25 AM
ok i understand that part, but just to make things clearer. vvt i also does the same thing as v tec. it also adjusts the lift of valves. it basically controls the valve to actuate at diff time.
by this then only it is able to control the fuel economy. i used to attend a course on vvti engine from toyota and lexus. do u have a site to where i can go? to further make me understand about the vtec system
thanks
by this then only it is able to control the fuel economy. i used to attend a course on vvti engine from toyota and lexus. do u have a site to where i can go? to further make me understand about the vtec system
thanks
jinz_s
09-04-2004, 11:33 AM
another thing.....visit my blog and tell what u think about it
http://torque_nm.blogspot.com/
http://torque_nm.blogspot.com/
Moppie
09-06-2004, 10:58 PM
do u have a site to where i can go? to further make me understand about the vtec system
thanks
If you take the time to read this thread several times it should give you almost all the information you need.
To get any deeper into the topic you would need to find a Honda Technical Manual with all the enginering spefics, and that would require a trip to a Honda dealer and a deep understanding of the enginering involved.
thanks
If you take the time to read this thread several times it should give you almost all the information you need.
To get any deeper into the topic you would need to find a Honda Technical Manual with all the enginering spefics, and that would require a trip to a Honda dealer and a deep understanding of the enginering involved.
CBFryman
09-15-2004, 08:07 PM
There are two, one for intake and one for exhaust. Granted they aren't valves in the sense of most combustion engines more that they are two holes and are both open, or uncovered for a very short period of time allowing exhaust gas to be mixed in with the fuel and clean air causing stinky exhaust and poor gas mileage.
That is what I meant, and yes this is a vtec guide but it is also talking about turbos, I was out to correct some misconceptions about turbos stated in the guide, that is all.
yep, just as in a 2cycle gasoline engine, even thought i know of no 2cycle gasoline cars...so this is irelevant....just thought id ad this in....i know of some 2cycle diesels (sp?) though...
That is what I meant, and yes this is a vtec guide but it is also talking about turbos, I was out to correct some misconceptions about turbos stated in the guide, that is all.
yep, just as in a 2cycle gasoline engine, even thought i know of no 2cycle gasoline cars...so this is irelevant....just thought id ad this in....i know of some 2cycle diesels (sp?) though...
choboi86
09-21-2004, 02:44 AM
So I understand VTI-E stands for Economy...
but what does VTI-S stand for??
and is there a difference between the two?
but what does VTI-S stand for??
and is there a difference between the two?
cowkiller6
10-07-2004, 04:24 PM
your right! wow, I read it 3 times and got more info each time
Moppie
10-16-2004, 06:44 AM
So I understand VTI-E stands for Economy...
but what does VTI-S stand for??
They are models of car, refering to engine, chassis and trim specs.
It's dependant on what country your in as to what models where made avliable.
The VTi badge is currently popular with Honda, it has been since about 95, but was used as early as 92. Iv seen it used on the Prelude, Integra, Civic and Accord, and everyone had a differnt engine in it.
And I know a NZ Spec VTi Civic is differnt to a Japanese spec VTi Civic, which is differnt to an Australian spec VTi etc etc.
Its also off topic, if you want to learn more then start with a search, there are threads in the Honda section with lots of details on differnt models, and if that fails start a thread in the right place.
This thread is about VTEC and related or similar systems used by Honda and other manufactors.
but what does VTI-S stand for??
They are models of car, refering to engine, chassis and trim specs.
It's dependant on what country your in as to what models where made avliable.
The VTi badge is currently popular with Honda, it has been since about 95, but was used as early as 92. Iv seen it used on the Prelude, Integra, Civic and Accord, and everyone had a differnt engine in it.
And I know a NZ Spec VTi Civic is differnt to a Japanese spec VTi Civic, which is differnt to an Australian spec VTi etc etc.
Its also off topic, if you want to learn more then start with a search, there are threads in the Honda section with lots of details on differnt models, and if that fails start a thread in the right place.
This thread is about VTEC and related or similar systems used by Honda and other manufactors.
brihamlin
11-24-2004, 11:56 AM
Indy Tech
09-23-2007, 04:37 PM
Thought i would just add this short and easy explaned
VTEC (which stands for Variable Valve Timing and Lift Electronic Control) is an electronic and mechanical system in some Honda engines that allows the engine to effectively have multiple camshafts.
As the engine moves into different rpm ranges, the engine's computer can activate alternate lobes on the camshaft and change the cam's timing. In this way, the engine gets the best features of low-speed and high-speed camshafts in the same engine.
VTEC (which stands for Variable Valve Timing and Lift Electronic Control) is an electronic and mechanical system in some Honda engines that allows the engine to effectively have multiple camshafts.
As the engine moves into different rpm ranges, the engine's computer can activate alternate lobes on the camshaft and change the cam's timing. In this way, the engine gets the best features of low-speed and high-speed camshafts in the same engine.
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