Forced Induction Basics
Red2.0Tib
06-24-2005, 12:47 AM
Blown, boosted, spoolin’ and sprayin’ have become sport compact gospel over the years, but why? What do these words mean? Well, they’re all terms spawned by Forced Induction (FI).
The term Forced Induction refers to the process of “forcing” larger volumes of air into the combustion chamber, along with larger amounts of fuel. This causes a more powerful “explosion”, resulting in increased power. There are two MAIN setups that are used for forced induction: Supercharging and Turbocharging. Nitrous oxide is also considered in this group on occasion, however it is its own entity.
Superchargers and turbochargers both offer legitimate horsepower gains, and both supply “boost”, however they work in very different ways. The biggest difference between the two is how they supply their power, and how that power is multiplied. Superchargers run off the cars power, using a belt and pulley to spin the “blower”. This means that as the motor speed increases the speed of the supercharger increases, resulting in increased power production. On the other hand, turbochargers use spent exhaust gases to spin a turbine, which in turn spins a compressor, resulting in more power. The turbo’s power delivery has a lot to do with the size of the turbine/compressor, resulting in different types of power. For example, smaller turbo chargers will spin more quickly, resulting in better low end power, but sacrificing high end power. Larger turbo chargers require more time to spool(turbo lag), resulting in less bottom end power, but offer more power from midrange thru top end.
Superchargers have changed over the years, from giant belt driven blowers that appeared on serious race built cars, to the new compact units that are becoming more common in the aftermarket, as well as from the factory. In today’s sport compact world there are two main types of superchargers at our disposal: Roots type units and Centrifugal type units. Both are viable options for those looking for reliable daily driven or even serious track machines.
Roots type “blowers” use two “screws” that spin in opposite directions, capturing air from the intake side and spinning it into the discharge side, where it is fed into the intake manifold, which doubles as the mounting surface for the blower. Roots blowers or positive/fixed displacement blowers move the same amount of air with each rotation, and only spin in one direction, unlike a Centrifugal S/C which can spin freely much like a turbocharger. This means that the roots S/C can provide the same efficiency at high or low rpm’s, resulting in very good bottom-end power and torque.
The biggest disadvantage to these blowers is they generate a lot of heat and suck a lot more power from the crank than other types of blowers (lower adiabatic efficiencies). Another reason is some air is trapped in the lobes of the screws and is not forced into the intake manifold. It is heated by the manifold’s temperatures, resulting in higher temps. Roots setups such as the Eaton are also rather bulky and make it difficult to locate near the crank drive, and this also makes intercooling difficult.
http://www.evilkokonut.com/upload/uploads/rootsblower.JPG
Centrifugal type superchargers operate by sucking air into a giant impeller/fan, the air enters into the center of the S/C, however it is soon pulled to the outside of the fan blades due to its centrifugal force and rotational inertia, hence the name. Outside of these blades is what is known as a scroll. The scroll’s job is to catch air molecules and feed them through a venture, which accounts for the internal compression of the blower’s housing. There are several advantages to Centrifugal superchargers. The simplicity of the design means fewer moving parts, and less worries. Also, unlike Roots type blowers, Centrifugal blowers produce minimal amounts of heat. Another advantage is they’re relatively small size. They are similar in size to that of a turbo charger and can be placed in various areas of the engine bay, unlike a roots unit. The biggest disadvantage to a centrifugal blower is that it requires high engine rpm’s (approximately 3,000rpm’s) to create “boost”. Due to this, they offer very little low end power in comparison to the roots blower and small turbo applications.
http://www.evilkokonut.com/upload/uploads/Centrifugalsc.JPG
ttp://www.evilkokonut.com/upload/uploads/centrifugal_supercharger_diagram.jpg
The final part of this will be the turbocharger. Turbochargers work using the engine’s spent exhaust gases, which spin a turbine, which in turn spins a compressor wheel. The compressor does just that, it compresses the intake charge and forces it into the combustion chamber. The compressor of a turbo works in the same way that the compressor in a Centrifugal S/C works. Turbocharger setups require turbo specific exhaust manifolds, to collect the needed exhaust gases. They also require a charge pipe to get the compressed intake charge into the combustion chamber. Turbochargers rely on two different types of bearings to keep them spinning freely: Fluid bearings and Ball bearings. Fluid bearing turbos are cheaper and more commonly used, however ball bearing units are much more efficient and allow for a smaller, lighter shaft (between turbine and compressor) resulting in faster spooling and decreased turbo lag. Another key ingredient in turbochargers is the waste gate. A wastegate is a valve that allows excess exhaust gases to bypass the turbine, to avoid overboosting and potentially causing harm to one’s turbocharger and engine.
The biggest advantage of a turbocharger is its efficiency, as it uses spent exhaust gases to power itself, rather than the engine’s own power like a supercharger. Also the impeller in a turbocharger spins only under acceleration, so there is very little parasitic loss. The biggest disadvantage to a turbocharger is heat. Since it uses spent exhaust gases, the temperature accompanied with a turbocharger can be very high. Another downfall of turbochargers is the lag often associated with them. It takes a certain amount of flow to spin the turbine, which can happen from a dead stop or when one lets off the throttle and allows rpm’s to drop. The amount of lag is directly related to the size of the turbo, the larger the turbo, the more lag that is seen. Another area to consider with turbocharging is intercooling. It is possible to use a turbocharger without, however high radiant heat from the turbine causes higher intake charge temperatures.
http://www.evilkokonut.com/upload/uploads/turbo-parts.gif
to be continued....
If someone would like this to be sticked at the top(or Important) feel free to do so ;)
The term Forced Induction refers to the process of “forcing” larger volumes of air into the combustion chamber, along with larger amounts of fuel. This causes a more powerful “explosion”, resulting in increased power. There are two MAIN setups that are used for forced induction: Supercharging and Turbocharging. Nitrous oxide is also considered in this group on occasion, however it is its own entity.
Superchargers and turbochargers both offer legitimate horsepower gains, and both supply “boost”, however they work in very different ways. The biggest difference between the two is how they supply their power, and how that power is multiplied. Superchargers run off the cars power, using a belt and pulley to spin the “blower”. This means that as the motor speed increases the speed of the supercharger increases, resulting in increased power production. On the other hand, turbochargers use spent exhaust gases to spin a turbine, which in turn spins a compressor, resulting in more power. The turbo’s power delivery has a lot to do with the size of the turbine/compressor, resulting in different types of power. For example, smaller turbo chargers will spin more quickly, resulting in better low end power, but sacrificing high end power. Larger turbo chargers require more time to spool(turbo lag), resulting in less bottom end power, but offer more power from midrange thru top end.
Superchargers have changed over the years, from giant belt driven blowers that appeared on serious race built cars, to the new compact units that are becoming more common in the aftermarket, as well as from the factory. In today’s sport compact world there are two main types of superchargers at our disposal: Roots type units and Centrifugal type units. Both are viable options for those looking for reliable daily driven or even serious track machines.
Roots type “blowers” use two “screws” that spin in opposite directions, capturing air from the intake side and spinning it into the discharge side, where it is fed into the intake manifold, which doubles as the mounting surface for the blower. Roots blowers or positive/fixed displacement blowers move the same amount of air with each rotation, and only spin in one direction, unlike a Centrifugal S/C which can spin freely much like a turbocharger. This means that the roots S/C can provide the same efficiency at high or low rpm’s, resulting in very good bottom-end power and torque.
The biggest disadvantage to these blowers is they generate a lot of heat and suck a lot more power from the crank than other types of blowers (lower adiabatic efficiencies). Another reason is some air is trapped in the lobes of the screws and is not forced into the intake manifold. It is heated by the manifold’s temperatures, resulting in higher temps. Roots setups such as the Eaton are also rather bulky and make it difficult to locate near the crank drive, and this also makes intercooling difficult.
http://www.evilkokonut.com/upload/uploads/rootsblower.JPG
Centrifugal type superchargers operate by sucking air into a giant impeller/fan, the air enters into the center of the S/C, however it is soon pulled to the outside of the fan blades due to its centrifugal force and rotational inertia, hence the name. Outside of these blades is what is known as a scroll. The scroll’s job is to catch air molecules and feed them through a venture, which accounts for the internal compression of the blower’s housing. There are several advantages to Centrifugal superchargers. The simplicity of the design means fewer moving parts, and less worries. Also, unlike Roots type blowers, Centrifugal blowers produce minimal amounts of heat. Another advantage is they’re relatively small size. They are similar in size to that of a turbo charger and can be placed in various areas of the engine bay, unlike a roots unit. The biggest disadvantage to a centrifugal blower is that it requires high engine rpm’s (approximately 3,000rpm’s) to create “boost”. Due to this, they offer very little low end power in comparison to the roots blower and small turbo applications.
http://www.evilkokonut.com/upload/uploads/Centrifugalsc.JPG
ttp://www.evilkokonut.com/upload/uploads/centrifugal_supercharger_diagram.jpg
The final part of this will be the turbocharger. Turbochargers work using the engine’s spent exhaust gases, which spin a turbine, which in turn spins a compressor wheel. The compressor does just that, it compresses the intake charge and forces it into the combustion chamber. The compressor of a turbo works in the same way that the compressor in a Centrifugal S/C works. Turbocharger setups require turbo specific exhaust manifolds, to collect the needed exhaust gases. They also require a charge pipe to get the compressed intake charge into the combustion chamber. Turbochargers rely on two different types of bearings to keep them spinning freely: Fluid bearings and Ball bearings. Fluid bearing turbos are cheaper and more commonly used, however ball bearing units are much more efficient and allow for a smaller, lighter shaft (between turbine and compressor) resulting in faster spooling and decreased turbo lag. Another key ingredient in turbochargers is the waste gate. A wastegate is a valve that allows excess exhaust gases to bypass the turbine, to avoid overboosting and potentially causing harm to one’s turbocharger and engine.
The biggest advantage of a turbocharger is its efficiency, as it uses spent exhaust gases to power itself, rather than the engine’s own power like a supercharger. Also the impeller in a turbocharger spins only under acceleration, so there is very little parasitic loss. The biggest disadvantage to a turbocharger is heat. Since it uses spent exhaust gases, the temperature accompanied with a turbocharger can be very high. Another downfall of turbochargers is the lag often associated with them. It takes a certain amount of flow to spin the turbine, which can happen from a dead stop or when one lets off the throttle and allows rpm’s to drop. The amount of lag is directly related to the size of the turbo, the larger the turbo, the more lag that is seen. Another area to consider with turbocharging is intercooling. It is possible to use a turbocharger without, however high radiant heat from the turbine causes higher intake charge temperatures.
http://www.evilkokonut.com/upload/uploads/turbo-parts.gif
to be continued....
If someone would like this to be sticked at the top(or Important) feel free to do so ;)
nisco
06-24-2005, 02:03 AM
i still think people are reading this like.... OOOHHHH thats what hes talking about
Red2.0Tib
06-24-2005, 02:26 AM
i still think people are reading this like.... OOOHHHH thats what hes talking about
LOL, this is what I feel like sometimes trying to explain these things: :banghead:
LOL, this is what I feel like sometimes trying to explain these things: :banghead:
millerkiller
06-24-2005, 02:23 PM
LOL, this is what I feel like sometimes trying to explain these things: :banghead:
that may be, but its was a great informative article when i read it on nt and it still is now. i think it can defintely offer some help to people looking for to get answers on F/I. besides anything that complicated that people seem to get right away, has got to be a crappy version.lol
that may be, but its was a great informative article when i read it on nt and it still is now. i think it can defintely offer some help to people looking for to get answers on F/I. besides anything that complicated that people seem to get right away, has got to be a crappy version.lol
BigTDawg
06-24-2005, 06:14 PM
:banghead: ....i'm just playin i just wanted to use that and make
KTiB
06-25-2005, 12:04 AM
ey, my friend told me that after like every 20k miles u need to like change the turbo or sumpin? true? cause i told him u didnt need to and he started givin me all this crap. so yea, i'd like to put it back in his face. haha
Red2.0Tib
06-27-2005, 12:25 AM
ey, my friend told me that after like every 20k miles u need to like change the turbo or sumpin? true? cause i told him u didnt need to and he started givin me all this crap. so yea, i'd like to put it back in his face. haha
Ummm no, your friends a moron. Now if you abused your turbo and never checked it out, weren't getting oil into your turbo , were running more boost than the turbo is desgined for, were getting ALOT of backpressure, you may see premature failure, but that is all stuff that is preventable. If this were the case all of those factory turbo cars WOULDN'T exist, period. Cuz there would be NO WAY a manufacturer, like say Dodge and the SRT-4 would be able to sell anyone a turbo'd car if after 20K miles it had to be replaced, now would they? I guess all of the turbo diesels, like say for instance the 525hp Cummin my dad had in his 2002 Freightliner would be a SERIOUS freak since he had almost 200,000 miles on it before he sold it! I wish people who didn't know what they were talking about would just shutup, cuz it seems to me that these are the people spreading info the most!
Ummm no, your friends a moron. Now if you abused your turbo and never checked it out, weren't getting oil into your turbo , were running more boost than the turbo is desgined for, were getting ALOT of backpressure, you may see premature failure, but that is all stuff that is preventable. If this were the case all of those factory turbo cars WOULDN'T exist, period. Cuz there would be NO WAY a manufacturer, like say Dodge and the SRT-4 would be able to sell anyone a turbo'd car if after 20K miles it had to be replaced, now would they? I guess all of the turbo diesels, like say for instance the 525hp Cummin my dad had in his 2002 Freightliner would be a SERIOUS freak since he had almost 200,000 miles on it before he sold it! I wish people who didn't know what they were talking about would just shutup, cuz it seems to me that these are the people spreading info the most!
free2roamaz
06-27-2005, 05:49 AM
First off, great info for guys like me who still dont know much. Secondly, I have a couple questions you may be able to answer.
One, when do I know when to put in a Super/Turbo? Like what mods should I do beforehand to keep from putting excessively needless strain on my engine and such? Oh, and the vehicle would be my i4, 2.0L.
Two, I have heard from a few people that there are certain ambient environments which make a huge diffence in whether to go with Turbo or Superchargers. Like I live in good ol' Hell Heat of Arizona. From what I am told, a Turbo wouldnt put out nearly its max potential HP when combined with this kind of weather. True or no, and if not, how do I know which to go with for my car?
Appreciate any feedback.
One, when do I know when to put in a Super/Turbo? Like what mods should I do beforehand to keep from putting excessively needless strain on my engine and such? Oh, and the vehicle would be my i4, 2.0L.
Two, I have heard from a few people that there are certain ambient environments which make a huge diffence in whether to go with Turbo or Superchargers. Like I live in good ol' Hell Heat of Arizona. From what I am told, a Turbo wouldnt put out nearly its max potential HP when combined with this kind of weather. True or no, and if not, how do I know which to go with for my car?
Appreciate any feedback.
scottsee
07-01-2005, 01:45 AM
you add force induction when you are looking for more performance in any car, anywhere.
ambient tempts do little for induction selection. supercharger have around 50% effency range where turbos have roughly upto 78%. Intercooler selection is important in diffrent areas. without spending much time here. envirement had little to do with performance, the small amount that it does have is minor. so the answer in no, he is incorrect.
ambient tempts do little for induction selection. supercharger have around 50% effency range where turbos have roughly upto 78%. Intercooler selection is important in diffrent areas. without spending much time here. envirement had little to do with performance, the small amount that it does have is minor. so the answer in no, he is incorrect.
Red2.0Tib
07-01-2005, 12:26 PM
you add force induction when you are looking for more performance in any car, anywhere.
ambient tempts do little for induction selection. supercharger have around 50% effency range where turbos have roughly upto 78%. Intercooler selection is important in diffrent areas. without spending much time here. envirement had little to do with performance, the small amount that it does have is minor. so the answer in no, he is incorrect.
Yes air temperature has little to do with the setup, except when it's really cold you will notice better throttle response and such,or when it's really hot you may notice a little more lag in the car. But different air "thickness" can play a big role in the initial tune. Someone in Denver would be forced to tune differently from say someone in Florida. The different densities and how tightly packed the air is can result in different AFR's throughout the rpm range.....
ambient tempts do little for induction selection. supercharger have around 50% effency range where turbos have roughly upto 78%. Intercooler selection is important in diffrent areas. without spending much time here. envirement had little to do with performance, the small amount that it does have is minor. so the answer in no, he is incorrect.
Yes air temperature has little to do with the setup, except when it's really cold you will notice better throttle response and such,or when it's really hot you may notice a little more lag in the car. But different air "thickness" can play a big role in the initial tune. Someone in Denver would be forced to tune differently from say someone in Florida. The different densities and how tightly packed the air is can result in different AFR's throughout the rpm range.....
scottsee
07-01-2005, 06:51 PM
air density in the combustion chamber will depend on your turbo & intercooler effencies!!. absolute pressure and ambent temp play a very, very small part in force inductoin. it does matter a little, and thats why you have airdensity meters in MAF's.
Absolute pressure isn't somthing to be consernced about when sellecting equipment. choosing the right size turbo and intercool for your displacment and effencie needs are more important.
Absolute pressure isn't somthing to be consernced about when sellecting equipment. choosing the right size turbo and intercool for your displacment and effencie needs are more important.
twospirits
07-01-2005, 10:16 PM
Great info there Red, but your pics are not showing up. If you need a place to hold the pics I can upload them to my website if need be.
again great info.
TS out
again great info.
TS out
Red2.0Tib
07-01-2005, 11:47 PM
Great info there Red, but your pics are not showing up. If you need a place to hold the pics I can upload them to my website if need be.
again great info.
TS out
Ya, evilkokonut.com went down like a two dollar hooker. His stuff might be back up, not really sure. I'll have to find the pics on my harddriver and get it done later.
again great info.
TS out
Ya, evilkokonut.com went down like a two dollar hooker. His stuff might be back up, not really sure. I'll have to find the pics on my harddriver and get it done later.
Red2.0Tib
07-01-2005, 11:48 PM
air density in the combustion chamber will depend on your turbo & intercooler effencies!!. absolute pressure and ambent temp play a very, very small part in force inductoin. it does matter a little, and thats why you have airdensity meters in MAF's.
Absolute pressure isn't somthing to be consernced about when sellecting equipment. choosing the right size turbo and intercool for your displacment and effencie needs are more important.
Ya when you're looking for the parts it isn;t really an issue, it's only a minor issue when actually tuning the car...
Absolute pressure isn't somthing to be consernced about when sellecting equipment. choosing the right size turbo and intercool for your displacment and effencie needs are more important.
Ya when you're looking for the parts it isn;t really an issue, it's only a minor issue when actually tuning the car...
scottsee
07-03-2005, 12:46 AM
I have heard from a few people that there are certain ambient environments which make a huge diffence in whether to go with Turbo or Superchargers. Like I live in good ol' Hell Heat of Arizona. From what I am told, a Turbo wouldnt put out nearly its max potential HP when combined with this kind of weather. True or no, and if not, how do I know which to go with for my car?.
question was about selection. not tuning.
question was about selection. not tuning.
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