Turbo Vs. Super


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2strokebloke
09-06-2003, 03:07 PM
I guess I'm the first one to post in here. So I thought I'd start off with a thread to discuss the differences between super charging, and turbo charging.
Anybody want to enlighten me (and others) as to what the pros and cons of the different systems are? :smile:

ccc880
09-06-2003, 05:06 PM
I want to be second to post... I like superchargers better :)

Sluttypatton
09-06-2003, 06:55 PM
I guess that makes me third.

The differences between turbo and supercharging depend on the type of supercharger one compares it to.

CENTRIFUGAL

If you were to compare a turbocharger to a centrifugal supercharger the differences would be small, after all a centrifugal supercharger is simply the compressor half of a turbocharger that is belt driven from the crank. The issue with these types of compressors is that they produce boost in a non-linear fashion, further compounding the issue that superchargers have with not being able to produce full boost until redline. This is because the supercharger is crank driven, so when the supercharger produces maximum boost must be directly synchronized with the engines redline, because if the supercharger were to produce full boost at half of the engines possible RPM, then in the other half of the engines RPM range the supercharger would choke and actually produce less CFM than before. When compared to a turbo, the turbo can build to its maximum potential very quickly in the RPM range and then be controlled by the wastegate to stay there.

I will address the other different types of superchargers in a bit, but I have run out of time so I will post again later.

Neutrino
09-07-2003, 01:49 AM
SWWWWWWEEEEEEEEEEETTTTTTTTTTTT.......we got a general FI forum............ :bananasmi :bananasmi :bananasmi :bananasmi :bananasmi :bananasmi :bananasmi :bananasmi :bananasmi :bananasmi



Go Igor :wave:

SaabJohan
09-07-2003, 02:48 PM
In general there are two types of compressors, displacement compressors (roots, screw) and dynamic compressors. Dynamic compressors are also called turbomachines and the centrifugal compressor is of this type.

Displacement compressors work by reducing the volume of the trapped gas and hence increasing its pressure. The gasflow is proportional to the rotational speed of the shaft and the flow is almost independent on the pressure increase.

The centrifugal compressor works by increasing the velocity of the flowing fluid with the impeller, and therefore its kinetic energy. In the following diffusor the velocity is reduced and the kinetic energy is transfered into a static pressure.

When the pressure is increased thermodynamic laws says that the temperature will rise, if no heat is supplied to or rejected from the working fluid (no friction, heat radiation, cooling and so on) the process is called adibatic. In reality this is not the case for any compressor, therefore there’s something called adiabatic efficiency which relate how much the temperature will rise in reality compared to what thermodynamic laws says. If the adiabatic efficiency is 100% it's an adiabatic process.

Compressors are doing a negative work, this means that they require power from an external source. This source can be an exhaust driven turbine or the engine itself, in any case the amount of power required depends on a few things. The power needed is the enthalpy change over the compressor multiplied with the mass flow per second, this can be written as:

P=delta h * m, where delta h is:

delta h = h outlet - h inlet

or if we consider the fluid to be thermally perfect:

delta h = (cT outlet)-(cT inlet)

where c is specific heat and T the absolute temperature

If we consider that the compression is an adiabatic process the outlet temperature would be:

T outlet = T inlet * PR^((g-1)/g)

Where g is gamma, specific heat ratio and PR is the pressure ratio defined below

PR = pressure outlet/pressure inlet

As we now can se the power needed to drive the compressor depends on the adiabatic efficiency, pressure ratio and mass flow.

The centrifugal compressor is one of the compressor types which has a high adiabatic efficiency, the ones in modern turbochargers have up to 80% efficiency while the ones that are engine driven usually have a little lower efficiency (I think this is because they use lower rpms). Other compressors like roots compressors have an extremely low efficiency, which usually is below 50%.

If we use and exhaust driven turbine to power the compressor we will use the heat in the exhausts which had otherwise been wasted. The power delivered by the turbine can be written, similar to the power needed by the compressor:

P = ((cT inlet)-(cT outlet)) * m

Under ideal conditions a turbocharger robs almost no power from the crankshaft, this means that the power output and engine efficiency can be higher with a turbocharger than with an engine driven compressor. However, exhaust flow and temperature is too low to at low speeds for the turbine to produce enough power to create a boost pressure, and if a smaller turbine is used it will cause a restriction at high speeds/loads and therefore a drop in peak power. But if variable nozzle area (usually called VNT or VGT) is used on the turbine we can increase the width of the turbines range so it will work earlier and cause less restriction at high speeds/loads, sadly it can only be used in diesels because of their lower exhaust temperature, at least yet.

Under low engine load the turbocharger will run with a low speed, and under high engine load it will run with a high speed. Since there is no connection with the crankshaft we must wait until we have enough exhaust for the turbine to supply enough power to reach a boost pressure. This will cause what is called “lag”, today we can however eliminate lag by using an anti lag system, ALS, but this is very hard on exhaust valves, exhaust manifold, turbocharger and exhaust system and of course very loud so it’s only used on racing cars. VNT turbines, ball bearing turbos and so on are also ways of reducing the lag.

Polygon
09-12-2003, 06:49 PM
Well SaabJohan has explained it very well so I will just leave you with my opinion.

i personally prefer Turbocharging to Supercharging or N2O. I feel it has the most upsides and the least downsides. I can explain myself further if you wish.

Leahcim
10-03-2003, 12:18 AM
Well I'm not sure I'm able to explain it much better than previously stated but I'll give ya a quick sum up which is basically how I first learned the diffrence.

Turbocharger - Driven by exhaust gas that spins a turbine at high speeds and works the compressor which compressed the air on the intake.

Supercharger - Most common is roots blower, Eaton most notably (used by jackson racing and used on many stock engines for high end cars). Superchargers are connected to the driveshaft by a belt that works the compressor.

Turbochargers are considered more efficient because it doesnt use up any potential energy instead it reuses wasted energy (exhaust gas). The only notable problem is what is known as turbo lag, which is caused by the turbine taking a few seconds to spool up at low RPM if the turbine is too large, or the problem of it overspinning at higher RPM if the turbine is too small for your engine.

Hope my 2 cents helps :)

ccc880
10-04-2003, 02:34 PM
turbos also sound better :iceslolan

Doug000
10-04-2003, 03:17 PM
Thank you SaabJohan.....

I am familiar with the principles behind the supercharger and turbocharger, but I have not even seen such a clean comparison of the 2 (err 3?) 'chargers in order for me to learn the differences, advantages, and disadvantages.

454Casull
10-25-2003, 10:16 PM
Great work, Johan.

Thank you SaabJohan.....

I am familiar with the principles behind the supercharger and turbocharger, but I have not even seen such a clean comparison of the 2 (err 3?) 'chargers in order for me to learn the differences, advantages, and disadvantages.
There seem to be two types of mechanically-driven superchargers on the market now: the Roots type (Eaton makes Roots superchargers, though they've added a few modifications to the lobes and other things), and the twin-screw AKA Lysholm type. Mechanically-driven superchargers have the advantage of infinitely-small boost lag (Roots superchargers do leak a bit of air at very low RPMs due to their design, not sure about twin-screws), but they use up some power. Lysholm superchargers are more efficient than the Roots type but less than a turbine-driven supercharger.

A fun tidbit - the supercharger on a Top Fuel dragster can take more than 600HP to drive. :)

Kurtdg19
10-26-2003, 06:53 PM
I wouldn't say I'm close to as knowledgable in the comparisions of turbo chargers vs. superchargers. Let me chip in my 2 cents and see if you guys think im on a right track.

A Turbo charger is a exhaust driven turbine that compresses intake air by a compresser.

A Supercharger is a belt driven turbine that compresses intake air by a compresser.

I heard that due to the fact that a turbocharger works off of the exhaust it tends to produce more heat which theirfore; wears it down faster than a supercharger since its is belt driven.
I do know that turbo chargers are more efficient than superchargers due to the fact their consuming wasted energy to create energy, as to a supercharger, that uses energy to create more.
I think thats why i prefer a supercharger more due to the fact that they don't produce as much heat than turbos so it doesn't wear on your engine as quick as a turbo would.

454Casull
10-27-2003, 04:20 PM
The only thing creating heat would be the breaking of the bonds of octane. Turbos don't produce heat, they run off it. Using a turbo merely increasing underhood temps.

krebs128
10-27-2003, 10:16 PM
well actually the turbo can produce heat. so many moving parts creates friction and the compression of air *can* actually make the fuel prematurely ignite-and that's called knocking.

454Casull
10-28-2003, 06:00 PM
well actually the turbo can produce heat. so many moving parts creates friction and the compression of air *can* actually make the fuel prematurely ignite-and that's called knocking.
I was talking about the turbine section. If you're talking about the compressor section, then turbos create LESS heat than crank-driven SCs because the air is pressurized more efficiently (centrifugal acceleration vs. positive displacement).

krebs128
10-28-2003, 10:17 PM
supercharger or turbocharger, they both produce friction which equals heat, now which one produces more heat? idk-i'll just have to take your word.

454Casull
10-29-2003, 09:10 PM
supercharger or turbocharger, they both produce friction which equals heat, now which one produces more heat? idk-i'll just have to take your word.
If there was enough friction to produce heat that wasn't in negligible quantities... well, there isn't enough to friction to produce a lot of heat.

Hypsi87
10-30-2003, 12:45 AM
As you all probabally can tell I'm a turbo nut. Something about superchargers I just don't like. ( they rob too much horsepower.)

Here are some other little tid bits on turbochargers.

Everyone always says "If a turbo is so great then why don't top fuel funny cars run them. The anwser is....In the NHRA rule book it states that they are not allowed to use any other type of forced induction.

A turbo will not increse the ammount of accuall air that your engine flows. That is because a turbo is a pressue multiplier not a preessure adder. for example lets say that the room you are sitting in has 1000 cfm of air in it. Well a turbo will take that 1000cfm and stuff it in the soda can you have sitting next to your computer. It's still 1000 cfm it is just more dense.

A turbo can spin 150,000 RPM's or faster depending on the size and boost level.

Boost is accually the ammount of air that your cylenders don't use. If your cylenders used all the air that was supplied by your turbo then how could pressure be built in the mainafold???

You can not build boost just by simply reving your engine ( I.E. building boost in neutral.) the turbos need exaust to spin and a engine under no load does not produce the exaust to spin the turbo fast enough.


Thoes big redneck tractor pull tractors have four to six turbos on them hooked up in sequence and they produce 100+ PSI :evillol: :smokin: :smokin:

SaabJohan
10-30-2003, 04:08 PM
Boost pressure is the pressure above atmospheric.

A turbocharger will increase air mass flow (but not volume flow) into the engine. 1 bar of boost means approx. twice the mass flow. Air mass flow is what makes power.

Maximum turbo speed depends on the turbo size, smaller one can use up to 300,000 rpm but larger only 100.000 rpm, this is because they are limited by blade speed.

The turbochargers compressor has a very high adiabatic efficiency, this means that very little heat are produced and that the power consumtion of the compressor is low. Adiabatic efficieny is infact higher than most belt driven centrifugal compressors.

Turbochargers last very long if they are used correctly. They usually last longer than superchargers.

454Casull
10-30-2003, 05:28 PM
As you all probabally can tell I'm a turbo nut. Something about superchargers I just don't like. ( they rob too much horsepower.)

Here are some other little tid bits on turbochargers.

Everyone always says "If a turbo is so great then why don't top fuel funny cars run them. The anwser is....In the NHRA rule book it states that they are not allowed to use any other type of forced induction.

A turbo will not increse the ammount of accuall air that your engine flows. That is because a turbo is a pressue multiplier not a preessure adder. for example lets say that the room you are sitting in has 1000 cfm of air in it. Well a turbo will take that 1000cfm and stuff it in the soda can you have sitting next to your computer. It's still 1000 cfm it is just more dense.

Boost is accually the ammount of air that your cylenders don't use. If your cylenders used all the air that was supplied by your turbo then how could pressure be built in the mainafold???

You can not build boost just by simply reving your engine ( I.E. building boost in neutral.) the turbos need exaust to spin and a engine under no load does not produce the exaust to spin the turbo fast enough.

Do you know what cfm means? It's an acronym for "cubic feet per minute"... How can you use a unit for fluid flow for volume? That would be like saying a lawnmower engine makes 20lb-ft of power...

Next - boost increases the density of the air, so the cylinders actually do use the boost.

</me owned> :)

SaabJohan
11-02-2003, 01:08 AM
To build boost we will need load (the amount of exhaust increase much more by load than it does by revs), by revving the engine in neutral the only load we have is from the crankshaft and flywheel inertia, and that won't do that much. To build up boost in neutral we will need an anti lag system.

CFM, cubic feet per minute is a volume flow unit, this is usually measured before the compressor in a turbocharged engine. But if we instead measure it after the compressor we will find that if we turbocharge a NA engine the turbochargered one will have the same volume flow as the NA one, but its mass flow have increased due to the higher density. However, if we measure before the compressor the volume flow into the turbocharged engine is higher than for the NA engine.

To build up boost the compressor must deliver more air mass flow than the engine consumes. To maintain boost the compressor must deliver the same air mass flow as the engine consumes but a higher volume flow.

disco192
11-07-2003, 03:49 AM
I just wanted to address the issue of turbo lag:

Turbo lag is a thing of the past. It used to happen because engineers put heavy turbos in cars with insufficient backpressure. Drive an old Saab or an old Volvo and you will know what im talking about. And when everyone says that superchargers are better of the bottom, i say bullshit.

Low end torque is also a thing of the past. New turbos with ceramic fins and extremely sophisticated bearing systems have almost NO lag when put in the right configuration. Read up on turbonetics ceramic ball bearing turbos, they are sweet.

And on the topic of low end torque, with todays transmissions you dont need power in the bottom half of your powerband anyway due to gear ratios. In a 6 speed you spend the whole time in the top 75% of your powerband while racing. Back in the day of 3 speed autos and 4 speed manuals, you did need power in the bottom half. But cars have 5 and 6 speeds now.

People need to grow up and realize that cars change with technology. Turbos dont have lag and you dont need low end torque (eliminating superchargers "advantage").

9ball
11-11-2003, 09:48 AM
http://www.superchargersonline.com/content.asp?ID=19

Here is a good article on this subject.

beef_bourito
11-23-2003, 04:58 PM
maybe a little off topic but why dont you just add a supercharger and a turbocharger, wouldn't they compensate for eachothers downsides?

454Casull
11-24-2003, 09:10 AM
Quite complex...

Sluttypatton
11-25-2003, 11:26 PM
Its been done, I beleive it's called "dualcharging", but 454's right, it's tricky.

beef_bourito
11-28-2003, 11:45 PM
yes i know it's tricky but what would be the advantages/disadvantages of dualcharging as opposed to just super or just turbo?

Polygon
11-29-2003, 04:21 PM
yes i know it's tricky but what would be the advantages/disadvantages of dualcharging as opposed to just super or just turbo?

Simple, none.

454Casull
11-29-2003, 09:52 PM
Simple, none.
None? Relative advantage? Or no advantages whatsoever?

Can you elucidate?

MustangRoadRacer
12-14-2003, 08:23 AM
there are also centifgal superchargers. not all are roots type.
anytime you compress the air it heats up, which is why intercoolers are used because with cooler air you can compress it more and run more advanced timing for more power.
more superchargers now have intercoolers. I know Vortech offers one they call the "aftercooler" which helps.
the only bonus to belt driven superchargers is that you have almost all of the boost available at VERY low rpm compared to a turbo.

Neutrino
12-14-2003, 08:43 AM
My personal preference is still the turbo

main reasons

easy to tune boost levels and response even on the fly...on super you have to change the puley

turbo will put out boost depending on rpm and load...super will put boost based only on rpm

turbos will cause backpresure but its negative effects are minor compared to the parasitic loss of a super

Polygon
12-14-2003, 02:19 PM
None? Relative advantage? Or no advantages whatsoever?

Can you elucidate?

In my opinion, none whatsoever.

454Casull
12-14-2003, 08:01 PM
In my opinion, none whatsoever.
From my perspective:

Pros

Instant boost
Negligible power loss due to supercharger at higher RPMs
Maximum boost available throughout rev range

Cons

Complexity of tubing
Doesn't fit in all cars

MustangRoadRacer
12-17-2003, 01:03 PM
I've seen a car with 2 turbos AND 2 superchargers.
It can be done, but the fact is, a twin turbo is enough for just about any application.
to get really strange, ford used 4 turbos on the GT40 concept.
it had 1,000 hp, so I guess it worked ok! :)

beef_bourito
12-19-2003, 10:43 AM
I've seen a car with 2 turbos AND 2 superchargers.
It can be done, but the fact is, a twin turbo is enough for just about any application.
to get really strange, ford used 4 turbos on the GT40 concept.
it had 1,000 hp, so I guess it worked ok! :)

how would you get 2 supers in there, are they like side-by-side on the hood?

454Casull
12-19-2003, 10:09 PM
I've seen a car with 2 turbos AND 2 superchargers.
It can be done, but the fact is, a twin turbo is enough for just about any application.
to get really strange, ford used 4 turbos on the GT40 concept.
it had 1,000 hp, so I guess it worked ok! :)
You mean the GT90.

Neutrino
12-20-2003, 02:19 AM
I've seen a car with 2 turbos AND 2 superchargers.
It can be done, but the fact is, a twin turbo is enough for just about any application.
to get really strange, ford used 4 turbos on the GT40 concept.
it had 1,000 hp, so I guess it worked ok! :)


well the veyron has 4 turbos too....its the only car stated for production that has that many i believe

Sluttypatton
12-20-2003, 05:32 AM
Would anyone care to take a stab at why 4 turbochargers are needed? I'm not sure why that was necessary on the Veyron. But it seems to me that it may have more to do with bragging rights than actual performance. Granted, it does have a 16 cylinder motor, but each cylinder is only 0.4995625 liters in displacement. When compared to 0.625 liters per cylinder for the Ford 5.0L, one can see that the size of each cylinder isn't actually that large. In fact, if the cylinder size remained the same but the motor were only an 8 cylinder, then it would be just shy of 4 liters of displacement, not a huge V8. If a single turbo can feed a proportionately larger displacement V8 efficiently, it stands to reason that two would be adaquate to feed the W16, especially since it is more than 2 liters smaller than two V8's.

454Casull
12-20-2003, 12:18 PM
Would anyone care to take a stab at why 4 turbochargers are needed? I'm not sure why that was necessary on the Veyron. But it seems to me that it may have more to do with bragging rights than actual performance. Granted, it does have a 16 cylinder motor, but each cylinder is only 0.4995625 liters in displacement. When compared to 0.625 liters per cylinder for the Ford 5.0L, one can see that the size of each cylinder isn't actually that large. In fact, if the cylinder size remained the same but the motor were only an 8 cylinder, then it would be just shy of 4 liters of displacement, not a huge V8. If a single turbo can feed a proportionately larger displacement V8 efficiently, it stands to reason that two would be adaquate to feed the W16, especially since it is more than 2 liters smaller than two V8's.
V8 = 2 turbos
W16 = 4 turbos?

Probably a combination of packaging and bragging rights.

SaabJohan
12-20-2003, 12:30 PM
Bugatti also used 4 turbochargers on the EB110 if I remember correctly. The use of several small turbochargers instead of fewer larger ones makes the boost to come a little earlier and the exhaust manifolds can be made shorter.

Neutrino
12-20-2003, 02:45 PM
Bugatti also used 4 turbochargers on the EB110 if I remember correctly. The use of several small turbochargers instead of fewer larger ones makes the boost to come a little earlier and the exhaust manifolds can be made shorter.


probably that is part of the reason...but i would be willing to bet - as patton said - that the main reason for 4 turbos was bragging rights

Holyterror
12-29-2003, 05:18 PM
Holy crap... there have been several ambiguous or erroneous statements made over the course of this thread that nobody addressed. I wish I'd gotten in on it sooner, but I guess I'll just have to play catch-up.

Originally Posted by disco192
People need to grow up and realize that cars change with technology. Turbos dont have lag and you dont need low end torque (eliminating superchargers "advantage").

I don't want to get into a big argument over this, but...


Turbochargers DO still have lag
Low-end torque is VERY IMPORTANT in many applications


In a world of technological ideals, there is no turbo lag. In the real world, it is still very much a part of reality. I don't recall this topic being limited to drag racing, and the idea that low-end torque is not important to a street car is absolute madness. I don't think I need to elaborate here.

As for twincharging (super + turbo), it's obviously expensive, requires a lot more plumbing, and must be controlled. Nissan did it successfully with the March Super Turbo (engine MA09ERT), and HKS briefly made a kit for the MKI MR2 - there are reportedly four of these running around the U.S. Done properly, it has the effect of a sequential turbo system with negligable lag, more low-end grunt, and serious bragging rights. It also gives you the disadvantages of both systems at different times. It's a major undertaking, and not worth the trouble to most.

About the "quad turbo" setups: it seems superfluous to me, but there are two main advantages on a very large engine. First and foremost, there is faster spooling (although twin ball-bearing turbos should still be plenty fast). Second, there is plumbing. Routing 16 pipes to two turbos can be difficult (space-engaging and inefficient at best). But the W16 should never have turbos anyway, the con rods being too skinny to stand up to serious power. Heck, I don't think the W16 should be built at all. The V16 is still more feasible, although I can't see any real advantage over the technically perfect V12. But that's a discussion for another day...

Okay, now that I've rambled about side issues, lemme tackle the main turbo vs. super argument. Superchargers, in any non-turbo form, take power straight from the crank. Supercharging will always decrease an engines ability to rev. Power and torque curves are often changed dramatically, making it feel like a totally different engine. The power increase is linear, making it a very pleasant car for daily driving, etc. Installation is simpler than turbo, and it has its own oil supply. Unfortunately, maximum boost can only be produced at one engine speed (usually redline), which makes the turbo much more preferable to me in racing. Plus, superchargers max out at only a fraction of the boost that most turbos can produce (although Saab supposedly has a 40 psi super on its experimental variable compression engine). It's less efficient, wears out faster, kills revability, and just plain can't make the kind of boost that a good turbo can. I think you can already see which way I'm leaning.

Turbochargers require more exhaust plumbing, oil lines, extra (possibly expensive) components for high boost levels, and time to spin down before shutting the engine off! Turbo lag is the most quoted downside, although somewhat alleviated by ball-bearing turbos and low-inertia turbines (as well as titanium shafts, coatings, and other advanced technologies). Superchargers give power from low speeds, offsetting the lower static compression that forced induction necessitates; turbos do not. That is the essence of turbo lag. Power is derived from exhaust gas, which is pretty much free energy. Turbos do, however, create some backpressure in the exhaust system, thus hurting exhaust gas scavenging. It's a pretty minor trade-off. They do not change power and torque curves as dramatically as superchargers, and large, slow-spooling turbos do not make for fun daily drivers. Turbos make more boost, do not depend on engine speed, last longer (if not abused), and look cooler (okay, that's extremely subjective). That's my take on it, in a nutshell.

Um, any questions?

Polygon
12-30-2003, 03:06 PM
They look cooler, and IMO sound much cooler as well. I never liked the whine of a super.

Sy.Berian.Wulf
01-09-2004, 06:29 PM
i think somebody has miss the whole point here... which is better? super or turbo...

Turbo is by far better...... yes with a few more pricely gadgets you can increase HP dramaticaly...

Along with a turbo, you put a wastegate...somebody forget that???
wastegate stores precious air needed to get the revs back up to the speed needed to have to turbo work efficiently and with a intercooler to bring the temp of the air down... u got a mean hp increase to mess with.... logicaly one puts a blow off valve in the system to prevent a bad surge in air pressure and potentialy damaging parts..... theres 1 rule with a turbo....

when it breaks... something else breaks with it...

supercharger has only the belt speed with which to drive its induction....thats no fun, power at low revs is useless.... whos gonna drag at 3000 rpm???... anyone?

johnnyBgood
01-09-2004, 10:24 PM
Well there are different types of superchargers. A centrifugal supercharger has the same compressor housing as a turbo, but it is attached to the accessory belt instead of driven off exhaust. Because it is almost the same design as a turbocharger, it creates massive power in the upper RPM range while creating almost none while in lower RPM's.

And where do you get that a wastegate stores air? The wastegate is there to control boost. When the turbo system hit's max boost, the wastegate is fully open letting the exhaust out a different route than the turbine.

An FI system is only as good as it is tuned. Some cars are made with superchargers and therefore, why add a turbo and remove the blower? Just increase the psi of the blower.

beef_bourito
01-10-2004, 08:59 AM
Hey, i'm a little confused, you guys are saying that with superchargers you only reach max boost at redline but here (http://www.kennedysdynotune.com/Supercharger%20Tech.htm) they say you can reach full boost from just off idle. Can someone explain?

454Casull
01-10-2004, 12:13 PM
Hey, i'm a little confused, you guys are saying that with superchargers you only reach max boost at redline but here (http://www.kennedysdynotune.com/Supercharger%20Tech.htm) they say you can reach full boost from just off idle. Can someone explain?
There are different types of superchargers - centrifugal, Roots, Lysholm, vane, Wankel, gerotor, etc. All of these types are powered from the crankshaft, which means the spin rate of the compressor(s) increases linearly with crankshaft speed, EXCEPT for the centrifugal type. Centrifugal superchargers can either be powered from the crank, or from the exhaust - and those are called turbochargers (turbine-superchargers). All types except centrifugal are positive displacement (same amount of air gets pushed through per spin) and therefore provide instant boost (i.e. as the engine revs up and requires more air, the supercharger also provides more air). However, with centrifugal compressors, the flow rate increases exponentially with spin rate.

If I made any mistakes, too bad, because I just woke up.

johnnyBgood
01-10-2004, 02:43 PM
Also, parasitic drag from superchargers vary depending on the type and size of the supercharger. The Vortech V5 G trim for example, draws 0.75 whp for every one psi of boost it creates. But on the opposite end of the spectrum, the drag roots type blowers on the massive V8's pull 300 hp from the engine. But that engine makes 1500 hp without the blower and around 6000 with. For positive displacement blowers, the lysholm is the least parasitic.

Sy.Berian.Wulf
01-10-2004, 04:39 PM
here where i live we got a goodie called a waste gate.... sure the turbo has a wastegate on it to control boost.... otherwise it would go mad... the graph is a parabola....therefore at some point it goes vertical compressing air.... the wastegate im talking about releases stored compressed air into the manifold which pushes the revs back up... go look at HKS racing and check out their products...

and anyway.... who races here at 1000 rpm????..... u pushing 6000 rpm at least at pull away.... if u wheelspin at pullaway... thats just poor driver...theres enough revs an backpressure for the turbo to cram air into your engine...

as for psi.... on a street car u realy dont wanna mess around with more than 1.5 bar at a compression ratio of 8.5:1.... realy... if u want like 5 bar... get a crank and cam that can do that and throw away your turbo... get a weber carb. then run methanol...swap out your injectors cause meth will eat a normal injector for lunch.

there are so may things you can do to a car to make it run like mad... you dont always need forced induction or N2O....

take a 355 chevy bowtie engine with 6" conrods then have a compression of 15:1 and 180 degree port heads..... u got a 10.5 sec 1/4 mile car.... anyway im off the topic..... someone wnted to know which is better....

http://www.coloradocobras.com/whipple/superchargers/supercharger-comparison-chart.html

johnnyBgood
01-11-2004, 10:26 AM
yeah, but a chevy 355 will not fit in my eclipse, sorry. 1.5 bar of compression (21 psi) is very attainable with a CR even of 10:1 not to mention 8.5:1. The EVO runs 19 psi stock. Tuned it can run around 25.

And I like my gas mileage. alot more than a 355 chevy with 15:1 CR will give me. Not to mention the fact that i would need to run race gas to prevent detonation.

454Casull
01-11-2004, 01:53 PM
here where i live we got a goodie called a waste gate.... sure the turbo has a wastegate on it to control boost.... otherwise it would go mad... the graph is a parabola....therefore at some point it goes vertical compressing air.... the wastegate im talking about releases stored compressed air into the manifold which pushes the revs back up... go look at HKS racing and check out their products...

and anyway.... who races here at 1000 rpm????..... u pushing 6000 rpm at least at pull away.... if u wheelspin at pullaway... thats just poor driver...theres enough revs an backpressure for the turbo to cram air into your engine...

as for psi.... on a street car u realy dont wanna mess around with more than 1.5 bar at a compression ratio of 8.5:1.... realy... if u want like 5 bar... get a crank and cam that can do that and throw away your turbo... get a weber carb. then run methanol...swap out your injectors cause meth will eat a normal injector for lunch.

there are so may things you can do to a car to make it run like mad... you dont always need forced induction or N2O....

take a 355 chevy bowtie engine with 6" conrods then have a compression of 15:1 and 180 degree port heads..... u got a 10.5 sec 1/4 mile car.... anyway im off the topic..... someone wnted to know which is better....

http://www.coloradocobras.com/whipple/superchargers/supercharger-comparison-chart.html
Something like that might exist but it's not called a wastegate.

SaabJohan
01-11-2004, 03:49 PM
Also, parasitic drag from superchargers vary depending on the type and size of the supercharger. The Vortech V5 G trim for example, draws 0.75 whp for every one psi of boost it creates. But on the opposite end of the spectrum, the drag roots type blowers on the massive V8's pull 300 hp from the engine. But that engine makes 1500 hp without the blower and around 6000 with. For positive displacement blowers, the lysholm is the least parasitic.
The power consumption for a compressor depends on pressure ratio, adiabatic efficiency and massflow + losses from bearings, gears, belts or from whatever power it.

The roots compressor found on Top Fuels consume about 1000 hp.

MustangRoadRacer
01-13-2004, 08:51 AM
but it makes about 5k horsepower.

2turboimports
01-13-2004, 11:33 AM
i've always believed that for streetability as far as Forced Induction goes(READ not a crazy ass track car):

4 cylinders - turbo
6 cylinders - turbo or TT
8 cylinders - SC w/N20

and if you're getting nuts and TRACK only go
8 cylinders - TT w/N20

SaabJohan
01-13-2004, 02:49 PM
Where turbocharging is allowed in "real" dragracing the twinturbo V8 engines beats the supercharged ones... even though they have lag.

Polygon
01-13-2004, 03:25 PM
Something like that might exist but it's not called a wastegate.

Yeah, that sounds more like a diverter valve.

2turboimports
01-13-2004, 06:22 PM
Where turbocharging is allowed in "real" dragracing the twinturbo V8 engines beats the supercharged ones... even though they have lag.

that's exactly why big ass wrinkle walls are a good choice for a big powerful 'laggy' tt stang.

that's right, right? wrinkle wall allows for the begginning movement of the rear axle to get over the lag, then grip like a bitch, whereas a stiffer walled slick would just start spinning once past the 'laggy' range?

Sy.Berian.Wulf
01-14-2004, 03:22 PM
well.... whatever it's called.... they seem to use it here on some cars and they have too much power ....

oh... and heres a recipie thats mad....

ever tried putting a poor 6 cylinder with a man truck turbo?.... say good bye to your tyres cause u might as well spin while idleing.... the compression on the turbo side of the man truck turbo is so crazy... they cant tune the car... too big.

MustangRoadRacer
01-15-2004, 04:03 AM
you mean a tractor truck turbo?
those are quite powerfull.

Sy.Berian.Wulf
01-16-2004, 05:48 PM
Yea.... a Man Truck Turbo... basicaly one of the biggest bad ass turbos uget... yes the turbo lag is bad..... but holy shit when it takes..... g-force that hurts.... the stupid thing spins if you rev it too much... ive never seen something drag down a strip... have some speed, drop into 6th and spin for a few minutes...(providing he has 2 inches of tread)...

its too powerful for a drag car... your pull away isnt good... but ull eat anyone in top end...

Corbin
01-20-2004, 02:10 PM
Best example of factory twincharging: Maserati 2.24v. twin turbo v6 with supercgarger.

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