Supercharger Vs Turbocharger

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#1
I know that both basically compress air into the engine to get more hp/torque. And I know they go about different ways to do it. My question is would a SC work on a higher lieter engine unlike a turbo? I see most SCs on trucks which usually have 4+ lieters and turbos are generally on 1.5 lieters hondas. So Would it be possible to put a stroker kit on then a SC?

Thanks
 
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#5
Ok, I've been doing a lot of studying on turbos lately, so I apologize if I ramble on. If I need to clarify, please let me know. Also, most of my knowledge resides with turbos, however I will describe superchargers as best I can.

Turbos and superchargers by function do the same thing; force induct (push) additional air into the engine. How they do it is where they differ. Your use of the car will define which one will better suite you.

Superchargers are belt-driven and are functioning all the time. Power is available immediately upon acceleration, even from a stand still...which is why they are ideal for dragsters. However, their power gain is limited by the size of the supercharger and the RPM of the engine. Also, because there are many moving parts, they are less reliable and there are more things that can go wrong.

Turbochargers, on the other hand, can be more reliable (if preoperly treated) because there is only one moving part; the turbine powered by exhaust gases. The ever present word 'lag' is basically the time it takes from the time you begin WOT (wide-open throttle) to the time the turbo kicks in (or spools up enough to increase the intake pressure). The larger the turbo, the greater the lag. Lag is not necessarily a bad thing. If you think about it, a car with no turbo is experiencing full-time lag. Smaller turbos have less lag, but then again they deliver a smaller boost in power. If you do most of your driving in the upper RPM band of your engine, lag isn't really much of an issue because there is plenty of exhaust gases flowing to keep the turbo spooled up.

Also, the larger the turbo, the greater power gain you will receive from it. Also, the larger the turbo, the less restrictive of an airflow your car will have. The draw-back is that you will have to wait a little bit longer to get it.

Turbos are more efficient than superchargers and the power potential is far greater than that of a supercharger. They net a higher gain per cubic inch than superchargers do.
 

mikev

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#6
equate said:
I see most SCs on trucks which usually have 4+ lieters and turbos are generally on 1.5 lieters hondas.
SC's give more power/torque lower down the rev range so for big truck and heavy cars the SC is better. is just Coincidence that you see them on larger engines simply because the vehical is larger in the first place. an SC (becuase its belt driven) also saps initial power away from the engine before providing the extra (bit like AC) so if you have a 800cc engine and a huge SC you may find there isn't enough power in the engine to get it spooled up quickly.
 

junglestylz

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#7
You also have to take into consideration the amount of heat that a turbo is subjected to. The supercharger also takes away power by being belt driven. For a straight line, SC. Speed, TC. On pretty much any older daily driver BMW, you could end up spending a lot of money on repairs. Superchargers are being prety much faded out now becase of the drop in size of cars. Even the tremendously powerful cars now use turbos. Turbo charged engines are somewhat more difficult to tune though.
 

flashinthepan

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#8
Great posts - especially since I know little about either !

It seems you see more 3.0's supercharged & more kits available or perhaps the Turbo's are so "universal" that you dont see them as often specifically for Bimmers.

It would be a downer to give up the smoothness and daily driving reliability for the swap, but the power would always be welcome.
 
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#9
If you want to learn about turbocharging pick up a copy of 'maximum boost.' It will tell you everything you need to know about turbocharging from fuel management to selecting the proper size turbo for your application. Its a really satisfying read and well worth the time. BMP carries them, I dont know who else has it.

With a turbo sized properly to the engine, you generally dont have to worry about lag. If you want the huge power numbers and need to go with a large turbo for high boost applications, its generally recomended that you use a small shot of nitrous off the line to get it spooling. M20 engine is already fairly well suited to being turboed, its got a fairly low compression ratio so you can run moderate boost without doing much more than slapping in some 5.0 injectors and a fpr.
 
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#10
I only brought this up becaus ein thie bimmer mag I bought i saw a 99 m3 with a SC putting out 480, then a z3 of some newer flavor putting out 408 with a SC. I really just care about accleration my 0-60 and QM is about it
 
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I was looking at a stroker kit but I hear it would be better just to drop a m3 engine in, only a bit more expensive but will allow further tuning.
 
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#12
My brother-in-law and I are in the research and prep stages for building a 2.8-3.0l stroker topped with a turbo. We're looking to get somewhere in the neighborhood of 360RWHP...

Hopefully, we'll have this kit done before 2004 is out. We're going all out on it. Custom intercooler(s), tubing/piping...etc. She'll eat M3s and a vfew various other items long before we're done. We'll probably get started in February on the actual building. We're taking the math and component research about as serious as a heart attack. Better research up front will save lots of time and $$$ down the road.
 


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