Forced Induction for Noobs...

wstar · 04-28-2009, 06:06 PM

Quote:

Originally Posted by Suave Devil

Great thread. Thanks Slidefox!

Hopefully one you guys can help me with a question that has been bugging me for a while. As far as I understand, the difference between a turbo and a supercharger is that although both force air into the engine, the turbo gets the air from recycling exhaust gases and the supercharger gets the air from the engine bay (or from outside if it's a musclecar-style roots type). The end results being similar, my question is the following:

What makes OEM companies choose one or the other? What are the engineers that design the engines going after? As far as I can tell, different companies have a preference for certain applications, although Turbos seem to be more popular overall. for example, Porsche - Turbo; VW - Turbo; Nissan - Turbo; GM - Supercharger

Any help you can provide with this would be appreciated

Thanks!

Suave

There's no difference in the type of air coming into the engine. Turbos don't put exhaust gasses into your intake, that would be absurd. Both Turbo and Super chargers will draw outside air through air filters just like a stock or aftermarket intake does. In both cases, you often want an intercooler to make the intake air colder and denser. In simple terms, an intercooler is like an extra radiator for your intake air.

The primary functional difference between turbos and superchargers is that turbos use the force of your engine's expelled exhaust gasses to spin up the impeller that forces high-pressure intake air into the engine, whereas a simple bolt-on supercharger uses the accessory drive belt on the front of the engine to spin up that impeller. Turbos tend to make more power more efficiently, but superchargers also tend to have less "lag" (latency between punching the throttle at low rpm and getting the full boost effect for the full power increase).

In my personal opinion (which isn't all that informed, so take it for what it's worth), turbos are a better option if you're looking for the highest peak horsepower, best 1/4-mile times (usually), or the highest max speed. Superchargers are better for more nuanced track driving where you spend a lot of time shifting through corners (assuming you can't get enough power without one. There's such a thing as too much power for reasonable handling on a given class of track, and in some applications a supercharger could be too much).