another question about superchargers

[andytk]

Right, next question.

Would there be any point in putting a part time supercharger on a car. What I mean is a charger that you can switch on and off. (a bit like the mad max effort)

After all, while you're cruising along you don't need all that power, so running a charger is a waste of power. The only downside I can see is that, while running off boost, your effective compression ratio will be a bit low.

I know that its been done in the past, indeed the first ever boosted cars had the superchargers kick in only when the driver pushed the pedal to the floor. Then ALL the boost came on. Bit like nitrous. Nice.

Andy

[rev-erend]

Yes - you only need a by pass pipe around the charger
- in theory.

All easy stuff.

Like you say - the idea has been around probably
since the 1920's.

[james]

If you were only cruising, you wouldn't need the power, so the CR of the engine wouldn't be much of an issue.

If it was in Mad Max, it must be possible. After all, the film is a documentary of Australian Police work. A bit like those programmes about a couple of coppers rounding up drunken Geordies on a Saturday night over here

James

[Fatboy]

Basically all you'd need is some type of friction clutch on the charger drive belt. As long as you didn't whack too much boost through it, you probably wouldn't need to lower the compression ratio too much either...

[MR2Mike]

The Mk1 MR2 SC has a magnetic clutch on the supercharger for exactly this purpose.

[GavinPearson]

If the bypass was there you could. But I'd think you'd be better off direct gearing the supercharger or using a turbocharger instead. The turbo would be inherently more efficient, although the supercharger might be easier to package.