Superchargers

[Marrahm]

Not an engineeer and i don’t even play one on tv. Just a question to the masses to help me learn something.

Is there a reason VW aero engines don’t have centrifugal superchargers for forced induction? Seems like they could have at least a couple benefits over other methods: 1) looks like they are relatively “pass through” on induction if the charger looses its drive or sticks. Minimal intake blockage and zero exhaust blockage means you just lose the compression benefit, but keep unforced power levels; 2) since its run from a pulley/gear or otherwise not off the exhaust, there should not be heat soak issues.

I woudl think they might not be as effective at really high altitudes, but at our altitudes, why would they not work at least as well as a turbo?

Thanks for any insights,
Mike

[Jlogan1]

I believe that turbos are more commonly used because they don't "steal" power from the engine to run like a belt driven supercharger. A supercharger that boosts hp up 100hp may have to use 20hp from the engine via the belt drive system. so you may only get a 80hp gain. Since a turbocharger uses exhaust gas it dosn't rob power from the engine so you get more use of the power generated!

[NWade]

Exactly what Jlogan1 said.

Plus, you need to attach the supercharger to the crankshaft somehow. Usually that's with a belt and a pulley; which would require re-engineering either the prop-hub and forward end of the cowling, *or* re-engineering the aft end of the crankshaft and the flywheel system. That would also likely mean a different accessory plate (and possibly changing the way that plate attaches the engine to the mount/Firewall). And once you get past all of those engineering challenges, you then have to contend with a belt that wears out, might come loose (and flail against another critical FWF component), etc.

I'm not saying that a Supercharger is bad; just that its not a magic-bullet or inherently-better solution when compared to a Turbo.

--Noel

[Bryan Cotton]

Turbos are also relatively pass through, but then the prop is a bit coarse.