slow wankle

I know of twincharging using a rooter style supercharger and a turbo. It just seems to me that the supercharger would begin to restrict the turbo. I was wondering if you could twin charge using a centrifugal style supercharger running it parrallel to the turbo. I wanted to know if the supercharger would begin to push air back down the turbo before the turbo had a chance to spool up, and once the turbo does spool up, would it begin to push air down the superchager? It seems to me that the air would all go to the engine since it is a vacume source, and the easiest place for the air to go, but if you are running a 7psi supercharger and a 20psi turbo, I don't know it the turbo would create too much presure and cause a sort of compressor surge for the supercharger... does anyone know enough of the physics behind this to tell me if it will work or not?

thanks (sorry about the long thread and the really bad run on sentences)
-John

mwatson184

alright, with twin charging it is more about pressure ratio's than pressure.

So you have a 7.5 psi pulley on your superchager, that means that the supercharger is displacing about 1.5 amount of the air that the engine would normally injest (atmospheric pressure is around 14.7psi, + 7.5 psi of the supercharger). So that would yeild a total pressure of 21.7 psi. Now, if the pressure before the supercharger is 20 psi from the turbo (as you stated) that is 20 psi of boost + 14.7 psi atmoshperic for a total of 34.7 psi before the supercharger. The supercharger then compresses this air at a ratio of 1.5:1, so total pressure would be 1.5*34.7, or around 51 or 52 psi. Subtract the 14.7 from there and you get around 34 PSI of actual boost from the combination turbo + supercharger.

Marques

Sponge Bob Square Pants

I don't think it would make much sense to twincharge using a centrifugal supercharger, or would it?

mwatson184

Centrifugal superchargers boost rises linearly with rpm, roots style maintain a certain boost throughout the rpm range. I can't see puting them together either.

Marques

REDAT

We've just about finished a twincharged AE92 levin. We had it running perfectly until my mate floored it, we had oil all through the intake and 500m trail of smoke behind us.

Anyway, the first setup had the supercharger running into the turbo. The new one will use one-way valves, and have both supercharger and turbo joing into a single pipe.

Irrelevant, but I'm bored.