supercharged engine ....what increases boost ?

[prolex-uk]

OK,

quick question...........

its my belief that improved exhaust flow (manifold) will not affect the boost level on a supercharged engine as its after the combustion process (opposite of a turbo where better exhaust flow increases boost/power)

I also think that a bigger intercooler will increase boost as will a induction kit/improved cold air flow

however its my belief anyone with more knowledge than me got any more info ?

why i ask is i have some manifolds that increase power on a N/A IS250 by 32 bhp and I'm hoping for + 40 bhp from my supercharged IS350 if i fit them. BUT the all alloy engine is not allowed past .4 bar and i'm worried this could do that...........

thanax for looking

[Scoobyweb]

You are correct that exhaust flow has no effect on boost levels with a Supercharger. A supercharger is belt driven from a pulley on the engine, it has absolutely nothing to do with the exhaust. To change boost levels on a supercharger you have to change the size of the pulley that drives it. There probably are other ways as well but none involve exhaust gases.
Thats the way I see it, someone may correct me.


Chris.

[James Breadvan]

Going for bigger diameter outlets on an aftermarket manifold makes power as does going for a large diameter exhaust to loose to gasses as quickly as possible.

A bigger intercooler will lose boost pressure as there is a larger volume to fill and a SC will only move a fixed amount of air for every engine revolution, plus the cooler air is more dense.

What sort of supercharger is it fitted with and what bar is it running now?

[prolex-uk]

running .4 bar with water to air intercooler

can't do more than .4 bar

[James Breadvan]

How come they can only do .4 bar standard. Has anyone tried to go higher?

Only way to make cheapish power is to change the exhaust/manifold for a really free flowing system. After that sounds like built engine time.