dallasyoung

Ok, my friend says that superchargers have constant boost, I know they do, I just thought it came at like 3k rpm's. So if I have it set at like 12psi, at idle it will have 12psi?Please explain.

civic disobedience

you should build up boost as the engine spins faster, at idle you should not be boosting, only as the rpms come up

jaydeem

correct me if im wrong, but the supercharger should feed as much air as a stock intake at idle...

civic disobedience

thats what I was trying to say... dunno too much about superchargers, just basics

go TURBO you will be happy not to keen on SC, nor is most of this board, only good in certain applications, but its your car, so build what is going to satisfy YOU!!

Spunkster

THe supercharger has a bypass valve that opens with vacuum. The only time the bypass valve closes is when the throttle is opened to a point at which there ceases to be vacuum and the valve closes thereby building boost. This is an aolmost insataneous change and returns to vacuum when the pressure equalizes at that specific throttle position.

Rory Breaker

Im trying to find a good diagram of the bypass valve, which is the mechanism that controls the extra air.

To answer your question, you do not boost at idle. Idle is stock. You could say boost is based on throttle position when you drive...WOT and instant boost. Partial throttle, instant few PSI.

MachAF

It won't have 12psi at idle. The jackson racing supercharger has a bypass valve inside that re routes the air back through the roots agian. This won't stress the engine. I believe it gets full psi at 2500 rpm at WOT. Not sure though.


[Modified by MachAF, 8:57 PM 4/6/2003]

Muad'Dib

WOT

sak

Here you go:

http://www.jacksonracing.com/pages/howorks.html

Contrary to popular belief, you don't really get max boost until like 5-6k rpm, but you will be making boost off the line, just not the max that everyone thinks that the JRSC does from idle.


[Modified by sak, 4:09 AM 4/8/2003]

Spunkster

You are making the max amount of boost that the blower can make at that RPM due to the efficiency of the roots type blower. It is not spooling like a turbo, so as long as you are at WOT then you are at max boost no mater where in the rev range you are.

sak

Would you like to take that comment back? I am aware that you have a JRSC too, but have you ever looked at where your boost gauge at when you floor it (WOT) at 2500rpm.

Here what a boost curve on a JRSC GSR looks like:

genop

nice graph!