Regarding a popoff valve (blow off valve, whatever) and a supercharger: Remember that the belt-driven supercharger is draining horsepower directly from the engine in order to produce boost. The boost produces more horsepower than it drains, but if you produce boost that you vent to the outside, that represents horsepower not going to the rear wheels. Turbos drain horsepower from the exhaust gases that are going out the rear of the car to drive the blower, so the drain isn't as big an issue there. Hence, popoff valves on turbos, but not so common on belt-driven units.

Just my .02.

 

You're correct, however the pop off valve only get triggered when the throttle body suddenly closes, causing a large pressure difference between the intake manifold and intake piping. Basically what I am trying to say is that even if you're simply throwing away horsepower, it's horsepower that you don't want anyways because you're decellerating, or taking the car out of gear, or whatever..

Chris

 

I was thinking this route because with stock internals 8psi would be about max I would want comfortably. The idea was to vent pressure so that you could have more boost at lower rpm... not for the popoff sound or whatever.... and immitate the power curve of the speedcraft turbo...much flatter and much less peaky. I could care less about peak numbers... if you are pushing good horsepower to the wheels all across the rpm band It would make for some good usable power.

 

I have heard tons of theories about this but never heard of anyone actually doing it

Basically you'd want a wastegate hooked up to your intake side...

Chris

 

And......??

 

Houston we have a problem. I got home really late last night and now I'm late for work so I'm heading there. I will explain more when I get to the office. Plus I can scan the dyno chart there and post it up. I need your guys help, don't know what's going on. Very big dip at 5500 every run which is killing my power. Timing? Fuel? Don't think my VAFC can trick the ECU with that much fuel being added. Prob going to have to go bigger injectors and SAFC. Any thoughts? I'll post the dyno in like an hour.

Mike

 

[QUOTE]Originally posted by m777erlin
[B]Houston we have a problem.

 

I think the part of the problem is that how VAFC adjust fuel.
Correct me if I am wrong, but VAFC adjust MAP sensor signal to change fuel delivery.
If that is so, substracting value isn't problem but adding value will cause problem like modified map sensor reading going postive value thus ECU going little crazy because of it.
That is my theory.

Mike's answer is try increasing fuel pressure or modify by adding adjustment plate to the fuel pressure but like the problem I had before, going to bigger injectors is a must and another fuel management other than VAFC. Because VAFC just won't get the job done right.

Mike looks like you need to knock on the door of AEM for another sponsorship, and maybe include me in there.


Another way no-one tried but should is adding another injectors working when approaching vtec. That way you can easily keep the drivability at low rpm with stock injectors and don't worry at higher rpm where more fuel delivery is required. This would be much simpler than standalone and cheaper. But I am just talking that out of my ass, so I can be so wrong.

 

Here's the dyno. Trevor, any thoughts?

A/F seems to be ok.

 

[QUOTE]Originally posted by 1Randyc
[B]Mike's answer is try increasing fuel pressure