supercharged owners

[Wizard]

I'm trying to hunt down the exact problems of my top end boost and hp. My fuel pressure at full boost (9lb) reads at almost 70psi. At idle it is 55. It has a PCMforless tune, but starves for fuel on top. Also 42lb injectors. Any help is grateful.

Wizard

[zippy]

you aren't running an fmu are you?

[Wizard]

nope, just a tune for Bryan.

[smithl3]

Wizard,

Sorry to hear about the problems. I run about 45-50 psi at idle and just shy of 70psi at WOT. That honestly doesn't make sense that your running out of fuel, your injectors are more than capable to supply fuel at 4800, my first guess is tune, but not sure. Bryan is great though he'll work with you. Good luck.

[BenKey]

How do you know you have been running out of fuel? Have you checked your injector duty cycle? From what you gave, sounds normal.

[Wizard]

I spoke to Bryan and he said all he needs to do is add some more fuel up top. I am sure the injectors are capable, but it just needs more fuel.

[BigTex]

I'd like to know how you guys are getting 70 psi without a FMU. Stock fuel pressure is 58psi, so peak on the stock regulator should be in that range.

 

70 psi and 42 pound injectors will support MUCH more than 350 hp.

[Wizard]

No FMU just a tune by Bryan, and the 42# injectors. I wish I knew more, but I don't. When I spoke to Bryan yesterday he thought he could add another 4% of fuel to the upper rpm range . I know that most guys got the Multec II injectors, I got the Delphi ones, still good?

 

I guess I'll try this and see what happens. Until that I will keep my foot out of the throttle.

Wizard

[BigTex]

delphi, multec II, GM 8.1L Marine = all the same injector.

 

Delphi makes the part for GM. Its the Multec II style. GM puts this injector in their 8.1L Marine crate motor.