I was curious what your fuel pressure was for those of you with mods similar to mine (see sig.). I checked mine the other day and it tested 45.5lb with vac line off. I have a feeling this is too low for the mods I have. Any thoughts out there on this?? I have already replaced my fuel filter so I know that is not restricting me.
Thanks!

 

Mine with the line off is at 53 PSI.. that is WAY WAY too much fuel. I wanna bump it down about 10 PSI

 

mods in sig, i run 58psi with stock pump and injectors. but i believe it will help me a bunch to upgrade to 30lb injectors, take my fuel pressure down to 45, and get a 58 TB. it feels like it runs outta fuel in the upper rpms... i really need a scanmaster...
jesse

 

I have a bigger cam than you, with 30LB SVO's, and a 58mm TB, and still run rich.. I gotta shoot that FP down some.

 

It is irrelevant what fuel psi you run. The PCM will compensate for the increased fuel psi by reducing your injector pulse width.

You program for the injectors. This has been proven time and time again that increasing your fuel psi is a short term gain. The PCM will learn, adjust and negate.

With your mods, I would just set it to 43-44 psi with vac line off. That is stock.

You pump your fuel psi down to 10 psi...bye bye motor....lean condition...I would sorta know that one... damn fuel pump crapped on me....still ran it.

30 lbs SVO's are actually designed with 39 psi in mind. I am not remembering the equation to get it right...I programmed my 30 lbs @ 31.6 lbs I believe.

 

i have my injector constant programmed for 30lb injectors, with stock injectors and 58psi the computer thinks i have 30lb injectors, so my pcm wont compensate
jesse

 

And your duty cycle is .....

Sorta forgot to mention that you tuned for such...

 

sorry, i took tuning for granted. i thought ppl would know there isnt much you can to these cars without tuning. about my duty cycle im betting it is TOO high, ive bought a set of SVO 30lbs. and will turn my fuel pressure back to 43psi. im also getting a bigger throttle body, do you think that with a
ported heads/bigger valves
xe224/230
gasket matched/ported intake
would i show better gains with a 52 or 58 TB?
thanks
jesse

 

The 52 or 58 MM TB debate is still in full swing today as it was years ago.

Personally, I would go with a 58.

 

thats what i was thinkin, couldnt hurt me, gonna buy one might as well get the big one, and not have to buy another when i do the stroker.
thanks
jesse

 

I am running 55psi right now, just so the duty cycle on the stock injectors isnt too high. I have to scan the car at some point and see what the actual DC is. Like Canton said, the computer controls the A/F, so upping fuel pressure will just lower duty cycle on injectors. I will eventually get 30lb injectors and drop the PSI back to 45.

 

Actually having a TB that's too big can hurt you. AIr will just be floating around if you car doesn't need the flow of a 58mm.

 

The problem is due to the fact that people still tend to use old carb equations to derive the required CFM needs.

I know myself I went from high 13's to 13.0's with a 58 mm TB, Gran MAF and tb bypass years ago when I bought the car with a stroker.

Now if you were getting a Monoblade....that I could see being an issue.