how much fuel psi should i be running?

stock lt1 with bolt ons
vortech v1 6psi i think and a pcm for less tune
right now im running about 45-50 psi and when i get in to it and about 5k rpm the car starts popping and falls on its face (feels like a rev limiter) any help will be thankful

 

Need more info...are you running stock fuel injectors with a FMU and an in-line TRex fuel pump?

 

im running 42lb injectors
no fmu & 255 intank pump

 

The "correct" FP is primarily a function of your AF ratio. If your are not too rich or too lean, your FP is basically OK. If you have an adjustable FPR, the FP is best thought of as a tuning tool. But for most combos, a stock FPR and therefore a stock FP works best. In that case, mixture adjustments may be made in a variety of ways. Primarily using the PE tables in the PCM.

Some random thoughts about FP to keep inb mind.

1. If the FP drops as load increases, the system is not delivering enough volume.
2. For any given pump, the volume available decreases as pressure increases.
3. The stock FPR is vacuum referenced and can therefore be thought of as a "1:1 FMU".
4. The volume and pressure potential of a pump is directly related to voltage. Being sure the pump is getting enough voltage is a key to adequate fuel delivery.
5. Using a heavy gauge power lead to the pump(s) is a good idea.
6. A Kenne Bell "Boost-a-Pump" or equivalent product is a very useful add-on that make make a marginal system completely adequate without a lot of cost or a complicated install.
7. The stock lines and fuel rails are adequate for almost any combo. You really need to be planning for mega-hp to make replacing these items necessary.
8. Inadequate feul delivery and a consequent lean condition is death for a blower motor.

Rich

 

Do you have any type of ignition box? What is your spark plug gap?

J

 

If you're running 42 lb injectors and no FMU, then your computer has (or should have) been reprogrammed for the change. If you didn't tell your tuner that you had an adjustable FPR, then he would have assumed stock fuel pressure as a starting point for your program (41 - 47 psi with the vacuum line disconnected). As Rich stated above, the engine needs to be tuned with a wideband O2 sensor on a dyno to ensure proper tuning.

 

i do have a crane black box with the hi-6 coil

i have ngk plugs but i dont know the gap

what is the correct spark gap for my car?

 

I wouldn't go more then .035 for gap. Are the plugs tr6's?

J

 

Do you have any type of boost timing retard? If not, that could be your problem. My car ran like crap until I intalled one. You can try running race fuel in it and if it clears up, thats prally what the prob is........Just a thought though.

 

ill have to check my plug gap they were put in years ago

i had a chip made by alvin @ pcm forless a 2-bar tune using a map sensor from a grand national maybe i dont have enough timeing retard at high rpm or boost

 

If you are running boost, there is no way you should be running plugs installed "years ago". You need a fresh set of properly gapped plugs in the correct heat range. Do new wires while you are it. When trouble shooting a blower car, step one is being sure that the plugs and wires are good.

Rich