94 z28 - 42lbs injectors were tuned and matched. 255walbro pump. running stock cam- ported heads/valve job and 8lbs with my s-trim blower. other boltons. do i need a FPR?

 

What fuel pressure did you tell the tuner you were running? He had to know the fuel injector flow rating, the manufacturer and your fuel pressure before he could tune the PCM for the injectors. He should have asked you that on a questionaire. If he didn't you could assume he assumed that you were running the stock 43.5psi. There is no reason to change that, once the programming is done. Do you have a boost referenced FMU, or is all the fuel handled in the PCM programming?

 

yes they are setup for 43.5psi. fuel is all handled in the pcm. so what ya think?

 

Why do you feel you would need to adjust the fuel pressure? Have you verified that the stock regulator keeps the fuel pressure at 43.5psi (vacuum line disconnected)? Have you verified with a wide-band that the A/F ratio stays where you want it at max torque and max HP points? If it ain't broke, it doesn't need to be fixed .

On the other hand, the 42's are probably only good for 550flywheelHP, considering the BSFC of a blower engine, so if you are making more than that, you might want to look at either higher fuel pressure or larger injectors.

You can run a higher pressure to extend the capacity of your injectors, and to reduce duty cycle. I run mine at 58psi, to help the 64# Bosch injectors flow a bit more...... But you have to "reprogram" when you change the fuel pressure, to reflect the impact on the injector flow rate.

 

i will be dynoing the car this spring so i guess i will have to wait and see then if i need a FPR... my goal is 500hp but since its a auto i might have like 400 some at the wheels maybe. the car run perfect at 130mph so i don't think fuel is a problem. thanks