Newbie Question (Fuel Pressure)

[neruve]

What types of changes do you make to run a lower base fuel pressure? Like if you wanted to run say 40psi (or 43.5) instead of 58 on an LS platform?

Are their any drawbacks to the lower pressure? With a boosted application I feel like this would give much more margin on injectors and fuel pumps.

If this is even possible on the stock computer?

Any/All input is appreciated.

[2xLS1]

It makes the injector smaller (lbs/hr). Just change the IFR table for the new injector size. What do you mean by margin? You are just going to be out of injector sooner if you do that. It might keep the fuel pressure up longer before you are out of pump, but the total fuel delivered to achieve a certain A/F ratio won't change. The IPW will be higher with the lower pressure.

[neruve]

I was actually thinking if you ran a set of SD 80s they may idle better at a lower pressure and it would allow higher power with the same pump as flow rates of the pumps drastically decrease at 70-80 psi if you are gonna have boost. I thought it would elevate some of the problems with idle with large injectors and allow you to run a more economical pump all while adding in a little bit of safety on both ends.

Would you also need to change the other injector data if they were made or is the flow rate table really all you would need to change?

[POWERZONE]

I would not suggest doing that but an external fuel regulator could get the job done if I am following correctly.

[nkautz]

If you have an adjustable FPR that is boost referenced , you can set your base pressure to 40 and it will increase as boost increases. You set your IFR to a single value across the board in the table. If the injectors flow 80lb/hr at 43.5psi then you would would set the IFR at about 75 for 40psi. Doing what you mentioned does help with idle/part throttle fueling smoothness.

[neruve]

Awesome, thanks for the info. Will all the other injector data stay the same other than the flow rate table? As in, if you had it tuned for it at 58 psi, could you just lower it to 40 adjust the IFR table and be good to go?