Fuel pressure regulator

[SamLogan]

Hey guys,

I have a quick question. I am currently putting a ls1 into my surf and have hit a wee bit of a stumbling block. The ls1s have external fuel pressure regulators and therefore i need to buy one. I know you use rising rate fuel pressure regulators in boost situation but do they also work in n/a systems?

Cheers
Sam

[Mattman]

Why do you want to use a rising rate regulator?

If you don't supply boost to a rising rate regulator then it won't rise.

[Ashohman]

maybe he's going to add twin turbo's to it later because the answer is always more horsepower!

[derk]

you want a constant pressure on the rail, probably need to google the specific value for your year engine but it should be somewhere between 50-60 psi

make sure you've got a good functioning vent on the fuel tank if it wasn't already efi the high pressure pumps can cause vacuum and cavitation problems with your fuel tank and system

[slide]

I know you use rising rate fuel pressure regulators in boost situation but do they also work in n/a systems?

Yea, pretty much.
Fuel pressure varies with manifold pressure. In a n/a it goes from vacuum with closed throttle (ie idle) to atmospheric with open throttle (full power). The fuel pressure changes with the change of air pressure (its a lot easier to spray fuel into a vacuum than into AT. pressure, in the same way it gets harder to spray fuel into boost.
Remember 'boost' is just pressure above ambient (and that ambient varies with altitude).

[4WDbits]

I think the early LS1 HSV used a rising rate regulator to reduce fuel pressure at low throttle settings. Don't know for how long they used them, maybe still do.

[3VILC]

Most of the factory ones are actually rising rate as well, just not adjustable, thats why theres a vacuum line too them. Toyota and probably others also add a vac solenoid so that the computer can switch straight to max rail pressure when you floor it, and/or variable or 2 stage pump voltage to adjust the supply pressure as well.

[SamLogan]

The only reason why i am wanting to use one is i cant seem to find one that is not. So it should be ok then. I am looking at a Tomei one. Hahaha i wish i could fit turbos but i don't think they will fit unfortunately.

Sam