Offroad-Express

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

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.

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

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

SamLogan wrote: 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).

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.

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.

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