Fuel pressure regulators

Tony8470

Registered User
I have some 42lb lucas injectors rated for 43.5 psi.
The stock FPR is rated for 39 psi

I have read that both you CAN'T use stock FPR and you CAN


Who has experience with these specific injectors and do I NEED an aftermarket one? Also I hear good things about the kirban FPR for stangs. Anyone else agree?

This really bugs me because they are both from reliable sources on the boards. Im in a pinch for cash now but the car has to be together really soon. So if I can run the car with the stock fpr untill I have some cash for an aftermarket one that would be fine.
 
I think you can with the understanding that the 42s won't be putting out quite as much as it would be at the full 43.5 psi. It should be fine if you don't expect to be close to maxing out the 42s. I'm sure some one else here knows a lot more about this than I do so someone with real world exp please chime in.
 
You can use the stock regulator or you can use an adjustable regulator to increase the pressure. If you have the ability to adjust the A/F ratio with a tuning device it doesn't really matter.

After having failures with both the Holley and the Aeromotive adjustable regulators, I went back to the stock regulator for several years when I was using 50# injectors. More recently I found the car was running lean and I installed a Kirban adjustable regulator just so I could raise the pressure enough to get it in a safe range until I could get my chip reburned. It worked fine.

Larger injectors (42# and up) get better atomization of the fuel at 43.5 psi than at 39 psi, which helps at idle. But they will run well enough at stock pressure that most people won't be able to tell a differince.

Another thing to consider before increasing base pressure, is if your pump still have enough flow at peak boost/fuel pressure and max rpms. Flow ratings drop dramatically above 55 psi, so make sure your pump is up to the task before increasing the base pressure.

David
 
David Neibert said:
You can use the stock regulator or you can use an adjustable regulator to increase the pressure. If you have the ability to adjust the A/F ratio with a tuning device it doesn't really matter.
I do not agree with this statement. Please reference the following thread:
http://www.sccoa.com/forums/showthread.php?t=31019&highlight=fuel+pressure
If an injector is rated at a particular pressure, it is typically what the manufacturer expects you to run it at. I think you will be hard pressed to find a manufacturer that will tell you the spray pattern will be the same at two different pressures which are 4 pounds apart.

Paul
 
I got a kirban 5.0 fuel pressure regulator, works very well- no complaints as of now... Got it on Ebay for the same price as the stocker.
 
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