Fuel Pressure Regulator ?

[96Camaro]

Ok. Well I was wanting to know if an ajustable fuel pressure regulator will give you a noticable difference in power. A respectable engine builder around here says that if you put an ajustable regulator on and turn it up to like 55 psi or so. That there will be a noticable difference. Just wondering if any of you guys have done it.

[Screaming mad]

Surly the engine computer will lean out after a couple of minuites when it see's the change, then you would feel no difference, so surly you will have to have the engine computer data updated with the changes as well.

[Kevin - Blown 95 TA]

Ok. Well I was wanting to know if an ajustable fuel pressure regulator will give you a noticable difference in power. A respectable engine builder around here says that if you put an ajustable regulator on and turn it up to like 55 psi or so. That there will be a noticable difference.

Don't listen to him. If you put extra fuel in there, your PCM (computer) will pull fuel back out to adjust for the rich condition to the extent that it is able (until it runs out of adjustment). Then, after several miles of driving and getting bad mileage, it will run normally. Besides, your car already runs too rich at WOT from the factory tune.

The only thing an AFPR can do for you is help you get a little more out of a set of injectors, up to a point. Or if you need a boost referenced rise in fuel pressure so you don't run lean when running a turbo or supercharger.

[Joe 1320]

Ok. Well I was wanting to know if an ajustable fuel pressure regulator will give you a noticable difference in power. A respectable engine builder around here says that if you put an ajustable regulator on and turn it up to like 55 psi or so. That there will be a noticable difference. Just wondering if any of you guys have done it.

What everone else said. Don't listen to the mechanic. The only thing is that the higher pressure *may* improve fuel atomization, but even that is stretching it.

[96Camaro]

Alright, thanks for the responses. But is there anyone here that has actualy done it?

[fastTa]

Alright, thanks for the responses. But is there anyone here that has actualy done it?

You just received some good advice from some experienced and knowledgable members. I persoanlly find it a bit disrespectful to turn around and say "BUT.... has anyone actually done it?"

It sounds as if your mechanic might not have a good working knowledge of the LT1 and it's PCM. The LT1's factory program is already on the rich side specifically in the Power Enrichment(PE) mode. You will find a temporary gain in power by reducing the rail pressure which will effectively lean it out a little. But the LT1 PCM ain't dumb, and it will quickly adapt to the change in pressure and make the neccesary adjustments negating any power gains you might have temporily seen. It is much better to just have the factory PE tables re-programmed by someone with experience doing so.

This is not to say that an adjustable FP regulator does not have it's place however. When you start to make some significant power with a built motor, it is common to run a "higher than stock" fuel pressure. This helps eliminate any fluxuations in the injector flowrate and the increased pressure behind the injector helps to maximize it's efficiency. An adjustable FPR then can be a helpful tool.

[Injuneer]

Yes... I have done it. Reduced the pressure (no vacuum connected) to 38 psi (stock is 43.5). The PCM immediately started increasing the long term fuel corrections (BLM's), bringing the fuel flow back up to where it wanted it, to maintain the programmed A/F ratio. I watched it "live" on my ScanMaster.

If that's not enough, here's an actual dyno test. As noted above, the gains (about 15HP) come from leaning out the overly rich Power Enrichment (PE) mode target A/F ratios (typically in the range of 11.7:1 on stock prgramming). If you look at the dyno chart, it clearly shows the HP gains from leaning out the system.

http://www.ws6.com/mod-7.htm

That's where most people stop.... they look at the picture and don't bother the read the notes under the dynoo chart. The tests clearly showed that the "gains" disappeared as the PCM corrected for the A/F ratio.

If that isn't enough to convince you, buy the damn AFPR and try it for yourself.

[96Camaro]

Alright, thanks for the info. Very informative.

[Kevin - Blown 95 TA]

Alright, thanks for the responses. But is there anyone here that has actualy done it?

I've done it too, but I also have forced induction so I need the boost-referenced AFPR that I mentioned, and have the ability to tune my PCM and monitor the results.

[Injuneer]

As Kevin and Kevin said, there are useful purposes for an AFPR. I use a Weldon AFPR, so that I can run my fuel system at 4bar (58psi). There are advantages in doing that, but it is not used to "tune". The higher fuel pressure helps atomize the fuel, minimizes the impacts on injector flow from small pressure fluctuations in the supply system, and helps keep the injector duty cycle low.

[RyanB58]

I have also used the AFPR. I installed it before I was an avid user of this site in hopes of the same thing your mechanic said. Boy was I wrong, it did nothing for the car being I have very little modifications.