i'm going to install an adjustable fuel pressure regulator,but my buddies say fuel pressure adjustment does'nt add any horsepower unless pressure is way off.is it worth doing or not? any help would be welcomed. thanks

 

i could be wayyyy off on this, but i always heard that too much fuel if thats what you mean will just drowned the car, like a carbed car would flood. i never hear people talk about adjusting the fuel pressure, as opposed to making sure the pump and injectors can keep up with the fuel needed after certain mods. (n20, f.i)

 

An AFPR won't help performance on a stock or mildly modified engine as you shouldn't be running into any fuel issues. They can be used to provide more fuel to make up undersized fuel injectors, by increasing the fuel pressure.

 

I think the stock computer setting makes the car run a little rich so you can tune it down a tiny bit if you like.

 

You can't "tune" with an adjustable fuel pressure regulator. While the stock LT1 tuning is excessively rich at WOT, turning down the fuel pressure will not lean it out.

The PCM will see (via the O2 sensors) that as a result of the lower fuel pressure there is less fuel being delivered, and lengthen the injector pulse widths to supply the correct amount of fuel in closed loop. It does that by increasing the long term fuel corrections. When you go into power enrichment mode (WOT), since the long terms were adding fuel in closed loop, the PCM will continue to use the Cell 15 long terms (BLM's) and it will run at exactly the same target A/F ratio (typically about 11.7:1) that is was tuned for at the factory.

You tune in the PCM, not using an AFPR. The mail-order tuners will guarantee you 10-15HP improvement on a tune for a stock engine..... all they need to do is lean out the PE mode target A/F ratio.

Here's a dyno chart showing the effect of reducing the fuel pressure using an AFPR. Most people look at the chart and say "wow.... it really does work, it gained 16HP". Unfortunately, they fail to look at the note below the dyno chart that indicates the power gains were lost as the PCM started to correct.

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

 

What if i went to the track and adjusted it and made several runs. How many passes would i get before the computer figured it out?