Re: Adjustable Fuel Pressure Regulator (archive)

Hi everyone, want to ask those who have had any experience with this item:
>What is the benefit of installing this product (performance, economy, etc...)
>What is the best on the market, price not an issue?
>Does it work best when in conjunction with other items (exhaust, ported manifolds, airfilters, etc...)
Thank you all for your input.

Increasing the fuel pressure increases fuel delivery obviously. Once you go to full throttle, the ECU ignores the oxygen sensor and opens the injectors a pre-programmed duration according to RPM. It's here that the adjustable FPR helps the most if your engine is running lean. 535i's are known to run lean, but not M5s. So I don't know how it will help. Too rich (too much fuel) robs power while too lean causes surge, high exhaust gas temps, knocking, etc.

Doubling the fuel pressure increases fuel delivery by 1.4 times. It's a square-root relationship. You would have to increase pressure by 4x to get twice the fuel output at the injectors, assuming the fuel pump can keep up. Just a bit of trivia...

Are you getting a lean surge or do you just want more power? If you're having driveablility problems, try a new O2 sensor, injector cleaner, or even removing the injectors and sending them off for cleaning/blueprinting. The Jim C chip is tuned for part- and full-throttle, so that's a better upgrade for performance. I noticed a HUGE difference at all revs and throttle positions from stock to the Jim C. It's also much better than the Dinan chip in my brother's M5, too.

JamesM

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