Originally posted by Geelo
When you run 8 injectors, are you also running a rising rate reg??

Yes, technically. But the FPR the 8-injector folks use only rises the rate of fuel pressure relative to the rate of boost similar to a stock turbo car, i.e. 1:1. Most associate the "RRFPR" to FPR's which raise the rate of fuel pressure a great deal more, anywhere from 2:1 to 12:1.

In my own mind, RRFPR's are the cheapest and quickest way to turn a n/a fuel setup to a turbo fuel setup. However, as noted above, any attempt to use this setup for high boost applications will result in lean conditions somewhere in the power band, if you don't accomodate by making it rich everywhere. The 420a in particular has its spots where more fuel is necessary demanded, whereas a RRFPR is completely linear and exponentialy in the manner it provides fuel. It just does not compensate at all for rises and dips in a torque curve.

In addition, I always found there seems to be a slight delay with the fuel enrichment after I hammered the throttle into boost. This sensation always bothered me, and was the main reason I sought out a "better" fuel system.