im gonna use a rrfpr have i got this right ot not ??????????

[e30turboed]

am i right in thinking that if i use a rrfpr or fmu in conjuction with my original fpr it will only affect fuel pressure once it has got to the level the original fpr is set at ? so if my standard pressure is 43.5 psi and i use a 10:1 fmu the fmu wont increase fuel pressure until im past 4.35 psi of boost and then sfter that 50 psi for 5 psi boost and so on ? i cant see any other way how they can work being there set on the return side i just wanted to check first.

thanks

[Ant]

for a 3 bar fuel reg, with a 1:1 rising rate you'd get 1 psi more FP per psi of boost

a 10:1 RRFPR would give you 10psi fuel gain per psi of boost, hence my comment about a higher flow pump if you go this route( walbro255 drops in minor mods req )

most work at a normal 1:1 in vacuum iirc

Cant comment anymore though, not something I have played with TBH, Gunni may be able to shed some light ?

[e30turboed]

ive just found a writeup on the net and it says a 10:1fmu on return side used in conjuction with original fpr will give 10 psi fuel for 1 psi boost so if uve already got 40 psi the fmu cant alter pressure until its reached the original fpr pressure and then after that it wont let any fuel return and build up to set pressure rate before dumping fuel through return line. so a 10:1 fmu at 8 psi boost will hold 80 psi fuel pressure irrelivant to what original fpr is doing. i know where im at now 22lb injectors and 10:1 should be good for up to 8 psi with good fueling everywhere according to deatchwerks fuel calculator