douwe

just want to no if they worth paying that bit more for any advise would be great thanks

proz07

iTrader: (6)

compared to what? are you refering to a 1:1 rise or like a 1:3 rise? two very different versions. the 1:1 is a must for a boosted engine your stock regulator is this. the 1:X style was a long time past way to 'enrich' fuel flow for a boosted engines in the early days which should be discarded asap as the 1:1 with programable fuel injection ECU's gives indefinatly better control.

z

scathcart

1:1 isn't a rising rate, its direct reference. The rate of fuel pressure rise has to be greater that the rate of manifold pressure reference to be a rising rate.

Rising rate regulators are still used quite a bit with supercharger kits, in the 8:1-12:1 range, typically called FMU's. The problem with them is the amount they increase the fuel pressure... at 40 psi base, 10 psi of boost with an 8:1 FMU, your line pressure is going to be 120 psi! This lowers fuel pump flow output, decreases fuel injector spray quality, and puts a lot more strain on the fuel system seals.

There is very little use for a RRFPR on a car with a tunable ECU. There are too many drawbacks too them, and really only compensate for injectors sized too small.