Fuel presure under boost
 

What will hapend with factory FPR when it registers positive preshure? I have all the stuf for boosting and i am waiting for p28 so I can be 100% redy for boosting. When I install every thing what will hapend with my fuel preshure? It reacts on vacum and when boostig there is no wacum.

Re: Fuel presure under boost
 

Just leave it alone.It will be fine.

Re: Fuel presure under boost
 

unless you plan on running about 20psi you will be fine, it still works as normal, i made over 375 with a stock unit

Re: Fuel presure under boost
 

What hapens when you hit WOT? Does FPR rises preshure or leaves it as it is because there is no vacum? I replaced my factory unit with adjustable fpr from fiat Tipo. So I planed to set it without vacum to 3bar and just leave it. I am planing to run blue top DSM-s.If I find them.

Re: Fuel presure under boost
 

when the FPR sees vaccume it LOWERs the fuel pressure to compansate the reduced air flow (close/part thottle)
when you go WOT or when it sees postive pressure, it loosen up and let the fuel flowing at the maxmium set pressure.
i`ve done 19~20psi on mine and the fuel pressure gauge shows normal reading even at full boost.

Set it at 3bar (44.1 psi) without vaccum will prob.ly give u a static pressure of 35-6 ish with vaccum, which should work fine IMO. but the vaccum hose must be connected or it will prob.ly foul all the plugs because it is running rich all the time even at idle, it also gives you ---- up mpg.

Re: Fuel presure under boost
 

You guys have to remember, every psi of boost decreases the fuel pressure into the manifold by one psi. So running 40 psi fuel pressure and 20 psi of boost will effectively lower your fuel pressure to 20psi. Just remember that when your injectors are maxing out and they are supposed to be able to handle more power.