Rb25 Turbo Fuel Reg

[MonstaS4]

Had my RB30DET on the dyno today hoping to up the boost to 15psi. Problem is it started to lean out at 12psi and feeding in more duty cycle to the injectors didn't seem to have any effect on the A/F ratio. I have a Bosch 910 pump which should be good for 450-500bhp, 550cc injectors and am using the standard turbo pressure regulator. My tuner thinks the reg is not holding the pressure high enough on boost.

Is this a fair call?

He has suggested a Malpassi, but i remember hearing that the pressure can fluctuate a little with these. Anyone have FIRST HAND experience with this?

[wolverine]

i would have thought the 910 would run out of ability before 450horses.

[R31Nismoid]

the fuel reg will be fine... unless its stuffed.

so i'd look at the power to the pump, are you running enough voltage?

[BHDave]

Did anyone check the fuel pressure when this happened? It's pretty easy to spot when the pressure stops rising with boost. If the pressure increases and then hits a wall then it's the pump.

My malpassi allows fuel pressure to fluctuate by about 1 psi eachway.

As nismod has stated it is worthwhile running a dedicated power feed to the pump with a relay triggered off the current pump power feed. It also eliminates the fuel pump speed control.

The 910 may be a bit undersized for your application, an 040 intank pump is pushing it at 260rwkw and the 910 is a bit smaller (i think).

[Dump_Pipe]

Sorry to hijack a bit here, you guys say the RB25DET fuel reg is fine up to very high power outputs, and i have heard this from a number of people.

So is the R33 RB25DE pressure reg the same?

[MonstaS4]

We ran out of time to hook up a pressure guage on the day. What i plan to do today is run some compressed air at 12psi into the reg and measure how much fuel is returned. At the same time i'll check the pressure. This should tell me... a) how much fuel the engine can use without the pressure dropping off and B) if the reg is actually working correctly.

Dump_pipe, I bought a R33 DE head for the conversion and changed the reg for an R33 DET unit. Part numbers are definately different. I guess the DE reg dosn't have the rising rate ability that the DET reg has.

[Driver]

do they make direct swap nismo ones to suit?

[gtst25]

do they make direct swap nismo ones to suit?

<{POST_SNAPBACK}>

Yes they do - mine cost 170aud delivered a year ago, very easy to fit too. I've also been told that melpassi's don't hold good steady pressure - haven't had first hand experience though with the melpassis but with the fuel press guage on the dyno my nismo held rock solid fuel pressure with a bosch 044- no flicker at all. But as everyone seems to say you don't need an adjustable reg unless going crazy on power or want to put more rail pressure.