Jump to content
SAU Community

Recommended Posts

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?

Link to comment
https://www.sau.com.au/forums/topic/83123-rb25-turbo-fuel-reg/
Share on other sites

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).

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.

do they make direct swap nismo ones to suit?

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.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Maybe they'll look to do a bunch of presales to help inject some cash fast for their financial issues...
    • Does it also misfire equally when revving?   Josh is very correct in what you should do. The coilpack harness wiring loom itself is a known problem due to its age and the number of heat cycles it has gone through. Throwing parts at a vehicle to diagnose the issue isn't a smart or good way to do it. Secondly, you may have a bad coil pack, you pop replacements in, they fix that issue, but messing with the harness breaks it, so the issue persists. So now you think "well it wasn't the coil packs" and have to continue chasing your tail, potentially swapping back in your shit coil packs and returning the good ones (yes, I've seen people do this because 'it wasn't the problem' and they want to save money). And suddenly, you've got two issues with the same symptoms...   Diagnose, don't use the spare parts shotgun.
    • Well the articals keep saying a Q50s (Skyline in Japan) with a new Manual gearbox. I like the talk about the new looks with the round tail lights. I hope they bring back the retro look like they did with the Z
    • Off the back of feedback we have decided to mix up this next Motorkhana at Avalon to have some targeted skills practice for beginners to advanced. Saturday 6th September 2025 8:30am Capped 26 entries Standard Entry Fee: $89 Members Entry Fee: $55 (SAU Victoria Only) Entries Close: Friday 5th February  Where: 55 beach road Avalon. https://maps.app.goo.gl/HNUE3EuNue3sJxh38 Entries: Limited to 26 entrants (Passengers allowed over the age of 14 with a signed disclaimer and same safety gear) Disclaimer: Download  Please electronically sign and email to [email protected] or print and hand in and Driver Sign In. To compete in this event you will require A valid  AASA General Speed licence or (Day license via the AASA Website for $50) MA Licenses are no longer accepted by AASA https://aasa.com.au/  A helmet, long sleeve clothing and a 1KG mounted fire extinguisher recommended (But not Mandatory). Further details within Supp Regs on the enty link. Entry Link > https://www.sauvic.com.au/entry/deca/20250906 You can bring and have a passenger in the car but they need to comply to the same safety and clothing as driver. Bring your car and get to battle others, win, lose or draw. I can guarantee you will have lots of fun. Any questions email [email protected] Entry List: 1.Anna S 2. Luke S 3. Jesse Givens-Lamb 4. Luca Stamatescu 5. Madeleine Stamatescu    
    • Wanna rewrite all of that in, say, 2 or 3 separate sentences, so that we can read it?
×
×
  • Create New...