Recommend a fuel pressure regulator for turbo?

[-nick]

Hi folks,
My cheap ebay special regulator is, well, cheap. I can't get it push anything under ~48psi (at atmospheric pressure), and it doesn't seem to be changing fuel pressure when I rev the motor / differing MAP values. The gauge reads up to 150psi (why??) and flickers by ~5psi at its steadiest.

Can someone recommend a decent regulator that won't break the bank? I was thinking of the MSD boost/vac referenced regulator from Summitt. However, they're rated at 36-45psi. If I set it for ~43psi, and run ~15psi boost, then shouldn't I want something that has a dynamic range up to 58psi? Or is the 36-45 rating the adjustment range at atmospheric pressure?

Also, from reading a few posts on here, I'm guessing that my current regulator could be the source of why I need to run a very rich idle just to keep the idle steady. My throttle response just off of idle is terrible too. I have a feeling that this is all related...

Help?!

[Minami Kotaro]

I'm using the MSD-2222A, which is actually a Bosch part, on my turbo ACVW. It will go to 50psi or above when on boost. It works very well and goes up exactly one psi of fuel pressure for every one psi of positive manifold pressure. I could only get it to produce around 42-43 psi of static fuel pressure at full adjustment.

Much, much better than the crappy rising-rate I had before; it would push 45 psi static to over 90 psi at 12 pounds of boost!

[PSIG]

... I was thinking of the MSD boost/vac referenced regulator from Summitt. However, they're rated at 36-45psi. If I set it for ~43psi, and run ~15psi boost, then shouldn't I want something that has a dynamic range up to 58psi? Or is the 36-45 rating the adjustment range at atmospheric pressure?...

Hey, -nick. I would have to agree with Minami Kotaro that the MSD modified version of the Bosch 001 regulator is about the best bang for the buck out there. It is made with better internals than even most of the big name stuff sold as tunerware. And you are correct that it's spec'ed range is 36 to 45 psig at atmo with proper 1:1 rate above that on boost.

David

[Ferret]

I don't know what car you have, but any OEM FPR from an EFI car sould do the job. If you are running MS you don't need any adjustability from the FPR.

[PSIG]

...If you are running MS you don't need any adjustability from the FPR.

Ferret, there are a number of situations where an adjustable regulator is desired - even with MS. Examples would be boosting an engine with injectors slightly too small where a bit of pressure makes it work, or the opposite, where they are way too big and a reduction allows them to be used with a reasonable idle PW.

I think the most common is with hot street or racing engines, where large injectors are used and the idle PW is tiny, where one setting is too lean and the next is too rich. The adjustable regulator is tweaked to tune the idle when it's stuck between two PW's - one of the issues solved by MS2 and Hi-Res but easily solvable with MS1 and an AFPR.

Anyway, it's a useful tool that can alter the variables enough to make everything work together better. I'm not sure that -nick needs one, but if so, the MSD AFPR is generally a good inexpensive choice up to 500hp or so.

David

[-nick]

Thanks folks! Just ordered the msd-2222. I figure there's no reason *not* to have the adjustability.

ps - is there a recommended value for the idle pulse width?

[Minami Kotaro]

I was going to say you ordered the wrong one, but ...

... when I ordered mine, Summit sold two versions: MSD-2222, which was non-vacuum-referenced, and the MSD-2222A, which was.

Now they only sell the vacuum-referened one under the MSD-2222 part number.

Huh.

[ecotec88fiero]

You will always want a rising rate FPR when you are putting the intake tract under pressure. Otherwise your injector's will not be injecting the amount of fuel they are rated for since the pressure ratio between the fuel pressure and the atmo. pressure are different than what they were tested at.
1:1 rise is perfectly acceptable and what most good tuner's will use.

[aero]

You will always want a rising rate FPR when you are putting the intake tract under pressure. Otherwise your injector's will not be injecting the amount of fuel they are rated for since the pressure ratio between the fuel pressure and the atmo. pressure are different than what they were tested at.
1:1 rise is perfectly acceptable and what most good tuner's will use.

I believe that a 1:1 regulator is what is called a boost referenced or boost compensating regulator. A rising rate is an FMU 12:1 ect. Thats just the way I've understood it.

[PSIG]

... ps - is there a recommended value for the idle pulse width?

Not really. You just lose adjustability and resolution as you approach your injector opening time. When you're so low on PW that the next step in injector time is a 10% jump, things can get kind-of sloppy.

You will always want a rising rate FPR when you are putting the intake tract under pressure. ...

Hi ecotec88fiero, welcome to MegaSquirt! You're correct in a basic sense and - not to detract from your good point - but let me rephrase so others who read this later avoid any confusion.

MS doesn't care if you are boosted or not. All it knows is that the pressure goes up - on some engines to about 100kPa and others more. So long as you tell MS what to expect for pressure it's happy. Therefore, for best operation, a manifold pressure referenced fuel pressure regulator is the best choice for MS boosted or not. You can tune around a non-MAP-referenced FPR but it is not recommended as a planned measure.

Also, as the term blow-off valve has had it's meaning changed in racing circles over the last 20 years, so has the term Rising Rate Regulator. MS wants a 1:1 ratio change of fuel pressure with manifold pressure changes across the entire range. So, if the MAP goes up or down 1 unit (PSI, kPa, "Hg, etc.), the fuel pressure does too. The RRR generally means that the ratio of manifold pressure to fuel pressure increases along with the MAP, increasing to (example) 7:1, giving 7psi fuel pressure increase to every 1psi MAP increase. Not good for MS. Be sure you have the correct type - whatever it's called.

David