School me on adjustable fuel pressure regulators

[burkey001]

Hi,

I am wanting to run an aftermarket fuel pressure reg, partially because my OEM one is possibly suspect partially because I'd like a little tuneability.

-Engine is an S50B30 euro motor.
-Fuel system is OEM main tank w/ in tank lift pump to 1/2 gal surge with bosch 044 HP pump.

I have a bunch of Magnafuel stuff already, filter, fittings etc and I would like to run Magnafuel reg in the boot next to the surge tank. I would remove the reg on the fuel rail and cap the vacuum line.

Per Magnafuel site I see two main types of reg available, a regular EFI one and a "1:1 boost reference" one. Now its pretty simple to assume I'd want the regular EFI one, which I presume is a rising rate FPR.

Question(s) is(are);

• what sort of rising rate do I want / need? I see various brands offer different curves... is one better than the other? under what circumstances?
• Anyone know what the std FPR does w/ regards to pressure increase v vacuum?

thanks
burkey

[jlevie]

Although it would be the more expensive option, I'd keep a fixed pressure regulator and tune the engine via the DME, even if that means going to a MegaSquirt. When using a stock DME you will wind up fighting the DME's built in desire to run the engine at 14:1. That and the ability get fin grained control over fuel mean that tuning is more effective.

[nando]

there is no reason to use an AFPR. also, you always want a 1:1 rate, unless you're doing the band-aid boost setup with a RRFPR.

it's definitely better to change the tune and leave the base pressure alone.

you live in the land of cheap standalones - I wouldn't even consider a RRFPR in your case.