Fuel pressure regulators

[panel]

Just trying to see what everyone's running and at what base PSI you are running and also if boosted or not and also if it's got a vacuum line connected to the manifold etc.If turboed is it above the throttle plate(s) or below ?

Also if your base PSI is 43.5 is this with the vacuum line connected or disconnected

Quote from 034 Motorsports:

MAIN FUNCTION

A FPR's main function is to maintain a consistent pressure differential across the injectors and the intake port pressure. What causes fuel to spray out of the injector and into the intake port is the fact that pressure is higher inside the injector than inside the intake port. For example, if base fuel pressure desired is 43.5 psi (a very standard 3BAR), then in order to deliver a consistent flow of fuel to the engine, a pressure differential of 43.5psi must always be maintained.

What this means is that during vacuum conditions, the manifold reference will actually lower fuel pressure as the intake is literally trying to suck the fuel out of the injectors. Under boost conditions, fuel pressure will be increased at a ration of 1:1, again, to maintain the reference, thus under 10psi boost, gauge pressure will be 53.5psi but the actual differential will still only be 43.5psi.

This is the most misunderstood function of the EFI bypass regulator, if you can wrap your head around this concept you'll understand the function of this part.

From the Sym Tech Lab site:

What kind of fuel pressure regulator should I use?

There are two main options, an adjustable 1:1 regulator and a standard static regulator.

The 1:1 regulator is the best choice for turbocharged vehicles as it increases the fuel pressure by 1psi for each 1psi of boost pressure. This feature balances manifold and fuel pressure which creates more headroom. You can also alter the base fuel pressure to perfectly dial in your fuel injectors. In other words, “you’ll get more out of your injectors.”

Adjustable fuel pressure regulators in other ratios (4:1, 10:1, 12:1, etc.) aren’t recommended.

Static regulators are best suited for naturally aspirated vehicles or turbocharged ones with low power goals (~300whp or less). Since they’re not adjustable and the base fuel pressure cannot be lowered, very large injectors are somewhat more difficult to control at idle. Also, since they don’t increase fuel pressure, less fuel will flow into the manifold for a given injection unit while in boost.

[miniman82]

I set mine to 45 PSI, vacuum line removed and plugged. This is on the 1915 turbo, reference is from the manifold though I want to try plumbing it to the compressor.

[panel]

Just found this while researching.

http://aeromotiveinc.com/2010/01/advanc ... -pressure/

[Steve Arndt]

3 bar 43.5 psi, vac line on regulator open to atmosphere.

Do not plug the reference line on the regulator. If you go up or down in altitude or barometric pressure the regulator needs to know this to maintain static pressure. If you plug the line, it will hold air pressure in the line.

I also learned recently that it is wise to run a length of hose from the regulator reference down and away from sources of heat. If the rubber membrane in the regulator is compromised it will leak fuel out the reference line.

[miniman82]

Do not plug the reference line on the regulator.

You plug the line when setting base pressure, if you don't you have a vacuum leak that throws off the setting. Once you have base pressure nailed down, you reconnect the line. This is standard procedure for the regulator.

[Steve Arndt]

When running the pressure regulator referenced to atmosphere do not plug the reference line, just run the hose down to a safe area in case the diaphragm leaks. . You weren't clear what you plugged. Obviously you don't want a vacuum leak. This applies to atmosphere referenced setups.


s

[miniman82]

You weren't clear what you plugged.

I thought I was pretty clear.

vacuum line removed and plugged

I figured it was common knowledge, but I guess it's not. I don't know anyone who doesn't reference the regulator to manifold pressure, it gives much more flow when under boost.

[Munchhausen]

If you dont connect you reference line to manifold you would need a very high base pressure to get enough out of your injectors specialy at boost. If not connecting reference line you decrease your injector size while increasing boost. Thats counterproductive.
Why so many people running static fuelpressure, speacialy in boosted application? Dont see any advantage.
Please make me a little smarter and tell me why.

munch

[Steve Arndt]

Lots of people run the regulator referenced to atmospheric pressure instead of map. That isn't the point of Panel's post. Keep it on topic. If you run ITBs with wild cam duration it works much better to have the FPR referenced to atmosphere. The fuel pressure will mirror the wildly oscillating map signal.

[miniman82]

Yes, but even with wild cams there are ways around it. That's why the megasquirt manual mentions vacuum accumulators, to smooth out the signal.

[Piledriver]

(Edit) I PERSONALLY found that It's far easier to get a decent tune NA with the atm referenced reg and a rock stable pressure, esp accel.
(assuming your injectors are sized so you can still idle at full pressure)

You can have the best of both worlds with a simple check valve off the manifold and small calibrated leak at the reg.
Under boost, you get your 1:1 rise.
Off boost, stable pressure.

[Redline Weber]

First: NEVER plug the Vacuum Reference (BARO Ref)

Be safe, if in open air vent AWAY from exhaust (sparks & heat) by a hose.

Second : BOOSTED engines SHOULD have the regulator pressure reference ABOVE the Throttle Plate
when the Injector Outlet is ALSO above the Throttle Plate.

The fuel pressure "base" adjustment is to the "order" of the injector used.

MY method is to bench test an injector BEFORE first sold, or by MY design at the time of engineering. (testing too done)
Observation in operation & Scope measurement in operation can determine best static pressure.

Third : BARO correction slope (EMS) will change with Vac Reference location (NPC/PPC)

Lance, BTW what Javad states is VERY correct.

[panel]

BTW what Javad states is VERY correct.

Who is Javad ?

Also......

Second : BOOSTED engines SHOULD have the regulator pressure reference ABOVE the Throttle Plate
when the Injector Outlet is ALSO above the Throttle Plate.

Aren't most boosted set ups with the 'Injector Outlet' below the throttle plates though?

Mine seem to have a lower than norm PSI rating:

BOSCH NUMBER LBS/HR CC/MIN GRAMS PSI BAR

0-280-150-803 37.1 389.9 280.5 39.15 2.7

[Steve Arndt]

Javad is the owner of 034 Motorsport. Partner in some ways with Redline on the ECU development, just different markets.

[kangaboy]

Reviving old thread.

Are there any modern cars that will likely be in my local Pick-n-Pull that will have a plug-n-play fuel pressure regulator?
I'm planning on using the fuel pump from a E150 Ford, assuming i can find one of those in the junk yard as well. Or something from a Volvo or the like.