LSs1Power

iTrader: (5)

I can't find a good 2:1 Fuel Pressure Regulator. Anyone using one? Im thinking about running a 2:1 FPR with the 96lbs injectors on a stock PCM so we can start around 30psi of fuel pressure and let it go up to 60-66psi with 15-18psi. The idea is to make the 96lbs injectors idle as best as possible.

V6 Bird

iTrader: (15)

I dont think ive ever seen one. I know of 1:1 which im pretty sure you are looking for but maybe not...A good 1:1 would be all you would need with those injectors anyhow to about 1200 hp. Let me know if Im wrong. Id like to look into the 2:1 if they do exist.

LSs1Power

iTrader: (5)

I have a 1:1 already.

Zombie

iTrader: (2)

What you want is an FMU. I have a really nice one that I never used, but it's 1/8 NPT fittings. You want 1/4 NPT.

http://www.cartech.net/fmu2020.htm

LSs1Power

iTrader: (5)

The link doesnt work for some reason.

smokinHawk

iTrader: (48)

works for me.
interesting product.

Fire67

iTrader: (3)

Why would you want to do this? Will the 96# injectors not supply enough fuel on their own w/ a std 1:1 regulator?

If thats the case, raise base fuel pressure and adjust with the pcm.

It would be interesting getting the pcm to get along with an FMU increasing the static flow rate of the injector as boost comes up.
Besides, FMU's are a bandage for people trying to run boost on a stockish motor with stock PCM programming.

LSs1Power

iTrader: (5)

The 96lbs can supply all the fuel I need with 60psi+ of fuel pressure, but the point of the 2:1 regulator is to run a very low FP on the 96lbs injectors something like 30psi to make it idle good and then increase the the fuel by 2:1 so I can get close to 60-66psi of FP at redline to supply me with the fuel needed at 15-18psi.

If i run the current 1:1 I only can run 45psi as the lowest FP and then it will only go up to 60-63psi at redline. The car won't idle as good down low and I will be limited to how much fuel i can get up top because im only seeing 15-18psi.

Ping King

iTrader: (20)

yea an FMU sounds like your best bet. Have you noticed any tuning problems with the 96# injectors with the 1:1 FPR?

thats what my setup basically is, but i havent really had enough time to mess with it

Old Geezer

iTrader: (3)

At 30# FP, the spray pattern will be less than desireable. [Not "pretty" to start with] .That would not enhance idle quality.

black98ws6ta

iTrader: (77)

Exactly, reducing the fuel pressure much under 42 psi will only result in worse quality. Id put it at 42, and reference 1:1 from there. If you cant get the 96's to idle good something is wrong, and if it idles at 13:1 sometimes you have to give soemthing up for a 1000 rwhp capable injector.

kp

iTrader: (34)

Spray pattern or not at very low pulsewidths changing the fuel pressure wont make that much of a difference.

I can go from 30 to 70psi at idle and the a/f hardly changes (i run open loop at idle).

Schantin

iTrader: (6)

Read the link. Nice piece, but what would be the advantage over a fuel pressure regulator? Both would require having a return system, and both raise fuel pressure based on increasing manifold pressure.

I personally have an Aeromotive that's hooked via a nitrous plug directly into my INTAKE. This way I'm at 58PSI till boost kicks in, then it's a 1:1 increase from there. It's making the tuning process much easier than having it drop below 58PSI at vacuum and then spiking over at 1bar MAP.

Anyhow, interested in opinions why FMU over FPR.

Fire67

iTrader: (3)

Remember that although FP is increasing with boost, your injectors will not flow more. The 1:1 increase in pressure is meant to keep the static flow the same, when the fuel has to fight boost presssure to exit the radiator. So if they wont flow enough at 45psi for you than you have to refigure some stuff. 1:1 keeps static flow constant when manifold pressure increases.

Let the PCM control fuel via pulsewidths, FMU's are bandaids for the people who wanna do FI but cant afford to do it right.

Fire67

iTrader: (3)

Yep, because the pcm is in control of A/F and will adjust on its own. You lower FP, the pcm increases pulsewidth and vice versa.

LSs1Power- We see what your trying to do, but your going about it wrong. You need to set base FP to get your total desired flow, let the 1:1 reg compensate for manifold pressure, and let the PCM do its job of controlling fuel.

By my experience as well as a few others, FMU's are inconsistant and flat out unreliable. Fuel systems are not meant to gradually increase flow on there own, they should always rely on the PCM to regulate flow via pulsewidths.

onfire

iTrader: (17)

Not in open loop. Ya get what ya get.

kp

iTrader: (34)

Actually not, a BS3 in open loop doent control anything

It just seems (at least on my car) at very low pulsewidth fuel pressure doesnt make a huge difference in idle afr. I'l leave the explanation to the engineer types

stevieturbo

I would tend to agree with Old Geezer too.

KP...weird that you can alter your fuel pressure so much, withouth changing AFR's

Even a 10psi change in my FP, will show an easily noticeable change in AFR's at idle.

kp

iTrader: (34)

Dont know really, I was doing it with the low-z 75s. I was just playing around one day and was trying it and was pretty surprised. Thast why I dont even boost reference anymore. It may have changed .25:1 a/f but nothing drastic.

Fire67

iTrader: (3)

Didnt think of open loop... But my point was that altering FP for idle quality shouldnt be done, rather the pcm should be able to handle it with proper tuning.

kp-
You wouldnt happen to have a copy/screen capture/anything of what your injector offsets looked like with the 75's would you? A .bin would be nice, but I most likely wouldnt be able to open it as I use LT1edit.