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Old 11-29-2001, 01:35 AM   #1
Scooby Specialist
Member#: 1997
Join Date: Jul 2000
Chapter/Region: MWSOC
Location: Des Plaines, IL
2006 Acura TL 6spd
STMGM6 alumni

Exclamation Fuel correction for high output NA(long)

I have been doing quite a bit of research on high output NA ej engines.

Specifically the ej25 putting out about and in excess of 200hp (That magical number... )

Thing is if you've been following the thread you know that the stock fuel system isnt upto the challenge of 200hp without going static. My car is exhibiting signs that its hitting the static limit. It acceration smoothly, stutters then as rpms climb it smooths out again ( fitting in line with the idea that the fuel system is okay, suddenly goes static resulting in a very rich condition, then leans out as the rpms climb again)

So what is the best way to fix this?

Start with the basics... 43psi stock fuel pressure with 280cc injectors. This gives us enough fuel for maybe the low-mid 190's before going static.

Running the BSFC calcs I found that 55psi fuel pressure will supply 200hp with a bit of room to spare (infact 50psi would probably do it)

Ive heard rumors that the ECU can compensate for upto about 25% more fuel pressure. Can anyone comfirm? This would be good for the closed loop mode at least. Open loop mode would be okay, but probably a bit rich.

First lets address with issue of raise fuel pressure on a NA car. Does anyone know if rrfpr's would work? I know the stock fuel pressure is referenced to the manifold pressure, but it seems that even the mildest ramp rate on the RRFPR would create a run rich condition. So what is the solution to raise fuel pressure in a NA car?

Ive read up on the Weapon R FPR.... reports are the gauge is inaccurate, and that they leak (apparently based on 6 units JC sports received a year or more ago.... only reference I could find)
$165 or so...

The Paxton FPR.... one mention on the boards, found the paxton site, but no mention of the fpr, the price or what it does. Saw a pic and it looks like the weapon R, gauge attached.

ISR carries a FPR for $199, functionality unknown.

Vortech make the s-fmu (that right?) for $300 (on site) that is a rrfpr with changeable plates. They have a fpr with only one plate that is considerably cheaper that still appears to be a rrfpr?

Cartech has several good rrfpr's for about $200. They also make a static FPR that appears to be more like what a NA car would need for $150ish. No real info on it though.

Seems a direct replacement for the stock FPR is what is needed. Any leads on the right equipment, or what works? (turbo guys??? you know fpr's!)

Can the ecu compensate the the extra fuel in closed loop, and what is the highest safe pressure to run the stock injectors? Ive heard stories about injectors sticking open above a certain pressure.

So Say we have the fuel pressure worked out. We need to tune the high end. S-AFC or hyper field fuel controlers seems to be the tickets. SAFC Ive found for $300 shipped. (groupbuycenter) and the hyper field... I know is cheaper, but with less adjustment.

Both of these should work fine in open loop.... exactly where they are needed.

Other questions. What fuel pressure is the stock fuel pump good to? Upgraded fuel pumps have a reputation for increasing idle fuel pressure to 50psi or so (up from 36ish) will a replacement FPR fix this?

Hopefully someone knowledgeable with exceeding the stock fuel system limits in a NA car can help out. Oh, and yes Ive searched extensively.
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