anybody using an adjustable fuel pressure regulator?
Thread Starter
Heel & Toe
Joined: Feb 2003
Posts: 20
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From: Greenfield IN
anybody using an adjustable fuel pressure regulator?
I have read that increasing to 50 psi works well. What about the addition of 24# injectors also. My engine is mostly stock. Only minor air mods.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: anybody using an adjustable fuel pressure regulator? (Jet Mech)
An AFPR is very useful in increasing fuel flow at WOT to match increased air flow resulting from mods; the ECM will maintain correct air/fuel at part throttle using O2 sensor data. To some extent increased fuel pressure can aid atomization of the fuel spray to improve combustion efficiency.
With only minor mods larger fuel injectors won't help power output and usually aren't needed until the capability of the stock injectors has been exceeded by serious air flow mods.
With my mods I run 48psi and my air/fuel at WOT is close to 12.6:1 which is close to ideal from a power standpoint. So, 50psi with stock injectors and less air flow would likely be too rich.
With only minor mods larger fuel injectors won't help power output and usually aren't needed until the capability of the stock injectors has been exceeded by serious air flow mods.
With my mods I run 48psi and my air/fuel at WOT is close to 12.6:1 which is close to ideal from a power standpoint. So, 50psi with stock injectors and less air flow would likely be too rich.
Racer
Joined: Nov 2001
Posts: 303
Likes: 0
From: Wichita Ks
Re: anybody using an adjustable fuel pressure regulator? (Jet Mech)
I have found that the stock l98 likes to be about 49-51 psi
with the fuel pump on-eng off.
If you are runing in the lower 40's with the stock puel press reg
then you will feel a hp increase. If you are running in the upper 40's
then save your money. The stock spec. for this eng is 41-49 psi.
with the fuel pump on-eng off.
If you are runing in the lower 40's with the stock puel press reg
then you will feel a hp increase. If you are running in the upper 40's
then save your money. The stock spec. for this eng is 41-49 psi.
Thread Starter
Heel & Toe
Joined: Feb 2003
Posts: 20
Likes: 0
From: Greenfield IN
Re: anybody using an adjustable fuel pressure regulator? (65Z01)
Thanks for your responce. I intend to do more on down the road with the intake system. Just thought that a AFPR to start would be good to trim fuel pressure as I go.
Also looking at a Hypertech performance chip to boot.
Also looking at a Hypertech performance chip to boot.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: anybody using an adjustable fuel pressure regulator? (Jet Mech)
For sure get the AFPR and a fuel pressure gauge. Initially set the fuel pressure to the current value at idle with the vacuum hose off and plugged. Then tweak pressure for best power at WOT.
I tried a used HyperTech Stage II chip and recently sold it to a Froum member for my e-bay purshase price of $50+shipping.
Save your $$ and put them into air flow & temp reduction mods, like exhaust, intake, thermostat, TB coolant bypass, cut-back spark plug electrodes and the like.
Your L98 will respond well to exhaust mods: 2 1/2" mandrel-bent front Y, hi-flow cat and good cat-back, some of which will cost about what that chip would have and be far more beneficial. Don't bother with LT headers till you get to cam & heads; you can do a little cleaning & porting on the stock shortie headers.
I tried a used HyperTech Stage II chip and recently sold it to a Froum member for my e-bay purshase price of $50+shipping.
Save your $$ and put them into air flow & temp reduction mods, like exhaust, intake, thermostat, TB coolant bypass, cut-back spark plug electrodes and the like.
Your L98 will respond well to exhaust mods: 2 1/2" mandrel-bent front Y, hi-flow cat and good cat-back, some of which will cost about what that chip would have and be far more beneficial. Don't bother with LT headers till you get to cam & heads; you can do a little cleaning & porting on the stock shortie headers.
