adjustable fuel pressure regulator

[Teds89IROC]

based on my air/fuel ratio on my dyno chart, think I should pick up an afpr? or even for the fact that I have some slight mods done to the car.



~Ted

[Batman]

You could but that A/F isn't too bad for a mostly stock car. You might gain 10 HP by bumping up the gas a little, but a lean car makes more power, but you are a little too lean if you want to race it. Not sure what a TPI motor likes but I know that an LS1 likes about 12.5:1 air fuel (give or take a little). Either way an AFPR is a good investment.

[Teds89IROC]

I was just seeing how during my peak power the fuel curve falls below the air and the perfect mix is at the end of my power band. It's also a stock pressure regulator, so maybe if it were replaced I wouldn't have that issue of it fluctuating like that.

~Ted

[Fozzi58]

I suggest you get it. TPIS makes one.

It made a WORLD of difference on my 87 TA. 305 TPI, 5-speed. Very noticable difference in power. May I also strongly suggest you get yourself a liquid filled fuel pressure guage and mount it inder the hood. Then you can see the pressure you are adjusting too. I set mine for 45psi when I was 'looking for trouble'. When I was done, I would drop it to about 28lbs. I was getting over 30mpg on the highway at that pressue and I had 3.73's out back, but the car chokes to death after 4300rpm.

[foff667]

you were at 12.5:1 at peak tq and 13.0:1 at peak hp...i wouldnt say thats very far off from where you should be on a dyno

[Batman]

Originally Posted by foff667

you were at 12.5:1 at peak tq and 13.0:1 at peak hp...i wouldnt say thats very far off from where you should be on a dyno

I agree, you won't gain much if anything but it doesn't hurt to have one. Do you need it, I don't think so, would it be a waste of money, again I don't think so, especially if you plan on more mods.

[foff667]

also they probably just used a tailpipe sniffer which will generally read a little leaner then it actually is...you might actually be right on target.

[Teds89IROC]

hmm, I see. I do plan on more mods, but nothing too extensive yet. I dunno what to do about this.

~Ted

[foff667]

personally id talk to jon prevost and see what he has to say...your a/f is so close to being perfect right now personally i would say no at least for the time being...but then again they are only like $50 and a very easy install...just leave it at the factory setting though.

[Teds89IROC]

do you know jon's s/n?

~Ted

[HardcoreZ28]

FasterThanYou is his screen name. I agree with leaving it for now.

[Teds89IROC]

ok, thanks guys. Maybe I'll invest that $80 from the holley afpr into some 5% tint for my rear hatch Then when more serious mods come, I'll get the afpr.

~Ted

[Fasterthanyou]

AFPR are for tools or people that can't afford larger injectors. I know that's harsh but I've got reasoning and no, I don't ACTUALLY consider you a tool, it's just me pushing a point without using curse words.
For only $40 more you'd have your burner and chip adaptor to retune your own chip controlling the AFRs based on RPM. An AFPR will only shift the WHOLE afr curve up or down. This is fine if you're just playing the dyno horsepower game. But for $40 why not have it so you can richen up the 4-5k range and leave the less than 4k rpm alone? Yes it's more difficult and takes more time than just turning the fuel pressure but it's a hell of a lot more fun when you don't screw up your cold starts .
I'd say you're near spot on with the afr but unless you try it either way you'll never know. I personally shoot for a 12:1 below peak torque and blend it into a 12.8-13.6 (depends on engine specific output) at peak torque and then back down to the mid to high 12's at high RPM. That's my start, then I try richer, compare the graph, then I try leaner, compare and make the required adjustments. I also isolate the timing because SA can hide a lot of horsepower if it's not utilized.