Iroc_Z28

I was just wondering what the a.f.p.r. done for performance i understand you can adjust the pressure with it but what does it help if you are running stock injectors that are say 22# ...i was just wonderin if someone could explain this to me...any help is appericated thanks

freeze92

The AFPR controls the pressure of the fuel going to the injectors. The advantage of being adjustable, is that you can tune the engine to match some moderate performance mods you may have done. The #22 pound on injectors refers to the amount of fuel that injector can flow in one hour, at a set constant pressure. Your computer adjusts the amount of time your injectors are open to control the amount of fuel entering the engine. An adjustable fuel pressure regulator allows you to raise or lower the amount of fuel entering the engine in the amount of time the computer tells the injectors to open, therefore adjusting for mods. Someone else might be able to describe this better, but that is the basics.

rondubbs

by increasing pressure the fuel gets atomized better , therefore creating more hp.
and more mpg.

JETHROIROC

The amount of fuel delivered by a given injector is a direct function of the time it is open (called injector pulse width sometimes), and the fuel pressure. Increase pressure and hold pulse width constant = more fuel, increase pulse width and hold pressure constant = more fuel. Changing the fuel pressure regulator will not change the injector pulse width, but it will still cause the injectors to squirt in more fuel because it is under higher pressure. And the atomization thing is true also. Hope this helps!

90Iroc

In my 1990 Iroc, what kind of pressure should be run through the 305 TPI with an AFPR? It has a complete MSD ignition and flomaster exhaust with gutted cats, and Ed Wright stage 2 performance chip and 160 degree thermostat, and JET air filters. These are the basic power adding mods to my car, the other mods are free mods, that I don't really know add up to give any potential gain in performance.

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"Clear your mind, relax, and float downstream."

rondubbs

90iroc,
i'd say to see what your stock setting is. then bump it up 2 psi. you need to get a fuel pressure gauge to measure this. 48-50 psi is good for modded 350s.. so dont go that high.

Iroc_Z28

ok guys so what is the best a.f.p.r. to get and are they hard to install..

rondubbs

do NOT get the tpis afpr.. the vacuum port breaks off very easily.
they are simple to install , just have to take off the plenum(8bolts). while the plenum is off , you might as well do the mat relocation. and doing the tb coolant bypass will allow you to keep the tb on the plenum when you remove it.
make sure the afpr you get has the t10 security type torx bit with it.

MINT1982CFI

I disagree about the TPIS a.f.p.r.;
I bought mine a while ago from them, and that thing is quite strong. I don't see how one could break the vacuum port unless they applied quite a lot of force to it.
I've got a 305, with basic Intake and Exhaust mods (catback, K&N, ram air) and my car came from the factory with the PSI set at 42. I set it to 48, and the thing screamed from then on.
It makes a neat sound around 82mph too,

Take Care

90Iroc

I do have an AFPR from JET. I think I set the pressure to 49 psi. Should I bring it down some? My stock setting was low, it's at the bare minimum of the scale the diagnostic books give. 39 psi I believe. Oh, by the way, the JET piece doesn't come with the security torx bit, I had to wait and find that surprise after I had everything taken apart. But the JET AFPR is a nice piece.

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"Clear your mind, relax, and float downstream."

[This message has been edited by 90Iroc (edited October 10, 2000).]

Tuned Performance

iTrader: (92)

TPIVette

I'm sure you're service is great.............I'm just not sure why you're bumping every 14 year old thread you can find?

Abubaca

iTrader: (3)

On a stock or nearly stock TPI set up, there's no real need for an AFPR. I completely agree with the higher pressure leading to better atomization, and it's certainly worth a very small minimal bump, but nothing you'd ever feel. When you've upgraded every last piece in search of every last bit of power, then sure, but until then it's not worth it. As for additional fuel, again, technically yes it CAN be used to fine tune, but again, nothing that's really necessary. If you NEED a tune, then get a tune, not an AFPR.

I think that if you already HAVE one, and you know what it does, how it works, then by all means, use it as another tool to help fine tune your car. If you DON'T have one, then I wouldn't go get one.

Vader

FWIW, it is also very easy to convert the stock FPR to an adjustable type.

formula forever

Im adding one this week. Just so cold here in chicago

cruzplcs

I got a question does anybody know why my car have a hard start up I have to press on the gas to keep it on and when it warm up it has a high idle I just installed some 24lb fuel injector and now it runs like **** it's a stock engine i think I just need a adjustable fuel pressure regulator or the prom and ecm need to be tune? What's the cheapest why to fix this? It's a 1988 Chevy camaro iroc z28 5.7

aliceempire

iTrader: (14)

I don't know about the cheapest way but the correct way is to have a prom burned for that size injectors. Or put the size injectors the prom currently is programmed for.

greenyone

iTrader: (1)

I'd suggest the Holley AFPR. Simply because it has a nice big adjustment wheel instead of a screw. So it's real easy to adjust by hand, instead of trying to fit a tool under the plenum to get at a screw.

foxxtrot82

I know this thread is getting some age, but my l98 SD has a holley adjustable fuel regulator. As low as I can get the pressure is 44psi vacuum line on and 54psi vacuum line off when the car is running. I have 24lbs used LT1 injectors, not ideal but they were free when the originals quit. The car runs great at wot. Don't have anything to compare to and see if the car actually runs better. The car sat for 4yrs until the problem was finally found. The car doesn't smoke when cranked or revved up high. Splash guards are removed, air foil, k&n filter, slightly better exhaust, super chip, 160 thermostat. There is a slight idle quality after warmed up, but the driveability has never been better when compared to before.

Hotrodp38

So If one wanted to put an afpr it would go on the return line? Tpi of course

Abubaca

iTrader: (3)

It replaces the stock, NON adjustable regulator between the two fuel rails, towards the back of the TPI.

Tuned Performance

iTrader: (92)

A aftermarket non tpi specific yes on the return line. You would need to modify the rail return or make a block off plate and remove the tpi fpr.
You can also use a front crossover tube on the rear.



3/4 npt





The return was blocked 1/4 npt tap after drilling to 7/16.