Caspers Adjustable Fuel Pressure Regulator

[jsos431]

I know I asked this before but it was awhile ago and I didn't get many answers. I know people bought the fuel pressure regulators and put them on and I am wondering if it was a good investment. On pfyc.com they say you should do this mod if you changed your exhaust and intake which I did both. Please tell me what you all think. Thanks

[jaketuff]

People have claimed to feel more top end with the AFPR.

When you add the intake and exhaust to the car you allow more air to flow thru the motor. This increase in air flow slightly leans the fuel mixture. That means there is slightly more air in the Air:Fuel ratio than stock.

The computer in the car can only adjust fuel output to a point. When you surpass that point the car will starve for fuel. The computer leans back at higher RPMs (lean is a better condition for building HP, rich - more fuel, is for torque, lower rpms), and at mid to high range WideOpenThrottle.

At WOT the car will run the leanest. So to be safe, people have bought the afpr and increased the pressure to force more fuel flow. This is very effective to cure a lean situation when you only have a few mods that add big airflow.

When you begin adding major boost, lots of headwork, big shot N20 you need to really up the fuel pressure or even switch injectors so that the car doesn't starve for fuel.

*If you starve the motor for fuel it will break apart. But with a CAI and exhaust along with the stock fuel system you are very safe from having that happen.

-Summary... if you plan on doing nothing more to mod the motor then the AFPR is not likely to benefit you much, if anything.

JOUT

[Irate]

Couple questions...

How adjustable is the FPR? Will I notice a difference in my gas mileage? Will it raise the pressure universally over the entire RPM band, or will it raise it differentially? Some pictures of it on the car would be nice for those people who have one...

[jaketuff]

Originally posted by IrateGT
Couple questions...

How adjustable is the FPR? Will I notice a difference in my gas mileage? Will it raise the pressure universally over the entire RPM band, or will it raise it differentially? Some pictures of it on the car would be nice for those people who have one...

Adjustability depends on the model... The AFPR from PFYC, I believe it can go as high as 48psi.... good for a slightly modded ride. Anything heavy as mentioned above you will want 60psi+.

You will decrease your MPG, but only SLIGHTLY with the PFYC AFPR.

The increase in fuel is universal, throughout the RPM band. PFYC, says higher RPMS. That is where you need it the most, as the car runs its leanest there.


(This is the Picture from PFYC.com, via gagt.com?) As you can see it is larger than the stock regulator. It still mounts up in the same location however.

Pat

[jsos431]

I plan on getting the bigger throttle body and gasket matching the plenums. Then headers in the near future. So should i get it? THanks for the replies.

[gagt2001]

jaketuff,


i was wonderin i have the tog headers,intake,exhuast,180 t stat,tps,and fpr what do u suggest runnin at wide open throttle.
stock at wot i think it was around 57 at least thats what my gauge recorded. i have it at 60 wot now just wonderin if its ok and not hurtin the car.






thanx alex

[jaketuff]

Originally posted by jsos431
I plan on getting the bigger throttle body and gasket matching the plenums. Then headers in the near future. So should i get it? THanks for the replies.

When you get the headers it amy be very helpful. Aside from that you can wait. There is not a major benefit to be had from the porting/matching of the plenums. The TB will provide decent gains however, the APOC TB that is, not those ported-out models.

Headers will allow you to flow through more air... and will necessitate some increased fuel for the best performance. But no major "lean" condition will develop even with the headers, just to optimize - do the AFPR and add fuel.

JOUT

[jaketuff]

Originally posted by gagt2001
jaketuff,
i was wonderin i have the tog headers,intake,exhuast,180 t stat,tps,and fpr what do u suggest runnin at wide open throttle.
stock at wot i think it was around 57 at least thats what my gauge recorded. i have it at 60 wot now just wonderin if its ok and not hurtin the car...

thanx alex

It is difficult to say "it's fine" without really hitting the Dyno or using an Autotap when you are seeking to perfect the mixture. It is very hard to determine the best mixture even within a large standard deviation otherwise, unless you closely, and accurately monitor the ratio. The popular Autometer Phantom (et al) guages are not as accurate as they may seem, consider them (cheap and) good looking, but not the best for the job. You need to get a very solid guage to determine the ratio (At least $100).

You could try turning up the pressure and time your WOT runs from zero and see if that makes anymore power for you. You will notice that the car will be TOO RICH on the topend if you see black smoke coming from the exhaust... I doubt you could ever get it that rich though with the AFPR. Even when you do this the benefit of adjusting the ratio is difficult to determine because each run must be VERY consistent. Unless mixture is drastically changed.

So, in conclusion I think you are okay, the car is not wasting much HP. But to make it the best it can be -
1. Get a bung placed into your downpipe so that a wide-band 02 sensor can go in and exactly read the ratio, do this BEFORE the cat, in the downpipe.
2. Hit a cheap dyno, one that will also read the Air:Fuel ratio with a wide band.
3. Tune the AFPR in for the most HP/Lbs-ft, just like on Horsepower TV.

Pat

[gagt2001]

thanx for the quick responce jaketuff

[phantom505]

Thanks for the good info. What is a good pressure to start with assuming the following are install: APOC CAI, 62mm TB w/ported upper, TOG heads, and a Borla catback? (And I did have the pipe between the cat and the resonator wided to 2.5" which I think is of little consequence)

As you may have read I'm a high altitude and I assume I run a bit richer than most people would normally.

So without having access to a dyno... what would be a good start?

[phantom505]

I just installed it and left it at 45psi, good enough until I can get to a dyno (one of these days).

It defineatly helped with the top end. I'm not sure if that is becasue of the headers or not, but it is nice.

[gagt2001]

45 at idle ?

[phantom505]

45 at idle with the vacuum off like the intruction said, which I assume means the TB will go to WOT

[Mystery8]

wow 45 is kinda low isn't it?

Mine stock is running 58, that's straight info from the shop guys after they blew up my first one.

I have yet to install the AFPR though...You sure it's at 45??

[phantom505]

I should hope.... the pyfc.com instructions/sales says that the stock is only 40 psi and that the AFPR is good to 48. That is taking the measurement from the passenger side of the engie next to the alternator.

[Mystery8]

did you hook up the gauge to the schrader (sp) valve?

maybe my shop guy was way off! I mean, he only blew up my caspers and all...i'm sure he can't be that bad.

[phantom505]

Whatever you call that relief valve on the back fuel rail. Just look at the pyfc.com insturctions.

[sprytown-gt]

Is this part still avable.

[PhantomLover007]

Damn... 7 yrs ago????

If you're trying to buy one check PFYC.com.

[Nick-G]

http://wot-tech.com/shop/all/3100-/-.../prod_135.html

It's not the caspers one but pretty much the same thing.