Hey everyone, i was wondering if getting one would help with a little performance gain on my 305TPI. I have Edelbrock TES Headers, w/a AMT Catback. How exactly do you use the AFPR and which is a good one to purchase?

 

AFPR

Located about halfway down.




A: The stock setting is 42 PSI. Much track testing has showed that any type of increase will greatly benefit both horse power and torque. Here's some dyno testing on a stock 350 motor which substantiates those claims:

42 PSI (stock) 46 PSI 50 PSI
RPM Torq HP Torq/diff HP/diff Torq/diff HP/diff
------------------------------------------------------------------------
2250 237.7 101.8 254.9/17.2 109.2/ 7.4 275.0/37.3 117.8/16.0
2500 241.7 115.1 262.1/20.4 124.8/ 9.7 283.3/41.6 134.9/19.8
2750 241.5 126.5 275.2/33.7 144.1/17.6 297.0/55.5 155.5/29.0
3000 237.1 135.4 278.2/41.1 158.9/23.5 305.5/68.4 174.5/39.1
3250 233.8 144.7 278.9/45.1 172.6/27.9 311.3/77.5 192.6/47.9
3500 241.0 160.6 278.2/37.2 185.4/24.8 309.5/68.5 206.3/45.7
3750 246.6 176.1 283.4/36.8 202.4/26.8 303.3/56.7 216.6/40.5
4000 250.4 190.7 278.3/27.9 212.0/21.3 298.0/47.6 227.0/36.3
4250 251.6 203.6 272.5/20.9 220.5/16.9 289.1/37.5 233.9/30.3
4500 253.5 217.2 257.3/ 4.2 220.5/ 3.3 277.0/23.5 237.3/20.1
4750 245.0 221.6 242.1/-2.9 219.0/-2.6 266.4/21.4 240.9/19.3
5000 227.6 216.7 225.0/-1.4 214.2/-2.5 237.8/10.2 226.4/ 9.7

It shows that by increasing the fuel pressure to 50 PSI, results in maximum torque increase of 58 ft-lbs (along with a much flatter torque curve) and a maximum horse power increase of 19 HP over stock. 46 PSI also provides a noticable increase which should work well for day-to-day street driving. An adjustable fuel pressure regulator (see Chap 5.2) is required to increase the fuel pressure.

 

Thanks, it's exactly what i was looking for. Any suggested AFPR to pick up?

 

-nikh23


They all are pretty good. Ive never used any so i cant tell you.

 

Thanks.

 

I would recommend a Holley APFR, you can adjust the FP by hand instead of using a wrench. I had to add three small washers for the bottom 3 screws so that I the screws would be tight, and I had to take a little metal off the side so it would fit properly. Once that was all done, it has worked well in the year and a half I've had it on.

 

Thanks, i'll be getting the Holley one then.

 

I've had fairly good luck with mine. Being able to adjust by finger is not a concern to me. Once the pressure is set correctly for the programming and setup, it should never need adjustment.

Mine was about $1.35. It may be as high as two dollars now, with inflation:

AFPR Conversion.pdf

 

Vader, i have asked a few people before but no one has answered my question.

About what MAX FP is possible with a DIY pressure regulator?

Thanks

 

If u can duplicate what that chart shows for a simple fuel pressure change, I will eat my shorts and bow to TPIS.

lol

I can promise u that will not happen, not now, not ever.

Advertising is great isnt it?

later
Jeremy

 

I believe it but......it is an illusion. You can say stock 350 and let the court open for ALOT of variables. ie. Stock 350, AFR heada? Stock 350, XE274 cam? Stock 350, 12:1 CR? and etc. etc. etc.

 

Where can i get most of the items? From home depot? I'll try this 1st. It wouldn't hurt. What is the max psi you can set the dyi with?

 

Sorry 91gta, you just asked that question.

 

I have asked it SEVERAL times yet i still wait on a answer.

 

I don't think you can gain hp with the only variable being increased fuel pressure either. I am interested in increasing the fuel pressure to get the most out of a set of injectors though. I wonder what the safest amount you can run is? I have the Holley AFPR.

 

I'm about at 50 PSI with vac without it's like 55-57 my car seems to like that better then that recommanded PSI everyone says. I don't even need to drive it to tell, i just kick open the throttle and it revs much faster then the recommanded and sounds just flat out stronger .it kinda has me thinking i might have 19lb injectors rather then the 22lb that vettes normallyl come with, my chip is setup for the 22lb so this might be whats goiing on my end?

 

Most injectors are advertised at 43.5 PSI, so if you up to 50 PSI it is like you are running larger injectors. www.racetronix.com shows you how much they flow at 43.5 and at 58.0 PSI.