Fuel Pressure / Speed Density

UglyFast88 · 09-24-2003, 09:21 AM

Hey all,

I just pulled off my Holley FPR last night, because I couldn't get my car to run like it did with the stock FPR. The stocker reads 31 at idle, and 40 at WOT. (no vac) I tried everything from 30 / 39 to 38 / 47 on the Holley and the car just wouldn't run like it did before. (and now)

What would you recommend for fuel pressure & timing with the following mods?

'98 Explorer SB
GT40P heads (shaved)
Cobra upper
Ported Cobra lower
Cobra roller 1.7's
Stock SSV cam
Pullies
Flows
CAI

Car ran 13.11 @ 106 with my old, chipped up Pirelli P600's, with 1.9 60's.

It'll be well into the 12's with the new Nitto 555 drag radials that were slipped on the pony's last night.

What do I stand to gain if I can get it tuned with the adj FPR?

Thanks in advance...

Dark_5.0 · 09-24-2003, 09:44 AM

I would start at about 41psi and 16 degrees of initial timing.

Every car is different but thats where my car likes it.

UglyFast88 · 09-24-2003, 10:00 AM

Oops- I forgot and you reminded me.

I was also at 16* initial timing, and tried 14 and 15* also.

The car just didn't seem to have what it did before. Last night, I wento out with the Nitto's (since I had to try them) and with the Holley, at 44 / 37 I could chirp 2nd powershifting. With the stocker back on, they lit up for about 18." I guess I had too much fuel going to it.

I'm taking it to the track tonight with the tools to swap the regulator, and I'll try both, just to see.

Thanks, Dark- I'll try your readings and see how it works. How much difference in performance did you get from stock to 41 psi?

Dark_5.0 · 09-24-2003, 12:41 PM

I honestly couldnt tell you how much difference I got from changing fuel pressure other than If I bump it up to 45psi I get a better mph and a worse ET

stang_racer20 · 09-24-2003, 05:30 PM

stock fuwel pressure is 39 psi. do you have any mods besides the regulator. i would leave around 42-45 psi if not, but it all depends.

88workcar · 09-25-2003, 07:15 AM

Put the stock one on and leave it alone.

UglyFast88 · 09-25-2003, 10:38 AM

Thanks, Workcar. That's what I did last night.

I was waiting for your post...

Thanks again, all.

88workcar · 09-25-2003, 06:06 PM

No matter what I do my works best at 38-39psi.

09-24-2003, 09:21 AM	#1
UglyFast88 Registered Member Join Date: Apr 2002 Location: Fordland Posts: 117	Fuel Pressure / Speed Density Hey all, I just pulled off my Holley FPR last night, because I couldn't get my car to run like it did with the stock FPR. The stocker reads 31 at idle, and 40 at WOT. (no vac) I tried everything from 30 / 39 to 38 / 47 on the Holley and the car just wouldn't run like it did before. (and now) What would you recommend for fuel pressure & timing with the following mods? '98 Explorer SB GT40P heads (shaved) Cobra upper Ported Cobra lower Cobra roller 1.7's Stock SSV cam Pullies Flows CAI Car ran 13.11 @ 106 with my old, chipped up Pirelli P600's, with 1.9 60's. It'll be well into the 12's with the new Nitto 555 drag radials that were slipped on the pony's last night. What do I stand to gain if I can get it tuned with the adj FPR? Thanks in advance... __________________ '88 Speed Density LX 1998 Explorer motor 1.7 Roller Rockers GT-40 lower ported & polished Cobra upper intake MAC CAI Aluminum Pullies FRPP P-Shortys Cop car cam (to insult) Competition Engineering F/R adjustables Flowmasters New black carpet and... '84 Racin' Tempo seats! Cars' best run in 2002 with stock 150,000 mile 302 with pullies, exhaust and roller rockers only... 13.27 at 101.5 mph

09-24-2003, 09:44 AM	#2
Dark_5.0 Registered Member Join Date: Apr 2001 Location: Staging lane Posts: 4,337	I would start at about 41psi and 16 degrees of initial timing. Every car is different but thats where my car likes it. __________________ 92' LX-Big brakes, Lots and lots of suspension, GT40X heads, Ported cobra intake, stock cam, Vortech SC trim. 00' Lightning-Stock 88'CRX-13 second ego killer

09-24-2003, 10:00 AM	#3
UglyFast88 Registered Member Join Date: Apr 2002 Location: Fordland Posts: 117	Oops- I forgot and you reminded me. I was also at 16* initial timing, and tried 14 and 15* also. The car just didn't seem to have what it did before. Last night, I wento out with the Nitto's (since I had to try them) and with the Holley, at 44 / 37 I could chirp 2nd powershifting. With the stocker back on, they lit up for about 18." I guess I had too much fuel going to it. I'm taking it to the track tonight with the tools to swap the regulator, and I'll try both, just to see. Thanks, Dark- I'll try your readings and see how it works. How much difference in performance did you get from stock to 41 psi? __________________ '88 Speed Density LX 1998 Explorer motor 1.7 Roller Rockers GT-40 lower ported & polished Cobra upper intake MAC CAI Aluminum Pullies FRPP P-Shortys Cop car cam (to insult) Competition Engineering F/R adjustables Flowmasters New black carpet and... '84 Racin' Tempo seats! Cars' best run in 2002 with stock 150,000 mile 302 with pullies, exhaust and roller rockers only... 13.27 at 101.5 mph

09-24-2003, 12:41 PM	#4
Dark_5.0 Registered Member Join Date: Apr 2001 Location: Staging lane Posts: 4,337	I honestly couldnt tell you how much difference I got from changing fuel pressure other than If I bump it up to 45psi I get a better mph and a worse ET __________________ 92' LX-Big brakes, Lots and lots of suspension, GT40X heads, Ported cobra intake, stock cam, Vortech SC trim. 00' Lightning-Stock 88'CRX-13 second ego killer

09-25-2003, 07:15 AM	#6
88workcar Registered Member Join Date: Oct 1999 Location: Pierre Part, La. U.S.A. Posts: 1,850	Put the stock one on and leave it alone. __________________ 88workcar 1988 Mustang LX 342. 417rwhp @ 6800. 28 X 10 ET Drag, 4.30s, 10.69 @ 126.43 1.42 60ft. 11.13 @ 127.7 on BFGs 1.72 60ft Rice Hater # 42 To be old and wise, You must first be young and stupid I'm somewhere in tthe middle.

09-24-2003, 05:30 PM	#5
stang_racer20 Registered Member Join Date: Jun 2003 Location: Wisconsin Posts: 348	stock fuwel pressure is 39 psi. do you have any mods besides the regulator. i would leave around 42-45 psi if not, but it all depends.

09-25-2003, 10:38 AM	#7
UglyFast88 Registered Member Join Date: Apr 2002 Location: Fordland Posts: 117	Thanks, Workcar. That's what I did last night. I was waiting for your post... Thanks again, all. __________________ '88 Speed Density LX 1998 Explorer motor 1.7 Roller Rockers GT-40 lower ported & polished Cobra upper intake MAC CAI Aluminum Pullies FRPP P-Shortys Cop car cam (to insult) Competition Engineering F/R adjustables Flowmasters New black carpet and... '84 Racin' Tempo seats! Cars' best run in 2002 with stock 150,000 mile 302 with pullies, exhaust and roller rockers only... 13.27 at 101.5 mph

09-25-2003, 06:06 PM	#8
88workcar Registered Member Join Date: Oct 1999 Location: Pierre Part, La. U.S.A. Posts: 1,850	No matter what I do my works best at 38-39psi. __________________ 88workcar 1988 Mustang LX 342. 417rwhp @ 6800. 28 X 10 ET Drag, 4.30s, 10.69 @ 126.43 1.42 60ft. 11.13 @ 127.7 on BFGs 1.72 60ft Rice Hater # 42 To be old and wise, You must first be young and stupid I'm somewhere in tthe middle.

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