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Forum nameTurbo/Nitrous Tech
Topic subjectStatic FP OR IDLE FP+ Disk Ratio = WOT FP??
Topic URLhttps://forums.2gnt.com/dcboard.php?az=show_topic&forum=i8&topic_id=77433
77433, Static FP OR IDLE FP+ Disk Ratio = WOT FP??
Posted by Semperboost, Oct-02-04 05:11 PM
Okay...I've searched older post on this and something just don't make sense. I've got the 30lb injectors/ SFMU (2.72 w/ restrictor) setup, idle at 22psi and my FP at 5psi is around 55psi. That makes it about a 6:1 ratio, right: 22psi + 30psi = 52. BUT...now shouldn't I be taking in account the static FP which is fuel pressure at 0psi.

BOOST/ VAC FUEL
-15hg 22psi IDLE
0psi 36psi STATIC
5psi 66psi WOT (2.72 DISK)

So am I just fugged up with this. Should I just switch to the largest disk and tune it down with the bleed valve? THanks

77439, RE: Static FP OR IDLE FP+ Disk Ratio = WOT FP??
Posted by Ryan_Hes, Oct-02-04 09:24 PM
Fist off..."WOT" fuel pressure means nothing. Fuel pressure at "5psi" is what you shoot for if your boosting that much. With the 310cc injectors, you should idle at 22psi. I idle at 30psi, but I use the SAFC to lean it down about 26% so my STFT is about 0 and I can run higher fuel pressure at idle, which makes the car happier. I idle at 30psi with the 310cc's.

Then for 5psi, 55psi is just about right. I have my fuel pressure at about 57psi, actually that is slightly rich but it's safe. I run the largest disk and the dark spring.

Hope that helps.
77442, RE: Static FP OR IDLE FP+ Disk Ratio = WOT FP??
Posted by Semperboost, Oct-03-04 05:04 AM
But doesn't it make sense to start at 0psi (static) then calculate your FP from there (disk ratio x psi = FP) I know when normally drive with no boost my FP moves so determining the overall FP from idle makes no sense.
77454, RE: Static FP OR IDLE FP+ Disk Ratio = WOT FP??
Posted by Ryan_Hes, Oct-03-04 11:39 AM
My fuelpressure doesn move unless I boost....it simply sits at 30psi. Only when I start to boost does it rise.
77484, RE: Static FP OR IDLE FP+ Disk Ratio = WOT FP??
Posted by MetalJim, Oct-03-04 07:58 PM
Ok, then yes you do have to account for static FP to find the rise. To find your static pressure start the car and then disconnect the vacuum line to the SFMU - the fuel pressure should rise up to the static pressure.

I have no idea what the SFMU does in vacuum but "normal" N/A regulators(like the 95s) would use a 1:1 rate. It sounds like Ryan's regulator doesn't do this...but yours does. :shrug


95 Eclipse RS : 5 speed
15.7 @ 87.9mph
Jeep TB writeup - http://www.dimensia.com:81/jimbo/JeepTBfor2gnt.html
77489, RE: Static FP OR IDLE FP+ Disk Ratio = WOT FP??
Posted by Semperboost, Oct-04-04 03:29 AM
I know someone knows this answer..it just seems that 66psi of fuel for 5psi seems way high and this is using the 2.72 disk.
77521, RE: Static FP OR IDLE FP+ Disk Ratio = WOT FP??
Posted by Semperboost, Oct-05-04 02:25 AM
bump
77553, RE: Static FP OR IDLE FP+ Disk Ratio = WOT FP??
Posted by Star Turbo Talon, Oct-05-04 02:17 PM
your not tunig the SFMU correctly read the instructions more careful and start over.

Terry

96 Eagle Talon ESI....Daily driver

97 Eclipse.........