[omgbossis21]

I was reading on rising rates earlier and noticed that alot of directions for various brands tell you too remove the vacuum line and check the static pressure. My question is lets say im running 48psi @ idle under vacuum, which I am. Now I know their is a math equation to figure out static pressure but lets say its 60psi. Then the rising rate adds 1lb of fuel pressure per 1lb of boost. Is it adding that on top of the static fuel pressure? I would think it is.... So if my static fuel pressure was 60psi (I can check later) then under boost I would be doing 70psi of fuel pressure! Is that how it works?

 

[wilburisthecoolest]

Something like that, but i dont know what im talking about aranoid:

 

[Genericbob]

'static' pressure (not sure if that is the correct term) is similar to running WOT on an NA engine. because there is no vacuum applied to the fuel pressure regulator. a RRFPR will add fuel under boost according to the ratio of the device you had purchased. (mine is a 1:1, and static pressure is 36psi, which is factory spec, well its been debated 36-31psi, under 10 psi of boost my fuel pressure should be 46psi) a 2:1 would read 36psi + (2 x 10psi(boost)) = 56psi. etc. so i believe you are correct.

sorry, i understand it but i've always been horrible at explaining.

 

[omgbossis21]

Static fuel pressure is reffered to as atmospheric pressure (or zero). Similar to a n/a as you said. However the fuel pressure at idle is not your static fuel pressure, that is your fuel pressure under vacuum. Remove the vacuum line so the fuel pressure regulator sees atmospheric pressure to see your static pressure. I havent tried it on mine but im sure it will be higher than under vacuum @ idle. If you rev the car up you will see your fuel pressure go up even though its not under boost. What Im thinking is since I cant see my fuel pressure when im driving , its going way higher than I thought. if its 48 under vacuum, say atmospheric pressure creates 60psi of fuel pressure, than under boost it would be like 70psi of fuel pressure! Im going to pull off my vacuum line to see how much higher the fuel pressure goes up.....

 

[Genericbob]

Originally posted by omgbossis21
[body]
Static fuel pressure is reffered to as atmospheric pressure (or zero). Similar to a n/a as you said. However the fuel pressure at idle is not your static fuel pressure, that is your fuel pressure under vacuum. Remove the vacuum line so the fuel pressure regulator sees atmospheric pressure to see your static pressure. I havent tried it on mine but im sure it will be higher than under vacuum @ idle. If you rev the car up you will see your fuel pressure go up even though its not under boost. What Im thinking is since I cant see my fuel pressure when im driving , its going way higher than I thought. if its 48 under vacuum, say atmospheric pressure creates 60psi of fuel pressure, than under boost it would be like 70psi of fuel pressure! Im going to pull off my vacuum line to see how much higher the fuel pressure goes up.....
[/body]

I apologize... like I stated, I'm horrible at explainations. What you said is exactly correct. ]

For comparison sake, with my vehicle, 36psi is at idle (under vacuum) and with a quick tug of the throttle it will jump up to 41psi.

 

[omgbossis21]

I just went outside to my car, fuel pressure is 48psi @idle under vacuum. Pull off the vacuum line and the fpr sees atmospheric pressure (static pressure or n/a max) 0psi (no vacuum no boost). Fuel pressure is now almost 70psi!!!!!!! Then you have 10psi of boost, 70psi @ atmospheric pressure + 10psi from boost = 80psi of fuel pressure! Getting new injectors this weekend.....

 

[Genericbob]

what size injectors are you looking at?

 

[omgbossis21]

red top mustang injectors #36, should work great!

 

[Genericbob]

36# injectors... damn... i must be doing something wrong... at 10psi, even w/ 30# injectors i'm running pig rich... and i have a lower fuel pressure.

my MAF is maxed out at 10psi as well (slight spikes to 11psi and MAF will read 100%, at the same time my SAFC has tuned my 30# injectors to run at 0% correction). are you maxing out your MAF? after i get my inspection and exhaust situation worked out i'm going to look into a more efficient intake setup.

 

[blackoutgt]

what ratios do rrfprs come in?... i have a 12:1 FMU but i think it might be a bit much... what do you guys think?

 

[omgbossis21]

Im not sure if Im maxing out my maf as i dont have my emanage hooked to a laptop yet. I was running pig rich (except under boost) until i just swapped to the beta ecu, instant tune down low with a bit of richness from the extra fuel pressure. If I was maxing out the maf I intended on just hooking up the pressure sensor to the emanage (its use is for when the stock maf is maxed out). Im running 11psi though....

blackout , you can get rising rates in a 1:1 ratio or a 2:1, not sure what else is available. Thats alot of extra fuel pressure off that fmu...

 

[lukeyn]

http://www.bellengineering.net/Pages/products_FPR_Instruction.html

I dont know if this will provide you with any extra knowledge but i thought it might help.

 

[omgbossis21]

I read that as well. However those type of fuel pressure regulators are meant to be used in conjunction with your stock one. Thanks anyway =-)