Resolved 1g guys, what fuel pressure you running?

[coryf1233]

Just seeing what fuel pressure 1g guys are running around with. I have it at stock right now.

Not asking for actual numbers. but will this setup with a 255 make some decent power. it pulls pretty strong , just wanted to see what you guys have made with this similar setup. My mods are as follows.

FMIC
3 inch exhaust
ported manifold
ported O2 housing
Hallman MBC 12-14lbs
Fuel Lab AFPR
Dejon intake

 

[rarest_90_DsM]

38psi with vac on a aeromotive fpr

 

[Detective Coating]

38psi with the vac line off, it should settle a little lower once the vac line is connected but that will depend on how much vac your car pulls.

 

[steve]

You can set the fuel pressure to whatever you want within reason but you'll have to retune the car to reflect the difference.

The stock tuning assumes a 36.3 psi base fuel pressure and the injector global and deadtime numbers in the code reflect that. When you change the base pressure it changes the effective flow rate of he injectors so you have to tell the ECU it's different or lie to the ECU with a piggyback about how much air is entering to correct for the change.

Without telling us what size injectors and turbo your running it's hard to discuss power.

 

[siccboostsi]

For example putting 45psi on the stock injector is actually going to flow a little more but the ECU will always think it is flowing the same amount b/c it is set at 36-37psi but if you put the SAFC or something you could always tell the computer what is going on.

 

[steve]

The stock 450cc injectors are rated at 43.5 psi as 450 cc/min. When run at 36.3 psi they flow about 411cc/min and at 45 psi they flow about 458 cc/min.

The way our fuel pressure regulator is set up, the car maintains the base pressure as the difference between the inlet (fuel rail) and outlet (manifold) pressures so that the injector delivers the same flow rate regardless of the current manifold pressure (or vacuum) and the ECU is programed with that value.

What you have to take into consideration when changing the base pressure besides the tuning is how much boost your planning on running, and what your fuel pump can deliver at the base + boost + loss pressure as far as flow. That include making sure that the pressure at the pump doesn't exceed the relief valve setting in the pump.

More info on how to calculate effective flow rates at http://www.rceng.com/technical.aspx

 

[coryf1233]

thanks for all that information, thats great. appreciate it

with vacuum hooked to the regulator pressure should be 27 something and with the vacuum off 37.5 is this correct??