afpr base fuel pressure

[captd108]

ok so i finally got my fullthrottlespeed afpr on yesterday and set the base fuel pressure at 39psi with vac line off. Now i just did that based on what i saw in a previous thread but am not sure if thats entirely correct. Ive searched for this and have seen many different base fp that people have used (range from 32-50)with vac off, and the sheet that came with the fpr says 38psi. so what is the actual base fp with the vac off that i should be using on a 2g. if this makes a difference right now i have a 255 fuelpump, safc, stock 450's and still on t25. Thanks

 

[David15151]

43.5

 

[captd108]

saw that one too but i thought that was for the 1g's

 

[heavyD]

Aren't the 1G's supposed to be at about 38 psi and 2G 42 psi. I have my 2G at about 43 psi.

 

[captd108]

mabye i mixed it up who knows but the fullthrottle instruction sheet said 38...mabye that was of a 1g if what heavyd said is correct

 

[qtxdevilz]

what if you have a 6 bolt in a 2g?38 or 42?im guessing 38 but i just want to confirm...

 

[steve]

The base fuel pressure you want to use as a starting point should match the ECU's idea of what's stock just to make it easier to dial in any corrections for injector size differences. So with a 2G ECU you might want to start with a 2G base FP.

After that you can run any base pressure that makes sense for your setup keeping in mind that max pressure is based on what your fuel pump can do before the relief valve in the pump opens, including any system pressure drops between the regulator and the pump based on your max boost pressure. So absolute max base FP = (Relief Valve setting - safety fudge - pressure drop to regulator - max boost). Also keep in mind that some injectors work better than others at high pressures and that fuel pump flow rates drop as pressure increases.

Changing the base pressure from stock changes the effective injector size.
New flow rate = (SQRT (new pressure/old pressure) * old flow rate)

Factory Base pressures:
1G NA 47.6 psi
1G T Auto 42.7 psi
1G T MT 36.3 psi
2G T 43 psi

Steve