Static fuel pressure?

[Tachyon]

Does anybody here run a static amount of fuel pressure in their car for higher boost applications? Example: 50psi of fuel pressure at both idle and maximum boost.

[Shane@DBPerformance]

You want your fuel pressure to go up with boost or else the car is harder to tune and your fuel injectors become very small. A lot of modern cars run a returnless fuel system that run a static fuel pressure, but when people start modding them a lot they usually convert to a return system that has the FP go up with boost.

Most fuel injectors are rated for 43.5psi. So if your base is 43.5psi and you run 30psi of boost, your FP will be at 73.5psi at that boost level to overcome the air pressure in the intake manifold. If you have 1000cc fuel injectors running a normal 1:1 setup like that then at 30psi they still flow 1000cc. If you ran a static pressure of 43.5psi, then at 30 psi of boost the injectors would actually only flow around 557cc.

[Tachyon]

You want your fuel pressure to go up with boost or else the car is harder to tune and your fuel injectors become very small. A lot of modern cars run a returnless fuel system that run a static fuel pressure, but when people start modding them a lot they usually convert to a return system that has the FP go up with boost.

Most fuel injectors are rated for 43.5psi. So if your base is 43.5psi and you run 30psi of boost, your FP will be at 73.5psi at that boost level to overcome the air pressure in the intake manifold. If you have 1000cc fuel injectors running a normal 1:1 setup like that then at 30psi they still flow 1000cc. If you ran a static pressure of 43.5psi, then at 30 psi of boost the injectors would actually only flow around 557cc.

I get what you're saying, but what if instead of even using a FPR, you just calibrated in a manual valve right after the rail (before returning the fuel line) so that the pressure is all ready at the limit (say 73.5psi for this example)? Would this be too hard on the pump to drive the pressure this hard all the time?

[Kevin 1G Drummer]

It would be alot harder to get the car to idle decently, or be driveable at part throttle/low boost if you were running a constant 73 psi.