Let's say a factory fuel system is designed to at 43 psi (3 bar). The fuel pump is upgraded and can provide enough fuel volume at a high pressure. The injectors can also support high pressures (pintle design).

Would there be any problems increasing fuel pressure to 58 or higher psi? Are stock fuel lines able to support this fuel pressure? What would be the disadvantage of increasing fuel pressure significantly instead of upgrading the injectors? The spraying pattern is suppose to improve with a higher pressure, correct?

* The injector constant in the pcm is going to be adjusted accordingly.

Thanks

 

Should be fine. I'm doing the same thing. Got FMS 30# and found that their duty cycle was in the 90's at WOT. Increased the fuel pressure from 43 to 55 and set the injector constant to 34.1 and the duty cycle is no in the 80's and the fuel trims are good. Just be sure that your fuel system can maintain that pressure under max load. I've got a Walbro 255 and noticed that the pressure would drop from 55 to about 53 at high rpm, full load.

 

One advantage of higher fuel pressures is the fact that it minimizes the injector flow variations caused by minor fluctutations in rail pressure. You can actually see variations in pressure due to G-forces on launch for example.

A 3psi variation on a 3 bar (43.5psi) system would impact flow by 3.5%, while you could reduce that impact to 2.6% by running 4 bar, or 2.1% by running 5 bar. I run Bosch 64's @ 58psi.

Some references claim better atomization with higher fuel pressures, but I would think that would depend to some extent on the specific type of injector.

 

I was just going to ask this question. Like 9C1 said, the whole fuel system is up to the challange and the car is correctly tuned with each increase, any disadvantages to say 80psi? 100psi? Is it safe to say that the more fuel pressure, the better for EFI?

 

IMO if ya have to go that high ya need to go bigger injectors.
Ya run into a problem controling them (opening and closing against that much pressure) I have found the problem at 55+ pounds but some get away with it and I haven't seen it on all that I have worked on at over 55lbs.So try it and see.