Optimum fuel pressure

[cmsapms]

OK, this might be a "how long's a piece of string" questions, but if you were designing a simple fuel injection system, what fuel pressure would you choose?

OK, some (hypothetical) details:-

90's 4 cyl 16 valve eurobox engine,
Standard head,
lumpier cams,
1 inlet runner per cylinder,
Injectors chosen to provide ample fuel at your chosen fuel pressure
etc.

...in other words, the sort of thing that might be put in a LoCaterField type kit car.

Would your fuel pressure be:

a. As low as practicable? (define practicable?)
b. The pressure at which your injectors' fuel flow is quoted?
c. something else?

and why?

[TheEnd]

About 3.5 bar seems to be popular.
Higher pressures mean better atomisation, so higher pressures would be better, but that means stronger pumps.
I know the E36 M3 3.2 runs at 5 bar which is unusually high, but at least with BMWs, most of the usual fuel injection is at 3 or 3.5 bar.

[DVandrews]

3 bar is common and you may be able to cannibalise a fuel rail with integral FPR, atomisation is improved with later multiple pintle injectors even at 3 bar. The advantage is that your average cooking injection pump is able to sustain 3 bar with relative ease.

Dave

[anonymous-user]

I run at 6 to 8bar depending on load

[packman10_4]

On a modified engine with the correct injector sizing 3 bar is the norm , with injectors that are stretched and running into the the top of there duty cycle ive run upto 5 bar .....

Also injector sizing effects your idle and emissions so does pintal holes generally the more holes the better
4 holes ideal 6 holes great 1 hole fuel is going in at hell of a rate ....