Fuel pressure / Flow Tests

[Frank F Parker]

>  When jgd was posting results from his injector tester some years ago he
> said most injectors would run up to 75psi or so before they started
> getting the dribbles at short pulsewidths, but the pressure/flow ratio
> was nonlinear and there was little to be gained by pushing most past 60
> or so.  But that was '94, and most of those were probably old type
> pintle valve injectors.  Some of the newer designs may be able to hold
> significantly more pressure, particularly the rotary disc types.
> 
I ran tests on the bench up to 90 psi with good patterns and flow that
conformed to the sq root press ratio formula.

THEN I backed that up with tests in the car tuning in a turbo 4cyl
using one of Corkey Bell's 7/1 fuel press regulators at pressures up
to 105 psi. All documented by taking data at 100 times/sec with data
logger monitoring fuel press, egt, O2 volt, man press , wide range O2
etc etc.

Results: Even when pressure eas changed from 70 psi on up, it still
resulted in more fuel. Only at 100 +psi did it stop following formula
but even then there was more fuel delivered at 105 psi than at 95psi.

These were stock Honda injectors- NGK I think? So at least in this one
instance the injectors worked at 70 + psi.

On a Chevy GTP program I worked on the fuel pressure, nat aspirated, was
5 bar- about 75 psi- for the better pattern we got.

regards,

Frank Parker