Pump Pressure

[Daniel Ciobota]

Wayne,

What you describe is pretty much the way an FMU (fuel management unit)
works for blown cars.  Those cars use the stock fuel pressure and fuel
timing curves until boost occurs.  The FMU increases the fuel pressure
in relation to boost (still at the stock fuel pulse timing), effectively
delivering more fuel to the chamber.  Be aware, though, that dropping
fuel pressure significantly from factory stock pressure (39psi on a
mustang) may also affect fuel spray pattern at the injector; those units
are calibrated with orifices which require a set minimum pressure to
give a good spray pattern.  On the other hand, increasing the pressure
(within sane limits) doesn't seem to affect the spray pattern at all.
There are some people running up to 100psi and still using stock
injectors with no problems.

Hope this helps,

Daniel



Wayne.MacDonald at zurich.com.au wrote:

> Does each injector require a set pump pressure to work correctly or
> will an
> injector still put out a good spray through a range of pump
> pressures?.
> I ask this because I was wondering if it would be possible to vary the
>
> injector pulse from long at low revs to short at high revs and control
> the
> fuel passed by the injector by regulating the pump pressure.
>
>      Wayne.