Join Date: Nov 2000
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Re: Mustang injectors in a 4.0/4.2
A few thoughts on the subject:
How are you going to compensate for the presumably increased fuel flow accross the board with these larger injector? They will flow more at idle, cold start, fast idle, open loop, wide open throttle, etc. Where's the tuning? I question the wisdom of tinkering with fuel pressure, as that's doing the same thing, increasing the fuel flow under all conditions, not just where you want it. If you really want to compensate on a speed density system for modifications that improve the volumetric efficiency of the engine, you need to be able to reprogram the computer to deliver more fuel, ie longer pulse lenghts, to the injectors, under the conditions requiring more fuel. The other stuff like altering temperature sensors, fuel pressure, etc is imprecise and alters fuel flow across the board. That's fine if you are tuning it for only one condition, wide open throttle, but I doubt that is the case.
Bigger injectors are needed if the duty cycle of the injectors under peak fuel flow is too high. They should be open no more than about 80% at wot.