Why does it matter if a fuel injector is boost referenced? Today with large injectors wouldn't an injector be able to handle all the fuel an engine requires without raising the fuel pressure with boost? I realize the chip would need to be altered to suit but beyond that, would an engine work correctly?
Why is fuel pressure boost referenced?
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"how does a posi track in a plymouth work, it just does"
why have a electronic sensor sense boost to raise fuel pressure when a fuel pressure regulator does it with the raised boost level via vacuum hose/ pressure line?
its so simple why even bother trying to make it better right
why have a electronic sensor sense boost to raise fuel pressure when a fuel pressure regulator does it with the raised boost level via vacuum hose/ pressure line?
its so simple why even bother trying to make it better right
What matters is the pressure difference at the injector. When the pressure rises in the intake, you need an equal rise on the fuel rail side just to keep fuel flowing at an even rate when the injector opens. It isn't a matter of flowing more fuel as boost goes up, it's a matter of maintaining flow.
I think.
I think.
DMan
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Originally posted by scottyb
What matters is the pressure difference at the injector. When the pressure rises in the intake, you need an equal rise on the fuel rail side just to keep fuel flowing at an even rate when the injector opens. It isn't a matter of flowing more fuel as boost goes up, it's a matter of maintaining flow.
I think.
Good answer and I think I can add a little detail. You want to have *constant* pressure drop across the injector so that when you're tuning, all you have to worry about is the pulse width, or the amount of time the injector is open. More time open, more fuel injected - easy that way. If you didn't reference the fuel rail pressure to boost pressure, then you'd have to consider that at high boost, less fuel is going in because boost pressure is now pushing harder against fuel pressure than before. Would make it a total pain to tune because things aren't linear. HTH.
Boost Reference..
Two things, really. As stated above, the control scheme for maintaining fueling is much simpler when the injectors have a constant differential pressure. Otherwise, as the boost goes up, injector would pass less fuel, and since the "closed loop" is not used for WOT, the chip would have to be programmed to increase pulse width. Since the chip doesn't know what the boost is, that would be tough.
Second, the injectors are almost all designed for a diff. pressure of about 45 psi. If you get too far from the design dp, the spray pattern gets messed up. So, the pressure regulator takes care of the problems.. until it starts to screw up.
Two things, really. As stated above, the control scheme for maintaining fueling is much simpler when the injectors have a constant differential pressure. Otherwise, as the boost goes up, injector would pass less fuel, and since the "closed loop" is not used for WOT, the chip would have to be programmed to increase pulse width. Since the chip doesn't know what the boost is, that would be tough.
Second, the injectors are almost all designed for a diff. pressure of about 45 psi. If you get too far from the design dp, the spray pattern gets messed up. So, the pressure regulator takes care of the problems.. until it starts to screw up.
