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Injector sizing and duty cycle

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Probationary Member
Nov 20, 2002
thomasville, t'ville_NC
Would it be a bad idea to go ahead and put bigger injectors say 650 or 750ccs in now and just turn the duty cycle down so i dont have to keep buying bigger injectors as i upgrade. Or is that bad on the injectors running a low duty cycle.
You might have timing trouble, (It's not that bad for my 750ccs) but that's pretty much it.
You could get say 880cc injectors, run the base fuel pressure at 27psi (they are rated at 43psi industry standard) then they would flow the same as 550's and the only thing you would have to account for (other than the tuning that people with 550's would have to do also) would be the longer dead time which wouldn't be too hard. Then as you start moving more air through the engine you could raise the fuel pressure up the the rated pressure and not have to buy injectors twice.

The only down side is that with "too" big of injectors it may not idle very well because of the long dead time (my 880's idle fine but i have a keydiver chip) and as said above if you use just an afc to try and compensate the ecu will see very low airflow readings and will advance timing way too fast. Easiset way is to get a custom eprom chip for the car or dsmlink of your a 2g guy but for the time being you could run the larger injectors at the lower pressure and get by with an afc ;)
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