Jets & Injectors ...

[FLATKITTY]

Forgive me if I am beating a dead horse on this one, but can someone tell me why carbs can change jets (IT 9.1.3.D.1.a), but FI systems cannot change injectors? It kinda made sense at a time when modifying the ECU was also not allowed. However, w/the passing of IT 9.1.3.D.1.a.6, why is the 'no injector rule' still in place?

[Greg Amy]

Because ECU-controlled cars and adjust the volume of fuel injected via pressure, duration, and duty cycle. - GA

[mossaidis]

Second, most OEM injectors perform up to 70% (if that) duty cycle for the stock performing engines. At the baseline 25%-30% IT adder, OEM stock injectors *should* be able to handle the extra fuel delivery.

[FLATKITTY]

Gentlemen ... THANK YOU both for your time & patience.

[Eagle7]

Second, most OEM injectors perform up to 70% (if that) duty cycle for the stock performing engines. At the baseline 25%-30% IT adder, OEM stock injectors *should* be able to handle the extra fuel delivery.

Not to nitpick too much, but I don't think that math works. Injectors should not be run beyond about 85% duty cycle. If your IT build exceeds that, your option is to increase fuel pressure (which can have negative implications).

[mossaidis]

Please nitpick... I am not totally educated in these matters. 70% was a very high in the sky numbers. I know most stock hondas don't get over 60% into capacity.

[joeg]

Since the rules allow us to substutute carbs (mostly Webers) on carbed vehicles, obviously different jets go with the Weber replacement.

[Robbie]

Not to nitpick too much, but I don't think that math works. Injectors should not be run beyond about 85% duty cycle. If your IT build exceeds that, your option is to increase fuel pressure (which can have negative implications).

Not true. Injectors can handle over 90% duty cycle without issues. The 85% number is out of date.

Also, the poster talking about injectors was saying that stock injectors of most IT cars are 25-30% oversized for the horsepower they are producing.