Minimum Fuel Injector Duty Cycle?
Thread Starter
Melting Slicks
Joined: Jun 2016
Posts: 2,979
Likes: 332
From: Woodinville WA
Minimum Fuel Injector Duty Cycle?
Is there such a thing as a minimum recommended fuel injector duty cycle?
Why I'm asking: I REALLY want to install a FIRST fuel injection intake on my 79 L82 C3 this winter and to go to port fuel injection; the challenge is that NEXT winter I'll be putting new heads and a new cam in the car and it's going to jump from 240ish HP to 400-420ish HP and I only really want to buy fuel injectors once.
My plan was to buy 35 LB fuel injectors which gives me a 75% duty cycle after the top-end is done, but those same 35 LB fuel injectors in my otherwise stock L82 would require an injector duty cycle as low as 40%; Is there an issue running fuel injectors at such a low duty cycle?
Adam
Why I'm asking: I REALLY want to install a FIRST fuel injection intake on my 79 L82 C3 this winter and to go to port fuel injection; the challenge is that NEXT winter I'll be putting new heads and a new cam in the car and it's going to jump from 240ish HP to 400-420ish HP and I only really want to buy fuel injectors once.
My plan was to buy 35 LB fuel injectors which gives me a 75% duty cycle after the top-end is done, but those same 35 LB fuel injectors in my otherwise stock L82 would require an injector duty cycle as low as 40%; Is there an issue running fuel injectors at such a low duty cycle?
Adam
Last edited by NewbVetteGuy; Sep 29, 2016 at 01:49 PM.
Burning Brakes
Joined: Apr 2008
Posts: 1,222
Likes: 93
From: shelbyville West Michigan
is the duty cycle on the high perf motor ALWAYS 75%? what is it at idle? low rpm driving around town?
My thoughts, if I understand what you mean by duty cycle correctly, is that no, of course not. those will be fine at 40%...
My thoughts, if I understand what you mean by duty cycle correctly, is that no, of course not. those will be fine at 40%...
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
You need to read up on fuel injection. Injectors have a min. time and a max duty cycle. To a certain extent you can alter the injection pressure to feed different HP motors.
Thread Starter
Melting Slicks
Joined: Jun 2016
Posts: 2,979
Likes: 332
From: Woodinville WA
Thread Starter
Melting Slicks
Joined: Jun 2016
Posts: 2,979
Likes: 332
From: Woodinville WA
Adam
Burning Brakes
Joined: Mar 2014
Posts: 904
Likes: 46
From: Crestline CA
Yes, there is certainly a minimum duty cycle but its more about time than actual duty cycle. The issue is that it takes time for the fuel to begin flowing after the injector opens, if the open time is too short the fuel never has time to flow before the injector closes and the engine wont idle. Good rule of thumb is to size injectors so that at maximum demand they are around 85% duty cycle.
