High lift and the effect of injector duty cycle
High lift and the effect of injector duty cycle Looking for a little theory about the effects of high cam lift and how it effects injector duty cycle. does duration effect duty cycle more than lift? large duration cam with low lift or short duration cam with high lift, which would typically see a higher injector duty cycle?
To reiterate what Mark said, injector duty cycle is a function adjustments made by the ECM, not directly related to any cam specs. Whatever "mods" you do (within reason) will be compensated for. Of course, this could go backwards too, if you make a mod that decreases the engine's output then your duty cycle will drop...
About 2 weeks ago, someone asked a similar question. If I remember correctly, the question was, "how does ramp rate affect duty cycle (or, injector output)?"
The answer was the same...that the injector function was based solely on air/fuel/temp.
The answer was the same...that the injector function was based solely on air/fuel/temp.
thanks for the responses guys. i was just trying to get an idea before i stuck the new cam in. I have HP tuners so i will just hook it up to the computer and find out the duty cycle after i install the cam. thanks again
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If you start to get up to around 85% duty cycle then you need bigger injectors...but you will find that with bigger cams your engine will need less fuel at idle, and just off idle, then about the same amount of fuel as your stock cam in the lower mid range, then more fuel as you get up higher in the rpm range. When I put in my big cam I had to really cut back my fuel, even the minimum cycle time at and just off idle.
If you do get bigger injectors, then you need to go in and change the flow rate table....a quick dirty way to do this is say your stock injectors are 28lb hour, and you are going up to a 42 lb hour injector you can highlight the whole table and divide it by 28, then multiply it by 42 to get real close.
If you do get bigger injectors, then you need to go in and change the flow rate table....a quick dirty way to do this is say your stock injectors are 28lb hour, and you are going up to a 42 lb hour injector you can highlight the whole table and divide it by 28, then multiply it by 42 to get real close.
If you start to get up to around 85% duty cycle then you need bigger injectors...but you will find that with bigger cams your engine will need less fuel at idle, and just off idle, then about the same amount of fuel as your stock cam in the lower mid range, then more fuel as you get up higher in the rpm range. When I put in my big cam I had to really cut back my fuel, even the minimum cycle time at and just off idle.
If you do get bigger injectors, then you need to go in and change the flow rate table....a quick dirty way to do this is say your stock injectors are 28lb hour, and you are going up to a 42 lb hour injector you can highlight the whole table and divide it by 28, then multiply it by 42 to get real close.
If you do get bigger injectors, then you need to go in and change the flow rate table....a quick dirty way to do this is say your stock injectors are 28lb hour, and you are going up to a 42 lb hour injector you can highlight the whole table and divide it by 28, then multiply it by 42 to get real close.
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