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Old 02-07-2009, 12:54 PM   #21
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Also I find it interesting your duty cycle goes up in the rpms. I thought max duty cycle was at max torque. So does that mean your max torque is at redline? Or am I remembering wrong?
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Old 02-07-2009, 02:01 PM   #22
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Originally Posted by ChuckyZ View Post
Also I find it interesting your duty cycle goes up in the rpms. I thought max duty cycle was at max torque.
No, max duration will typically be at peak torque. But think about what duty cycle is- it's duration / cycle time (the time elapsed for one full rotation of the crank, assuming two squirts per otto cycle.)

As RPM increases, cycle time decreases. So for a constant injector duration, duty cycle will increase proportional to RPM. Even if injector duration decreases slightly after peak torque, duty cycle will still continue to rise as duration will be decreasing by a relative small amount compared to the decrease in cycle time.
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Old 02-07-2009, 03:33 PM   #23
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No, max duration will typically be at peak torque. But think about what duty cycle is- it's duration / cycle time (the time elapsed for one full rotation of the crank, assuming two squirts per otto cycle.)

As RPM increases, cycle time decreases. So for a constant injector duration, duty cycle will increase proportional to RPM. Even if injector duration decreases slightly after peak torque, duty cycle will still continue to rise as duration will be decreasing by a relative small amount compared to the decrease in cycle time.
Ahh that makes sense since we are worried about 85% because there is not enough time to open and then close the injector before the next event. DUH!. Thanks Joe.
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