Calculating available injector PW.

[Six_Shooter]

No, I'm not asking about duty cycle, I'm asking about available time to have an injector open, which then duty cycle can be calculated.

I just simple want to know how to calculate available time to open an injector versus RPM.

It seems from this discussion I still have some head room, but I'm seeing pulse widths reported in the 9 ms range. I just wanted to make sure that I wasn't having a commanded PW of longer than what is actually available.

If I was going to push this engine any farther I'd likely put my larger injectors in sooner than later, but I'm planning to pull the engine this winter and sell it, so I may not worry about it.

[1project2many]

No, I'm not asking about duty cycle, I'm asking about available time to have an injector open, which then duty cycle can be calculated.

I just simple want to know how to calculate available time to open an injector versus RPM.

The available time to have an injector open is the time equal to 85% duty cycle. That's it. Calculate time for one revolution, apply correction for number of pulses per revolution, scale to 85%. If your ecm is commanding more time than that then you're in the market for larger injectors.

This chart:
RPM......PW ms
1,000....60 ms
2,000....30 ms
3,000....20 ms
4,000....15 ms
5,000....12 ms
6,000....10 ms
Gives the amount of time for one revolution of the crankshaft. You can also say this represents "static injector on time" with one pulse per rev.

For max injector time at one pulse per revolution use this chart:
RPM......PW ms
1,000....51 ms
2,000....25.5 ms
3,000....17 ms
4,000....12.75 ms
5,000....10.2 ms
6,000....8.5 ms

If you are seeing 9ms above 5700 rpm the injectors are exceeding 85% and you are using fuel pressure as the primary system control. If you are seeing 9ms at 6600 rpm or above you have no electronic control over injection and are relying solely on fuel pressure.

Simple enough? :)