how a diesel works.

What is a typical WOT injector duration on a 500HP at 3000rpm?

Is the injector open more than 90deg crankshaft rev?

How early does the injector fire BTDC?

Just wondering if more than one injector was open at the same time, and if that's true, wouldn't it be better to use an oversized injector with less duration to maintain rail pressure?

Just curious.

Sounds like you spoke with a certain someone???

Was just thinking about whether 2 injectors are open at the same time. I have no idea what kind of duration a diesel runs.

Does different programmers/modules etc. have different PWM and injector/enginie timing schemes etc. from one to another? Since you specified the 500hp this may be an easier question to answer but I'm curious if it can vary by the method of getting to 500hp@3000rpm.

that's one reason people have been going to bigger injectors..

Time to Crack those injectors McRat. :grd:

How long the injection event lasts is dependant on the type of injection system used and whether the system is a single strike or a multi strike system. Im certain you are asking about a common rail multi-strike system since the Isuzu uses this arrangement.

First, I guess the thing to do is figure out how long a crankshaft revolution takes in milliseconds at a few different rpm levels.

60 sec/min / 1500 rpm = .04 or 40 milliseconds
60 sec/min / 2000 rpm = .03 or 30 milliseconds

And so on.

Most of the systems of multi-strike will have a duration of less than 1 millisecond per event. A 6 shot system may stretch these events through the compression, power and part of the exhaust strokes. With the "on time" being less than 400 microseconds for each shot in a 6 shot system. The Isuzu does not use 6 shots. Neither does the ISBe.
2 and 3 shots are used. Not being as flexible as the 6 shot we will need longer duration and perhaps need to begin event number 1 later and the main event will need to be much longer in duration. With a post event figured in for the newer ISBe 600 and up engines. I dont know what the LLY uses, but it has EGR so I suspect the post event may not be.

A 2 strike strategy will look very similar to this at 2500 RPM: Pre shot @ 17 BTDC and with a duration of 10 crankshaft degrees. Main shot at 1 BTDC and a duration of 15-20 crankshaft degrees. With the events moved up or down in duration and their start of injection in conjunction with engine speed and load. The 3 strike strategy used in a catalyst engines may have the post event very late. Perhaps during the exhaust stroke for post oxidation of the exhaust gases generated during the main event and to warm the catalyst.

The injectors are never open very long, but may be opened and closed many times during the strokes.

Don~

So the total event should be way less than 90 deg, which is the magic number for a V8.

With the fuel pressures available, it dosn't take much time to inject the desired quanity of fuel.

One event in itself is less than 90 degrees. In the example above it is a duration of 10 and a duration of 20. For a total of 30 degrees of crankshaft rotation the fuel is being injected. These are examples only. The real numbers are not the same, but dont exceed 90 degrees in most 2 strike systems. Remember that the injection is not constant, but in 3, 4, 5 and 6 multi-strike configs can be much longer than 180 degrees of crankshaft rotatation and will have the injector on and off throughout the 180 degrees.

Don~