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Message: [QUOTE="Tim @ P.I.S., post: 165287, member: 744"] I hope most of you already have the basic concepts of the HEUI injectors in the 7.3. If not there are several sites that give very good details on their basic operations. First off to help you understand how I get my info lets go over the test bench. The bench is driven by a PC with software to interface a FACTORY Power Stroke IDM. THe PC gives the same signals the factory PCM would. I have control over RPM, pulsewidth and injection count. The hydraulics control the fuel psi and the ICP on the injectors. This is as cloose to an actual engine duplication as I have seen. There are a few others with simular setups out there. For example a normal test would be programmed 3000 rpm's with 4ms/pw for 1000 shots fired. The fuel pressure would be set to 65psi and icp to 3000psi. On a normal set of 160cc/30% injectors you would get a test beaker with 170cc output. Why 170cc? I base a set of 160cc injectors off the design of an AC code injector. That way if another test bench were used you should still get 160cc output MAX. Other various tests would also be run to show balance through the RPM band. Just holding the injectors open for an over-extended amount of time will only show you what the fuel capacity actually is. THis basicly tells you if it works or dosn't. Running an injector at the min pw required will actually show you a balanced set. And testing at low rpm, low icp will tell you just how balanced they will run in a truck. Now, on to the fun stuff:rockon: The factory IDM and pulse width. Through testing I have found the limits of the factory IDM. 1000rpm = 14.2ms/pw 1500rpm = 9.4ms/pw 2000rpm = 6.7ms/pw 2500rpm = 5.1ms/pw 3000rpm = 4.1ms/pw 3500rpm = 3.2ms/pw 4000rpm = 2.9ms/pw 4500rpm = 2.5ms/pw 5000rpm = 2.2ms/pw 5500rpm = 1.8ms/pw 6000rpm = 1.6ms/pw 6500rpm = 1.5ms/pw 7000rpm = 1.3ms/pw 7500rpm = 1.1ms/pw 8000rpm = 1ms/pw 8500rpm = .9ms/pw 9000rpm = .8ms/pw 9500rpm = .75ms/pw 10000rpm = .7ms/pw Now you can see that a perfect set of 160cc/stock nozzle injectors, that requires 4+ms/pw to empty will fall short. It is not diffacult to build even a 238cc injector to completely empty at 4800rpms. At 5000rpm it will begin to cut short at only flowing 215cc. 300cc/200% are currently requiring 2.9ms/pw to fully empty. Feel free to post your questions/comments/ect. I hope this as entertaining to read as it was to learn. [/QUOTE]