Low Z vs. High Z injectors?


Jun 8, 2001
With the new 57# high-impedence injectors out, is there any benefit to the low-impedence variety?
Obviously, the "high-Z's" don't require a modded injector driver so I can run the stock ECM, but I have heard that the spray patterns with the low-Z's make them easier to tune and give better manners.
I have heard the same thing. Drawing from peoples' comments when comparing MSD 50s .vs. Siemens 72 or 83s (in V8s), they've all said the car behaved better w/ the larger, low Z, injectors as oppossed to the 50s.


Think about it. I venture to say that a multi-billion dollar, multi-national company with a sterling reputation and virtually limitless engineering resources may know more about how to make top notch injectors and the performance of said injectors than the mensas spreading those rumors...

MSD 50's used to be the cut off point between high Z, and going to a low Z injector. Now they have a 57# injector.

The reaction time of the injector and driver (saturated vs peak and hold) is where the confusion comes from. Saturated 2.0 ms, P&H 1.5 ms. When stepping up to larger injectors, low pulse widths (2.0 and less) is often commanded at idle, and the reaction times of the P&H made things easier to control.
The actual design of the 57 (See link above) make them a bit quicker and easier to control.