Gary -- I was just making a little fun of myself

Frostie, can you give a us a run-down on rpms, boost, and EGT's at wide open throttle with your set-up? E.G.: 1500 rpm, WOT boost en egt #'s (before you toast things), then 1700, then 2000, then 2400, then governor . . . or as close as you can. I am gathering that with the 14 you are getting a "sweet spot" somewhere in the low 2000 rpm range, but then get higher EGT's up near the governor. Is that right?

Thanks!

Alec

 

Gary and Alec-
Thought I'd add another long post to the pile. This is kind of a case study of heavy loads and how a powertrain engineer wants the engine used, based on my experience with a truck I sometimes drive at work. The truck is a '96 Ford 26k GVW with a Cummins 5.9 and an Allison 4 speed. The Cummins has a 14 cm non-wastegated housing on the turbo, the engine is rated for 185 HP @ 2500 and 550 ft# @ 1500, max governed RPM is 2900. Now it seems like the obvious thing to do when driving this truck would be to keep the RPM somewhere between 1500 and 2500, that should keep the engine happy, right? Well, no. Here's how the powertrain engineer who set up the Allison thought it should run: torque converter stalls at 2000 RPM, under load the transmission will downshift if RPM falls below 2200. It will not upshift until 2600 RPM. Seems like a terribly inefficient waste of all that nice torque, doesn't it? Before I got gauges on my work truck (the one in my sig), that's what I thought. Then I saw how hot the EGT gets down near peak torque, and this setup started to make some sense to me. The rule of thumb I came up with is this: When you're working an engine hard, you should always keep the RPM closer to peak HP than to peak torque, even if this means going higher than peak HP.