C7 Peak Performance Levels

[Craig P.]

I've read some threads that mention peak torque and horsepower levels for various diesel engines, and how one should drive according to these levels.

Still being fairly new to my diesel, can anyone explain how this works, and what RPM range I should be operating my C7 in?

Thanks!

Craig

[bdpreece]

You can go here for the performance info for all the C7 engines. http://www.catrvclub.org/PDF_Docs/C7..._Sheet_707.pdf

[Craig P.]

Thanks Brian, I saw that sheet already, but it didn't state anything about an optimum cruising RPM for hills and flatlands. I remember reading a thread about these numbers somewhere, but I don't recall when or where I saw it.

Craig

[RCtime]

Craig
I also had these same questions you have. I also read performance sheet.
I soon realized my driving habits dictated the optimum performance level of my engine.
I usually set the cruise control about 63mph-6th gear @ 1750 rpm. There it is, whether optimum or not, thats what I get, and it usually handles, most small hills etc. just fine.
Larger hills, grab 5th-4th and rpms around 1900-2100 for best cooling, the steepest of the steepest hills, you do what it takes.
Thats my optimum performance level of my cat..
If the true optimum performance level was say (example 1400 or 2000 rpm) of my engine, it just wouldnt fit.
I know what your asking here, and I didnt come close to answering it, but how can you drive using numbers. Interested in the replies, because I want to know and learn also.

[Poptop]

What kind of mileage are you getting at the 62-65 mph? Haven't done enough testing yet on my 300 Cat to know what I'll get at the different mph.

[radams]

When I am in the flatlands or hilly country I let the engine and the transmission take care of making the decisions to maintain my speed. Now when I get to the mountains I drive by keeping the rpms where the engine develops it's maximum torque. In the C7 I believe that's in the neighborhood of 1450 rpms. I do that by using the keypad on the Allison and keeping the speed appropriate for the gear.

Once you're up and over the top remember what the lowest gear was that you used to get up and then use one gear lower to go down, use the exhaust brake, and stab the brakes occasionally to keep from shifting to a higher gear. Once things start to level out let the engine and transmission handle the duties.