bmg9b wrote:
Hmmm.. I wasn't towing.. but I usually keep the Jeep in the 1,000 to 2,000 RPM range (6-speed). Is that too low? I feel bad reving it up past the 2,500 RPM mark.
Just like anything I think moderation is the key. Too low of an RPM puts stress on the main bearings. Very low RPM under high load is also tough because your oil pressue is lower at low RPM. Too high of an engine speed puts stress on the valve train.
I have an automatic libby, but I have owned a lot of manuals (and still do). My guess is that I would shoot for a cruise RPM of 1,800 - 2,200 regardless of my speed. I definately would not "lug" the motor cruising in lower 1,000 RPM range. It's probably much better for your engine to cruise at 2,500 RPM than it is to cruise at 1,100 RPM.
In my S2000 I cruise down the freeway at 4,000 RPM at 70 MPH in 6th gear. I'm sure that motor would be happy doing that for 200,000 miles. But that motor hates to be lugged down low. Cruising anywhere under 2,000 RPM and it starts complaining.