I'm in agreement that the critical aspect is not the rpm's but the load and the time under load. I recently had the opportunity to take the 126 on I-64 from Norfolk all the way through West Virginia and into Ohio. I-64 has a five mile uphill climb going westbound with a 7% upgrade most of the way. The maximum speed that the 126 could sustain was 68 mph, and, at the very top of the hill, where the grade increased slightly, the speed dropped to 62 mph. It was a rather sudden drop and was slightly disconcerting. But, no issues. The five minute run under maximum load at approximately 3100 rpm definitely produced the desired results, without the need to suffer transmission wear due to high power shifts and without the need to run the engine at maximum rpm. I wish that I could find more grades like that locally.

I live not 20 minutes from that very stretch of interstate you are talking about. If you take the 77 south exit at Beckley, there are plenty of the same type grades. Pretty much anywhere here in WV you are close to a good steep road.

G'mornin' Folks,

I just read this entire thread.....amusing isn't the half of it.....

I, too, live in West Virginia....and we sure do have our hills.....WV would be a diesel owners paradise, if we had more gas stations that served diesel!!

As I remember, from my schooling daze, a diesel engine runs best at 90-95% load. As was stated earlier in the thread, load isn't speed. Running your auto at high RPM, even in lower gears, is not truely load......it takes a good hill, headwind, trailer, or the parking brake engaged (not recommended) to put an automotive diesel under load......a trunk load of bricks may help here....

Before I retired, if we had to run the ship's main engine at reduced loads due to bad weather, fog, heavy traffic, etc.....we would bring the engine up to full throttle every couple of hours, if possible.....
After a long period of maneuvering, as in up the Mississippi to N'awlins....upon departure, we would run at reduced speed for a bit and water wash the turbochargers...we had factory installed connections for this operation.....then run up to full throttle, and keep her there until an hour before arrival at our destination....this could be days or weeks at 95% rated load....

SB

__________________

Diesels:
'85 300D, "Max, Blue Benz", 155K, 27.0 MPG
'84 190D 2.2, "Eva, Brown Benz", 142K, 40.2 MPG
'77 240D (parts car)
'67 Eicher ES 202 Tractor "Otto" (2cyl, Air Cooled, 30HP)
Gassers:
'94 Ford F-150, "Henry", 170K (300 Six) 17.5 MPG
'85 190E 2.3, 148K....Parts Car
'58 Dodge W300M Powerwagon (Flat Fenders) Less than 10 MPG