Originally Posted by dwight69
We tow a 28 RB Serenity with a 2020 Tundra Crewmax. Like other posts the numbers are all within limits. I estimate we're at 80-85% GCWR.
The tundra and trailer rig pulls like a dream. However, at highway speed, 55-60 mph, uphill grades often bring engine revs up to ~4000. I normally slow down to keep the rpms below 4000 if I can. We average 9-10 mpg in hills and 11.5 on flat roads. Love the Tundra and plan a Colorado trip next spring. Any experience or comments would be appreciated.
You might find it interesting that engines can be relatively less stressed using higher RPM than grunting torque.
Torque is directly proportional to cylinder pressures. Using less RPM means relying on more torque to produce the necessary climbing power, and cylinders correspondingly dealing with higher compression and heat loads. Not unlike biking, trying to lug a gear up a hill versus downshifting and using more strokes to ones advantage.
By allowing the engine to run at higher RPM, an engine can actually run less stressed, and cooler with more oil and coolant flow. While potentially using less gas as the A/F mixture doesn't have to be as rich for extra cylinder cooling.
This can also be true for the transmission as it has a better chance at locking up the torque converter, utilize gearing advantages, with more fluid circulation.
With the 5.7L, you are also be leaving 80HP+ on the table. Not saying you have to use all of it, but there are advantages to running at higher RPM at the same pace. It's a Toyota after all and these engines are reliable smooth running mills.