I've been fortunate with my 2020 2.7L F150 towing a 7000 lbs trailer, the worse I ever see is 220F doing a 1000ft climb on a local road with switchbacks and curves that necessitate slowing and accelerating between 15 mph and 40 mph a few times. After manually locking out gears to target 3000rpm minimum rev the worse I see now is 215F. Long highway climbs are also in the 210-215 degree range, usually sustaining 2500-3000 rpm. Flat highway is 205 ish and 2000 rpm, and unloaded flat highway driving is around 195 and 1800 rpm. In and around eastern TN.

 

Agreed, they can dump a lot of heat into the coolant. I'd expect as much as a 5ºF jump, if the radiator was as big as it should be. As things stand, it's like the intercooler, will heat soak if you push the turbos too hard for too long.

 

Now with 400HP half ton trucks, we're able to dump a million BTUs per hour into the radiator. That's enough to heat the last 20 houses I've built.

 

Yeah realistically these trucks can only sustain maybe 200 hp worth of sustained output with the stock cooling system. The newer ones with bigger radiators maybe closer to 250.

 

Two weeks ago towing through WV I had my engine temp touch 241 on a pretty long 5% grade. Usually it’s under 230 where I can’t sent the number.

2015 3.5 EB Max Tow with 9k GVWR trailer