Steve Peeters said:
Linda mentioned a gas truck the F250 turbo,
I think this is a mis-read, so I need to clarify, as the engine issue can make a significant difference. The F250 gas engines (I think all years?) are naturally-aspirated, not turbo-charged. The F250
diesel (and the ecoboost in the F150) is a turbo. In my new F250 gasser owner's manual, Ford states one must reduce the "gross combined weight [rating] by 2%" for every 1,000 feet elevation change above a baseline of 1,000 feet. Thinner air (less O2 partial pressure) affects the combustion. In the "towing" section of the manual, they don't specify that this means only for the gas naturally-aspirated engine, and the manual of course addresses ALL F250 models, including the diesel. So I don't know what's up with that, but it has been my understanding that you don't lose power/capacity with turbo-charged engines at higher elevations. Others could chime in here to better clarify.
Interestingly, in previous versions of the F series trucks owner's manual that I accessed many months ago via Ford Owner's internet site, they stated a loss of
3-4% towing capacity with each 1,000 ft. change up in elevation. When I run the numbers, one using GCVWR at 2% and the other using just tow capacity at 4% reduction, the weight reduction recommendations are comparable.
I plan on spending most of my time (I plan on living full-time in the trailer) at elevations of ~4-7,500 generally, with occasional forays up to ~10,000 feet above sea level.
This is how I interpret that info as an estimate of possible expectations. If Ford is correct, that could potentially mean a loss of up to ~20% of the CGVWR ability at the highest elevations I expect generally -- with the naturally-aspirated gas engine. IF, my F250 as equipped, is rated at 22,000# combined, then that drops to 17,600# combined when at the highest elevations. With a truck weight of about 7,300 lbs, which remains constant, that leaves a towing capability of about 10,300# in round numbers, which is significantly lower than the rated 15,000# towing capability. The truck would be at its tow limit since the trailer and hitch will be right around 10,000#.
That's another reason I went for what might seem like too much excess capacity in the truck. It's not really
excess for the environments I'll be in. I don't have any experience with how this will play out in "real" life (i.e. not having towed or driven a truck at higher elevations), so I"ll find out I guess.
I think it's been mentioned before on this forum that the other BIG truck manufacturers don't provide this warning, so I guess there is debate about it. I did find some internet articles discussing this issue with regard to other manufacturers who if I remember rightly, sorta weasel-worded their way around it. I think elevation consideration is one of the major reasons for choosing diesel turbo-charged engines (or any other turbo-charged) and with good reason. Again, others could post more direct info about this as I'm certainly no kinda expert on engine operation and performance.
If choosing a naturally-aspirated engine, however, don't forget to consider the impacts of elevation on the truck's performance and abilities if you plan on towing time above the baseline of 1,000 feet. Linda