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Old 08-08-2012, 02:05 PM   #1
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You lose towing capacity when climbing to higher elevations?

Someone posted something yesterday in another thread about losing 190 lbs (IIRC) of towing capacity for every 1,000 feet of climb in elevation. Is this really the case? I don't doubt it it all. Does this figure vary much between TV types and engine sizes/types?

We were at a cg a couple of weeks ago at about 4,000 ft, which isn't even that high. The propane stove struggled to boil water due to the thinner air. We didn't have too much trouble pulling the TT up, but probably because the road wasn't that steep.

I am assuming that this is something that should be kept in mind for those towing closer to TV max. tow ratings? For a just 5,000 foot mountain pass, that'd be a loss of about 1,000 lbs of towing capacity. Wow.

Light just went on - I guess that's why so many boil over near the top of mountain passes. Their engine outputs are way down due to reduced oxygen in the air.
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Old 08-08-2012, 02:12 PM   #2
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Someone posted something yesterday in another thread about losing 190 lbs (IIRC) of towing capacity for every 1,000 feet of climb in elevation. Is this really the case? I don't doubt it it all. Does this figure vary much between TV types and engine sizes/types?

We were at a cg a couple of weeks ago at about 4,000 ft, which isn't even that high. The propane stove struggled to boil water due to the thinner air. We didn't have too much trouble pulling the TT up, but probably because the road wasn't that steep.

I am assuming that this is something that should be kept in mind for those towing closer to TV max. tow ratings? For a just 5,000 foot mountain pass, that'd be a loss of about 1,000 lbs of towing capacity. Wow.

Light just went on - I guess that's why so many boil over near the top of mountain passes. Their engine outputs are way down due to reduced oxygen in the air.
That's why tow vehicles have a pressurized cooling system. Don't remember the actual numbers, but the higher the elevation the lower the temperature water boils. Vaguely remember it drops approx. 10 for every 5000 ft increase in elevation
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Old 08-08-2012, 02:16 PM   #3
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You don't loose any suspension capability to tow, but yes, you do reduce engine power. Also the thinner air does not cool the radiator and trans as effectively, therefore everything runs hotter. The AC in the tow vehicle will not cool as effectively either, so folks keep turning it down, adding even more load on the engine. Not too much to worry about with V8 or larger gas, and the turbos on the diesels keep them happy. It's usually the V6 and smaller that have a reduced rating in the manual. Others will come along and tell me I'm wrong.
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Old 08-08-2012, 02:26 PM   #4
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Someone posted something yesterday in another thread about losing 190 lbs (IIRC) of towing capacity for every 1,000 feet of climb in elevation. Is this really the case? I don't doubt it it all. Does this figure vary much between TV types and engine sizes/types?

We didn't have too much trouble pulling the TT up, but probably because the road wasn't that steep.

I am assuming that this is something that should be kept in mind for those towing closer to TV max. tow ratings? For a just 5,000 foot mountain pass, that'd be a loss of about 1,000 lbs of towing capacity. Wow.
All engines loose efficiency at higher elevations. I don't know if you can pull less, but the engine is going to work harder. Plus the fact many times you are pulling up steep hills. Besides engine performance, tow ratings are calculated according to frame strength, and also braking capacity. Those will not change at altitude...only your engine will struggle more.

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We were at a cg a couple of weeks ago at about 4,000 ft, which isn't even that high. The propane stove struggled to boil water due to the thinner air.
Huh ??? I agree with dunnnc here......the water will boil at a lower temperature, making the water boil easier.
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Old 08-08-2012, 02:32 PM   #5
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The propane stove struggled to make heat, as the orifice to mix the air and propane is set closer to sea level. With less oxygen available, due to altitude, the mixture was rich, actually cooling the flame, and causing it not to produce as much heat. That is probably why the comment about the stove struggling. Yes water does boil at a lower temp, the lower the pressure.
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Old 08-08-2012, 02:33 PM   #6
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windrider, yep, it's V6 in our case.

The temp. gauge never moved on our recent long distance trip. But interestingly, we had to go to a Ford dealer while away to get a new water pump installed because it suddenly started making wierd noises. I guess the water pump was cooling okay but got an extra hard workout on our trip.

Definitely going to move up the ladder to a V8...
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Old 08-08-2012, 02:41 PM   #7
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Interesting comment on boiling water at higher elevs. Could our regulator be faulty I wonder? The tips of the flames were really yellow and clearly not generating much heat. What we have is one of those new Coleman grilles. Fridge worked fine.

So even if the stove is not producing as much heat, the water will boil at a lower temp. and you will be okay anyway?

Some friends were using one of those small/flat green Coleman stoves - the ones that use a small screw-on cylinder. It seemed to take all day to get a big pot boiling to make a big batch of spaghetti.

Maybe it's bad water at the cg??
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Old 08-08-2012, 02:45 PM   #8
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With 50/50 mix of antifreeze boiling point is about 225at sea level , 218 ish at 5k ft, and just 208 at 10k....in a pressurized system. Less dense air transfers less heat as well.........thats about all i remember....lol
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Old 08-08-2012, 03:05 PM   #9
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The non-turbo gas engines have a lot harder time at altitude.
With our turbo diesel I can hardly tell the difference, and the fuel mileage actually goes up in the mountians. Go figure!
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Old 08-08-2012, 03:08 PM   #10
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Clarification - when I mean towing capacity, I was referring to the engine's and cooling system's capacity going up inclines to higher elevations. We had a cooling system flush and new coolant done just before the trip.

Going up a couple of passes on the I-5 in southern Oregon, we were the ones over to the right creeping along with some trucks with 4-way flashers on. Expected to see the temp. gauge move but it didn't budge. Engine sounded like it wanted to puke and explode but it didn't. More power available in 1st if needed though and would allow me to speed up but 2nd gear is too tall and revs seemed to be pushing the engine to its max. capability. Not fun that's for sure.

Engine a LOT thirstier going up the steeper roads. Less than 7mpg. Ouch. We are only towing 5,000 lbs too.

I guess the problem then is if you are pushing the engine near it's max. power output and the cooling system can't keep up. Would love to get a diesel, that's for sho.
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