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Old 06-25-2017, 09:41 PM   #1
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Overdrive and towing a trailer

Hello all, first post on here. We recently purchased our first motorhome, a 2017 Thor Chateau after owning three trailer trailers before this. We went on a short trip last week and we towed a flatbed trailer with atv's on it for a total of around 4,000 lbs. During slight inclines the motorhome wanted to shift out of 6th and into 5th even with the tow haul mode on. Is there not anyway to lock out overdrive? When I dropped it down to 4th the rpm's were just too high. Suggestions?
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Old 06-25-2017, 10:05 PM   #2
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Tow/Haul does not stop it from downshifting when required to move the load. It stops it from "hunting" between gears when the load is too hard for the high gear but too easy for the lower gear.
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Old 06-25-2017, 10:16 PM   #3
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The designed operating limit on the Ford Triton V-10 is 5,250 rpm continuous operation. The computer will not let the engine exceed this rpm under any circumstances. The computer senses engine vacuum and and uses that and RPM to determine if more power or better fuel consumption is achieved by shifting to a higher or lower gear. Individual gear selection is only provided in 1, 2, 4 in the 6 speed transmission. When climbing the western mountains, I usually shift into 4th at bottom of the pass and and maintain 4,000 rpm (max power RPM) all the way up. It saves shifting wear on the trans and keeps the trans from overheating when pulling a 4,500 lb load. Using the Five Star Tune will allow the trans to remain in a higher gear in high load situations.
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Old 06-26-2017, 12:07 AM   #4
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The Ford V10 is an engine that loves to run at high revs. You won't hurt it, but the noise might drive you nuts.
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Old 06-26-2017, 01:39 AM   #5
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All good information. It just seems like 2300 rpm's was too low for it going up a slight grade so when it shifted into 5th the rpm's were around 3,000 which was perfect. 4,500 rpm's (4th gear) seemed excessive with the noise and for fuel economy purposes. I guess it is what it is.
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Old 06-26-2017, 02:27 AM   #6
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All good information. It just seems like 2300 rpm's was too low for it going up a slight grade so when it shifted into 5th the rpm's were around 3,000 which was perfect. 4,500 rpm's (4th gear) seemed excessive with the noise and for fuel economy purposes. I guess it is what it is.
I'm not following the problem, or why you shifted to 4th.

If the transmission shifted to 5th on its own and the 3,000 RPMs was perfect, then why not let it do what Ford engineers programmed it to do?
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Old 06-26-2017, 02:40 AM   #7
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Great question Chance. I was wanting to lock it into a gear so it wasn't shifting all the time and causing excessive tranny wear. That is why I tried 4th gear but didn't like it due to the rpm's.
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Old 06-26-2017, 02:59 AM   #8
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Great question Chance. I was wanting to lock it into a gear so it wasn't shifting all the time and causing excessive tranny wear. That is why I tried 4th gear but didn't like it due to the rpm's.
Ah well that is what a few people have responded: You needn't worry about the RPM's the engine computer will take care of that (and yes the V-10 loves to scream).
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Old 06-26-2017, 03:22 AM   #9
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Great question Chance. I was wanting to lock it into a gear so it wasn't shifting all the time and causing excessive tranny wear. That is why I tried 4th gear but didn't like it due to the rpm's.
That 6R140 transmission is so overdesigned for the torque of the V10 that I wouldn't worry one bit about letting it shift up and down all it wants. If you were driving the motorhome with a stick shift, you'd likely be shifting a lot too. There is absolutely nothing wrong with that -- that's what transmissions are designed to do.

If you want to lock it into 4th manually and RPMs are too high, one option is to slow down; although I doubt you'd want to go slow enough to get RPMs back in 3,000 range.
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Old 06-26-2017, 11:32 AM   #10
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Thanks all for the feedback!
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Old 06-26-2017, 02:07 PM   #11
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I agree, like someone said "the V10 loves to scream". The problem is I don't like listening to it after having a fiver and diesel 1-ton.

We are in the middle of a 7,000 miles plus trip, currently in northern Utah where there are a couple pretty large hills soon to be mountains heading into Oregon.

In this type of terrain cruise control is out for me with a gasser V10 engine. I do use tow/haul but shut if off at times. For example coming down a gradual straight slope where I don't care if my speed builds to 70 or 75 I will shut if off so it doesn't force a downshift. Before climbing I will turn it back on but will give just enough gas to maybe go down one gear and run 3300 to 3400 up the next hill. My speed my drop from 65 to 55 but I would rather do that then listen to the V10 screaming at over 4000 rpm just to keep my speed over 60.

Up and down these hills yesterday coming west out of Wyoming into Ogden Utah I got 7.5mpg pulling trailer with 1,200 pound trike on it. So this works good for me.
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Old 06-26-2017, 03:16 PM   #12
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I studied internal combustion engines as part of my formal engineering education (not claiming to be an expert but know more than most on how they work) and there is nothing about the V10 that tells me these engines like to rev. Scream, as in make lots of noise at high RPMs, is a more accurate description. I've owned a couple and driven many more and they all sound horrible at high RPMs. I'm personally looking forward to Ford replacing them with a truck-specific V8.

Given the V10's power and torque curves, there isn't that much to gain by reving them at high RPMs anyway. By 3,500 RPMs you're going to get most of what's available, particularly for the 2-valve engine; and the 3-valve isn't that different.

Like Joe, I'd rather slow down a little than put up with the noise.
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Old 06-26-2017, 03:58 PM   #13
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Installing the 5 Star Tune made a big difference for me. Shift points are better suited for the heavy load of an RV, they are much quicker and better timed. I haven't run enough miles to see if the tune makes any difference in mpg but when you're driving a big square box not much will. I know many other owners have said what a difference 5 Star makes and I certainly agree. Not cheap, but what is!!!
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Old 06-26-2017, 04:01 PM   #14
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Installing the 5 Star Tune made a big difference for me. Shift points are better suited for the heavy load of an RV, they are much quicker and better timed. I haven't run enough miles to see if the tune makes any difference in mpg but when you're driving a big square box not much will. I know many other owners have said what a difference 5 Star makes and I certainly agree. Not cheap, but what is!!!
I had a 5-Star on my F-350 for use pulling the 5th wheel. No difference in mpg--a big difference in perceived power and much crisper shift points. mpg probably went down a little because it made the truck (by itself) much more fun to drive around lol
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Old 06-26-2017, 06:09 PM   #15
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The other Internet myth often repeated is that the V10 is a gas guzzler. I don't think it is. The BSFC may not be the best by modern standards but it's not that bad either. If you replaced the V10 in most large Class As or Cs with any gasoline engine, the MPG would be just as horrendous.

This happens because large motorhomes require a lot of power, not because the V10 is all that inefficient. Unfortunately, V10s are often used in heavy duty applications requiring over 100 HP on average, so fuel consumption is high. And then when the owner only gets 7 or 8 MPG he often blames the engine as being a gas guzzler. Maybe they should blame the MH manufacturer for building a 20,000-pound vehicle with over 100 square feet of frontal area and shaped like a brick.
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Old 06-26-2017, 06:45 PM   #16
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The other Internet myth often repeated is that the V10 is a gas guzzler. I don't think it is. The BSFC may not be the best by modern standards but it's not that bad either. If you replaced the V10 in most large Class As or Cs with any gasoline engine, the MPG would be just as horrendous.

This happens because large motorhomes require a lot of power, not because the V10 is all that inefficient. Unfortunately, V10s are often used in heavy duty applications requiring over 100 HP on average, so fuel consumption is high. And then when the owner only gets 7 or 8 MPG he often blames the engine as being a gas guzzler. Maybe they should blame the MH manufacturer for building a 20,000-pound vehicle with over 100 square feet of frontal area and shaped like a brick.
I think the stigma here is "10". With 10 cylinders the V-10 is perceived as a "huge" engine and thus along with that perception comes the gas guzzler idea. You could have a 6.8L V-8 and I don't think it would get the same treatment.

Heck GM had an 8.1L V-8 and I don't think it had the same perception as Ford's V-10 does.
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Old 06-26-2017, 07:18 PM   #17
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I think the stigma here is "10". With 10 cylinders the V-10 is perceived as a "huge" engine and thus along with that perception comes the gas guzzler idea. You could have a 6.8L V-8 and I don't think it would get the same treatment.

Heck GM had an 8.1L V-8 and I don't think it had the same perception as Ford's V-10 does.
Completely agree. If I recall correctly, a long time ago Motorhome Magazine did a comparison of similar gasoline motorhomes with GM V8 versus Ford V10 and they found, as expected, both had similar performance in many ways.

Today engines are making 2 or 3 times more power than they did when I was in school, but the brake specific fuel consumption, while it's improved too, hasn't changed nearly as much. Lower emissions is what's changed most, and what seems to be killing the Ford V10.


By the way Jamie, Ford recently released power and torque figures for F-150 gasoline engines for 2018 model year, and it's amazing how much power they are getting considering they are tuned for pickup service. Even the standard 3.3-L V6 makes tons more power than my old Mustang's V8. And the F-150's 5.0L V8 makes more power than any V10, and is now rated at 400 lb-ft of torque.

With these kinds of results, the upcoming truck V8 should achieve 500 lb-ft easily (before HD truck derating).
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Old 06-26-2017, 07:20 PM   #18
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I agree - 6.8L is "only" 415 cubic inches. Certainly not huge when one remembers that 350 used to be ubiquitous in anything bigger than a subcompact car. GM's 454 V8 was a fine engine and when I had one in a 22 ft Class C it got the same mileage or worse than my current Ford. It's gonna take a fair amount of fuel to make upwards of 100 hp which is what my scan gauge says it takes at cruising speed.
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Old 06-26-2017, 08:43 PM   #19
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Exactly, and it replaced the 460 cubic inch V8 that I believe was used on E-Series Class Cs through 1996. And before that Ford had a SuperDuty truck engine that was up to 534 cubic inches (8.75 liters) in size.

The upcoming truck V8 in the 6.9 ~ 7.0 liter range isn't really that large historically. By comparison Ford 427, 428, and 429 engines used in classic Mustangs and other cars were all in that same 7-liter range.
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Old 06-26-2017, 10:14 PM   #20
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Well even the 2.7L Turbo gets 325hp and 375 ft-lb of torque for that matter.
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