How much does horsepower come into the towing equation?

[VernDiesel]

Best answer yet except you don't own a large diesel truck. And didn't ask about anything that would make one remotely necessary to use as a tow vehicle. But I know when you BS with other guys its always easy for them to recommend you spend your money to get X because they like it when they might not actually do that themselves when put in your shoes. There was no monetary goals or other realities tied into that "recommendation." I mean if you & the wife are ready to trade your 2018 on a larger more expensive truck so that you have plenty of overkill for whatever you might buy that is a lot larger than the TTs you & the DW like and are looking at currently sure.

Ok donhauler this post is not about selling you on a big diesel truck etc. Its about your stated question & goals. First yes you want a WDH but not with the long obsolete add on friction bar. Get one with built in sway control and springbars sized for the tongue weight range of the TT you buy.

The GM GCVWR is an important number as to what your truck can safely & reliably tow. It already takes into account your motor gearing etc etc. So if your GVWR is 7,100 and payload is 1,840 then your truck should weigh 5,260. Add you DW some gear say 500 pounds and it would be 5760.

Take your GCVWR of 12,800 subtract out the 5,760 and you have 7k to work with. Most commonly people add almost 1,000 pounds from dry weight to wet weight. So if you are looking at your stated dry TT weight of say 5,100 you are looking a wet weight of 6,100, well under the safe & reliable limit of the 7k or your GCVWR according to GM and the SAE Society of Automotive Engineers J2807 tow standards.

Biggest thing for stability & safety is to set up your load IE truck trailer and WDH so that you comply with GM spec limits for steer & drive axle weights and GVW. Adjustment goals at the scales would be to generally replace your unloaded steer weight and to get your tongue weight in the 10 to 15% range of gross trailer weight. The CAT scale weighs steer drive & TT axles separately and at the same time to show this on your scale slip. Then just adjust your WDH and or TT loading and or bed load until you make the combined unit as safe and stable as can be as proven by the numbers.

Last sure a more powerful or turbo motor could run up a grade faster. So.. its not a race and its not going to be too slow or it wouldn't have passed the J2807 standard for that. If its peak torque is at 3,900 rpms know that climbing a grade with TT may spend some time in the 3,500 to 4k range. Again GM has certified even warrantied it to be safe and reliable for this.

Oh and Horsepower and torque when it comes to towing at the limit are more about the relationship to each other. At least as I see it. To a point you can gear toward a horsepower or a torque bias and the rpm range. People have favorites as to the bias but really you want enough of both for a strong and fast enough TV. You only need enough of each for the gearing you have to A move the load in X gear (torque) and B move it fast enough in X gear.(horsepower) With only enough torque to hold X gear then more horsepower is needed to move that gear faster and up the rpm range. So if you don't have sufficient torque to pull off a taller gear you better have more horsepower to make up for it. In this case GM & J2807 has certified their to be enough of the combination and gearing plus brakes suspension etc for a GCVW of 12,800.

[jeffkirk]

I have a Rockwood 2506S trailer, dry weight of 5274, GVWR of 6631. Pulled by a 2015 GMC Z71 4X4 Crew Cab with the V6 Ecotec 3 engine. After loading up for a two week trip with all our regular stuff, plus a Honda generator and 2 bicycles, I went to the weigh station. I weighed the truck front axle unhitched, total truck unhitched, front axle hitched, truck hitched, and truck and trailer hitched. From these weights I calculated front axle tongue weight, rear axle unhitched, rear axle hitched, hitch weight, trailer total weight, and trailer hitched weight.
Results indicate no load specs were exceeded, although GCWR (truck and trailer) was only 280 lbs under the 12,800 limit. Also the rear axle hitched weight was 3670, under the recommended 3950 by only 280 lbs. Hitch weight was 11.6%. Front axle was 250 lbs lighter hitched. This load is the max I would ever be carrying. Me, the wife and a dog.

As a result of these weights, I adjusted the WD hitch angle to put more weight on the front axle and less weight on the rear. Results are 100 lbs more weight on front axle and 260 lbs less weight on rear axle. (weighed at a different time with less load)

I have no issues pulling this trailer. Plenty of power and good handling. I usually travel at 65 mph, mostly without cruise control. Get about 11.5 mpg.

I have all the numbers if you're interested. Good luck!

[Hersbird]

Originally Posted by TitanMike

To answer the core question "How much does horsepower come into the towing equation", start with the definition of "Horsepower".

It's simply a measure of ability to move a given amount of weight, a given distance, in a given amount of time.

Torque is important but it can be created through gear reduction. In theory you could tow a 5,000# trailer with a tow vehicle powered by a 5hp Briggs and Stratton lawn mower engine. The gearing required to create enough torque would slow the process down to the point that it may take an hour to make it from your driveway to the end of your block.

To maintain highway speed over the varying terrains Horsepower will be required. Torque also helps as you will require less help from lower gears in the transmission and differential.

In my experience the closer you get to the max weight rating of a tow vehicle the slower you are going to go up those hills that every highway has. Go up into the mountains and you may worry whether you will even make it up some hills.

As someone else said, don't be afraid to "wind it up" if you have a smaller engine. That's the only way the little engines make horsepower. For some of us who used to own "flatheads" the thought of winding an engine up to 4-5,000 rpm scares us. Fact remains that that's a nice comfortable RPM for most modern engines (Redline on my truck starts at 6100 RPM).

Yes, more truck is good but sometimes we just have to work with what we have.

This is right on. Also think of it this way, the other day I was changing the front axle on my Subie and had to apply about 700 ft-lbs with a long breaker bar to the front axle nut to break it free. So I am physically capable of delivering more peak torque with a lever and my body weight than my 2004.5 Cummins does at it's peak. Yet if I worked every muscle in my body as hard as I could I doubt I could deliver more than 1 horsepower for 3 secs. Tour de France guy's peak at maybe 2hp but average about 1/2 of a HP. So torque is great, but without motion you have zero horsepower. So it's really both. Yes with my lever I could move my truck and trailer up the biggest, highest pass in the world with just my mighty muscles. It would be very, very slow as I have little horsepower. Now my 290hp minivan, with only 270 ft-lbs could also do it, but 600+ times faster. Still not as fast as a 385 hp/930 ft-lbs diesel would do it. In the end 300hp is 300hp, doesn't matter how it's made, it is a measure of the work being done. There are certainly advantages of making it at a low rpm like a diesel when it comes to other factors like fuel economy and longevity but 300hp is 300hp.

I love my Cummins for towing but the last week I have been using it as a daily driver and it just plain sucks. I sold my daily driver Subie, but as soon as we get back from Yellowstone this weekend the Cummins is going up on Craigslist as well. I'm going to get a 5.7 hemi Commander, maybe a 3.0 diesel Grand Cherokee, or possibly a 6.2 Tahoe Denali or Escalade. Something around $8-13K should do the day to day much better, and still tow the camper 5-10 times a year. I love getting good MPG with the tag team Subie and Cummins but the amount of miles I drive per year, I could switch to a Hummer and it wouldn't add more than $300 to my annual fuel bill.

[donhaller]

Originally Posted by VernDiesel

Best answer yet except you don't own a large diesel truck. And didn't ask about anything that would make one remotely necessary to use as a tow vehicle. But I know when you BS with other guys its always easy for them to recommend you spend your money to get X because they like it when they might not actually do that themselves when put in your shoes. There was no monetary goals or other realities tied into that "recommendation." I mean if you & the wife are ready to trade your 2018 on a larger more expensive truck so that you have plenty of overkill for whatever you might buy that is a lot larger than the TTs you & the DW like and are looking at currently sure.

Ok donhauler this post is not about selling you on a big diesel truck etc. Its about your stated question & goals. First yes you want a WDH but not with the long obsolete add on friction bar. Get one with built in sway control and springbars sized for the tongue weight range of the TT you buy.

The GM GCVWR is an important number as to what your truck can safely & reliably tow. It already takes into account your motor gearing etc etc. So if your GVWR is 7,100 and payload is 1,840 then your truck should weigh 5,260. Add you DW some gear say 500 pounds and it would be 5760.

Take your GCVWR of 12,800 subtract out the 5,760 and you have 7k to work with. Most commonly people add almost 1,000 pounds from dry weight to wet weight. So if you are looking at your stated dry TT weight of say 5,100 you are looking a wet weight of 6,100, well under the safe & reliable limit of the 7k or your GCVWR according to GM and the SAE Society of Automotive Engineers J2807 tow standards.

Biggest thing for stability & safety is to set up your load IE truck trailer and WDH so that you comply with GM spec limits for steer & drive axle weights and GVW. Adjustment goals at the scales would be to generally replace your unloaded steer weight and to get your tongue weight in the 10 to 15% range of gross trailer weight. The CAT scale weighs steer drive & TT axles separately and at the same time to show this on your scale slip. Then just adjust your WDH and or TT loading and or bed load until you make the combined unit as safe and stable as can be as proven by the numbers.

Last sure a more powerful or turbo motor could run up a grade faster. So.. its not a race and its not going to be too slow or it wouldn't have passed the J2807 standard for that. If its peak torque is at 3,900 rpms know that climbing a grade with TT may spend some time in the 3,500 to 4k range. Again GM has certified even warrantied it to be safe and reliable for this.

Oh and Horsepower and torque when it comes to towing at the limit are more about the relationship to each other. At least as I see it. To a point you can gear toward a horsepower or a torque bias and the rpm range. People have favorites as to the bias but really you want enough of both for a strong and fast enough TV. You only need enough of each for the gearing you have to A move the load in X gear (torque) and B move it fast enough in X gear.(horsepower) With only enough torque to hold X gear then more horsepower is needed to move that gear faster and up the rpm range. So if you don't have sufficient torque to pull off a taller gear you better have more horsepower to make up for it. In this case GM & J2807 has certified their to be enough of the combination and gearing plus brakes suspension etc for a GCVW of 12,800.

Thanks! Appreciate the time you took

[donhaller]

Originally Posted by jeffkirk

I have a Rockwood 2506S trailer, dry weight of 5274, GVWR of 6631. Pulled by a 2015 GMC Z71 4X4 Crew Cab with the V6 Ecotec 3 engine. After loading up for a two week trip with all our regular stuff, plus a Honda generator and 2 bicycles, I went to the weigh station. I weighed the truck front axle unhitched, total truck unhitched, front axle hitched, truck hitched, and truck and trailer hitched. From these weights I calculated front axle tongue weight, rear axle unhitched, rear axle hitched, hitch weight, trailer total weight, and trailer hitched weight.
Results indicate no load specs were exceeded, although GCWR (truck and trailer) was only 280 lbs under the 12,800 limit. Also the rear axle hitched weight was 3670, under the recommended 3950 by only 280 lbs. Hitch weight was 11.6%. Front axle was 250 lbs lighter hitched. This load is the max I would ever be carrying. Me, the wife and a dog.

As a result of these weights, I adjusted the WD hitch angle to put more weight on the front axle and less weight on the rear. Results are 100 lbs more weight on front axle and 260 lbs less weight on rear axle. (weighed at a different time with less load)

I have no issues pulling this trailer. Plenty of power and good handling. I usually travel at 65 mph, mostly without cruise control. Get about 11.5 mpg.

I have all the numbers if you're interested. Good luck!

Thanks Jeff, great compare.

[mrfikser]

Originally Posted by Hersbird

This is right on. Also think of it this way, the other day I was changing the front axle on my Subie and had to apply about 700 ft-lbs with a long breaker bar to the front axle nut to break it free. So I am physically capable of delivering more peak torque with a lever and my body weight than my 2004.5 Cummins does at it's peak. Yet if I worked every muscle in my body as hard as I could I doubt I could deliver more than 1 horsepower for 3 secs. Tour de France guy's peak at maybe 2hp but average about 1/2 of a HP. So torque is great, but without motion you have zero horsepower. So it's really both. Yes with my lever I could move my truck and trailer up the biggest, highest pass in the world with just my mighty muscles. It would be very, very slow as I have little horsepower. Now my 290hp minivan, with only 270 ft-lbs could also do it, but 600+ times faster. Still not as fast as a 385 hp/930 ft-lbs diesel would do it. In the end 300hp is 300hp, doesn't matter how it's made, it is a measure of the work being done. There are certainly advantages of making it at a low rpm like a diesel when it comes to other factors like fuel economy and longevity but 300hp is 300hp.

I love my Cummins for towing but the last week I have been using it as a daily driver and it just plain sucks. I sold my daily driver Subie, but as soon as we get back from Yellowstone this weekend the Cummins is going up on Craigslist as well. I'm going to get a 5.7 hemi Commander, maybe a 3.0 diesel Grand Cherokee, or possibly a 6.2 Tahoe Denali or Escalade. Something around $8-13K should do the day to day much better, and still tow the camper 5-10 times a year. I love getting good MPG with the tag team Subie and Cummins but the amount of miles I drive per year, I could switch to a Hummer and it wouldn't add more than $300 to my annual fuel bill.

you might also want to look at the Toyota tundra with the 5.7 and tow package...costs a little more but the resale makes up for it (for gas motors anyway)… just tossing that out there..

[bikendan]

Originally Posted by mrfikser

you might also want to look at the Toyota tundra with the 5.7 and tow package...costs a little more but the resale makes up for it (for gas motors anyway)… just tossing that out there..

Just make sure you look at the payload capacity sticker. Tundra's are well known for low payload capacities, especially the crew cabs and higher trim levels.
I never found any with a payload over 1500lbs, when I was shopping.

[Hersbird]

Originally Posted by mrfikser

you might also want to look at the Toyota tundra with the 5.7 and tow package...costs a little more but the resale makes up for it (for gas motors anyway)… just tossing that out there..

I did look, but at Sequoias (and Land Cruisers and Lexus LX570). Funny even though the Lexus was the most expensive originally, seems to really take a beating in price once they go over 125-150,000 miles. $75,000 down to $22,000 in 8-10 years. A similar mile and year Sequoia is at least $18,000 (while only $40k originally) and I'd pay 20% more for the tank Land Cruiser or LX570 as long as it had the 5.7. Still I can get a really nice 5.7 Jeep that year and mileage for 1/3 the Sequoia or 1/2 a 6.2 Denali, which go about $14,000. The Jeep was available with an amazing Quadra-drive system those years with 3 electronic lockers like you find in a Rubicon Wrangler. My hangup is it's a little bit smaller inside than any of the above mentioned SUVs. The Land Crusier and LX570 also have amazing 4wd systems... Maybe I'll go check the classifieds again...

[Hersbird]

Originally Posted by bikendan

Just make sure you look at the payload capacity sticker. Tundra's are well known for low payload capacities, especially the crew cabs and higher trim levels.
I never found any with a payload over 1500lbs, when I was shopping.

Really the only SUV with big payload is the 2500 Suburban (with some as much as 3000#), then the 2009-10 Hummer H2 (with about 2000#). Everything else I mentioned above (and even things not mentioned like a Excursion) run 1400-1800 pound payload.

[moose074]

Originally Posted by tomkatb

Remember payload does not include any person, fuel. Cooler, bike, dog or receiver hitch.



Thus your payload is likely #1200. Add a dirt bike, a few bikes and a cooler and that does not leave a lot of trailer tongue weight. The factory number does not include propane or batteries usually located in the worst location. Then, how much stuff you hall.



Then too, long trailers tend to wag the truck. A 3/4 ton is simply heavier and less prone to allow sway.



The overloaded tow vehicle is not pleasant to drive.



Look at max trailer weight and 12% tongue.

Payload does include full tank off fuel and driver though usually a small one

[bikendan]

Originally Posted by moose074

Payload does include full tank off fuel and driver though usually a small one

Payload capacity does NOT include driver, just full tank.
TOWING capacity is the one that includes a 150lb driver and full tank.
Many get this mixed up.
Payload Capacity considers the driver as an Occupant.

[Hersbird]

I did end up getting a 2500 Suburban, or more specifically a 2500 Yukon XL. 2002 6.0 4x4 with the 3.73 gears. So I have big payload but only a 7500# tow rating which should be good. Better gears would give me a 9500# rating and the 8.1 would have pushed it as high as 12,000#. My trailer is worst case 7000# and probably in the mid 5's, but now I can seat 6 or more in total comfort and its drives sooo much better than a 2004 Cummins 6 speed day to day. Maybe even better than anything it was only $3900 in really nice condition (perfect interior, not a scratch hardly on it let alone a dent, 75% new AT tires) with 220,000 on it. It does leak a bit of oil, and had a rough idle when cold. Probably the oil cooler lines, and an intake manifold gasket leak but at this price I could afford a brand new L96 360hp GM crate motor with warranty if it dies tomorrow and still have money leftover from the Ram.

[luker0]

Originally Posted by Hersbird

I did end up getting a 2500 Suburban, or more specifically a 2500 Yukon XL. 2002 6.0 4x4 with the 3.73 gears. So I have big payload but only a 7500# tow rating which should be good. Better gears would give me a 9500# rating and the 8.1 would have pushed it as high as 12,000#. My trailer is worst case 7000# and probably in the mid 5's, but now I can seat 6 or more in total comfort and its drives sooo much better than a 2004 Cummins 6 speed day to day. Maybe even better than anything it was only $3900 in really nice condition (perfect interior, not a scratch hardly on it let alone a dent, 75% new AT tires) with 220,000 on it. It does leak a bit of oil, and had a rough idle when cold. Probably the oil cooler lines, and an intake manifold gasket leak but at this price I could afford a brand new L96 360hp GM crate motor with warranty if it dies tomorrow and still have money leftover from the Ram.

Great vehicle and tow really well.

The 6.0 is notorious for losing exhaust manifold bolts. Usually shears several studs as well. Worth looking into some ARP studs and bolts.

We did not have an issue with oil leaks but had a lot of problems with the transmission pan leaking fluid. Fixed it 4 times before finally selling it and getting the 2014 Silverado.

[Hersbird]

If I have to do exhaust bolts, I will probably do new heads and long tube headers as well. Then might as well do the short block and put a better cam in it as well. I'm almost looking fo an excuse at this point to turn it into a 450 hp/450 ft-lb beast. I don't think they are leaking as it is quite as a church mouse, a little piston slap when it first starts on a cold morning.

[marcfriedman]

I get the feeling that the trucks is your daily driver ? I haven't read the entire post so I apologize if this has already been addressed. I have a 05 f250 that is not the most desireable vehicle to navigate on city streets. Somehow I get the feeling city driving is easier with a 1/2 ton truck. Not sure if this is accurate.

[moose074]

Look at the horsepower and torque specs just 10 to 12 years ago they where horrible compared to today’s numbers yet people still towed from point a to point b no problem. I towed 100k + using a gm 6.2 diesel less than 170 hp but the rear gears were ridiculously high like high teens or low twenties and couldn’t go over 25 mph with foot all way to floor