Towing at 80 mph.

AudiOn19s · October 26, 2020

I need some input on a new truck purchase. Currently I have a 2007 Sierra SLT with a 6.0L (LY6) and 4l60. I've towed for years with this thing towing race cars on open trailers and it tows perfectly fine at 80 mph without a ton of drama.

This year I started towing a smaller, enclosed trailer but the trailer has 7' 6" interior height with an air conditioner on top of it and it's an absolute parachute behind the truck. The truck tows perfectly fine at 70-ish mph but when you get to 75-80 mph it wants to constantly run in 3rd gear and when it's in top gear it is nearly impossible for it to get into converter lock. The thing has 250k miles on it and this is pretty much the last straw for it so I'm searching for new trucks. Trailer weight fully loaded is only 2200 or so lbs so it's not heavy, it's just horribly inefficient from an aero standpoint.

Will the modern 8 and or 10 speeds resolve my issues and just lock in in a gear that won't be 3500rpm +? I tend to think the 5.3 with the 8 speed or 10 speed would have enough variables in the gearing to overcome the aero drag issue I'm dealing with, but I wouldn't be opposed to the 6.2 if it's absolutely necessary.

So back to the original question. Give me your towing experiences at 80mph with the new trucks. This is pretty much #1 factor in what truck I'll decide to go with.

ljramsey · October 26, 2020

I have a 2020 with a 5.3L engine and the 10 speed transmission. I tow a 26' travel trailor and know it puts a strain on the truck to run 75mph or more. I typically keep it at 68 mph when towing.

redwngr · October 26, 2020

With more gears to pick from it will be able to find one that can produce the necessary torque level at a lower engine rpm.

Sounds like the enclosed trailer has much higher frontal area.

If it does have more frontal area it won't pull as easy as the other trailer.

Grumpy Bear · October 27, 2020

11 hours ago, AudiOn19s said:

I need some input on a new truck purchase. Currently I have a 2007 Sierra SLT with a 6.0L (LY6) and 4l60. I've towed for years with this thing towing race cars on open trailers and it tows perfectly fine at 80 mph without a ton of drama.

This year I started towing a smaller, enclosed trailer but the trailer has 7' 6" interior height with an air conditioner on top of it and it's an absolute parachute behind the truck. The truck tows perfectly fine at 70-ish mph but when you get to 75-80 mph it wants to constantly run in 3rd gear and when it's in top gear it is nearly impossible for it to get into converter lock. The thing has 250k miles on it and this is pretty much the last straw for it so I'm searching for new trucks. Trailer weight fully loaded is only 2200 or so lbs so it's not heavy, it's just horribly inefficient from an aero standpoint.

Will the modern 8 and or 10 speeds resolve my issues and just lock in in a gear that won't be 3500rpm +? I tend to think the 5.3 with the 8 speed or 10 speed would have enough variables in the gearing to overcome the aero drag issue I'm dealing with, but I wouldn't be opposed to the 6.2 if it's absolutely necessary.

So back to the original question. Give me your towing experiences at 80mph with the new trucks. This is pretty much #1 factor in what truck I'll decide to go with.

L5P Duramax

Sqrls · October 27, 2020

I tow roughly the same kind of trailer as you. Between 2000-4000 lbs (depending on what I have in it), 8 ft tall, flat front, and 5 ft wide. I also see the front bending in at speed acting like a nice air brake. I had a 2015 and a 2018 CC std bed with 5.3/6speed combo. It would pull it no problem in the city, but at 70+ it would stay in 5th cruising, but to pass it would definitely go to 3rd and 4th. Uphill would need to downshift at times, but still better than 3500 rpm always.
Now I have a 3.0 diesel CC std bed. Pulling that same trailer + 1000lbs in the bed, the only time I notice the trailer is when it bounces around at 75+.

With the 5.3, I got 11-13mpg towing it, barely got 15 @ 60 when I tried to see the best I could get.

With the 3.0, I get 20-21 at 70-80mph, 18-19 city if I get on it at lights, and 23-25 if I’m cruising in traffic at 60-65.

I totally get how you are feeling about the downshifting. The truck should have more than plenty of power for a trailer that light, but the truck struggles at times and works annoying hard pulling it. The diesel does not feel this way.

If possible, try to get an extended test drive where they let you take it home, and try the trailer out.

bshort · October 27, 2020

Towing at 80? Cool. No, the 10 speed will not go in to 10/lockup either.

Donstar · October 27, 2020

I'd simply slow down. The fuel savings will more than compensate for the few extra minutes it takes to get to your destination. The faster you pull a parachute the more it resists. I did a lot of trial and error with my travel trailer and found the sweet spot just shy of 70. My truck could cruise at 80 but the fuel consumption at $5+ per gallon made this a senseless choice. I still arrived at my destination in good time, relaxed and with a little more cash in my pocket!

DemonWorks · October 27, 2020

I tow at 80 and had the 5.3 with 8 speed before the duramax. The 5.3 will rev out as it needs to, to maintain your speed. It gets the job done but yeah, the rpm's climb often. The 3.0 duramax does a much better job of maintaining speed. i was happy with my 5.3 but this duramax makes me look back and rethink how great it really was.

For reference, I tow an open car trailer @6000lbs total

Grumpy Bear · October 27, 2020

Current motors for the 1500 series trucks.

Ecotect3 4.3 = 305 pounds feet torque at 3,900 rpm

2.7 Turbo = 348 pounds feet torque between 1,500 and 4,000 rpm (boost limited)

Ecotec3 5.3 = 383 pounds feet torque at 4,100 rpm

Ecotec3 6.2 = 460 pounds feet torque at 4,100 rpm

Duramax 3.0 = 460 pounds feet torque at 1,500 rpm

Pick your poison

ArTurf · October 29, 2020

Wind resistance aka drag increases exponentially above 60 so................

AudiOn19s · November 3, 2020

appreciate the feedback here. Thanks for the input.

IOMTT · March 28, 2021

Towing capacity in WEIGHT is deceiving. FRONTAL AREA is where the resistance is at cruise speed. Chevrolet referred to it in their owner's manual towing section in the past. Ever wonder why they show a flatbed trailer hauling granite blocks or a small tractor in their TV ads?

Put a 5th wheel camper with the master bed in the front on there.... it will separate the toys from the trucks.

aliveguy5 · March 29, 2021

I have a 6.2L 10 speed and tow a slightly over 11 foot high TT that weights between 7,500 and 8K depending on the trip. When weather permitted I have towed it at 80mph before and I never needed to maintain 3,500 rpm unless I was going up a steep hill. A L5P Dmax would be your best option but if you are staying in the 1/2 ton category you can find your pairing without a worry.

Grumpy Bear · March 29, 2021

That total weight, 2200 lbs loaded. I've carried that much in the bed. Never at 80 mph. Can't hardly stop the thing from 60 .

No not Pepper. I wouldn't do that to here. Company work truck Skidded load of steel. Panic stop from 40 mph got my attention. Load slid six inches up the bed. Ouch! :crazy: