Torque and Trailer Towing in my 4.8L Chevy

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cortttt

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Here's the issue - a baby V-8 with little low end torque may have to tow a 5000 lb trailer in the future. I'm not worried about on-road - although I would hardly look forward to some hills. Off-road is my concern as I tend to get into some somewhat sketchy areas and do get stuck from time to time.

With the 6.6L vans - reportedly with nice-low end torque - rarely available and with used vans at an astonishing premium - I'm stuck with this van for now. So what to do to get more low end torque?This van has simply terrible low-end torque. It's unable, for instance, to make it up dirt hills. (It has a limited slip by the way). So how to increase that? I've thought of swapping an 6.0 L engine in for the 4.8L and driving it for another 100K. I haven't found any shops that would be interested. I don't know if a turbocharger can be added to it? Or if it can if that's a good idea at all.

There's also the possibility of adding 4x4 - very expensive - but less than buying another van.

The last choice is to just be very careful where I take it.

Anybody towing with a 4.8L engine?
 

tx2sturgis

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What year is the van, and does it have tow/haul mode? Is it a 4 speed? What is the rear end ratio?

I had a Ford E-250 with the 4.6L V-8 and I cant remember the gear ratio, but it was the 'economy' ratio...not designed for trailer pulling. The van got really decent fuel mileage when not towing but it struggled when pulling a cargo trailer of about 2500 pounds when pulling uphill and with any kind of headwind.

Pulling a small trailer with a motorcycle on it was fine...almost no wind resistance there.

The best luck I had was to just drive slower, and lock out the overdrive, and leave it in tow/haul mode which changes the shift points. It did struggle sometimes but I always got where I was going.
 

bullfrog

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You basically have the wrong vehicle for what you intend to do. With newer vehicles your only choice in most cases is to sell the vehicle you have and get a better one designed to do what you need. Almost any changes you make will affect economy, reliability and longevity negatively. A very nice 3/4 ton 4x4 big block Suburban is also cheaper to buy than a new van. Modified older vehicles are easy to find but 10 MPG is pretty common. Maybe an older Cummins diesel Excursion if you like Fords and diesels. My $2,500 4x4 3/4 ton 1987 Suburban with all new everything when it is done and completely rebuilt with one ton axles, 4L80e trans and 205 transfer case with twin sticks will have cost me about $18,000 which over half is high dollar ([email protected]) labor that I paid for as I’m getting to old to do. Average stock restored prices are around $15,000 now days. If You could do all your own work probably $10,000 to $12,000 would get a reliable 100,000 to 200,000 miles of driving at 10 MPG. New vehicles are pretty much twice that or much more but will probably hold their value and get better mileage. Keep looking and you will find what you need it may just cost a little more than you want to pay.
 

jasper

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What tx2sturgis mentioned about rear end gear ratio. It should be shown on the build plate or on a small tag at a differential bolt. Changing the gears to something about 3.70:1 to 4.10:1 allows for much better hill climbing, but means higher rpm at the same highway speeds, with less mpg, as now. If you don't need to drive as fast cross-county, losing a few mpg can be more acceptable than more expensive options. Sometimes, driving slower highway speeds can keep the mpg close to what is was before a ratio change.

Do you mean it can't climb dirt hills because of wheel spin, or simply won't go? A higher numerical gear ratio allows the engine rpm to increase and stay in its power band in low gear driving slowly up hills.

It also usually causes a lying speedometer, but a mental note by using a GPS or smartphone app speed reading is a workaround. A rather substantial differential change can create a different vehicle. Possibly good or bad.

I'm ignorant of the total effect on the latest vans with respect to engine control systems.
 

cortttt

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What year is the van, and does it have tow/haul mode? Is it a 4 speed? What is the rear end ratio?

I had a Ford E-250 with the 4.6L V-8 and I cant remember the gear ratio, but it was the 'economy' ratio...not designed for trailer pulling. The van got really decent fuel mileage when not towing but it struggled when pulling a cargo trailer of about 2500 pounds when pulling uphill and with any kind of headwind.

Pulling a small trailer with a motorcycle on it was fine...almost no wind resistance there.

The best luck I had was to just drive slower, and lock out the overdrive, and leave it in tow/haul mode which changes the shift points. It did struggle sometimes but I always got where I was going.
2010 / has tow/haul mode / 3.42 / its got the 6-speed

I'm not excited towing on the road but not really worried about it. Slow and steady. So long as it has time to build up speed it's fine. It's the dirt roads - particularly in the desert that I'm worried about =.
 
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cortttt

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What tx2sturgis mentioned about rear end gear ratio. It should be shown on the build plate or on a small tag at a differential bolt. Changing the gears to something about 3.70:1 to 4.10:1 allows for much better hill climbing, but means higher rpm at the same highway speeds, with less mpg, as now. If you don't need to drive as fast cross-county, losing a few mpg can be more acceptable than more expensive options. Sometimes, driving slower highway speeds can keep the mpg close to what is was before a ratio change.

Do you mean it can't climb dirt hills because of wheel spin, or simply won't go? A higher numerical gear ratio allows the engine rpm to increase and stay in its power band in low gear driving slowly up hills.

It also usually causes a lying speedometer, but a mental note by using a GPS or smartphone app speed reading is a workaround. A rather substantial differential change can create a different vehicle. Possibly good or bad.

I'm ignorant of the total effect on the latest vans with respect to engine control systems.
Changing the gear ratio is a good idea - don't know why I hadn't thought about that. All the Chevy vans to my knowledge are 3.42. That might be the best first option!.

It simply won't go up some hills - so there the gear ratio change makes sense as well. I know it's not cheap but that might be the first thing to try. Thanks.
 

cortttt

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You basically have the wrong vehicle for what you intend to do. With newer vehicles your only choice in most cases is to sell the vehicle you have and get a better one designed to do what you need. Almost any changes you make will affect economy, reliability and longevity negatively. A very nice 3/4 ton 4x4 big block Suburban is also cheaper to buy than a new van. Modified older vehicles are easy to find but 10 MPG is pretty common. Maybe an older Cummins diesel Excursion if you like Fords and diesels. My $2,500 4x4 3/4 ton 1987 Suburban with all new everything when it is done and completely rebuilt with one ton axles, 4L80e trans and 205 transfer case with twin sticks will have cost me about $18,000 which over half is high dollar ([email protected]) labor that I paid for as I’m getting to old to do. Average stock restored prices are around $15,000 now days. If You could do all your own work probably $10,000 to $12,000 would get a reliable 100,000 to 200,000 miles of driving at 10 MPG. New vehicles are pretty much twice that or much more but will probably hold their value and get better mileage. Keep looking and you will find what you need it may just cost a little more than you want to pay.
It is the wrong vehicle for sure - or is the most difficult vehicle for sure - and it would be cheaper to pick up a pickup. For now a van is needed. If in the future it isn't = a pickup, Suburban or something like it would be better. Good luck with your rebuilt Suburban. Something like that might be in my future = I like to keep cars going.
 

bullfrog

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Get a good 12 volt air compressor and some air down valves set to about 10 to 15lbs. Lowering the pressure in dirt or sand will give you more traction and decrease the diameter of the tire basically giving you a more torque. Be sure to not go so low you loose the bead seal of the tire and straight a head steering is best till you are unstuck and you can air back up.
 

Happy Camper

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Depending if you want to modify the engine, you can get a different cam that helps with your torque issue and also puts more torque in the rpms you need it most.

I bring that up because it's probably a better solution than regearing and would most likely cost less.
 

cortttt

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Get a good 12 volt air compressor and some air down valves set to about 10 to 15lbs. Lowering the pressure in dirt or sand will give you more traction and decrease the diameter of the tire basically giving you a more torque. Be sure to not go so low you loose the bead seal of the tire and straight a head steering is best till you are unstuck and you can air back up.
Yes - very helpful. It took me five years to try that and it quickly got me out of what appeared to be an ungodly mess :)
 

cortttt

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Depending if you want to modify the engine, you can get a different cam that helps with your torque issue and also puts more torque in the rpms you need it most.

I bring that up because it's probably a better solution than regearing and would most likely cost less.
Thanks - I hadn't thought of a new cam at all :)
 

mudbunny

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As far as the axle locker, look on your option sticker. It is in the glovebox or stuck on the underside of the hood, most likely. Look for a G80 rpo code, that is the factory locker. It locks when one wheel spins a certain amount more than the other. It unlocks above 20 mph or so.
 

Happy Camper

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Thanks - I hadn't thought of a new cam at all :)
Years ago I bought a truck that had been used as a landscaping truck. While it was a work vehicle it had a full rack and towed a trailer. They put in a cam more suited to it's work.

That was a 305, which is normally a dog. That truck had so much more torque and pull than it would have stock. I used it hauling my work stuff around for years.

While they are in there you should consider having wear items checked as well. Or maybe you know how to do it yourself.

Good luck!
 

riptorn

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As said previously
1, RV TQ Cam
2, Bigger Injectors
3, Higher Stall Torque Converter
4, A Computer reprogram by a Good Dyno Tune Shop,
If you can do 1-3, you may do it for less than $2,500, extras included. And you'll lose MPG,
Had a '05-2500, 4.8 for 179,000+miles, sometimes pulled heavy trailer's, NOT ENOUGH POWER!
Now '16-2500, 6L, 6spd. 3.05 RP, Same trailers, in tow haul mode no problem,
No replacement for displacement,
Both pulled 2 lane roads in Black Hills and Ozark Mouton Range
MPG not bad for a brick (without trailer),
 

cortttt

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As said previously
1, RV TQ Cam
2, Bigger Injectors
3, Higher Stall Torque Converter
4, A Computer reprogram by a Good Dyno Tune Shop,
If you can do 1-3, you may do it for less than $2,500, extras included. And you'll lose MPG,
Had a '05-2500, 4.8 for 179,000+miles, sometimes pulled heavy trailer's, NOT ENOUGH POWER!
Now '16-2500, 6L, 6spd. 3.05 RP, Same trailers, in tow haul mode no problem,
No replacement for displacement,
Both pulled 2 lane roads in Black Hills and Ozark Mouton Range
MPG not bad for a brick (without trailer),
Nice! Thanks for all the ideas. I was thinking about a tune as well. I wonder how much torque that would provide. Probably worth it just to try it out and see what it produced.

I found a shop that would swap in a 6.0L - $12-15K - lots of money - but the power would be great. The 4.8L has been great but in retrospect it would have been nice to get the 6.0 to start with.
 

Aesop

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Here's the issue - a baby V-8 with little low end torque may have to tow a 5000 lb trailer in the future. I'm not worried about on-road - although I would hardly look forward to some hills. Off-road is my concern as I tend to get into some somewhat sketchy areas and do get stuck from time to time.

With the 6.6L vans - reportedly with nice-low end torque - rarely available and with used vans at an astonishing premium - I'm stuck with this van for now. So what to do to get more low end torque?This van has simply terrible low-end torque. It's unable, for instance, to make it up dirt hills. (It has a limited slip by the way). So how to increase that? I've thought of swapping an 6.0 L engine in for the 4.8L and driving it for another 100K. I haven't found any shops that would be interested. I don't know if a turbocharger can be added to it? Or if it can if that's a good idea at all.

There's also the possibility of adding 4x4 - very expensive - but less than buying another van.

The last choice is to just be very careful where I take it.

Anybody towing with a 4.8L engine?
In September 2021 I towed a 6×12 interstate single axle loadrunner cargo trailer from Murray, Utah to Eastern Oregon. the cargo trailer weighed 1530 pounds and as our tow vehicle we used a 2005 gmc savana 2500 with the 4.8 and 4 speed automatic. I think the lowest mpg we got was like 9 mpg but that was coming up over the hills on i84 between Ontario and baker city. we could definitely feel the Weight of the little cargo trailer when we were towing it empty. no idea how it will tow with stuff in it. i think the gear ratio is like 4.10 or something. actually, come to think of it, i remember feeling some heat coming up from the floor in the dentral middle of the cargo area of the van when we were towing it, no idea if that was heat from the transmission from towing it or not. but we did have the tow haul button engaged when towing it sometimes, not on all of the trip did we have that button engaged.20210918_160031.jpg
 

cortttt

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In September 2021 I towed a 6×12 interstate single axle loadrunner cargo trailer from Murray, Utah to Eastern Oregon. the cargo trailer weighed 1530 pounds and as our tow vehicle we used a 2005 gmc savana 2500 with the 4.8 and 4 speed automatic. I think the lowest mpg we got was like 9 mpg but that was coming up over the hills on i84 between Ontario and baker city. we could definitely feel the Weight of the little cargo trailer when we were towing it empty. no idea how it will tow with stuff in it. i think the gear ratio is like 4.10 or something. actually, come to think of it, i remember feeling some heat coming up from the floor in the dentral middle of the cargo area of the van when we were towing it, no idea if that was heat from the transmission from towing it or not. but we did have the tow haul button engaged when towing it sometimes, not on all of the trip did we have that button engaged.View attachment 32126
Thanks - that's food for thought as I would be towing much more.
 

JimMcBride

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From a different perspective: find out your torque peak rpm and take advantage of whatever is there for you as it sits. You'll want to use a tachometer to hit the mark. I find it really helps with my small block (4.7L) Tundra towing a toy hauler at 4500 lbs. Drive that sucker!
 
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