'02 Sierra 6.0 poor towing power

[RustyBucket]

My 2wd 6.0 powered crew cab Sierra seems to lack the low end torque to tow comfortably. Had the truck since new, 185,000mi and have towed a variety of campers car trailers & boats. It won't stay in OD at 65-70mph on level ground. If I block it out of OD and run 2700-3000 rpm it tows better but gives 8 mpg. If I let it seek in and out of OD the transmission temp. goes up and worries me. Truck is stock and has given good trouble free service. It gives about 14mpg on the road not towing. It has 3.73 gear & 265/75/16 Michelin tires. I've towed between 2,000 & 9,000lbs and it acts about the same. It's done this for 14yrs. Wondered if there is a tuning/reprogramming fix that would help it.

[b454rat]

IMO, the LS engines just don't have the torque of the big block they replaced. I had a 97 ECLB, 4wd, 454/4l80/4.10s and 265 or 285s, but with 2 big blocks in the back, a set of 1 tons, welder and tanks, towing a RCSB on a dolly, never dropped below 70 with the cruise on, pulling any hill I went up. Don't think it even dropped out of OD....

[clinebarger]

The 6.0L was never meant as a replacement for a Big Block, It was the replacement for the 5.7L. As the 8.1L was available until 2007.

I first would advise to Slow the "F" Down!, 65-70 is pretty fast for towing duties when you don't have the torque for it.

4.10 gears would help, If this is a 2500HD, I'm surprised in doesn't have 4.10's.

I must have installed a hundreds of Magnacharger Superchargers on 6.0L 2500HD's because this very compliant. Some of them had Thousands of dollars in modifications.....Headers, Exhaust, Custom Tuning, Custom Cam profiles, Cold Air Intakes etc with Little to No results!

Run a LS6 Valley Cover for better "Oil Control" & a Synthetic 5w-40 dual rated motor oil if interested in the Supercharger.

It may be cheaper to find a wreaked ('01/'02) 2500 Suburban with a 8.1L & do an engine & engine harness swap.

2500HD's with 8.1L's had a Allison 1000 transmission, The swap is doable but more work.

[GASoline71]

Man, I just leave my 6.0L ('06 K2500HD Silverado) in tow/haul mode and it has more than enough grunt to tow. I tow a 29 foot 5th wheel over mountain passes. I never use OD while I'm towing as most everywhere around these parts has either an incline or a decline no matter where you go.

Gary

[RustyBucket]

Originally Posted by clinebarger

I first would advise to Slow the "F" Down!, 65-70 is pretty fast for towing duties when you don't have the torque for it.

4.10 gears would help, If this is a 2500HD, I'm surprised in doesn't have 4.10's.

Thanks for the responses Y'all... clinebarger, I was hoping you'd respond with a magic quick fix, but no such luck huh?
I agree about the speed, I think I speed up trying to bring the RPM up so it doesn't shift down, which doesn't work.
The truck is a 1500HD SBCC
I know it's only 14 cu.in. bigger than a 350sb. I towed a lot with a '92 GMC G30 passenger van, TBI 5.7, od trans & 3.73's. I think it shifted down less and I KNOW it gave better fuel mileage both towing and not towing.
I'd like to have a new Sierra Duramax/Allison but this one's paid for and still looks and drives pretty good.

[Tom]

If I couldn't tow at 70mph I'd be getting a new engine or truck. My 26' international box trucks at the moving company would do 75mph fully loaded wit 1600 cubic feet of crap.
LS engines have huge intake ports. They will never make great low end torque. That's what we get for wanting big HP from the factory and no forced induction. Changing the gears isn't really any different then just cruising in 3rd since your power complaint is at freeway speeds.

[72MARIO]

I just got back from a trip pulling my 25' camper down into PA from Ontario Canada. with our Lq4 4l80 swapped burbn. On the way down I didn't notice power to be a issue...but on the way home I experienced the same thing your describing the hunting between 3-4 at 65 MPH get up to 75 and it fine, but I don't like towing at that speed. The power is there just up higher in RPM 3rd gear is a huge increase in rpms
I really should look at the elevations going south to north and see what the diffirence is. I have 3:42 gears and a 27" tall tire I wish I would have kept the 3:73 for towing

[clinebarger]

Originally Posted by RustyBucket

Thanks for the responses Y'all... clinebarger, I was hoping you'd respond with a magic quick fix, but no such luck huh?
I agree about the speed, I think I speed up trying to bring the RPM up so it doesn't shift down, which doesn't work.
The truck is a 1500HD SBCC
I know it's only 14 cu.in. bigger than a 350sb. I towed a lot with a '92 GMC G30 passenger van, TBI 5.7, od trans & 3.73's. I think it shifted down less and I KNOW it gave better fuel mileage both towing and not towing.
I'd like to have a new Sierra Duramax/Allison but this one's paid for and still looks and drives pretty good.

The LQ4 is already giving you the maximum low end torque!, Doing any mods other than a Supercharger or adding Displacment will not help......Or move your max Torque output higher in the RPM range.

A old G30 is way lighter than your 1500HD, That is why Vans have such a high Payload capacity, Did you ever notice the G20 Vans had 1/2 ton suspension but the Payload of a 3/4 Ton Pick-up?

Tom has a point about the Intake Port Volume (210cc on a 317 Casting), But the shape of the port helps with Velocity so they don't act quite like a Gen 1 SBC 210cc head.

Stroking your existing engine is an option, A 4" stroke, And a 4" Bore would put you a little over 400 Inches, It sure is easier too spend someone else's money

[b454rat]

Why I can't wait to get the 8.1 in my truck....

[storm9c1]

You said that's a 1500HD crew cab? It's already a heavy beast by itself. I've always felt the 1500HD is a bit of a joke. You really don't get a serious tow rig until the 2500 and 3500 trucks.

Don't tow with OD. And take the 8mpg hit. That's your only choice until you get into serious mods or engine swaps. My tow rig has a 383 stroker, and on big hills, I can't use OD either. A stroker motor of any kind will help.

[RUN GMC]

SO a cam swap into a 5.3 like i was planning to do will not really help or will it......and I was planning to use this Cam motion spec'd cam.......that says it will help with mid-range torque for towing at high way speeds.......would this be a waste of time?

http://store.cammotion.com/53-l-325ci-95-compression-2

[homemade87]

That cam has some proven results . In my opinion it would be worth the trouble to install if you tow a lot . Here is some real results with this cam . http://ls1tech.com/forums/dynamomete...hp-22rwtq.html . 41rwhp is nothing to sneeze w/ exhaust , cold air intake . No major mods . A tune would be in order to get the most from the cam . If I ever have to go in my 5.3 for any reason I am putting this cam in . You may not see exactly 41rwhp but I bet you would see a significant gain .

[GASoline71]

Seriously... if you want low end grunt. You need a diesel rig. Gas powered rigs need RPM to make TQ.

Gary

[RustyBucket]

I agree Gary, I just don't tow enough to justify spending the money. I nearly traded my 6.0 on a Duramax when it was about two years old but chickened out. I recently sold the Nova so I'll be towing less yet. My buddy has an '06 Silverado 1500 CCSB 5.3 and tows a trailer like mine for his Nova(faster than mine). I've driven both rigs & I don't think my 6.0 pulls any stronger than his 5.3 pulling a comparable load. His truck definetly gives better mileage not towing.

[GASoline71]

I hear ya. The wife and I do eventually want to get a larger 5th wheel. But I'm in the same boat as my truck is paid off, and I don't want to fork over the cash for a Duramax right now.

So... we're looking at MOTORHOMES!

Gary

[Alex V.]

The 6.0 has nearly identical torque output as an LE8 (Quadrajet truck) 454, with about 70 more horsepower. I believe the peak torque is about 1000 RPM higher on the 6.0 than the 454, too - from the 6.0 trucks I've driven, I can tell it. The trucks got heavier, yes, but comparing several different Vortec or non-Vortec 350 and 454 trucks and Suburbans to their LS 5.3 or 6.0-powered counterparts I just don't see that efficiency was one of the areas they improved upon. My FIL's 1500HD is rated just 400 lbs. less in GVW and 800 lbs. less in max. trailer weight than my '85 C3500, and it feels like, while a close comparison, the 6.0 would kill itself keeping up with the 454, and only burn less gas when empty.

[Marv D]

Originally Posted by GASoline71

I hear ya. The wife and I do eventually want to get a larger 5th wheel. But I'm in the same boat as my truck is paid off, and I don't want to fork over the cash for a Duramax right now.

So... we're looking at MOTORHOMES!

Gary

Gary hopefully your looking at a diesel coach. I've pulled my trailer with the heavy cars and the light sand rail in it with:

a (rented) 34' coach with ford v-10 / 5spd trans, OMG How pitifully underpowered that pig was)

then a 33' coach with a 8.1 workhorse,, again horribly underpowered

and a Damon 36' with a little 275HP Cummins,, OMG I love this motor.,, 13MPG loaded at 62MPH her ei the desert floor

Then I towed with a Alpha with a 400HP Cummins and seriously creamed my jeans. Thought I was in heaven...

until I pulled with a 40' Fleetwood and a 425HP CAT. holy $#!+

My buddy says,,

GAS is for RACING,, DIESEL is for TOWING.

It don't matter if it's a 3/4 ton or a 34' motorhome. If your towing,,,, you will LOVE diesel (well everything except the price tag of the rig, but in the end I really believe it's worth it )

[storm9c1]

I agree, diesel is definitely the way to go. But if that's outside your means, as it was for me, and the engine is out for a rebuild or a cam swap, consider stroking it and tuning it for torque. Throw away some of the high-RPM racing knowledge, towing is not a high RPM application. That's the last thing you want. Stroking and tuning for lowest RPM peak torque is the way to go. It's the next best thing to diesel.

[BossHogg69]

Originally Posted by RUN GMC

SO a cam swap into a 5.3 like i was planning to do will not really help or will it......and I was planning to use this Cam motion spec'd cam.......that says it will help with mid-range torque for towing at high way speeds.......would this be a waste of time?

http://store.cammotion.com/53-l-325ci-95-compression-2

Originally Posted by homemade87

That cam has some proven results . In my opinion it would be worth the trouble to install if you tow a lot . Here is some real results with this cam . http://ls1tech.com/forums/dynamomete...hp-22rwtq.html . 41rwhp is nothing to sneeze w/ exhaust , cold air intake . No major mods . A tune would be in order to get the most from the cam . If I ever have to go in my 5.3 for any reason I am putting this cam in . You may not see exactly 41rwhp but I bet you would see a significant gain .

I have an '05 ccsb 2wd GMC 1500 with the towing package (not HD) and I have a 5.3, Blackbear tune, K&N FIPK, Long tube headers, 2.5" exhaust, Comp LSr 215 cam, Yank Truck Thruster converter (2600 stall) that I do some towing with, and while it has a lot of power and is fun to drive unloaded, it still does everything RustyBucket describes when I tow with it. Now, don't get me wrong, it has plenty of power to tow up hills, pass, etc - I just towed a 20' enclosed car hauler from Arkansas to Pennsylvania and back and it would do it at 65-70 no problem, but it was in 3rd gear @ 2800 rpm and averaged 8.5mpg there and back. Couldn't tow in OD because the trans would 'hunt' at the slightest elevation change, trans temp would rise and would not stay in OD with the cruise on, and struggled to stay in OD if I just feathered the throttle without the cruise on. The engine never got hot or acted up, it just doesn't come online until just under 3,000rpm. I've had this truck since '06 and have done a lot of towing with it, from utility trailers, car haulers, used it to haul shingles from roofing jobs and anything else in between.

I'm inline with Clinebarger on this - all I could think about when that enclosed car hauler was behind me was "man, a 402 would be awesome right about now".

[jjzepplin]

Ok. I am no expert but I always thought you were not supposed to tow in OD. I thought this was a warning from the manufacturer on any truck.
The clutch in your converter will likely burn up quickly and leave your trans in bad shape. It's just not meant to hold a load that big.

[b454rat]

I never towed out of OD, always left in. What's the sense of having that extra gear if you can't use it?? I think truck manufacturers don't take into account hills and mountains. Yeah a 1/2 ton will pull that 6k trailer no problem, just don't hit a hill.....

[jjzepplin]

Oh I'm thinking of the lockup. My bad.
I still don't tow in OD though.
I just drive a little slower. At 70mph stopping or correcting while towing is a sumbeotch.

[GASoline71]

Originally Posted by Marv D

Gary hopefully your looking at a diesel coach. I've pulled my trailer with the heavy cars and the light sand rail in it with:

a (rented) 34' coach with ford v-10 / 5spd trans, OMG How pitifully underpowered that pig was)

then a 33' coach with a 8.1 workhorse,, again horribly underpowered

and a Damon 36' with a little 275HP Cummins,, OMG I love this motor.,, 13MPG loaded at 62MPH her ei the desert floor

Then I towed with a Alpha with a 400HP Cummins and seriously creamed my jeans. Thought I was in heaven...

until I pulled with a 40' Fleetwood and a 425HP CAT. holy $#!+

My buddy says,, It don't matter if it's a 3/4 ton or a 34' motorhome. If your towing,,,, you will LOVE diesel (well everything except the price tag of the rig, but in the end I really believe it's worth it )

We are! Used ones about 5 to 6 years old are in our price range. My parents snow bird down your way every year and the old man has been keeping an eye out for us.

Gary

[haysonj]

I have a 03 Silverado with the 5.3 and I have towed my 5000 pound boat all over California without a problem. The speed limit while towing is 55 so I normally set the cruise at 60 mph and the truck will maintain the speed even in the mountains. The truck does have a tow button which I think does something with the lockup and I always use it when towing. It also gets around 14 mpg when towing and 18 to 20 when not towing.

[burnin oil]

Originally Posted by GASoline71

We are! Used ones about 5 to 6 years old are in our price range. My parents snow bird down your way every year and the old man has been keeping an eye out for us.

Gary

I am a total diesel guy myself but I would not waste the money on a diesel class A motorhome unless I actually planned to travel a lot. Maintenance costs are a lot higher and the V10s actually get decent milage, even if they are a dog to drive. I am a full timer and see a ton of snowbirds with the gas rigs for this reason. Most of them just don't travel enough for the price kick. I-95 corridor twice a year is about all. If it makes you feel good my Dodge 5500 gets around 8mpg hauling my 5ver. The trailer is 16k empty with a 12k truck. Get a whopping 12 empty on a good tank.

I had a 2003 2500hd with a 6.0L and it was the worst tow vehicle I have ever owned. NV4500 and 4.10 gears and the thing couldn't run 70mph for over 45 minutes with an empty car trailer in tow before the computer started kicking the power output down. Mileage was not all that great either. I didn't miss that one going down the road one bit. Traded it in on a 04.5 Dodge diesel that got around 19 empty.