I have an 04 GMC Sierra 1500 crew cab with the 5.3L engine and 3.42 gears. The previous owner added 20" wheels and tires and a flowmaster muffler, otherwise the truck is stock. My Outback 30BHQ is around 7500lb dry, and I want to add some mods to improve towing. I also only get 12 mpg city and 14 hwy not towing and I am a fairly conservative driver. I have had the truck checked out by the best mechanics in the area and they say it there are no issues with it. I wonder if the taller tires might have something to do with the mileage. I currently am running 1500 rpm at 60 mph (Corrected). My thoughts are to change to a 4.10 axle ratio and purchase a programmer. By my calculations, the 20% lower gear ratio should increase my rpms at 60 to about 1800. Any experience/recommendations on a programmer? Will these changes help my towing ability?

Changing to 4.10 gears will definitely help. However, you don't have enough truck for a 7500# Dry Weight trailer so your towing experience is still going to suck. That generation of 1/2 ton chevy's is practically limited to around 6,000# loaded TT towing weight (note I said loaded not dry meaning probably 4,500# dry). (I have a 1/2 ton '05 with your engine and heavy duty tow package, and absolutely would not tow your empty trailer with it, much less loaded. I love that 1/2 ton but it is just not enough for your trailer)

Will these changes help my towing ability? No. You could even add a supercharger but that will only increase power, not towing ability. There is much more than just power required for good towing ability. You'll be lacking in payload, axles, suspension etc, as with most 1/2 ton trucks trying to tow that size and weight of TT. You're probably looking at close to 9000lbs once loaded up so even if you could pull it you're likely over several of the trucks ratings.

New member, welcome to the Forum.I'm blunt...often probably too blunt:You have a big trailer and a relatively (light duty)truck. Pouring money into mods like re-gearing and a programmer is not going to give you better mileage or more payload. You will be wasting your money and will probably soon need transmission work.It is a 1/2 ton truck and a heavy bunk house trailer...probably means family - kids and lots of gear.You are in 3/4 ton territory...big block or diesel.Hopefully others will give you a more positive outlook.

I hada 2002 Chev with 5.3, 3.73 and towed 7000-lb (loaded) 5vr. Wasn't a lot of fun, especially at high elevations or into headwinds.Replaced 5with with a 9300-lb (loaded) 5vr and replaced truck with 2500 Chev, 8.1, 4.10. Towing was fun after that. Acceleration, no problem merging on interstate highway. Having the 4.10, I towed at 58-59 mph, just after o/d kicked in. Mpg's towing, avg 9.3 - about the same or slightly less than the 1500.You're in 2500 territory, which screw around putting band-aids on your 1500?

X2 on what was posted above. Mine is an 04 also with 3.73s and is rated to tow around 7700lbs if I remember correctly. If your truck is a 2wd it may be a little more. Besides the tow rating your payload isn't that great, I'm at 1000 lbs with me in the seat and 3/4 tank of fuel.I am right at 7000 lbs, my GVWR, with this set up, ready to camp. Thats just me and my two little dogs and my stuff.I can get around 17 mpg on the road solo if I keep it under 65 mph. 75 mph gets me 15 mpg. Towing like the pic under 65 mph is 12-13 mpg. I'm running 285/65-18 tires.

Power mods on Sierra 1500 CC with 5.3L | Good Sam Community

16 Replies

ChooChooMan74
Explorer
Mar 28, 2014
I usually try to side with people who are on the edge or just over their limits, trying to run with what they have, because, more than likely, they can't afford a new truck. If you can't afford a bigger truck, do what you can with what you have. But I feel, like the others, that the trailer you have would be better if towed with a 250/2500 series truck. Good luck and be safe out there dude.
GWolfe
Explorer
Mar 28, 2014
X2 on what was posted above. Mine is an 04 also with 3.73s and is rated to tow around 7700lbs if I remember correctly. If your truck is a 2wd it may be a little more. Besides the tow rating your payload isn't that great, I'm at 1000 lbs with me in the seat and 3/4 tank of fuel.

I am right at 7000 lbs, my GVWR, with this set up, ready to camp. Thats just me and my two little dogs and my stuff.

I can get around 17 mpg on the road solo if I keep it under 65 mph. 75 mph gets me 15 mpg. Towing like the pic under 65 mph is 12-13 mpg. I'm running 285/65-18 tires.
johnrbd
Explorer
Mar 28, 2014
I hada 2002 Chev with 5.3, 3.73 and towed 7000-lb (loaded) 5vr. Wasn't a lot of fun, especially at high elevations or into headwinds.

Replaced 5with with a 9300-lb (loaded) 5vr and replaced truck with 2500 Chev, 8.1, 4.10. Towing was fun after that. Acceleration, no problem merging on interstate highway. Having the 4.10, I towed at 58-59 mph, just after o/d kicked in. Mpg's towing, avg 9.3 - about the same or slightly less than the 1500.

You're in 2500 territory, which screw around putting band-aids on your 1500?
downtheroad
Explorer
Mar 28, 2014
New member, welcome to the Forum.

I'm blunt...often probably too blunt:
You have a big trailer and a relatively (light duty)truck. Pouring money into mods like re-gearing and a programmer is not going to give you better mileage or more payload. You will be wasting your money and will probably soon need transmission work.

It is a 1/2 ton truck and a heavy bunk house trailer...probably means family - kids and lots of gear.

You are in 3/4 ton territory...big block or diesel.

Hopefully others will give you a more positive outlook.
camp-n-family
Explorer
Mar 28, 2014
Will these changes help my towing ability?

No. You could even add a supercharger but that will only increase power, not towing ability. There is much more than just power required for good towing ability. You'll be lacking in payload, axles, suspension etc, as with most 1/2 ton trucks trying to tow that size and weight of TT. You're probably looking at close to 9000lbs once loaded up so even if you could pull it you're likely over several of the trucks ratings.
hmknightnc
Explorer
Mar 28, 2014
Changing to 4.10 gears will definitely help. However, you don't have enough truck for a 7500# Dry Weight trailer so your towing experience is still going to suck. That generation of 1/2 ton chevy's is practically limited to around 6,000# loaded TT towing weight (note I said loaded not dry meaning probably 4,500# dry). (I have a 1/2 ton '05 with your engine and heavy duty tow package, and absolutely would not tow your empty trailer with it, much less loaded. I love that 1/2 ton but it is just not enough for your trailer)

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Power mods on Sierra 1500 CC with 5.3L

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