I currently tow with a 2002 Avalanche 1500 with a 5.3L. I am looking to get a 3/4 ton tow rig to better handle the TT and our gear. I have a line on a 2000 Chevy CCSB K2500 with a 5.7L Vortec/4L80E, not sure on gear ratio.Anyone have feedback on towing with a 350? I know it's not going to have huge diesel power, or tow like a big block, but will it be at least comparable to the 5.3L? The transmission upgrade will be a good thing, I know that.For reference, the TT has a 6k GVWR, and we pack around 2 adults, 3 small kids and 2 dogs, plus all the stuff that goes with it.

The 5.7L is a 255H/330T. Peak torque is around 2700rpmThe 5.3L is a 285H/325T. Peak torque is around 4000rpm.Stock to stock I would rather have the 5.7 personally. The powerband is more useable since it peaks at a slower speed. If that truck has the 4.10 axle, it will be perfect for towing in 3rd in the 60-65mph range! I had a '97 K1500 with the 3.73 and it was a little bit on the tall side. My trailer weighs around 6k and it was a little on the heavy side IMO. I had a hard time keeping the torque convertor locked (so trans heat was an issue) with my tall TH. A more normal height (shorter) trailer would have helped. I did pull a 35hp tractor on a flatbed, prob 7-7500 total weight (very low wind resistance), and it handled it surprisingly well! For me the weak link was the trans. If mine would have been a 5spd manual trans, I would still have that truck. I upgraded only because of my trailer. I don't know if having the 80E over my 60E will make a large difference in trans tuning. I think it will out tow the 5.3; you just don't have to spin it as hard to make the power. I sold that truck with 244k. The low cylinder was 165, the others were 170-175. The weak links are the lower intake manifold gaskets leaking coolant, stupid plastic distributor, poppet injectors that can leak fuel. I feel they are easy to work on. If it is a clean truck, get it. It will do better than the Avalanche.

Not sure where the above numbers come from but my truck's engine is rated at - 315 hp (235 kW) @ 5300 rpm and 335 lb·ft (454 N·m) @ 4000 rpm of torque.I also see numbers for the 5.7 as being 255 hp (190 kW) to 350 hp (261 kW) at 4600 rpm and 330 lb·ft (447 N·m) to 350 lb·ft (475 N·m) of torque at 2800 rpm, which is closer to the numbers given above.Agreed that the 5.7 is better for pulling based on the fact that it makes more torque lower down.

I had 1990 Chev 1500, 5.7, 3.73, std cab, longbed - chipped, Flowmaster muffler and Thorley headers and K&N air filter. Replaced it with 2002 Chev 1500, 5.3, 3.73, ext cab, shortbed - totally stock.Towed 5000-lb loaded 5vr. The 5.7 "felt and sounded" like it would out-tow the 5.3. But I timed both on several uphill onramps, full throttle, and the 5.3 won every time, but not be much.The 5.7 felt stronger off the line but the 5.3 felt stronger midrange on up. MPG were roughly the same.

There have been several times I have had the Av spun up to 3500-4000 RPM on a long steep hill, and while that is within the operating range, it is too high for my comfort level.I would love to trade it in on a Duramax or Powerstroke, but I do not want a vehicle payment on a truck that sits 80% of the time (I have a company car). If I end up with the 5.7 truck, it will get intake/exhaust and maybe a cam in the future. The 80e is a good trans, much more HD than the 60e. It is supposedly a rust free truck, and the engine/trans were rebuilt approx. 50k ago.I'm familiar with the shortfalls of the treefiddy, and find them easier to work on than the newer LS engines, and much easier than a modern diesel.My TT is an Aerolite, which IIRC is lower profile than most others.Edit: Found out it has 3.73s. I was hoping for 4.10s. The Trailer Life guide for 2000 says a 3/4 ton 4x4 with the 5.7 and 3.73s is rated for 6800lbs, while my Avalanche with 3.73s is rated for 7k. Doesn't make much sense, but I would think a 3/4 ton leaf-sprung truck would handle the weight better.

Honestly, while the ride performance would be better with the 2500, I don't think there is nearly enough "engine" performance gained to make that switch. I towed a 5000GVWR HTT with a 94 Caprice with the 5.7L LT1 (260HP/330#-ft) and swapped to a 3.42 axle. It did fine towing, and at this time it was only four of us. I later had an 05 Suburban with the 5.3L (295HP/330#-ft) with the 3.42 axle. The Suburban with the tow haul mode actually towed that trailer better from every aspect. I honestly think 30 less HP and the high first gear of the 4L80E will make that 2500 seem like a dog compared to your Avalanche to get rolling. wmoses wrote:Not sure where the above numbers come from but my truck's engine is rated at - 315 hp (235 kW) @ 5300 rpm and 335 lb·ft (454 N·m) @ 4000 rpm of torque. I also see numbers for the 5.7 as being 255 hp (190 kW) to 350 hp (261 kW) at 4600 rpm and 330 lb·ft (447 N·m) to 350 lb·ft (475 N·m) of torque at 2800 rpm, which is closer to the numbers given above. Actually, the early 5.3L were rated at the 285. The 5.7L that went into the trucks was rated at the 255HP. The 350HP 5.7L was the LS1 that went into the F-Bodys, Corvette and GTO.

5.7L Vortec vs. 5.3L Vortec | Good Sam Community

12 Replies

wmoses
Explorer
Oct 16, 2013
Not sure where the above numbers come from but my truck's engine is rated at - 315 hp (235 kW) @ 5300 rpm and 335 lb·ft (454 N·m) @ 4000 rpm of torque.

I also see numbers for the 5.7 as being 255 hp (190 kW) to 350 hp (261 kW) at 4600 rpm and 330 lb·ft (447 N·m) to 350 lb·ft (475 N·m) of torque at 2800 rpm, which is closer to the numbers given above.

Agreed that the 5.7 is better for pulling based on the fact that it makes more torque lower down.
boogie_4wheel
Explorer
Oct 16, 2013
The 5.7L is a 255H/330T. Peak torque is around 2700rpm
The 5.3L is a 285H/325T. Peak torque is around 4000rpm.

Stock to stock I would rather have the 5.7 personally. The powerband is more useable since it peaks at a slower speed. If that truck has the 4.10 axle, it will be perfect for towing in 3rd in the 60-65mph range! I had a '97 K1500 with the 3.73 and it was a little bit on the tall side. My trailer weighs around 6k and it was a little on the heavy side IMO. I had a hard time keeping the torque convertor locked (so trans heat was an issue) with my tall TH. A more normal height (shorter) trailer would have helped. I did pull a 35hp tractor on a flatbed, prob 7-7500 total weight (very low wind resistance), and it handled it surprisingly well!

For me the weak link was the trans. If mine would have been a 5spd manual trans, I would still have that truck. I upgraded only because of my trailer. I don't know if having the 80E over my 60E will make a large difference in trans tuning. I think it will out tow the 5.3; you just don't have to spin it as hard to make the power.

I sold that truck with 244k. The low cylinder was 165, the others were 170-175. The weak links are the lower intake manifold gaskets leaking coolant, stupid plastic distributor, poppet injectors that can leak fuel. I feel they are easy to work on.

If it is a clean truck, get it. It will do better than the Avalanche.

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5.7L Vortec vs. 5.3L Vortec

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