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bfourman's avatar
bfourman
Explorer
Oct 16, 2013

5.7L Vortec vs. 5.3L Vortec

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.

12 Replies

  • 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.
  • 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.