A 5.3 with 3.08 or 3.42 rear end gear ratio is not going to be a pulling machine. Put 4.10 or 3.73 gears under it and there will be a world of difference. The mechanical advantage of the lower gear ratio is huge. The max torque delivered to the ground hits much quicker and is multiplied with lower ratio gearing.
The 6.0 is virtually the same engine as the 5.3 with the only difference being the 6.0 is 4" bore and 5.3 is 3.78" bore. The 6.0 is 10.0 compression and 5.3 is 9.6:1 compression. Higher compression yields more torque and only slightly more HP. Both have a 3.62" stroke.
The GM LS3 6.2 engine is also a small block with 4.065 x 3.622 bore and stroke but with 10.7:1 compression. This Generation IV engine has differences in the heads and valve train among other things to get it's big power from.
As for fuel, the higher the compression the more octane will be needed to reduce spark knock or detonation OR retarded timing which will cost you HP and TQ. The only thing octane does is slow the burn rate of the fuel thus allowing more advanced timing curves. Low octane 85 to 87 will actually make more power in a low compression engine since it burns faster and hotter then high octane fuel.
In choosing a truck for light towing loads I would look for the engine that makes the most rear wheel torque at the lowest rpm using the same gear ratio. For heavy towing get a big block or a diesel that has big torque just off idle.
Torque is what gets the load moving. Hp is what keeps it there.
If you are going to do a lot of towing, you can forget about getting great fuel mileage for the most part.
I think the 5.3 and 6.2 are aluminum blocks and 6.0 cast iron block. Therefor the 6.0 is built for heavier workloads.
Comment