Three-Quarter-Ton Test Results - With Trailer:
Three-Quarter-Ton 1/4-Mile Assessment:
Out of the three-quarter-ton trucks, it's GMC's new 6.0-liter Vortec Max V8 / 6-speed heavy duty transmission combination that has the best setup for the level 1/4-mile. The gear ratios perfectly match the engine's torque curve. It was also the only truck to get above 80-mph with a trailer when we ran it at MPG over a mile long road course.
What's interesting, though, is Dodge's HEMI gearing. Both our Ram and Sierra had 3.73:1 final drive ratios, but check out second gear. It's much higher in the Ram, at 1.67:1, than in the Sierra, at 2.36:1. There wasn't much of a time difference from 0 to 40-mph between the trucks unloaded, but as soon as the 10,500-pound trailer was hooked up the 0 to 40-mph delta grew to almost a full second. The HEMI fell behind because it lugged against that 1.67 ratio. We think the results would have been much closer if the HEMI had the same, or near-identical, spacing as the Vortec Max's cogs.
By the way, Dodge is the only truck of the three that uses the same transmission with their gas engines in 1500, 2500 and 3500.
When we compare the GMC against the Ford, the 4.30 final drive ratio in the Super Duty handicapped that truck unloaded but definitely helped it while towing - at least at the start. The two trucks swapped the lead with each other twice, up to around 50-mph, before the GMC's six-speed transmission and its excellent gear spacing once again proved decisive - enabling a V8 to beat a V10.
Towing a trailer tells a different story with transmission gear spacing and final drive ratios - which is the reason final drives are lower in three-quarter-ton and one-tons versus half-tons.
When you buy a heavy duty today, one of the few performance decisions still under your control is determining the final drive ratio - particularly for a gasser. There isn't a dramatic difference in fuel economy between a 3.73 and a 4.10, but towing acceleration and less tranny downshifting are going to make the 4.10 a better choice for a gas truck. If you're purchasing a diesel, it's not going to be as important.