It’s time to put the new 2024 Chevy Silverado HD 2500 with the 6.6L (L8T) gas V8 on the world’s toughest towing test – the Ike GauntletTM. We also compare it directly against the 2024 GM HD Duramax turbo-diesel V8-powered truck. We pull the same identical 5th-wheel toy-hauler camping trailer that weighs about 14,000 lbs up and down the tallest and steepest interstate in the country.
2024 Chevy Silverado HD
This is a midcycle refresh for GM’s heavy-duty pickup truck lineup. The 2024 Silverado HD LTZ has a new exterior and interior design. The 6.6L gas V8 is upgraded from the older 6-speed automatic transmission to the new 10-speed Allison-branded transmission. Can the latest transmission make that much of a difference and turn this gasser into a very capable towing rig? Let’s find out!
Naturally, the 6.6L Duramax V8 is more powerful and capable, but it also costs $9,500 more than this base gasoline engine. Why not save some money and go with a traditional V8?
The 6.6L gas V8 (that I nickname “Tiger-Jet”) is a 5th-generation LT-family engine. It’s a small block push-rod engine with direct injection. It combines the tried and true features with the latest engine cooling and fuel injection tech. It’s rated at 401 horsepower and 464 lb-ft of torque. It does not offer cylinder deactivation, and this engine has a good reliability record so far.
This is an 8-mile stretch of the I-70 in the Colorado Rocky Mountains. It goes up to the continental divide and the Memorial Eisenhower / Johnson tunnels at 11,158 feet above sea level. The maximum incline is a 7% grade. Kase and I happen to run this during one of the hottest August days of the year. The ambient temperature was reading 75 F near the top of this run.
Naturally, this truck does not have an exhaust brake to help with slowing it down (it’s not a diesel). However, the 10-speed automatic transmission does very well with grade-shifting. It downshifts with confidence on the way down the mountain and gives the engine its best chance to help and slow down this 14,000-lb ATC Game Changer toy hauler. We loaded a Polaris Ranger (3-seater) inside the trailer.
Many gasoline V8 trucks we have tested needed 10 brake applications to descend the 8-mile stretch. This 2024 Silverado HD needed just six brake applications to keep the speed in check. This is a good performance.
The high elevation of the Ike Gauntlet robs naturally aspirated engines of power. Our Banks Data Monster gauge showed Ambient Air Density (AAD) at 66%. It means 34% of density and potential power is gone. The truck made it up the mountain in just over 10 minutes. This is two minutes slower than a Duramax V8 truck with the same trailer, but it is also way quicker than the last 2020 Silverado HD 2500 gas V8 we tested with a gooseneck trailer. The new 10-speed automatic is helping.
In the end, I would purchase this gas V8 combination in a truck with fewer options and features in order to keep the curb weight of the truck lower and its payload higher. This Silverado HD 2500 LTZ 4×4 has a payload of just over 3,200 lbs. If this was an LT or a Custom – it would be a bit lighter. If you plan on towing occasionally and you tow a trailer under 12,000 lbs – the gas V8 is a good choice. If you tow often, and you tow heavier – then it makes more sense to spend $9,500 more and get the diesel.
Join us in the video below.