Car Buyer Labs

Car Buying Advice, Tips, and Reviews

A dark blue 2021 Chevy Silverado 2500 HD LTZ is towing on old red pick up truck on a trailer.

Which Chevy Truck Has the Most Horsepower?

Horsepower is the bread and butter of performance. Whenever someone asks about a vehicle’s ability to power down the road, tow, haul, or make its way across rough terrain, the first thing that they usually want to know about is the horsepower. So when it comes to Chevy trucks, which model offers the most horsepower? The answer is simple: it’s the Chevy Silverado HD. This highly regarded truck features a pair of powerful 6.6L V8 engines – one diesel and one gasoline. If you want the most horsepower available from Chevy’s line of production pickups, then the Silverado HD is the model to choose.

Chevy Pickup With The Most Horsepower

Now that you know that the Chevy truck with the most horsepower is the Chevy Silverado HD, your next questions are probably which configuration offers the most horsepower and how much does it have? This is where things get fun. In the first place, it is actually not a single Chevy model that has the most horsepower – both the Chevy Silverado 2500HD and the Chevy Silverado 3500HD share that title. In fact, these two full-size trucks even offer more power than Chevy’s commercial line of vehicles, including the top of the line 6500HD

That’s right, the two heavy-duty pickup trucks from Chevrolet can both be equipped with a 6.6L Duramax turbo-diesel V8 engine that outputs up to 445 hp and 910 lb-ft of torque. However, despite sharing the same engine, they do not have the same performance. If you want a powerful engine to tow or haul cargo, then the Silverado 3500HD has beefed up suspension that allows it to tow up to an impressive 35,000 lbs. Meanwhile, despite having the same engine, the Silverado 2500HD maxes out at 18,510 lbs.

A popular Chevy Truck, a red 2021 Chevy Silverado 3500 HD, red is parked in a plant nursery.

What Makes The Duramax Turbo-Diesel So Powerful?

Now that you know which Chevy truck puts out the most power, you’re probably wondering what makes the Duramax 6.6L V8 so powerful? Well, it’s a combination of things, but a lot of it has to do with how it produces torque and how it matches its power output through the Allison 10-speed automatic transmission. A powertrain is more than just the engine itself, and Chevy has done an amazing job building every aspect of its heavy-duty powertrain so that it will provide maximum power and reliability.

To begin with, the Duramax is simply a large engine, displacing a full 6.6 liters (that’s 1.74 gallons). High displacement means more fuel and air can be mixed together inside the engine, producing more torque – just imagine the power of igniting almost two gallons of air and gasoline. But this large size is just the beginning of what sets the Duramax turbo-diesel apart and makes it the most powerful truck engine in the Chevy lineup.

While you may have heard the expression, “there is no replacement for displacement,” that isn’t quite true. You can artificially increase displacement by fitting an engine with a turbocharger or a supercharger. These devices force even more air into the engine, further increasing power. In the case of the Silverado HD’s Duramax, the turbocharger can provide up to 43.5 PSI of boost, which is nearly three times atmospheric pressure. That means that instead of 6.6 liters of displacement, you have almost 20 liters of displacement (around 5 gallons of air and fuel).

Finally, the Duramax is a diesel engine. This means that it offers a much higher compression ratio of 16:1, while gasoline engines tend to max out at a compression ratio of around 12:1. The higher compression ratio allows the Duramax to generate torque more efficiently. Further, diesel fuel has a higher energy content than gasoline, giving you more power for the same amount of fuel. Altogether, these features combine to give the 6.6L Duramax turbo-diesel its phenomenal 445 hp and 910 lb-ft of torque.

A black 2021 Chevy Silverado 5500 HD is parked on a construction site.

How Does The Allison Transmission Help?

A great question. The Allison 10-speed automatic transmission found in the Silverado HD is the key component that allows the truck to make use of all of its power. Not only does this transmission have the strength needed to withstand the 910 lb-ft of torque that the Duramax diesel can generate, but it is also tuned to provide a perfect balance between power, efficiency, and drivability.

While the engine produces power, the transmission is needed to convert that power to something usable. While the engine is spinning at thousands of revolutions per minute (up to 3,450 rpm in the case of the Silverado HD Duramax), the wheels will be rotating much more slowly. The transmission gearing serves to reduce the speed of the engine output down to the speed of the wheels. However, older transmissions only offer six or fewer gears to choose from, possibly forcing the engine to run at less than efficient speeds, limiting top speed, or providing insufficient power when starting off.

By having no fewer than ten gears to choose from, the Allison transmission can keep the engine running at its more efficient and effective speed. Plus, it includes a sophisticated transmission control module that optimizes shift times based on the electronic monitoring of sensor inputs. This allows it to adjust the shift pattern to match the task at hand, providing more power when towing or limiting power when driving on slippery surfaces.

Having ten gears also means that the Silverado HD can also use a remarkably low 3.42:1 final drive ratio. While not strictly part of the transmission (the final drive is located in the rear axle), the final drive ratio will affect transmission performance. Normally, a high ratio is needed to generate maximum torque at the wheels, but that comes at the cost of a lower top speed and increased fuel consumption. However, with ten gears, the Allison transmission can compensate for those traditional weaknesses and provide both low-end torque and top-end efficiency.

Enjoy the Power of the Silverado HD

Every year, trucks get more powerful and more capable, and it can be hard to keep up with the latest options on the market or know what features to look for when shopping for the most powerful truck that you can find. However, Chevy has always been at the forefront of truck design, and its latest Silverado HD model is a truly exceptional vehicle with incredible power. If you desire a truck with enough horsepower to make a sports car blush while towing and hauling massive loads, then the Chevy Silverado HD series with the 6.6L Duramax V8 turbo-diesel is the best choice.

To top it off, Chevy even offers two different models equipped with its top of the line powertrain. While the Silverado 3500HD will provide you with some of the highest tow and payload ratings on the market, the Silverado 2500HD provides you with the same exact Duramax engine and Allison transmission. Choosing between the Silverado 2500HD and Silverado 3500HD can be a tough choice, as both models are excellent trucks. Determining which model is the best for your needs will require careful consideration of what you intend to use your truck for. But with 445 hp and 910 lb-ft of torque under the hood, you will never lack for power with either option.