When it comes to towing, which holds greater significance: horsepower or torque?

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The timeless debate continues: horsepower versus torque—which truly matters?

For years, car enthusiasts have argued over whether horsepower or torque plays a more critical role in a vehicle's performance, daily driving experience, and overall value. But what sets them apart? Horsepower delivers the acceleration needed for high-speed overtaking, while torque provides the low-end strength required for quick starts and heavy lifting. Simply put, torque gets the job done, but horsepower ensures it’s done swiftly.

Fans of torque appreciate the raw, low-end power that larger engines deliver; they gravitate toward robust vehicles such as the forthcoming Chevrolet Camaro SS, equipped with a V8 engine producing 408 pounds-feet of torque, ensuring impressive acceleration from a standstill. On the other hand, those who prefer the high-speed thrills provided by horsepower might opt for a car like the Honda S2000, boasting 237 horsepower at a peak of 7,800 rpm, though it only offers 162 pounds-feet of torque—hardly substantial.

While these vehicles can achieve remarkable speeds, they often fall short in meeting the everyday demands of typical drivers. Most of us will never take our cars to a racetrack or drag strip, and with gas prices constantly fluctuating, owning a car with excessive horsepower or torque seems impractical. However, there’s one scenario where having ample power proves useful—towing. Whether you’re pulling a work trailer or transporting your boat for a weekend getaway, you’ll need a vehicle capable of handling the load with ease and safety.

So, which is more crucial for towing—horsepower or torque? In this article, we’ll explore the answer to this question and examine how each factor influences your decision when selecting a truck.

Measuring Torque and Horsepower

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Let’s start with the fundamentals. Horsepower quantifies work, which involves applying a force to an object and moving it in the direction of that force. To put it simply, one horsepower equates to 33,000 pounds-feet per minute (4,562.41 kilogram-meters), or the energy required to move a 330-pound (149 kg) object 100 feet (30.5 m) in one minute. 

Torque, on the other hand, is a rotational force that twists or turns an object, such as a wheel. For instance, when you use a lug wrench on a bolt, you’re applying torque. Unlike horsepower, torque can be exerted even if the object remains stationary. It’s measured in pounds-feet, representing the force in pounds applied to a lever measured in feet. For example, if you apply 100 pounds (45.4 kg) of force to a 2-foot (0.6 m) lug wrench, you’re generating 200 pounds-feet (27.65 kg/m) of torque on the bolt. For a deeper dive into torque, check out How Force, Power, Torque and Energy Work.

Once torque is measured, calculating horsepower becomes straightforward. The formula is as follows: Multiply torque by the engine speed (in rpm), then divide by 5,252 to determine the horsepower at that rpm. For example, if a vehicle produces 350 pounds-feet of torque at 4,000 rpm, the calculation would be (350 X 4,000)/5252, resulting in approximately 267 horsepower. In essence, torque measures the amount of work being done, while horsepower indicates how quickly that work is accomplished [source: Polk].

In the following section, we’ll explore why torque is particularly advantageous when towing a trailer.

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Torque and Low-End Power

Most drivers understand that torque equates to low-end power, enabling a vehicle to accelerate effectively at lower rpm levels. Torque is essential for moving a vehicle from a standstill and tackling steep inclines. Heavier vehicles require more torque to start than lighter ones, which is why torque is crucial for towing—it’s what enables you to haul heavy loads. While car advertisements often highlight horsepower for performance and sports cars, truck commercials tend to emphasize torque [source: General Motors].

A vehicle’s towing capacity indicates the maximum weight it can pull. Modern trucks, such as the Dodge Ram 3500, can tow up to an impressive 16,000 pounds (7,257.5 kg)—more than double the truck’s own weight of approximately 7,000 pounds (3,175.1 kg) [source: Edmunds.com]. This towing capability is directly tied to the engine’s torque. The engine generates torque, which rotates the crankshaft connected to the transmission. The transmission gears then convert this torque, enabling the vehicle to move and tow loads safely.

Frequent towers understand the importance of keeping their vehicle in a lower gear than usual. For a five- or six-speed transmission, this typically means towing in fourth gear; for a four-speed, third gear is usually ideal. Lower gears provide more torque, which is why accelerating from a stop or passing another vehicle on the highway in the highest gear can be challenging, regardless of horsepower [source: Autotropolis].

Picture towing a trailer up a steep hill. If you’re driving a truck like the Ram mentioned earlier, you’re hauling significant weight, so a slow ascent is necessary. This requires keeping your engine rpm low, which is where torque becomes essential. High horsepower won’t assist you when towing at low rpm—what you need is the low-end power that torque delivers.

While torque has been the focus, what about horsepower? What part does it play in towing? We’ll delve into that in the next section.

Horsepower and High-end Speed

We’ve established that torque delivers the rotational force needed to move a vehicle from a standstill and at low rpm levels. But what role does horsepower play when towing?

As previously mentioned, horsepower becomes crucial at higher rpm levels. It’s what enables you to overtake another vehicle on the highway. For instance, if you’re driving your Honda S2000 and encounter a slower car ahead, downshifting and accelerating allows you to speed past it—thanks to your horsepower. As you accelerate and rpm levels increase, that high-end power kicks in, making passing possible.

The same principle applies when towing. If you’re driving your truck while hauling another vehicle, you may need to pass slower drivers. Accelerating to overtake them puts your horsepower to work. In short, if your engine lacks significant horsepower, don’t expect smooth acceleration or passing while towing.

To reiterate, torque enables you to perform the work, while horsepower allows you to do it quickly. Horsepower is what helps you accelerate when you’re already in motion and pulling a heavy load.

In the next section, we’ll examine various truck engine types, how they generate torque and horsepower, and which might best meet your towing requirements.

Maximizing Towing Capacity

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It’s widely known that most large commercial trucks and certain heavy-duty trucks are powered by diesel engines. The reason? Diesel engines produce greater torque. Unlike gasoline engines, diesel engines lack spark plugs and rely on compressed air to ignite the fuel. This requires the piston (cylinder) to travel a longer distance to compress enough air for ignition. This distance, known as stroke, directly correlates with increased torque [source: Mason].

Let’s compare two truck engines. A Dodge Ram equipped with a 6.7-liter Cummins Turbo Diesel engine delivers 350 horsepower and 650 pounds-feet of torque. In contrast, the same truck with a 5.7-liter Hemi gasoline V8 engine offers 383 horsepower and 400 pounds-feet of torque. Notice the difference? While the gasoline engine has slightly more power, the diesel’s torque far surpasses it [source: Dodge].

Although both trucks have similar towing capacities—15,650 pounds (7098.7 kg) for the gasoline engine and 16,350 pounds (7416.2 kg) for the diesel—the diesel’s low-end power makes towing significantly easier. The diesel engine achieves its peak torque at just 1,500 rpm, barely above idle. This means you don’t need to rev the engine to start towing, as the power is already available.

Diesel engines, fueled by energy-dense diesel, offer better mileage than gasoline engines, allowing for longer towing distances without frequent stops. However, trucks with gasoline engines generally have a lower base price. Diesel engines are typically more expensive due to their robust construction, designed to handle the higher forces generated by diesel fuel. A vehicle's towing capacity depends on various components, including wheels, tires, suspension, and transmission [source: Haulmark].

Generally, the larger the towing task, the bigger the engine displacement required. Towing places significant stress on the engine, so higher torque helps minimize wear and tear on the vehicle [source: Sunrise Trailer Sales].

After extensive comparison, the verdict is clear: torque is more critical than horsepower for towing. High torque at low rpm allows you to move heavy loads effortlessly. Some diesel trucks generate twice as much torque as horsepower at near-idle rpm, enabling them to tow trailers or boats with ease.

Horsepower plays a crucial role in enabling a vehicle to achieve higher speeds on the highway and at elevated rpm levels. Yet, if you’re unable to get your trailer moving from a standstill, no amount of horsepower will make a difference.