What was the horsepower of the Model T engine?

The Ford Model T engine produced 20 hp.

That figure came from the Model T’s 177-cubic-inch (2.9-liter) inline-four engine, a low-compression side-valve design built primarily for simplicity, reliability, and inexpensive production. Its output was modest even for an automobile, but the car was also relatively light and geared for practical transportation rather than high speed.

The engine’s low compression ratio made it forgiving of low-octane fuel and easier to start by hand. Early cars used a water pump, but most Model T engines relied on thermosiphon cooling, in which heated coolant rose and cooler coolant descended naturally. The engine could propel the car to roughly 42–45 mph, depending on conditions and specification.

The 20-horsepower figure is often confused with later Ford ratings or with the Model A, whose 201-cubic-inch engine produced about 40 hp. It also should not be interpreted using modern horsepower expectations: the Model T’s engineering priorities were low cost, durability, repairability, and compatibility with mass production.