Car Features 6 min read

Inside the Model T Engine: 177 Cubic Inches and 20 Horsepower

177 cubic inches, 20 hp, 83 lb-ft: the Model T engine specs checked number by number, including the 22 hp early rating and what the engine left out.

Dan Reeves

October 31, 2026

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1924 Ford Model T, engine bay at mountain pass

The Model T engine specs at a glance

Start with the hard numbers. Most of them come from Ford's own literature and survive cross-checking. A few carry an asterisk, and I will tell you which.

Item	Figure	How solid
Layout	Inline four, side valve (L-head)	Solid
Displacement	177 cu in (2.9 L)	Solid
Bore x stroke	3.75 in x 4.0 in (95.25 x 101.6 mm)	Solid
Rated power	20 hp; some early cars listed at 22 hp	20 solid, 22 for early cars
Torque	83 lb-ft	Single main source
Compression ratio	3.98:1 on most engines; about 4.5:1 on the earliest	Varies by period
Construction	Cast-iron monobloc, detachable cast-iron head, 3 main bearings	Solid
Lubrication	Splash, no oil pump, oil shared with the transmission	Solid
Cooling	Thermosiphon, no water pump (after the earliest 1909 cars)	Solid
Fuel	10 gal tank, gravity feed, no fuel pump	Solid
Fuel economy	13 to 21 mpg (Ford figure)	Ford's claim

Run the arithmetic on the bore and stroke and you get 176.7 cubic inches. Ford rounded up to 177, and the math agrees. The stroke is longer than the bore, so this is an undersquare engine built for pulling at low speed, not for revving.

Twenty horsepower, or twenty-two?

The 20 hp figure is the standard rating and the one to quote. It is a brake horsepower number from the period. There is no SAE net figure for the Model T, because that measurement did not exist yet, so do not compare it straight against a modern engine's rating.

The 22 hp figure is not a typo. Some listings for early cars quote 22 bhp, and The Henry Ford's own 1909 touring car, built at Piquette, is recorded at 22 hp at 1,600 rpm. The early engines also ran a bit more compression, about 4.5:1 against 3.98:1 later, which fits a slightly higher rating. Later engines settled at 20 hp. A 1922 Model T in a museum collection is listed at 20 hp at 1,600 rpm.

Do the specific-output math and you see what Ford was after. Twenty horsepower from 2.9 liters is under 7 hp per liter. That is a modest figure, and it was deliberate. A lazy engine at 1,600 rpm wears slowly, tolerates bad fuel and forgives an owner who never reads the manual.

Torque: the number that actually moved the car

Horsepower sells. Torque pulls. The Model T engine made 83 lb-ft, and one museum record puts that peak at 900 rpm. Treat the exact rpm as a single-source figure, but the shape is right: the T made its useful pull just off idle.

That matters because the car had only two forward speeds through its planetary transmission. With a 3.64:1 standard rear axle, a long-stroke engine that pulled from low rpm was what let a two-speed car climb hills and drag through mud. A peaky engine with the same 20 hp would have been miserable in that chassis.

Put it against the car's weight and the numbers are honest. Twenty horsepower for 1,200 to 1,650 pounds is roughly 60 to 83 pounds per horsepower. Slow, but the T was light, and light is the cheapest performance there is.

"Twenty horsepower sounds like nothing until you check what it had to move. The T was light, geared low and torquey off idle. The spec sheet is modest. The result was a car that went almost anywhere a horse could."
Dan Reeves

What is missing: no pumps, no battery, one adjustment

The spec list is as interesting for what the engine lacked. There was no oil pump: the flywheel and moving parts splashed oil around, and the engine shared its oil with the transmission. There was no water pump after the earliest cars. There was no fuel pump either: a 10 gallon tank under the front seat fed the carburetor by gravity, until 1926 moved it into the cowl on most models.

The carburetor itself was a single side-draft, single-venturi unit, made by Holley, Zenith or Kingston depending on the year. The manual describes it as having "but one adjustment", the gasoline needle valve, worked from the dash. Ignition came from a flywheel magneto, a timer on the front of the camshaft and a coil box, with a 28-notch spark quadrant under the steering wheel at about 2.85 crankshaft degrees per notch. Each of those systems has its own story, and there is more on that here.

Fewer parts meant fewer failures and cheaper repairs. It also meant the driver did some of the engine management by hand. That was the trade.

A run that outlasted the car

Ford built the engine from September 27, 1908, and did not stop when the car did. Model T engines kept coming until August 4, 1941, almost 170,000 of them after car production ended, for service and industrial use. Racers used the block too: Cragar, Navarro and Frontenac all built speed parts around it.

Production efficiency was part of the engine's story. When Ford put engine assembly on a moving line in November 1913, assembly time fell from 594 minutes to 226. Precision machining was good enough that Ford could skip testing the engine before it went into a chassis.

The replacement was a different engine altogether. The 1928 Model A got a 200.5 cubic inch four rated at 40 hp at 2,200 rpm, with 4.22:1 compression on most years, a water pump and an oil pump. No engine parts interchange between the two. For the full breakdown of the Model A four, see its own article. The short version: double the power, from only 23.5 more cubic inches, and one more lesson that 20 horsepower was a choice, not a limit.