Otto’s silent engine (1876) — the first four strokes

1876·~3 hp at 180 rpm·~14% — 3× its rivals·Single horizontal cylinder·Town gas·30,000+ by 1890

· THE STORY

Fire, tamed into four strokes

In 1876, at the Deutz works near Cologne, Nicolaus Otto built a gas engine that compressed its charge before lighting it — and ran so smoothly beside the clattering engines of the day that it sold as the “silent” engine. It made about three horsepower at 180 rpm, bolted to a workshop floor and fed from the town-gas pipe in the wall. More than thirty thousand were sold, and its four-stroke cycle is still the heartbeat of nearly every petrol engine on Earth.

~3 hp at 180 rpmPower~14% — 3× its rivalsEfficiency

· WHY IT MATTERED

Compress first, then burn

Earlier gas engines drew in their mixture and lit it at atmospheric pressure — barely four per cent of the fuel’s heat became work. Otto squeezed the charge into a fraction of its volume first, so the burn pushed against a piston it could really lean on. Efficiency roughly tripled, and compression ratio is still the first number an engine designer fights for.

GO DEEPERWhere the fuel’s energy goes →

· WHY IT MATTERED

Four strokes, one job each

Draw in, squeeze, burn, blow out — each job gets its own full sweep of the piston. Only one stroke in four delivers power; the flywheel’s stored momentum carries the machine through the other three. That clean division of labour is what made combustion controllable, buildable and endlessly scalable — from mopeds to Le Mans.

· WHY IT MATTERED

From curiosity to industry

A steam plant needed a boiler, a stoker and an hour’s notice. The Otto engine started in minutes and bought power by the horsepower, not the boiler-house — small workshops could finally afford an engine at all. And his own engineers, Gottlieb Daimler and Wilhelm Maybach, soon left to shrink it, speed it up and put it on wheels: within a decade the four-stroke was mobile, and the car became inevitable.

· TRY IT

Run the four strokes

One cylinder, the four strokes, live: run it, pause it, or drag the crank through the cycle yourself — and notice how much of the time nothing is pushing at all.

Readout

Power2.8 hp

Power strokes per second1.4

Compression ratio (1876)≈ 2.5 : 1

Thermal efficiency~14%

Only one stroke in four pushes — at 170 rpm the flywheel gets a shove 1.4 times a second and coasts between them, which is why it is the biggest part of the machine. Modern engines spin forty times faster and share the job across cylinders, but the cycle is Otto’s, unchanged.

GO DEEPEROpen the full demo →