How car engines are made

Most of an engine is one lump of cast metal with holes bored in it, plus a crankshaft that turns piston pushes into spin.

stations: 8
things upstream: 42
raw sources: 18
steps from the ground: 6

The short version

A car engine begins as molten iron or aluminum poured into a mold to make the block and head. Machines bore the cylinders to a fine finish. Pistons, a crankshaft, valves and spark plugs are then fitted. Fuel burning in the cylinders pushes the pistons, and the crankshaft turns that back-and-forth push into spin.

Pour the engine block

Molten metal fills a sand mold shaped like the block, with hollow cores that become the water passages. Iron is cheap and wear-resistant. Aluminum is lighter, and its cylinders may be lined with iron or steel.

Goes in
Pig iron Aluminum Silica sand
Cast the cylinder head

The head caps the block and holds the valves, the spark plugs and the passages that let air in and exhaust out.

Goes in
Aluminum
Bore the cylinders

Cutting tools drill and bore each cylinder to size, and honing leaves a fine cross-hatch finish. The piston must slide in the cylinder with almost no gap.
Cast the pistons

Small engines usually use aluminum pistons, while larger ones may use iron. Machines then cut the grooves that hold the sealing rings.

Goes in
Aluminum
Turn the crankshaft

A steel crankshaft has an offset throw for every piston. Its journals are ground smooth to ride on bearings.

Goes in
Steel
Assemble the short block

The crankshaft drops into the block and is held by main bearings. Connecting rods then link each piston to it.
Mount the head and valves

The head goes on with a gasket between, then camshafts, valves and spark plugs. A timing belt or chain makes the camshaft turn in step with the crankshaft.
Fire it up on a test stand

Engines are run briefly with fuel and checked for leaks, pressure and noise before being sent to the car line.

Goes in
Gasoline

End of the lineCar engine Next it goes into car, locomotive, motorcycle.

Worth repeating

Most spark-ignition engines use one spark plug per cylinder, though some use two.
Charles Kettering's electric self-starter, fitted to Cadillacs around 1910 and 1911, replaced the hand crank.