internal-combustion engine - a heat engine in which combustion occurs inside the engine rather than in a separate furnace; heat expands a gas that either moves a piston or turns a gas turbinecylinder block, engine block, block - a metal casting containing the cylinders and cooling ducts of an engine; "the engine had to be replaced because the block was cracked" four-stroke engine, four-stroke internal-combustion engine - an internal-combustion engine in which an explosive mixture is drawn into the cylinder on the first stroke and is compressed and ignited on the second stroke; work is done on the third stroke and the products of combustion are exhausted on the fourth stroke gas engine - an internal-combustion engine similar to a gasoline engine but using natural gas instead of gasoline vapor gasoline engine - an internal-combustion engine that burns gasoline; most automobiles are driven by gasoline engines heat engine - any engine that makes use of heat to do work poppet, poppet valve - a mushroom-shaped valve that rises perpendicular from its seat; commonly used in internal-combustion engines reciprocating engine - an internal-combustion engine in which the crankshaft is turned by pistons moving up and down in cylinders rotary engine - an internal-combustion engine in which power is transmitted directly to rotating components self-starter - an electric starting motor that automatically starts an internal-combustion engine supercharger - compressor that forces increased oxygen into the cylinders of an internal-combustion engine valve-in-head engine - internal-combustion engine having both inlet and exhaust valves located in the cylinder head |