| Subject | English | Spanish |
| environ. | four stroke engine | motor de cuatro tiempos |
| environ. | four stroke engine An internal combustion engine whose cycle is completed in four piston strokes; includes a suction stroke, compression stroke, expansion stroke, and exhaust stroke | motor de cuatro tiempos |
| mech.eng. | four-stroke cycle engine | motor de cuatro tiempos |
| mech.eng. | four-stroke engine | motor de cuatro tiempos |
| transp., mech.eng. | pressure charged four-stroke diesel engine | motor Diesel de cuatro tiempos sobrealimentados |