REV THE ENGINE is a phrase that is commonly used to describe the act of accelerating an engine to its maximum speed. The term is often used when referring to cars, motorcycles, and other motorized vehicles. The crossword solutions GUN and RACE are related to this phrase as they both involve the use of engines. GUN is a 3 letter word that can refer to a firearm, but in this context it could also be used to describe the sound of an engine revving up. RACE is a 4 letter word that is associated with competitive driving, which often involves revving the engine to its maximum speed.