Definition of "valvetrain" []

• The collective mechanisms and parts that control the operation of the valves in an internal combustion engine. (noun)

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• "The springs are components in the engine valvetrain and are compressed by rocker arms."
• "The SkyActiv program also includes lightening of the reciprocating parts (forged steel pistons, rods, crank), as well as reducing frictional losses (roller-rocker valvetrain) and parasitic losses."
• "The 3. 5-liter V6, the volume engine, gains variable valvetrain timing for a horsepower boost to 285 plus claimed fuel economy improvements."