engine revs

[jakeyseven]

just out of curiosity, when we say engine revs at 2000 for example , is it the crankshaft spinning at that speed or are the pistons moving at that speed

[dagm182]

Revolutions per minute (abbreviated rpm, RPM, r/min, or r·min−1) is a unit of frequency of rotation: the number of full rotations completed in one minute around a fixed axis. It is used as a measure of rotational speed of a mechanical component

[jakeyseven]

Originally Posted by dagm182

Revolutions per minute (abbreviated rpm, RPM, r/min, or r·min−1) is a unit of frequency of rotation: the number of full rotations completed in one minute around a fixed axis. It is used as a measure of rotational speed of a mechanical component

what i mean is when the engine is turning , for example 2000 revs , is it the pistons moving up and down at that speed or is it the crankshaft moving at that speed

[silver04rollas]

Originally Posted by jakeyseven

what i mean is when the engine is turning , for example 2000 revs , is it the pistons moving up and down at that speed or is it the crankshaft moving at that speed

No piston speed is completely different. Piston speeds are much higher than what the rpms are. They are measured in feet per minute and not revolutions per minute. Piston movement is one of the pre-requisites for the engine to complete its's revolution.

[olbus]

Not sure of your question, but each piston moves up and down with each rotation of the crank. It takes two complete revolutions of the crankshaft for one firing in a 4 cycle engine, so each piston is firing at 1/2 the rpm of the crankshaft. Crankshaft at 2000, each piston firing 1000 times.