If it's a cold engine, you can cause friction wear on the cylinder walls, piston rings, and pistons.
It can cause excess gas to go into the exhaust and ignite in your catalitic converter. Gas ignition in your exhaust melts the ceramic emission filter, which then makes the car run like having potatoes in the tailpipe.
Believe it or not, even though the car isn't in gear, the gears still will turn, so if you rev it up, it'll cause gears to wear down.
Here is more input from others:
Excessive revving of an engine causes overpressure in the crankcase. It causes unhealthy expansion in the pistons and the valves.
The man kept revving the car's engine as though he was a teenage boy showing off.
No revving your engine dosent damage it.
Spinning the tires in snow to get unstuck while revving the engine is bad for the car. This is bad for the transmission on the car. The best way to get unstuck in the snow, is to use the car mats to free the car by placing them just to the front of all wheels, then gently stepping on the throttle.
Revving your engine past its shift points is never a good idea. Unless you are on a track day, revving your engine past its limits not only means consuming more gas, but your car starts revving heavily and if you continue to do so, you will damage your transfer case.
It depends how high you're talking about. If you mean revving all the way to the red line then yes this is bad for the engine. But the rpm shouldn't exceed 4000 rpm. If it is slightly below this then it is fine.
Increasing the rpm (revolutions per minute) would be revving the engine.
NO it will not. Over revving engine, Rocker are adjusted to tight, Bad lifter. These are some common causes of that.
Becuase you're revving the engine. Becuase you're revving the engine.
To rev the engine simply means pressing the accelerator down with the car in neutral as if you are preparing to take off fast for a race.
As long as the engine is at full operating temperature and you do not rev it beyond the red line, you more than likely will do no damage, but it is still not a good idea. Revving a cold engine will do damage for sure. Revving the engine can cause a sudden drop in oil pressure, cause the engine to over heat and it doesn't help the main crankshaft bearings any good as they and meant to be revved under a load(in gear).
The most common cause of engine revving is a dirty or clogged air filter.