It can hurt if done repeatedly, let me explain.
The first piece most would not expect to encounter damage is the manual transmission, autos are different. When you free rev you engine while not in gear, you are still spinning the crap out of the transmission, but not entirely normally. The lubrication system of a manual trans is mechanical, meaning a manual transmission relies on itself to spin entirely to lubricate completely internally. Repeated high revs at a stand still in neutral can be bad over time.
Next, with no load on the engine, the computer will run a leaner fuel mixture, and not adjust the timing as it would if normally driving down the road. This means that your standing still high revs are running the engine leaner than normal, which over time, causes damage.
Lastly, as said above, with no load on the engine, the computer knows this, so the throttle response you feel and hear while standing still is different than what you would feel and hear while driving down the road.
It other words, it's kinda pointless is what I'm saying, even if it does sound cool. If you need to rev the engine while standing still, do it sparingly, and keep the revs below 4000rpms.
On a side note, I don't know if the owners manual states anything about free revving while not it gear driving down the road, but I can tell you that all high performance motorcycles have it in the owners manual, and usually stickered on the tachometer or gas tank, to not free rev the engine, as it could cause damage, for the same reasons as above.
. but am just curious, can this damage the valvetrain or bearings when im giving throttle without a load? thanx
hehe
