Engine rev

While at outdoor exotic car show, the sponsor would have all of the owners rev their engines every hour for the crowd. Although it sounded cool, I have always been told this is not good for the engine while in neutral. Is this true? Thanks in advance for you comments!

 

as long as it is hot when you rev it and you do not take it to far it will not harm it.
(but don't make it a habit)

 

I was told a number of years ago that if the engine can rev to say 8,000 rpm while under load, there would be no harm in revving the engine to 8,000 rpm with no load. There is no difference. I'm not sure if I believe it. I see the logic, however. True or False and Why?

 

I've been taught that in an engine under load (more than just friction load) and at high RPM , the piston inertial loads (deceleration loads at TDC) are partly offset by gas loads (exhaust backpressure or compression loads). At no load (or only friction load), the piston inertial loads at high RPM (not reduced by gas loads) can cause piston failure. I've also been taught that most high RPM piston failures occur at the instant when the throttle is closed, unless the engine is over-revved. I don't know by personal experience or testing, but that's what an automotive piston design engineer told me in the late 1960s/early 1970s when I was dyno-developing engines for Ford.


Tom Kizer

 

+1
as explained by an automotive engineering instructor - but without any detail.
full 'on throttle' to full 'off' throttle with the engine in gear

I'd love to hear 'why'?

rgds,
Vincenzo

 

What's with these how can I abuse my car threads that are popping up lately?

 

People just want to be told it is OK to act like an idiot 17 year old.

 

I hope we're not seeing the market down turn put these cars in the hands of too many idiots.

 

worse, I hope those idiots are not flooding the market with their thrashed eingines.

 

I don't think this is necessary to do every hours what the owner has done. This is harmful to the engine while in neutral.

 

I wouldn't rev period, let alone every hour, no matter how much you paid me.