ORIGINAL: the Wasp
I cannot agree,, I think a more correct statement would be that the average flyer would be surprised to see how little airflow an engine needs to keep it at a good running temperature, many times I have had my hands behind running engines/props, you can not tell me a prop alone will not cool an engine, a prop creates much more airflow than a flywheel-fan on a weedeater, ,, I have often put my hand behind my running weedeater and noticed "how little airflow there was yet there is so much heat being removed,,
I will agree our engines do get more cooling in flight, , but fact is, most engine damage to our engines comes in flight from tuning too lean,,
Well it doesn't really matter if you or anyone else agrees, it's just the way things are. Perhaps my statement might have been made more clear had I added "sufficient" cooling from the prop wash?
Unless you have access to cylinder head temps like the full scales to monitor engine temps while ground running, you don't know. A full scale will actually run longer without getting hot on the ground with the cowl on than it will with the cowl off as what little airflow is being produced by the prop wash in that area is directed through the baffling on the cylinder heads.
I do agree that most damage occurs from lean runs in the air, but running them on the ground for extended periods is not a good idea in my opinion. As for the manufacturers, unless 3W has changed something they recommend ground running them for quite awhile, while ZDZ will void your warranty if it fails due to heat and you've been ground running it.
So in some respects, this question is a bit like discussing oil mixes....
