Is that for real?
I dunno but probably explains the Slick 50 demonstrations and how unvalid they are especially when they spray it with water to cool it down with no oil. Of course there is damage on the wear parts but the cap should have been compared to a cap from an engine that had been run with oil for the same time instead of comparing it to a new rod cap.
I’m a bit undecided on this video. I wonder if the fact that the engine is an air cooled and probably has a very low compression ratio has something to do with it.
It looks like the crank is turning a bit purple in one spot.
Also, the engine isn’t doing any kind of work.
Tester
[quote=“ok4450, post:3, topic:103234, full:true”]
I’m a bit undecided on this video. I wonder if the fact that the engine is an air cooled and probably has a very low compression ratio has something to do with it.
It looks like the crank is turning a bit purple in one spot.
[/quote]Looks like a generator or lawn tractor motor to me. Definitely air-cooled.
There’s a couple issue i see. First, the engine appears to run cooler because it’s being viewed from outside without oil to conduct the heat from the hot friction surfaces to the outer metal surfaces where temp is being measured. Air is very poor thermal conductor compared to a liquid.
Secondly, the engine was first run with oil. That deposited surface film on everything. 15 minutes with no load is not enough time or work to completely displace the film. It did wear but would have been much worse if actually dry or run with load.
Almost useless experiment imo.
When a governed engine is run with no load, the governor only opens the throttle enough to hold the rpm the governor is set to so there is a very high intake manifold vacuum, in other words, a very low intake manifold pressure.
When the manifold pressure is really low, the piston has to go 3/4 or more of the way up the cylinder before the pressure is atmospheric and the “compression” starts at that point instead of at the bottom of the piston stroke.
Even high compression engines have a low dynamic compression ratio when the throttle is closed and the engine is unloaded. That’s why detonation goes away if you lift your foot off the gas a little while climbing a hill.
The results of this test are only applicable for this engine, working under similar conditions. Also, I am not sure if the temp is the thing we should be looking at. At any rate, I feel it was a waste of an engine.
I ran across that video and wondered just how bored that fellah was to throw away $200 and waste a perfectly good day on such a useless experiment(?). But I was amazed that the engine didn’t begin knocking and seizing after a few minutes of being run dry. I am still not convinced that the automobiles in the television commercial were actually operated without oil, though.
The engine is similar, if not identical to the one on a chipper/shredder that I have and after 6 years it still starts quickly and runs well.