ORIGINAL: downunder
But because it was now running 1000 revs faster I decided on one final check by reducing the revs to the original 12,000 on the APC. That gave a head temp of 200F but was right on the verge of 4 stroking rich. Which would have been perfect for running in anyway.
So a fine pitch prop cools just as well as any other.
Brian,
This is not very typical of you, to reduce the RPM by running the engine as rich as a hog...
You were supposed to do it by using a larger diameter prop, with a 4" pitch, so the RPM would be reduced back to 12K...
AND, break-in as mostly done even by you, on an ABx engine (when you are not too busy trying to break one of my 'myths'...), the engine is richened to 500-800 RPM below peak;
not 1,800 RPM.
So on the 10x6, the engine should have been spun at about 13,000-13,300 RPM.
The Xx4 prop that you were to use should also have peaked at 13,800... Possibly an 11.5x4 APC and it should also have been spun at about 13,000-13,300 RPM, for your "test".
AND, I hope you were using a thermo-couple, glow-plug-gasket sender type thermometer; not one of those totally worthless, infra-red, visual thermometers.
I am really flattered by you regarding things that I write as 'mythical'.
I just wonder why you try to break them all... Just regard them as axioms. They work; don't they?
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The Pope,
Don't call me 'the pope'. I am too Jewish to be one...