Paul wrote:

In the overall scheme of things the temp of the plug tip will have little
to do with the heat transfer to the incoming charge. The surface area to volume
ratio of a rotary is such that most of the heat transfer is from the
400 degree rotor and rotor housing surface areas.
Paul Lamar

Paul, I am wondering....

Why aren't ceramic, plasma sprayed, thermal barrier coatings used on the rotor faces?
I used to do a bit of work in the jet engine business and these were used all the
time. And when I went to one of our vendors for the plasma spray I saw many cylinder
head combustion chambers and pistons tops being done for the larger diesel engine
overhaul shops and OEM's.
Blake

Mazda tried it in 1991 for the Lemans four rotor engine. It did help a little but it
was
down in the single percentage points like 3%. Hardly worth the cost. To really
work well it needs to be thick and that raises durability questions.
Paul Lamar

Hmmmm.....

Is this number (3%) for increased power output (good idea) or for decreased thermal loading
and heat transfer (better!) of the rotor.

I don't know what they would charge for an alumina spray on the three faces, but I don't
think it would be horribly expensive as long as you deliver it mostly prepped.

Later,
Blake

You know now I am not sure. I thought it was in the Lemans engine SAE paper but it
may have been another Mazda SAE paper. The Lemans engine had cermet coatings
on the aluminum end and rotor housings. On a 13B it must be done only on the
rotor. If any of it comes off you are in big trouble. Little more power
a little less heat loss and a little better BSFC. It will be hard to measure
unless you do back to back dyno runs.

Paul Lamar
 
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