I'm a builder myself, but I've never seen this on any rotary engine. THis came out of a customers engine sent to me for rebuild several months ago, and I just now stumbled upon the pics on my HD and thought I'd ask if anyone else has seen this before. On an otherwise good rotorhousing (both of them in one engine, btw) there are areas about a square inch that are raised up, almost bubbled. Not chrome flaking of any sort. The layered material under the compression surface has actually broken loose and begun to raise up. The pics suck, but they give you a good idea.

Anyone ever seen this before? Care to take a stab at a cause? The engine had no warpage or history of overheating. This was a basic stock nonturbo s4 13b, 125k or so miles. Owner reported a loss of compression overall. No apex seal damage, but the rotor tips had rubbed these bubbles a bit.

 

 

Yeow!
Delam!


-Ted

 

hot spots in the combustion maybe??

 

Coolant passage blocked? octane booster? Looks kinda like it heated up way faster than the surrounding material.