I understand that running lean in a rotary, ex: boost spike to 16psi with not enough fuel, can break apex seals. My question is what exactly is the physics that happens to make the seals break off?

 

detenation

 

Detonation *

A/F mixture is sooooo unstable that it can ignite before reaching TDC (max compression). This puts the most force on the combustion chamber (And the exhaust has nowhere to go). The force will try to get out anyway it can.... through the weakest point. It won't blow the housings apart, nor the rotor. The side seals are too tight to the housings and nice and flush. The apex seals, however, are at an odd angle to the housing and will have the least resistance to force. Therefore, they will break first under extreme stresses.

 

The leaner the mixture the hotter it is. The hotter it is the more likely it is the mixture will ignite before the spark plugs fire. This is pre-ignition or detonation. Detonation is a very violent explosion and places a lot more stress of the apex seals than normal combustion, which can (and usually does) cause them to break.

 

ooooook I got it now, I had a pretty good idea but now I really know so thanks.