Jaba. There are two separate engines being discussed here.
Take it easy on me
The J230 was a CHT overheat event. I highly;y doubt it was pre ignition or detonation as the engine gave no rough running sympotm at all,
With all respect, it is apparent you do not clearly understand what either of these events actually are, and no you will not notice rough running at all in either case, until preignition kills the cylinder The only indication was the flashing light warning me the CHT was over 180 deg's. That was late upwind, about to turn xwind on a normal 80 kt climbout on a 28 deg day. By the time the turn was completed the CHT was 210 deg's, then 220.
Could have been a lot of heat build up from some unintended machining going on, but this is pretty much how preignition goes That was when I levelled out, reduced power and returned to the strip.Where it subsequently stopped.
Yep that too. But it may have been a circlip problem (refer SB) and subsequent chewing up metal.
My questions relate to the valve failure at 300 hours in the 2200 with an engine that has logged history in 4 channels on CHT and EGT. None of which show anomalies. no overheat issues indicated. jab quote that valve seats start dropping out at 250 degs (see engine inspection report).
When we have one engine that fails at 220 degs, and jab saying 250 is where the seats let go. Why, has this 2200 engine dropped a seat with NO over tempt issues.
Thats the 64000 dollar question
Add some more zero's on the end 
So the 220d failure, was this a valve too? How did the 300 hour one fail? What were the guides like? I am not at all defending the Jab engine build, just trying to help in the understanding. 250dC is too hot to run the engine at but should not have seats falling out of the head 