N89SE received it's Airworthiness Certificate June 13, 2013! Yay!

So I put the covers on it an pulled it out of the hangar for a start up and taxi test.

I have not run it this year while finishing the airframe.

So I started it up, a bit behind the curve on the EC-2, chasing the mixture around etc, then settled in to a nice smooth high idle and taxi'd down to the far end of the runway where I ran it up to 4400 +RPM, checked the water & oil temps, (158 & 167) pulled out on the runway, and fed the power to it for a 2 or 3 second burst, to be pulled off to prevent flight.

Well the thing started well enough, I pushed the throttle slowly to about 2/3, and as the plane gained some speed, the CATTO 68x74 prop unloaded a bit and the RPMs went up. The acceleration was profound for about 2 seconds followed by a POP! as or just before I started to pull the throttle back.

Then came the grey smoke as I shut down the fuel pump and glided off the runway to the taxiway.

A few guys came running to help. One asked 'How ya doin'?" Medium I replied. (I'm OK and nothing is burning). Yada Yada, The plane is back @ the hangar, and the oil leak (spew) is a cracked block at the last oil tap fitting on the top gallery, by the distributor pulse counter. (1986 type)

Today I stripped the engine and pulled it off the airframe. Looking in the ports, all the tip seals move and are springy, but I think I detonated it, some damage is visible. Maybe in a previous tethered run (to 40" manifold press), and this time it let go. compression was down (prop pull method) I wonder if detonation under boost will crack the block (end irons)?