Saab B204 Engine blew up after 45 mins - Autopsy help!

Check the state of the oil pump and the strainer in the sump. You can see it's full of sludge in your picture.

One of the Saab engines is notorious for the strainer clogging leading to oil starvation. I would pull the sump and give everything a good clean out on your next engine before fitting.

I did know that, and had recommended others to do that too.

People do the oddest things!

taking the engine apart was painful - It was so clean and the cam showed no signs of use....

Just thinking that would be an awesome award for engine management!

I am going to award myself this 'Dunce' trophy to myself for putting in an exceptional amount of work on a 500 quid car, 6 months of evenings and weekends doing everything nicely only to blow it to bits on my first test run.

I remember vividly whilst polishing the alloy rocker cover to shiny aluminium "this engine is not going to be good - when has anything in the engine bay been tarted up in a really time consuming way EVER been a good luck charm for me and cars in general? "

Never! - I once spent too much on a chrome plated coil on a VW beetle. Damn thing was a micron smaller than the original so one day it slipped out of it's bracket, caught the main pulley and absolutely anhililated the engine bay. There were dents on the outside of the decklid from the force of the 'Pinball machine effect' - I really hope I have learned something this time.

HA!

Yes, a worthy addition to a black museum.

The strange thing is the crank journal does not look like it has seized, on the con rod one bolt is shown as clearly sheared, is the remains of the other broken of as well or has it come unscrewed?

I was once doing Power runs on cosworth YBG on a very expensive 4wd dyno also used for emissions development we were looking for the cause of a strange ticking noise with microphones on the engine, under full load around 6000rpm it went from tick to a knock then an almighty bang in 2 or 3 seconds, conrod and piston had virtually cut the the sump and crankcase in half filling the dyno and with a mixture mobil 1 and YBG fragments, it cost over 10 grand to clean the dyno!

root cause was a conrod bolt coming undone.

Is the knackered piston seized in the bore? It's a odd one that, it looks more like hydraulic lock damage than a crank oiling failure but from the photos you've posted the cylinder looks dry.

Was this run without water?

I've had a seized piston in one car before, a 944 S2.

The root cause was seen to be severe overheating, which tied in with the ropey cooling system it had.