Going off thread, the mention of crankcase explosions, filled me with fear. Read a book on main propulsion engines and there was a photo of the after effects of one in an engine with two staircases leading from bedplate level to cylinder head. Both were twisted like paper clips!
Apparently, the rate of pressure rise was such that the varnished brown paper bursting discs, intended to guard against such things, failed too slowly to prevent damage.
I witnessed one from across a car park in a motorway service area. Sudden bulge in bonnet, and clouds of smoke, from a car which had screamed down the motorway and entered the car park at about 70 mph with tyres screaming, before switching off
A colleague worked at Blackstones when they were trying to develop "explosion proof" crankcase doors. Apparently, seeing a door weighing over a hundred weight flying across the shop was something e!se.
Another colleague was standing beside an engine on test when it suffered a crankcase explosion. The sump fell onto the bedplate, leaving the flange still securely bolted to the underside of the crankcase!
There is a two cylinder Allen diesel engine, with various windows, motored as an exhibit, at The WaterWorks Museum, in Hereford.
Howard