The only failures I’ve seen from egts are pistons melted down on one side down to the ring land, causing low compression and lots of blow by, and precup cracking past the fire ring of a headgasket, which blew the gasket out. There’s a lot of surface area that is exposed to the flame front in an idi engine. All of those failures were on trucks with no pyro, so who knows what temp those failures actually occurred at. I’d like to buy a beat up factory turbo truck, and put a big pump on it to run it through some tests. I want to know at what psi of drive pressure the headgaskets fail after retorquing them, and at what egt things come apart at. Yes it’s automotive homicide, but it’s for science!
So... you are talking about me then? Because that's more or less what I've done:
My '93, bought it about December 2016. Overheated it in February 2017 due to the belt tensioner breaking. It started weeping coolant a little from the corners of the gasket. So... Shove a big pump on it and crank it up!
April 2018 was when the head gasket finally let go, after towing an empty trailer to my dads that day. I'd pulled plenty of full trailers before that(and by full, generally 8-9K total trailer weight).
I never had a pyro the entire time I ran that engine.
Pulled that motor out for new gaskets and a freshen up, and swapped in... a '93 factory turbo motor from the JY. Cost me $370 inc turbo. It knocks, it ticks, it smokes at full throttle and EGTs jump pretty quickly... but I haven't seen any leaks yet. Still not getting more than 13-15 PSI of boost though.
Of the motor that came out of the '93, it was an '88 block that had evidently been bored .020 over, probably back in 2001 judging by the date written on it. Still looked pretty darn good inside, though I did see what almost looked like small spider cracks in the exact center of every piston, within a quarter's diameter. I took a wire wheel to it and they disappeared(could just be metal smearing).
Either way, it's getting some rebuilt heads(done by Typ4), the Typ4 cam, studs, and my big pump and we'll see what happens.
Speaking of head bolt retorque, I've checked on a couple of well worn engines(including the '88 motor in my '93 after I saw the leaks), and the bolts were all to spec. No tightening needed/available.