Hey everyone,

Have to start with some tragedy, but there's no better way. My S90 Executive suffered a massive engine failure after driving for 40 miles with an oil leak. Partially my fault for not being more conscious of it, but never having experienced lubrication problems with a car and having a faulty oil light on the dashboard pretty much set me up for disaster. Among other things, a rod from either cylinder 2 or 3 broke and slammed into the left wall of the engine block. On top of that, I discovered that the engine had absolutely no oil in it, which was strange, because the oil levels were fine when I first bought the car three weeks before and up to when I first set out on this journey to have the car assessed for whatever servicing was needed. Needless to say the engine is ruined and needs to be replaced.

I'm willing to deal with this, having had some exposure to mechanical work and just being plain curious about what made that B6304 tick. But I've been having problems with sourcing a replacement S90 block. Given my location I have to ship the engine in, and given the costs of any short and long-block engines I find, that makes pricing a bit hefty. I've observed though, that the succeeding S80 uses an identical motor, only transversely mounted for front-wheel drive. I've also observed that these engines are somehow considerably cheaper. My question now begins:

Can an S80 motor, either turbo or naturally aspirated, fit an S90? Will the mounts bolt up properly or are there modifications I need to make to make it fit? I'm hoping to reuse the S90 head and sump, provided that those weren't damaged in the catastrophe. At the very least, will the bare block be able to directly replace the damaged one? Then I can probably source the pistons, rods and other internal workings as I go along - that's also come up to be somewhat cheaper than trying to ship in an entire engine.