Engine Swap

Alright, this is a pretty in depth question I know, but what would be necessary to do an engine swap. I'm not really interested in performing one but I'm just curious and trying to learn what I can about this.

To start things simple, lets assume we're going to drop in a Turn-key Crate engine that is of similair size to the one its replacing. Let's also say they are both V8's with 32 Valves.

The most pressing question I have concerns the transmission: What would mandate a transmission upgrade to accomodate the new engine? I know that a significant power difference could be a cause, but what else? Are there some situations where a new transmission is not necessary, just something like a new clutch or flywheel or something of that manner?

Much appreciated.

Man, transmissions don't just bolt on to all engines. Every transmission is of different shape and size. Same thing goes for the engine. You would have to get an engine that is known to be compatible with the tranny. Second issue is the wiring harness. Engines don't just bolt on like they use to in the pre-electronics era. Some engines comes with oil pressure sensors and some don't, and you would have to accommodate that. There's so many issues these days, that if you're not comfortable with customizing work, then it's best left undone. From the looks of it, a lot of people don't bother these days. And if they do, they just buy an engine that was built to fit in the place of the original.

Like I said, I'm not really interested in doing an engine swap, I was just curious as to how it was done and what factors have to be taken into account.

I'm aware transmissions don't just bolt on. Thanks for the reply though.