I imagine it would destroy the engine and the transmission, but it’s just a guess.
You’d prolly destroy the transmission as it would take most of the strain.
That said it may not even be possible to get it into gear. Synchros certainly wouldn’t handle it well and I’m not sure how easy it works be to rev match it.
It’s called a “money shift”, and, assuming there isn’t a gate or interlock in the transmission to stop you, you will massively over rev the engine, and destroy it.
There’s a few videos on YouTube of it happening.
When I owned my workshop I once had to replace the engine in an old Ford Fiesta that had this happen.
From what I could tell they went from 4th to 1st.
The damage started when the middle two pistons broke and allowed the conrods to separate from them pulling out the wrist pins as they did. Then the free floating conrods hammered the pistons into the head destroying the valves, rockers and pushrods too. After that the rods had bent enough to allow them to fall out of the cylinder and punch a hole in the back of the block, then the sump then parts of the rods exited through the front of the block, One of them destroyed the radiator as it left.
That is my rundown of the series of events from what I could work out at the time.
That was an interesting read. Thanks for sharing mate
No problem, It was interesting to strip the car down and work out what had gone on. This was before the days when we all had cameras with us otherwise I would have lots of pics of the carnage.