What is this part
 

Found this inside of a project rx7 I picked up recently... any idea what it is/if it's vital?
https://cimg0.ibsrv.net/gimg/www.rx7...d5bffc21e2.jpg

Sending unit for oil pressure gauge.

Would having this disconnected prevent the car from starting? It turns but won't start

Nope.

Disconnected from its electrical plug only? -> Car will start & run fine, but the oil pressure gauge on the dash won't work; it will either read 0 or full scale, don't recall which.

Now to state the obvious, if that sensor was mechanically removed from your engine, and you try to start & run the engine, you'll have a mess of about 5 quarts of oil spewing out of it from where the sensor is supposed to screw into the rear plate within a minute or so. Trashed engine follows if you don't shut it down immediately.

All of that was implicit in "nope".

While that's true, the OP has a post count of 3, which implies a lack of experience. Couple that with his picture of an obviously uninstalled oil pressure sensor, and as far as we know that part could be a spare part that came with his project car, or it was removed from the engine - the OP didn't say. So I erred on the side of caution as I didn't want the OP to misinterpret your "nope" answer to mean "Yahoo, I can fire her up right now and not worry about putting that thingumajiggy back in". I may have just saved another FC from the scrap yard :lol:

I guess we can now discuss whether that is a good thing or a bad thing.

Wow that got depressing really fast. I hope yours doesn't end up in a scrap yard- I would literally cry.

T'wasn't meant to be depressing or happy at all, just realistic.
Not saying anything about this particular car but having spent a lot of time in the yards, there are in fact, cars that simply belong there, not on the street.
Two observations...

- Since the end of Cash for Clunkers- which saw some really nice cars get destroyed, most of the FCs I ve seen are pretty crap and hardly worth the effort.

-Inherent in the creation of a consumer good (which a car most certainly is) would be the ultimate demise of the product. Some things last longer than others but nothing is immortal.
Just like putting down a beloved pet, at some point your car has to go.
(If it seems like I anthropomorphize my hardware....well, yes, I do.)

Was from the dude whom I bought it from father's T2 fc; Mine was still installed!