3.15 LSD in a 318?
 

i dont know much about LSD's...

can i put a 3.15 LSD into my 318 convertible?

You sure can:)

I believe the 318ti sport came with a LSD, not sure of the ratio. Im also not positive if you can swap a 318ti diff into a non compact. I'm pretty sure you can. Unfortunatly you can't swap a 325/328 diff in without cutting away at the rear subframe, and i think the driveshaft is of a different length. You can also have a custom diff made, they're stupidly expensive 2-4K$

I doubt it will fit (it's from a e36 M3). It will also be really slow off the line.