has anyoen heard of taking an prelude b20 crank and putting it into a ls bottome end. my friend was talkin to me about doin that but didn't quite know it you could. and would it even be good for turbo if it does work?

 

hmmmm..... i do believe it's the same crank. both will yield an 89mm stroke. not exactly sure if its the same. b20b/z cranks are the same as ls'

 

Yeah it fits it is a 95mm crank. The rod ratio goes to shit though. Techinically it could be built with factory parts. Prelude crank, b16a rods and whatever pistons you want. R/S ratio would be about 1.37:1 though, which might get you a couple of passes before you stuck a piston through the block or spun a bearing.


If you wanted to get forged internals you could get an eagle ls rod that is .137" longer than stock and a piston with the wrist pin moved up .250" to make room for the increased stroke and slightly longer rod. This would yield a r/s ratio in the range of 1.48:1. This wouldn't be too bad for a race or low mileage motor that would at least see a change of rod bearings every couple thousand miles or so coupled with a very light piston. Definite no go on a turbo motor though. If you look at the really fast turbo B motors they all run a stock 87.2 or 89 mm crank.

 

Crank swaps are usually ls cranks into a gsr motor.

 

alright guys thanks for the help, i appreciate it.

 

I tried this and it does not work without some major hacking of the block and or rod. The crank will fit into the block and spins over fine. The problem is when you bolt the rod to the crank and try to spin it over, the big end of the rod will hit the very bottom of the cylinder. It didn't look like there would be enough strength left in the two ofter all the grinding.