what would be the compression be at if i was to replace the b16a2 crank with a b18b1 crank?

 

hmm... i have ls crank and rods in my b16

 

Compression is not changed by a crank. Displacement is. If you put an LS crank in a b16 you have to use LS rods and custom pistons because of the difference in deck heights. But if you use the correct parts on a 81mm bore B16 with a LS crank you will have a displacement of 1.83 Liters. Check on here for custom pistons by Tech43 if you want to use an LS crank.