well i heard it is a good idea to put a b20 block with a ls head well what is the difference between a ls block and a b20 crv block? thanks

 

bore size = bigger displacement = more torque

 

They're essentially the same block with about only 2 differences.
The B20 its built upon the B18B block. All Honda did was change the sleeves out to accept a wider piston and added a wider piston. Everything else (rods + crank) are LS spec. Even the head is the same, all you need to do is replace the B20 intake manifold in favor for an LS or skunk2 manifold and its ready for a civic/integra chassis.

 

There is one other difference between the B18A/B18B and B20 block. And that is the oil breather. It is on the back of the block on the B18A/B18B but in the valve cover on the B20. As for the head, only the B18B has the same head as the B20. The B18A head is different. The intake ports are smaller.