B20 Vs B18
 

what the difference with the heads, what if i put a ls Head on the B20 block whats the out come what so good about that and what so bad about it

heads are the same - same mold
ls cams are a little more aggressive

B20 head has larger valves than the B18B head, and supposedly flows more.

well I finally decided to look that up....youre right

33mm int valve and 84mm combustion chamber

and produces better flow numbers! Its the intake manifold that is so restrictive on this engine, obviously designed for torque, efficiency, and throttle response.