what do you guys think would handle more power and would be faster providing that they boost the same amount and have the exact same setup and both are stock motors. also which motor would be able to be built better for turbo?

 

b18a

 

B18a, the B20 has extremely weak sleeves that are known to crack under boost

 

B18a would hold up better with boost and at higher psi.
But,8psi on each the B20b will come out on top and spool faster.

 

Go with the LS motor. A B20 is only an LS motor with a 84mm bore and weaker sleeves.