I have a 1995 Integra LS with (stock) B20Z swap already installed. I plan to do a VTEC conversion and have studied and researched quite a bit on the subject. I plan to use the stock B20Z bottom end, GSR head/cams, and don't plan to rev over 8K. What I need to know is if I need to worry about the pistons smacking the valves.
I have read (in my search) both ways (that it will and that will not). Perhaps it is because the lower compression B20B engine has shorter pistons and the (higher compression) B20Z has taller pistons. Maybe the B20Z smack and the B20B does not? Can anyone give me a definate answer, from personal experience?

 

It really has nothing to do with the piston being shorter or whathaveyou. The intake valves on the VTEC head is larger than that of the B20's so the valve relief will not be large enough. It doesn't have to be though, check piston-valve clearance if you using the stock pistons. Some people use the stock ones without machining and get away with it. As a caution, check clearance and make necessary adjustment to valves or whatever to hav it done right.