I heard that if you take a non-vtec block (LS/B20) and put on a vtec head (B16/GSR) it would up the compression by 1.0? In other words, if a stock LS motor is 9.2:1 CR, swapping the head with a B16 head the compression would then be 10.2:1? If this is true, is it the same with the B20?

 

That isn't true.... If you had a stock B20B motor you would have a C/R of 8.80:1, swapping a B16 head on that would bump you to 9.1:1 and a GSR (P72) head would raise you another .15:1 over B16.... this only happens because the difference in the size of the combustion chamber... The B20's is 45cc, B16's is 42.7cc, and the B18C1 is 41.6cc. The LS motor would be a little different starting with 9.2:1 a B16 head would bump you to 9.55:1 and the GSR would go up to around 9.75:1.... Remember these are all with stock bottom ends... Hope this helps.. Peace