questions about ls/vtec

I have a 90 integ Ls and some friends of mine have told me that I should put a vtec head. The question I have is that: will a vtec head from a '94 and up integ fit on the block I have??? One of my friends told me that the two won’t fit because the 90-93 blocks are different from the '94 and up blocks and because of that, the heads are different too as far as the way they will fit. If this is true, then wouldn’t the head off a civic si not fit fit as well???

Sorry, but your friend is smoking crack. The 90-93 B18A blocks are exactly the same as the 94+ B18B blocks. Any B-series DOHC VTEC head can fit onto the B18A/B block to make a LS/VTEC motor… just some modification is needed and some machine work. All B-series DOHC VTEC heads (I’m talking PR3 and P72) heads have the same bolt pattern, so you can make either fit the same way. A head off of a Civic Si is a PR3 head… same chit as a JDM SiR head (PR3 stamp on it). Even a Type R head is stamped PR3, but has another number after it showing that it is a Type R head, but same thing otherwise. To answer your main question, any B-series DOHC VTEC head (that’s from 89-2000) will work on a B18A/B LS block… just that modifications are needed to make it work properly.