hi, i got a 1991 civic hatch si. i don't know what to do anymore. i was plannoing to do an engine swap (ls vtec) but most of the guys said that it ain't gonna pass smog. then theres another option that im thinkin about, i saw in another website that i can just change the head into a z6 (whatever that is) to have a vtec on my car. please help me. i dont know what to do or where to start. thanks

 

I highly suggest you do research on engine types and engine swaps before you dive head first into this "pool". There are a lot of informative articles to be found on this site. Here is your first step: https://honda-tech.com/zerosearch

 

if you do a complete swap you shouldnt have problems passing smog. doing a hybrid or other mods you may have issues.