90 Mustang 2.3 4 cyl LX has bad engine tap/knock. HELP plz.

From what I have been told trying to convert a naturally aspirated engine to turbo is more costly than it's worth. I wanted to install a turbo kit on a 1995 Mitsubishi Eclipse GS years ago and was told engines not designed for turbo applications aren't built to withstand the pressures exerted by turbocchargers, that the cost to convert was more than the car was worth. You would be better off trying to find a wrecked svo with a good motor, although that will be a task in iself as there weren't many of them made and they have become collectors items. If you do find one, I would also check out your state's emissions laws to see if you can get away with it.

Not sure about the knock but. By "converting" to you mean strapping a turbo to your current block or putting an svo/merkur/turbocoupe engine in? Well trying to put a turbo on a NA motor is highly not recommended and a ton of work, and usually alot of money. The cast internals found in the NA engines don't accept boost well. On the other hand. Dropping a 2.3 Turbo from a thunderbird TC, an SVO, or an XR4Ti is easy, cheap (depending on where you live), and perfectly safe. Tranny/engine mounts match up, the block is nearly identical (except for the turbo oil lines). The only things you need to change are the exhaust and a very small amount of simple wiring (NAs used a MAF setup while the turbos used VAMs and the computer recives signals in different ways from these 2 sensors - a few easy and safe wiring changes can fix that). Many people have done this swap and are pushing 350+ hp out of the stock block. There are tons of write ups out there and make friends with the guys in the 4cyl section (including myself) to get any extra info you need! Hope that helps