does a crx engine series d15b2 have potential and if so what can i do to improve this engine? also is this a crx si engine

Turbocharge it. Building it n/a will be a waste of time and money.

no it's not the si engine, the si engine is a D16A6. Best mod for the D15's are to convert it from DPFI to MPFI, overall best mod for any 4th gen is a swap IMO

overall best mod for any 4th gen is a swap IMO
Or that. Turbocharging/Swapping a 1900lb CRX is a great combo for speed.

This site has a few people who have turbocharged that engine or similar engines.

www.homemadeturbo.com

does a crx engine series d15b2 have potential and if so what can i do to improve this engine? also is this a crx si engine

that engine (if in good condition) has potential..
I've seen NA crx's blow supras out of the track.
It's gonna be mad expensive though
Needs a lot of time in the garage and lottts of money.
And if you want it to run that fast, you probably wouldnt want it as a daily driven car.

I myself have a 91 civic with the same motor and I can tell you DPFI sucks!!! Do a swap you can do a LS swap cheap in a 4th gen and it will be really quick.
Also the D15B2's that people boosted on homemadeturbo.com all blew up, if I am not mistaken, so don't go that route unless you convert it to MPFI.