I do not know the answer, but I am going to take a wild guess that if
it is possible, the cheapest route would be an engine/transmission
swap. Electronics would also need to be swapped out.

Elliot Richmond
Itinerant astronomy teacher

Wow, I didn't think Honda was still putting carbs in cars in '90, let alone into
Preludes.

In any case, it should certainly be possible, although I doubt a complete
engine/tranny swap would be necessary or even cheapest, as Elliot suggests,
unless the FI version uses a direct-injection system.  At the very least you'd
need the electronics and intake system (air intake, throttle body, etc.), and
possibly the intake manifold.

I can't point you to any Prelude-specific info, but I believe a few folks at
www.3geez.com have done a carb-to-FI swap on 3rd-gen ('86-'89) Accords, which
are a close cousin to the Prelude.  Could probably start there.

Thanks for the help guys.  It will probably be cheaper to upgrade to a newer
lude, with the VTEC engine.  Its a shame because I just love the shape of
the 3rd gen, after that they got very "samey" looking as the other jap
coupes of the period.

Cheers

Keith