For those of you who are considering an engine swap, I can't reccommend a better choice than a Mazda rotary from an RX-7. The rotary fits nicely in the engine compartment with only slight modifications to the cross-member and the transmission tunnel. The only clearance problem is between the header and the right side steering control arm. I used a header kit from Racing Beat in CA (aftermarket RX-7 supplier)to fabricate my own header. The first bend is very tight, but I have been driving the car for an estimated 20-25K miles and haven't burned a hole in the headers yet. While not lightning quick, the car is lively and has been extremely reliable. With only three moving parts in the engine, there isn't much to go wrong except the occasional starter or alternator failure. My car does run hot and I avoid rush hour traffic in New York city, but I used the stock Alpine radiator. I plan on changing to a larger capacity radiator and think this will cure the problem.
The conversion required a little over a year to complete, but a lot of general restoration of the car was involved as well. How much you spend on an engine is proportional to how much horsepower you feel you need. I would say plan on spending around $1,000 to $1,500 for a slightly modified rebuilt engine. There are several different models of the RX-7 engine. I would suggest using a 13B from the early 80's. These seem to be more abundant and parts for the earlier 12A are getting harder to find. The biggest factor in horsepower is the size of the intake and exhaust ports. I would reccommend giving your engine what is usually refered to as "street porting". You can have a shop do this when you buy the engine or there are books on how to do it yourself. The rest of the parts needed to complete the conversion will probably run about another $1,000. Keep in mind parts for the rotary engine are not cheap either. The spark plugs have a special three prong electrode and run about $6 a piece!
The list of bits and pieces needed for this conversion seems endless. If anyone is seriously considering installing a rotary I would be happy to answer specific questions and share the drawings I made when fabricating all the various bits and pieces.
If you want to convert the engine in your Alpine for whatever reasons-go with the rotary. It makes the car great fun to drive and I take great pride in the fact I did virtually all the work myself.
Scott Rohr Series I B9000839 (Powered by Mazda)
PS. I still haven't seen anyone confirm an earlier car that runs:-)