Dear Ohighway,
This is a bit long, but in case anyone else is interested: I would actually recommend using a 13B. Better parts availability and more power. The 13B is only a couple of inches longer than the 12A, so the fit is still excellent. Surprisingly, rotary engines in my experience anyway, are not very fuel effiecient. I get about 18 MPG. Something you might want to keep in mind with today’s fuel prices. The best places for performance parts are Mazdatrix and Racing Beat. The former is in Long Beach, CA – and just down the road from my house actually. Racing Beat is in Anaheim, CA. They have a great catalogue with some interesting information on performance rotarys. They charge for it, but it’s worth it.
The biggest problem, and I think Barry mentioned this, is the exhaust. You’ll have to build the header yourself or find someone to do it for you. You won’t find anything off the shelf that will really work. If you can weld and have access to either a stick or MIG welder, Racing Beat has a header kit that you can work up yourself quite nicely. Even if you have it done by a shop, get the kit. The rotary exhaust temps are much higher than a piston engine and you really need the extra thick-walled tubing for it to last. Oh yeah, the Alpine appears to be a bit shorter than the RX-7, giving a shorter exhaust system and no room for the beefy muffler they use on the RX-7; and I have never really managed to get mine very quiet. I kind of like it a little loud, but some may not.
Depending on where you live the cooling system may be a problem as well. When I built the car originally I lived in Seattle. The mild climate was no problem for the stock Alpine radiator, butI moved to New Jersey and the hot summers there were really tough on the car. When I moved to Los Angeles I decided this had to be fixed. I spent a lot, about $400, on a custom made aluminum radiator – best money I spent on the car. No over-heating problems at all. If you live anywhere except the Pacific Northwest, plan this in your budget.
A couple of years ago I installed a webber carb and intake assembly from Mazdatrix. That made a huge difference in power from the stock RX-7 carb I was using.
Most of the rest of the pieces you will have to fabricate are pretty easy and you can do with a modestly equiped garage. Bottomline is plan on spending a couple of grand on the project, but this really depends on how much you do yourself and how you want your engine built. I’ve done everything myself except for the radiator and cutting the driveshaft. Well, and a large airplane manufacturer formerly headquartered in Seattle was kind enough to do a little free machining work for me before my dad became a retired engineer. A driveshaft will only run you about $100 at most any shop and I don’t think you could ever do it as good as a shop can.
Unfortunately, I have lost or misplaced many of the photos I had of the various stages the car has been through. Mostly due to a careless changing of hard drives in my computer last year – damn it. However, I can look around and see what I can send you if you’re interested.
Hope you go for the conversion and feel free to ask any questions you may have. I’ve owned this Alpine since 1984. When I got it, it was more or less a planter box for blackberry bushes. I got the car running, then started the first conversion in 1987. I had the rotary running by 1989. During the early 90’s my job with a travel company kept me from making much progress on it though. In the mid-90’s I got back into it and after a little moving around and several incarnations, I really just “finished” a fairly complete restoration and the final version of the engine swap in about 2002. This car was also my daily driver until about 1999.
It seems the most popular choice for conversions is the (Ford?) V-6. You can find lots of discussions about that on saoca.org and here too I’m sure. I’m really happy with my project, but I’ve enjoyed the process as much as the finished product. If you decide to go the rotary route; I’m sure you’ll end up with a car you’ll enjoy, a realiable driver, and very decent performance, although the basic engine cost will probably be a little more.
Good luck with your project,
Scott Rohr
Lakewood, CA (Los Angeles)
Series I Alpine – rotary conversion
Series II Alpine – future project
Mk III Jensen Interceptor – newest toy
Lotus Elan +2 – currently stalled project with a friend