How hard is it to work on a 12a?

[Saga]

I've been eyeballing an extremely clean 85 RX7 in town for giggles lately, but the more I think about it, the more I become fascinated with what I could possibly do with it. I just sold my daily driver ('07 Legacy) and am either driving the truck ('07 Sierra) or the bike ('07 ZX10R). The truck gets horrid mileage for around town, and the bike can only be used when it's not snowing in Nebraska.

Looks like this car dropped the 13b in it at 113k miles and they put a 12a into it. Only downside there is that there is a significant loss of horsepower from that engine downgrade. But it'd make a great kit car if I either beefed the hell out of the 12a in it, found a turbo'd 13b, or just did a GM V8 conversion.

Car runs fine and needs minor clutch work and can be picked up as is for free (owner just wants it out of their garage).

Thoughts? Suggestions? Nay-sayers? Buy a real sportscar? I just want a toy I can break things on that can be made to go vroom. 😉

 

[aleckz]

Hello fellow Nebraska resident. I'd say if you have the time, the car knowledge, and the money, then it would be a great idea.

However, if you were to lack one of those then I'd say pass on the deal and buy a car that is already quick and not a money drain.

 

[Saga]

I have the time, the money, but lack the car knowledge - however, I am very good friends with someone who is extremely skilled and loves to teach, so it would be a joint project.

I just don't know if I should go through with a V8 conversion or try and beef the hell out of the rotary in it.

 

[Arkaign]

Do it or don't do it, but don't mess with the 12a. Provided you have some decent garage space and the time to mess with it, it sounds promising. You can almost *steal* GM 5.7s, they're so widely available. Just find some real experienced sources to tell you about hooking up the fuel system, a custom wiring harness, gauges, pedals, etc, etc. It's going to be a monster of a job.

 

[Saga]

Why would you recommend not messing with the 12a? I tend to really like the rotary design, but I could just as easily drop a 350 into it and get it to the 500+ HP mark. Would require a lot bigger rubber on the rear to utilize the power, though.

Wish it had the 13b, though.

 

[Arkaign]

Well, the reason for skipping the 12a, is to make any reasonable power you need boost, and you're still not going to be making any torque. Also problematic with those early-80s rotary motors is the oil line that can break in some VERY inconvenient places. Whereas once you go through the hell of switching to a 350, you can work on it, get parts for it, and rebuild it with ease for the foreseeable future with no issue at all. Nothing would suck more than pumping a bunch of money and time into fixing a 12a up, only to have major issues with it before long.

 

[Saga]

I always really enjoyed the old RX7's. Out of curiosity, if you could get the car for nothing, what would you do?

 

[Arkaign]

Originally posted by: Saga
I always really enjoyed the old RX7's. Out of curiosity, if you could get the car for nothing, what would you do?

If I had the spot for it to sit while it got road-worthy, I'd take it hands-down. I have a spot in my :heart: for fixing up classics, and the first-gen RX7 is now a 'classic' in the true sense of the word.

I'm thinking of finding some cool but unloved 70's-era car to work on myself. I loved the big ugly Thunderbird in 'The Crow', so I might go that route.

 

[exdeath]

If you really want something nasty and want to make something unique and see yourself spending alot of time and money in this as purely a hobby, try and source a 20b 3 rotor.

Personally I'd stay with the rotary. Part of the fun of being into different cars is the fact that they are well... different.

 

[darom]

I used to own a 1986 (auto) n/a 13b and a 1988 (stick) 13b turbo'ed rx-7s. 1986 had a low compression engine and after a year I couldn't start it any more. The 1988 TII was a very fun car, the handling was excellent, the lack of the low-RPM torque was noticeable. Everything worked on that car: a/c, pop-up lights, power steering etc. I still miss that car and wish I hadn't sold it. I got a 76 Datsun 280z as a replacement. '88 gas mileage was solid 18mpgs (premium fuel) in town with occasional 6-6.5k shifts.

If I were you, I would either rebuild a 13b using the right apex seals to make it more reliable or buy a j-spec low mileage 13b. I wouldn't mess with a 12a.

There is an excellent forum on Yahoo dedicated to rx-7s. A lot of knowledgeable people who like their cars, get together for b-b-q's often 🙂 Subscribe to it and ask your question there.

Actually, I would look for a TII 2nd gen (manual) in a nice shape instead. They sell for about $2k nowadays. Make sure to check the compression, turbo oil leaks, radiator condition.

Good luck with your decision.

 

[Saga]

I'm getting the car for nothing and it's incredibly clean. Rust was almost non-existent, which is pretty amazing for an 85.

I have no problems getting rid of the 12a. Would the j-spec 13b work be the easiest stock transmission friendly engine to beef the hell out of? Doing a V8 swap would run me anywhere from $5,000 to $11,000 including a custom transmission and probably having to widen the bodykit to make it all fit. Ideally I'd love to not touch the body much outside putting much fatter rubber on the rear.. in a perfect world I'd love it to be as sleeper as possible, avoiding most of the flare people tend to do nowadays and just making it an absolute beast under the hood.

 

[exdeath]

20b 😛

You can get the complete engine with turbos, harness, computer, etc., sometimes even transmission for about $3-4k and there are conversion kits to swap a 20b into anything that would accept a 13b. It's still alot of work but nothing like custom transmission or body modifications. Just a lot mounting and electrical work.

The only drawback is that the parts are a little harder to come by; you'd be wise to stock up on a spare e-shaft and balancer, ignition coils and igniters, and all the stuff unique to a 3 rotor.

 

[bruceb]

Rotary engines are hard to build yourself. Lots of tricky assembly and you need to be 100% sure the rotor housings are not warped. Also if you plan on going over the 8K redline, the stationary gears need to be upgraded and staked into the housings. Look at the two links below, both of which have been making great power out of the rotary since it came out in 1971 .. they can provide advice, parts or entire engines, ready to just drop in.

http://racingbeat.com/

http://www.rotaryengineering.com/