tudsinhaler

I'm finally giving up on my Opel motors and am going to transplant a Rotary into my 1970 Opel GT body.

I want it to be easy, but I also want the best perfomance the first time out.

I may have to steer clear of the turbo as my passenger side engine bay is quiet tight, so which stock rotary setup is my best starting point to begin with.

This will also be a daily driver so reliabilty will be key, and I'm in texas so the one that adapts to cooling the best in traffice with A/C is also a consideration.

I've looked at teh 12a's and the motor mounts look like the easiest to work with, and I've owned 88's and 89's non turbo's and I'm comfortable with the FI quirks, so tell me in your opinions, Torque and driveablity which are my best options.

-Bret

Aviator 902S

Hey Bret,
How much horsepower did the original Opel GT 4-cylinder put out? What is the curb weight of the car? You'll most likely (adviseable to) also use the Mazda transmission, which will mean a custom drive shaft.If the differential (assuming you intend to use the stock Opel unit) is not very durable you may want to stick with the 12A, since it produces between 101 hp and approx. 150 hp depending on whether or not you are using the stock Mazda exhaust and emission system.
Since your car is a 1970 model, I doubt you'll want the unnecessary complexity and power-robbing characteristics of all that emissions crap, but you'll need a very skookum exhaust system to handle the pressure and heat from the rotary. Racing Beat sells a very good header/ pre-silencer/ muffler combo to make best use of the potential hp of the rotary.
Then go with an aftermarket (holley, Webber, or other) 4-barrel carb that's been jetted for the rotary's requirements and, if you intend to use the stock oil-metering system rather than pre-mixing, modded to accomodate the oil-metering lines.
If you intend to use the stock metering pump, it's adviseable to use a metering pump adapter (available through PCV technologies--e-mail them at unicorn@gdsys.net or phone: (850)834-4905) that blocks off oil flow from the pan and instead feeds 2-cycle oil from a separate reservior. This is way better for your rotary apex seals than the 4-cycle oil from the pan, since 2-cycle oil burns much cleaner than 4-cycle oil and will not plug up your seals with unburned deposits. I'm running one on my 12A-powered '85 GSL.
The 13B in stock form produces more power than the stock 12A (146hp vs. 101 hp), but I'm not sure if the stock fuel injected intake system will fit under the hood of the Opel. If it won't, you can always convert it to carbureted, and it will still take up no more significant amount of space in your engine bay than the 12A. Keep in mind however, that if you mod it out to produce substantially more power than the stock Opel engine, your stock Opel differential may not be able to handle the extra power.
It sounds like you have an interesting plan here. Hope everything goes well for you and keep us posted!
Cheers,
Brett.

tudsinhaler

Stock Horsepower, egh.
The opel in High Performance version was supposed to pump out about 80hp. With just ignition and carb upgrades you can get to 95.
My last motor was a.-090 oversized piston job, larger valves, auto-x cam ported intake, insane header and a billet aluminum flywheel. I think at that I am lucky to pump 125, maybe 150 but I'll go low since my foot is the only indicator I've used so far.

My differential is supposed to be good to about 150. Really most if not 90% of my driving will be on the highway, so I'll stick to the original until it is dead. Afterall I have to get some mileage out of the cost of my 4 wheel disc conversion.

From this and the previous thread I'm looking at leaning towards the later model 13b's just because I can't find any early 13b's to my knowledge. I also like having the idea of fuel injection, however this is just the idea of an engine management system, not what happens by the time I get the motor installed.

And for weight, I'm at 2300 for stock setup with the original cast iron 4 banger.

Aviator 902S

Sounds like a good weight, not far off that of the 1st gen rex. As for fuel-injection: again, you have the advantage of a car built prior to 1971, so you're not limited by emission-control requirements. With the 13B you're starting with more cubes so you can't go wrong there either. The T-II tranny will bolt right up as well, and it's much stronger than the N/A trans. But the exhaust mods alone will give you an impressive hp advantage.
If you're planning to use a freshly rebuilt 13B, you might want to consider having Adam at Rx7 Specialties in Calgary build you one. His prices are reasonable, his work is amoung the best in the business, and he's very good with mods, including 3mm apex seal conversions for '86 and up 13B's, porting, custom water jacket mods for better cooling in the spark plug areas, and of course, dis-abling that annoying thermal by-pass valve that keeps cooling oil from entering the rotors until after the engine reaches 158F. (This was a useless emissions device that Mazda introduced on 13B engines in 1986 to help the engine warm up sooner thus reducing pollutants. It did way more harm than good).
Adam ships engines to re and re mechanics all over North America, so that should give you an indication of his price-competitiveness.

tudsinhaler

I'll try and get in contact with him and check it out.
I'll most likely begin with a bone stock setup to get all the fabrication and bugs worked out of the system and then go performance.

I'm going to go in search for an s5 setup this week and take measurements and hopefully have a purchase done by friday and a trial fit by the weekend.

I'll keep everyone posted and I'll drop a pic or 2 over for you guys and always know that when in Ft. Worth, the beer is on me.
-Bret

Aviator 902S

Yeah, keep us posted. BTW, Adam's business hours are M-F, 9am-5pm Mountain time.