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Discussion Starter · #1 ·
I want to add a bigger grin factor to my gt but I don't want to cut it up. So, the 2.4 seems the most obvious choice, I have a shop that will build me a turbo cheap so maybe a 2.4 turbo would be kind of interesting. But, there is a lot of buzz around rotarys. Lightweight, makes tons of power, and revs really really high. So, how much work is involved with putting one of these in? Do you simply grab a tranny out of an old rx7? How could you ever get that thing to fit, its pretty big if I remeber from when my friend had one (the tranny). You would have to make motor mounts. What about driveshafts, and linkage, etc. Are there kits, or do you simply have to make everything yourself? Also, which rotary is the most promising for a gt the 13B since there everywhere or a bigger rotary like the 20B (or would that one even fit?). My budget for the engine is going to be around $3000, and am not afraid to do the work myself, but am not going to have 300 hours of spare time this summer simply for the car (I wish I did). So what do you guys think, is it worth going to a rotary or should I stick with the simplicity of a 2.4?
 

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Detritus Maximus
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Rotaries offer many options. 12a, 13b (4 or 6 port), 14a (turbo), 20b, and the Renesis (soon to be out for much money). The two big issues involved will be the cooling system and the exhaust. They generate alot of heat and noise. Regular exhaust components may not hold up to the heat and you will need a GOOD muffler to knock the noise down. The radiator will need to be highly efficient have electric fans. And some heat shielding under the floor. For ease of installation, the 12a and 13b are the better choices. Cost will be about the same, but the 13b will give a little more power. Trying to put a f.i. rotary into the Opel will increase the complexity and cost.
For carbs, there are several choices, some no longer in production. The best would be to find a new Weber/Mikuni/D'ellorto set up specifically for the rotary.
The engine itself, without fuel injection, is small. 15-18" in diameter and about 20 " long. This will allow some shifting of the engine back and forth to accomodate one of the many transmissions available.
Simplicity, light weight, trans choices, and, if you learn about rotaries, excellent reliability.
 

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Discussion Starter · #3 ·
trannies

So, when you say 'many tranny choices' is there a preferred one? Also, I'm still a bit concerned getting it all to fit, I just want to clarify that its simply a matter of building engine and tranny mounts...no cutting, right? The cooling system and heat shielding are issues that I will have to deal with if I got with a turbo 2.4 or a rotary so thats no big thing. Finally, I heard that rotary's need a 'tuned' exhaust is this true or simply an urban myth? The turbo rotary that you mentioned kind of sparked my interest...turbo just has a good ring to it :) Thanks again for your help.
 

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Detritus Maximus
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As far as 'trans choices', there are at least four different housings and a variety of gear ratios, as well as 4 or 5 speeds. The turbo trans is the biggest housing. It would be the hardest to fit. The shifters can be in different places on the transmissions, too. So the right housing/gear ratio choice and the ability to move the engine/trans back and forth a little will help in getting the shifter into or close to the stock hole in the Opel tunnel.
I don't think there would be any cutting. This swap has been done already, so if you can track down the guy who did it (maybe ask 'Bob'), he might have all the info needed.
The easiest, although, not necessarily the most accurate, way to look at the rotaries is as the equivalent to a 2.6 6 cylinder. The 13b is stated as a 1.3, but the rotors are turning at 1/3 eccentric shaft (crankshaft) speed. They are sometimes likened to a 2 stroke because of the firing cycle. Hence, 1.3 rotary is kind of like a 2.6 6.
Exhaust choice is important. But much of the exhaust for the early RX and 78-85 RX7s can be adapted to other cars (LOTS of mix and match possiblities).
Turbo =2 x $$ and work. If you go that route, you will tear stuff up unless you tube frame. Much like the small block Chevy. Probably more streetable, though
:D :D .
Check out www.rx7forum.com and look in the rotary powered cars forum. This is one of the best rotary only sites for info on these motors.
also go to www.mazdatrix.com for specialist advice and some tech info.
 

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A friend of mine has an E-Mod Bug Eyed Sprite with a Supercharged 13B rotary. Its putting out a serious 400Hp. To my knowledge, the 3 rotor 20Bs were never imported, but a couple of guys out of Texas tore up the field at Solo Nationals last year in a 3 Rotor Bug Eye.

What everyone is telling you about cooling and exhaust is not to be taken lightly. Its also HELL on the drive line. However, you can easily(relatively speaking) get 190-225 Hp out of a NA 13B. So, yes they offer A LOT of power for the weight and are small enough to allow placement behind the front wheel center line for better weight distribution.

But with a budget of $3,000, you won't be able to crack open a rotary engine. You'll just have to find one in good enough working condition.

I guess it depends upon how "handy" YOU are. If you have to pay someone else for every little thing, you'll burn up $3000 pretty quick.

Good Luck
Paul
 
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