ok here my question i recently bought a 87' rx7 and i have plans to put in a 20b but im not sure if i should use a stock tranny or something that can handle more hp....hopefully i want to push between 600-800hp range...i heard a lotus elise tranny will fit....true or false?

 

stock trannies are great, and they're only like $200 when you blow them up. can't beat that with a stick.
a 20b will tear up that lotus tranny with haste.

if you're ambitious, there are adapters so you can use a t5 (which can be built very sturdy), and you might even find a t56 adapter somewhere.

 

*$& Pistons,

I looked at the same situation last year. What I found out is that you'll need to convert the clutch, probably the drive shaft,rear etc... if you go away from mazda the parts. There is a racing transmission out there(6 - speed-can't think of the name) that would fit but is was like $10,000! Search the threads, there is a lot of info on this subject! I ended up going with a cryo treated turbo ll trans that has held up so far. FYI, If you stay with a mazda trans, get a high end($$) twin plate clutch.

 

t-fiddy six has great gearing for a 3 rotor, but if you're really pumping out that 600hp, you'll bang through them pretty quick. i'd stay stock or go t5. with the t5, you've got limitless gearing choices if you have it built. that way you can get the car into the 200mph (assuming eveything else is up to the task) range.

 

thanks for the advice much appreciation for all of u.....

 

Also keep in mind that you need to find a transmission that can handle (1) the torque AND (2) shifting at high rpm. Most of the gearboxes that satisfy (1) are designed for large displacement motors and don't have syncros that can handle high rpm shifting.

 

6500-7k isn't very high.

 

If your 87 is an NA car then the tranny will probably blow up shortly after the 20B swap. They aren't that strong. The TII tranny is much stronger.

A Lotus Elise tranny WILL NOT WORK! A Lotus Elise is a mid engine, rear wheel drive car with the engine and tranny out of a Toyota Celica GTS. That's a transverse engine mounting. The tranny and diff are one unit with the halfshafts attaching to it, not a driveshaft.

Any trans that may be of use in a RX-7 will need to be from a car of the same drivetrain layout (front engine, rear drive). Some of those won't even work (Corvette, Porsche 928) due to having a transaxle in the rear, where the tranny and diff are in the spot where the diff is in an RX-7.

On another note, be aware that a 20B swap will cost you well over $10k to do and will require lots of custom work. It's not a bolt in sort of affair.

 

o ino ive been savin for a long time and hopefully by the end of the year ill hav enough...this is some thing ive only dreamt of doing and soon its gonna be a reality