apparently their is a manual on how to build a 4 rotor engine crank out of two rx7 cranks. has anyone heard of it, own it or know where to get one? if so can you let the rest of us know.

 

Hmm I have never heard of this manual, but I know its been done several times. Im also curious about this

please some one come threw with it dammit please

 

The R26B is a Mazda race engine, as I'm sure you know. It was not built with two 13B shafts but a custom 3 piece shaft. Theoretically you could build a similar shaft with two eccentrics but probably not in the way you are picturing.

Now, there are many ways to build a 4 rotor with two 13B/12A cranks but it won't be the same as the R26B. There are also kits available (Precision Engineering/Kiwi RE).

 

^ How's your four rotor going by the way?

 

it's gotta be more fun than building an RB26.

 

there are a few shops selling 3 piece e-shafts, and the custom center plates to accomodate the 2 extra stat gears. it's still uncommon but becoming more found.

 

Ya Hi. The shop I work at makes the best shaft ever known to the rotary world.

 

You can buy the real deal from Mazda. Its well over $100,000.

 

I'm thinking I'll have all or most of the parts ready by the end of the summer.

 

Sounds good! Figured out the shaft coupling yet?

 

Yep. Paying someone else to do it.

 

Aint that the best way to do it.


Im sure you'll let us know little secrets of how that went. I been looking at all the high tourque couplers we use at my work for the idea of 2 joined shafts. Problem is the couplers are about as large as a 12A shortblock.

 

$100,000?

cheaper than an RB26 too....

 

Oh there's bigger problems then that...

 

Mazda's design is best with the tapered shafts. Clearly it's reliable since it's used on the 20B. Splines will work but the evidence points to a short life when operated over a wide RPM range. Thus, taper seems to be the only option for something that's street driven.

Basically at this point I know what I'm going to do as far as port timings, housings, EMS, intake, etc. What I get done this summer will depend on how quickly Tina gets finished.

 

The taper definitely spreads the tq more evenly, not to mention that once it's locked in it doesn't take much to keep it from seperating. That's why it's used so widely with milling and drilling. It's also simpler to make a taper and key it than a spline.