I have a pair of rotors from a 74 RX-4 13B and can't find much in the line of specs for them, like how much they weigh, compression ratio etc...

I do know that they come stock with 3mm apex grooves and I am wondering if they would be any good for a PP engine build?

It also looks like the side seals are thicker? Are these still available through Mazda? or am I screwed?



Would the irons from this motor be any good for making power (do they flow good)? I read in that book "How to modify your Mazda" that the 74 13B's had the largest stock ports of any rotary up until 1990? They don't look any bigger than stock T2 ports.

The one thing I'm pretty sure of is that they, the irons, aren't nitrided and wear is more of an issue.



And the c/r s/b 9.2:1. http://www.monito.com/wankel/engines.html#Mazda



Here's some info. from a couple of old 4port 13B rotors I've got lying around.



#1 - "A", "1757", ~11lbs

#2 - "B", "1757", ~11.5lbs



3mm ?pc. apex seals and it looks like the side seals are real close to 0.04"(1.02mm).



btw both rotors came out of the same engine.

those rotors use the same side seals as every 68-85 motor. 12lbs and 9.2 compression, isnt really the hot ticket

So not much good for perfromance application eh?



Well thanks for the info!

nothing wrong with em, but either the s4 or s5 rotors are lighter and have higher compression

I find it interesting that half a pound is an acceptable variance between rotors.



Should something like this bother the **** retentive when building an engine? Would the bearings last noticibly longer if they were the same letter series?

I just had to replace C rotor with a B. The C was unuseable. Now the engine has a B and a C. I would have been in trouble had they been A and C.

Yeah they will be too heavy for PP's higher RPM