Been following this guy on Facebook for a while and wanted to share it with yall in case you haven't heard of it. It's still a work in progress clearly, but very promising. He's planning to start with 8:5:1 / 9:0:1 / and 10:0:1 comp rotors. Would be cool to see something like this hit the aftermarket. I'll quote some stuff directly from his page.

"Multi piece, 4032 aluminum, 24 dowel pins, 24 roll pins and 18 grade 5 titanium cap screws. Will be hard anodized and compression faces ceramic sprayed. I'm using piston material tech and bringing the weight down to 3kg per rotor."

"the three compression baths are modelled off three of Mazda's common designs, S4 Rx7 Turbo, FD Rx7 and Rx8. Mazda have done the testing and development, so I won't deviatefrom that, rather the primary focus is producing rotors that are over
1kg lighter than a Renesis rotor, with having side seal, apex seal and compression baths options and combinations, something that has not been available aftermarket before."

These rotors will be very close to 3kg when finished, so over 1kg lighter than renesis.

Brilliant work! Very interesting to see the impact of the apex seal springs on the rotor. Hoping the wear on the rotor long term will be minimal. (question)
have a look at the 3rd photo you'll see a round fixture that is grey in color. That is a sample that was anodized to create a hard oxide layer at around 50 to 60 Rockwell. This aluminum also has excellent wear properties, hence why 4032 is used on pistons. The life cycle of these rotors may not be as good as iron. There's wins and trade off's with using piston material technology. (answer)

This is his page: https://www.facebook.com/groups/566372170567629/user/1268601356/
Edit: Can't add his page as he's in a certain facebook group called ROTARY LIFE, but ill post the images.

 

Looks expensive.

 

probably right

 

and nothing similar has ever stood the test of time for very long, always experimental and then … poof - never to be heard or seen from again

the other thing to consider is that the stroke on an e-shaft is small and they only orbit at 1/3 the e-shaft/output rpm, so the gains are not as great as the weight reduction might seem. These being multiple piece bolt-together the reliability factor comes into play. The overall orbiting diameter relative to inertial force is not that large either. And that aluminum stress cycles and is also not a high temperature material, I’m not sure it’s the best choice over other materials that might not be as light, but more fitting to the application. A piston is a completely different set of circumstances than what a wankel rotor will be subject to.

In the end I’d favor the heavier, stronger/thicker 8.5CR T4 rotor for turbo use, which can be modified to be lighter and/or lower CR as well. Unless you’re racing and looking for the last tenth you should likely skip making them lighter, but posdibly more on just truing them up and getting the combustion chambers equalized, or also clearanced and balanced if being using for higher rpm. With full bore clearancing, lightening, facing, and lower CR they will be around the Renesis weight.
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it would be neat if these saw the light of day. NSU tried aluminum rotors, and its not going to be a drop in thing.
Aluminum and Iron have very different heat conductivity, so the way the rotors are cooled needs to change drastically.

 

After trying lightened rotors in an FD, no thanks, you need some weight in the rotating assembly to drive nice below 3.5k.

 

that is a life hack to get a big port to be more street-able. my buddy has a stock flywheel on his P port, for budget reasons, and it drives like a stock car on the street.

 

Eww LOL is my 1st thought.
Slow tip-in throttle from big ports plus slow rev from heavy flywheel.

But p-ports are low volume small ports (with big port timing) compared to big ported side ports- so you dont have so much slow tip-in throttle issues from low port velocity.

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In the '60s the OEMs had dimesional stability issues with the Aluminum rotors. Im sure alloys and hard anodizing plus coatings would help a bit.

But a different material would probably be much better. With CNC machining or 3D printing a thin webbed stainless or inconel rotor would be lighter than stock and have the dimensional stability.

Plus you wouldnt need the steel inserts for the apex seal grooves (Aluminum just wont last) like Mazda had on the MX-03 3 rotor's (JC Cosmos concept car) Aluminum rotors.