Very early days, but Mazda has a new Rotary they are putting in the MX30R. i thought i would start with just some pics and observations.
first thing, well its a big change, 1 rotor, aluminum irons, err side housings. its also 840cc (?) so its bigger, apparently its closer to the 13A from 1971...

second thing, bellhousing bolt pattern is different. kind of looks like it uses the same nut to hold on whatever is going to go in there (no clutch, no torque converter)
5 bolt stationary gears, and actually since there is only one gear the other is like a dummy bearing holder or something, haven't seen that in the pics yet


the thing on the rotor housing is a fuel rail, same pressure sensor as the other skyactive engines, since there is a rail there must (might?) be 2 injectors?


front view, its got an oil pump that looks something like the S2 Rx8. basically it uses a piston engine style oil pump and eliminates the front cover O ring
i wonder what that tumor looking thing is on the bottom, the piston engines have a normal oil pressure plunger, but then they also have a solenoid, so the ECU can control oil pressure
front stack looks like same concept, but also looks like they didn't share any parts




water pump is completely new, again looks like the skyactive stuff
you can see the inlet on top. the feeds to the engine have changed a lot
the big studs are to mount the engine transversally in a FWD car.


the combustion recess is the first thing that grabs your eye, again rather like the piston engine

since its not symmetric, it makes the rotors front and rear if you wanted a 2 rotor, unless you move a stationary gear


once you look closer, its using Rx8 style corner seals, but no cutoff seal.
the side seals also move, closer to the edge, but also meet the corner seal in a different place
hopefully that bearing is like a mockup or something, lol


Rotor and housings, basically completely different

maybe 1 injector, and 2 bolt holes, but then why the rail?

 

that rotor design is interesting. From the position of the gear it looks like the leading edge is opposite the recess, total opposite of the Leading Deep Recess design of the 12A.
Even the last patent drawings from 2020 show the recess on the leading side. Maybe something to do with the rpm this engine runs at?

 

Peak power at 4,700
74hp
830cc

I know this one is basically a generator motor, but I think Mazda needs to give up on the rotary as being practical. Think of how small the combustion chambers on piston engines are and how large the combustion area is in a rotary. The amount of spark generated by 6 plugs vs 4 if comparing to a v6. That spark mixed with as much or more air in a smaller space will make a more efficient engine. Not trying to kill the thread….love the rotary, but the need to find a high end niche for a rotary cause it ain’t practical.

The finally went direct injection though

 

The **** are you ever even talking about? The amount of spark plugs?? Rotary is still the most compact and power dense ICE layout. Efficiency is a bit of a problem but can be nade to run on nearly a ny fuel and fine tuning to a specific fixed rpm as a generator is well worth the r&d. Pretty sure audi were ******* around with the same idea 10 years ago too

 

The rotary has 6 combustion chambers, which is why I compared to a v6. If you compare it’s 2600 cc or 2.6L to even an NA 2.5L 4 cylinder piston engine it is out of its league. Nissan 4 banger

• Standard 2.5-liter direct-injection gasoline engine
• Up to 28 city and 39 highway mpg
• Up to 248 horsepower and 273 lb-ft of torque

I’m simply saying the rotary should be catering to a different market. In the end it may be Mazdas downfall.

 

but this is a different market, its a generator for the electric motor.

 

The combustion chamber is shaped horribly for good combustion. We're in a late stage of internal combustion engine design where all gains to be had are with miniscule tweaks here and there. It's been well proven that for best efficiency and emissions, an undersquare engine with a 4 valve head is It. The combustion chamber will have minimal surface area near TDC relative to displacement.

 

there’s nothing on it that readily works with what exists, that alone should snap some of the dreamers back to reality.

based on my own experience, probably a lot of the same bad assumptions still in play here that were made about the Renesis as well.
.

 

1. do you think the single plug is a product of the thinner rotor or the direct injection ... or ... i guess, possibly it's totally unrelated to either of those things?

2. also, just thinking out loud because of j_tso's post ... but maybe the recess design is a product of the direct injection - specifically, it's location?

i think i had read about Daimler/Mercedes-Benz, somewhere in that timeframe, also thinking about developing a hydrogen-powered rotary. i think it was meant as an adjunct powerplant, too.

 

From experience, the trailing plug is only important at idle and low load. I wonder if Mazda has any SAE papers on the subject, now.

A hybrid generator should never be at idle or low load. That's when the ICE should be off and the vehicle should be running on electric.

 

the DI piston engines piston looks more like this 8C combustion recess than anything else we've seen previously. so yes, the DI lets you place the combustion more better

 

here guys, I bought a Japanese mag with a bunch of info about it! Google translate is your friend

They made a bunch of "unseen" changes like the rotor housing chroming process, side plate plasma sprayed cermet coatings, metering oil injector setup, exhaust port shape changed, etc
other interesting changes is a thicker apex seal 2.6 mm, the side seals further inward from the edges and no scallops when compared to rx8 rotors, only a leading sparkplug with no trailing, the oil and water pumps are completely different, etc

Those complaining about the 75hp@4500rpm figures haven't put too much thought in it.
Doing some simple approximate Math you can see this new rotary has potential! It could get 300hp@9000 on a 1660cc 2-rotor.

The RX-8 got about 175 hp per liter if going by 230hp 1.3L while meeting emissions standards for the time.
The 8C at 300hp and 1.66 L is about 180 hp per liter, basically maintaining the power density while considerably reducing fuel consumption and emissions! This is without any electrification to help so the final setup can be even better.

The CX-90 8-speed transmission has an integrated electric motor with about 17 hp and 110 lb ft of useable boost. If this or a manual trans with this is used with the rotary it can be programmed to be used as torque fill during low tq or efficiency areas of the rotary and it doesn't need a large battery.

 

IIRC this engine is not destined to ever be connected to a transmission, it's a range extender for an EV, basically a true series hybrid. Like a locomotive except with a battery too.



No concessions need be made for light throttle emissions/drivability, it can be optimized for a narrow operating window.

 

Good stuff there. I can get most of it translated, however the resolution on the kanji is a little low for my OCR app (and even my eyes), but I think about 80% can be recognized correctly.

And I had it backwards, it's actually an extreme version of the Leading Deep Recess design.

 

Here's that PDF in English.

 

Damn, when I read the title I had visions of some rich but bat-**** crazy guy stuffing a rotary engine in an Alfa Romeo 8C.

Nope just a range extender for Mazda's new flagship...an electric SUV that can't go offroad.

 

lmao, i never would have thought of that. its kind of a neat car, it looks good and sounds good, but the rest of it is not great

 

I just stumbled across this yt video and it touches on some factory processes for the 8C especially in the first 5 minutes or so.


I was equally impressed with the automation they use.

 

someone with the funds and the desire can buy 2 - 3 - 4 of these, reverse engineer some things, get billet side plates and custom eccentric shaft and other parts and build something really legendary!

 

so the interesting thing here is that the Ironic SP car has a 2 rotor version of this engine, probably. Mazda has already done it.
the only part that would be really hard to do is the other rotor, the combustion recess isn't symmetrical, so you need a front and rear rotor, like a 12A
the rest, eshaft, tension bolts, center iron, are all possible

 

That never crossed my mind tbh. It's been a minute since I've looked, but has anyone succeeded in putting billet rotors into production? Seems to be the only realistically achievable way to do this in the aftermarket

I was sent this image by a friend with just the text "an RX8 tuning shop just took delivery of this". Trying to get clarification of who, but it appears someone out there has the idea

 

Actually plan B might be to do like the 8C Alfa Romeo. which had basically 4 inline 4 cylinders with the power take off in the center
or go full Alfa Romeo and do a Bimotore, which just had two engines...

probably easier to package than two straight 8 cylinder engines.
car has prancing horse on it, because the guy who ran the Alfa Romeo Grand Prix team was Enzo Ferrari

interestingly this thing is still rwd, each engine drives one wheel... did not do well

 

Instead of machining a mirror image rotor on a 2 rotor (or more) 8C based rotary it would be easier to machine your billet center plate to hold the stationary gear so its on the same side and use two standard 8C rotors.

Leave the bearing out of that center stat gear and put it in the end housing as usual since 2 bearing 2 rotors work fine and are much easier tolerances/ self correcting tolerances.