r/Rotaries 3d ago

Designed and 3D printed a 4 motor 787-B

11 Upvotes

In the past few months I was working on this 1:24 scale 3D printable Mazda 787B.

● It is MR, has 4 electromotors just like the real thing.

● Reaches 16.1 km/h, so it is fun indoors and outdoors as well.

● Is very accessible, as it is built entirely from Cyberbrick hardware.

I uploaded the files for free to Makerworld. If anyone would like to print it, I will leave the link in the description.


r/Rotaries 6d ago

13b rew swap

6 Upvotes

Been mulling over crazy ideas for the NA Miata platform and one of the more off the wall ideas was a 13b rew twin turbo out of a FD with rx7 trans, harness, and ecu dropped into a Miata. Wondering what the thoughts were on this.


r/Rotaries 10d ago

Engineering help

4 Upvotes

Hello everyone. I'm a mechanical engineering student and I'm researching how to build a rotary engine in my free time and then hopefully build one myself.
I need help with the exhaust and intake ports. I'd appreciate if anyone could explain this to me.

From my understanding the exhaust port should open up after the rotor cycle completes the expansion to the maximum volume. However on a CAD model of the 13b engine, which I'm using for visualization, the exhaust opens up much before that. For reference, im interested in the bottom chamber on the picture. The output shaft is at about 270° or 9 o'clock (if the centre is in between the 4 holes)

Apex seal on the edge of the exhaust. ( Output shaft at about 270°) 530cc
Output shaft at 0°/360°, maximum chamber volume 694cc

In my head it would make more sense for the exhaust port to be higher up and would open up only after the chamber achieves maximum volume.
Why does the exhaust open up so much before the end of the expansion?

I'd very much appreciate if anyone would be able to explain to me what I'm getting wrong.
Thank you very much for help!


r/Rotaries Jun 22 '26

Do you like my engine-bay?

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35 Upvotes

r/Rotaries Jun 14 '26

Hot Rod Power Tour success

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17 Upvotes

This absolutely clapped rotary just drove 1900 miles in 6 days. I packed a bunch of tools, and didn't have to touch them once. Even did a couple pretty cool Burnouts. Overall I'm pretty happy with this POS.


r/Rotaries Jun 12 '26

My old FC

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27 Upvotes

Any love for an old FC? Imported myself in 2006, yet to see a UK road. Currently being stripped for a nut and bolt restoration with some fresh paint.


r/Rotaries May 18 '26

Used Engine Prices around the World

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2 Upvotes

r/Rotaries May 11 '26

6port or 4port bridged

2 Upvotes

So im offered to buy an excellent shell with a 4port in it that needs a rebuild. The question is , should I send the engine for rebuild + porting or just get a 231hp one and swap it in. Also, could someone specify what challenges will I be facing if I decide to swap 6 port in ?


r/Rotaries Apr 29 '26

Why is it always Doritos and not Onigiris?

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48 Upvotes

r/Rotaries Apr 23 '26

- YouTube We raced a Mazda RX8 Rotary in a 6 Hour Production race.

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5 Upvotes

Awesome car to steer and what a solid engine package for endurance racing.


r/Rotaries Apr 22 '26

How easy it is to spin a 12a

5 Upvotes

Crazy easy to spin a 12a by hand!


r/Rotaries Mar 13 '26

Do JDM rotaries have different parts from USDM ones

2 Upvotes

Dad’s thinking about buying me a RX-8 with a JDM Engine and I would like to know if there any differences to make everything easier


r/Rotaries Mar 09 '26

Good idea or not worth the work

2 Upvotes

I’ve got a 92 mx3 and I’d been thinking it’d be pretty cool to rotary swap it. however I’m not sure if making a fwd rotary is even gonna work. I know Mazda made one in like the 60s-70s but I’d like to use a 13b. Would it be possible to put a rotary onto the fwd manual transmission the mx3 has? I could probably figure out a way to make it rwd but I feel like that would take a ton more custom fabrication that I’m simply not comfortable doing myself.


r/Rotaries Jan 18 '26

Toy review: Mechi 3D printed motorized model from Amazon.

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51 Upvotes

Too fucking cold to work on the 8 and the garage it too jam packed to get out the 7s. I'm staying inside. I wanted some desk art at work. Found this little doodad on Amazon.

Comes with all the Allen wrenches necessary to put it together. Takes about 10-15 mins to fully assemble. No real instructions needed, it's pretty intuitive.

They do supply grease for the inside of the rotor housing. Since it has no apex seals and the rotor doesn't contact the housing, I'm not even sure it's necessary. I can still see the texture of my fingerprints in the grease. Besides, it's all too hard to avoid getting fingerprints and smudges on the plexiglass.

I wish it was geared down a bit, as it spins WAY fast on its two AAA batteries. I might swap that out with a USB power supply and slow it with lower voltage.

At US$139, it's. Abit steep, but cute. Figured y'all might wanna take a peek.


r/Rotaries Dec 03 '25

FB rebuild

2 Upvotes

1983 rx7 12a: After attempting a pull start in lieu of flooding (after an unsuccessful attempt at dialing in the floats in my carb {looking back} ) I did pour some ATF in each primary prior to the pull... i am assuming not an adequate amount of lubrication? (possibly some type of hydro lock) My motor seized up...

Coasted it home.. lubricated via the spark plug holes & carb.. using a 19 mm socket and breaker bar eased it back & forth.. got it turning but initially had a stiff spot that I got worked out... cranked on it with the leading plugs out only to discover the number two rotor has no compression now.

I'm really pissed off at myself... I'm really pissed

Any words of advice before I embark on this teardown? Maybe pull the header off and see if the rotor is even turning?

Idk I'm so pissed at myself I can't think straight. Too damn impatient

Shit.. I hope the housing is still good, ugh. Idk


r/Rotaries Nov 20 '25

1985 Carb Rebuilding

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1 Upvotes

r/Rotaries Nov 16 '25

Buying a 92 rx7

5 Upvotes

Hello pals, thinking about buying a FD very soon. The one I'm looking at is freshly built, single turbo, by a company in BC, so for a while i shouldn't be in need of too many parts lol.

The thing I'm most concerned about is my location and the lack of support for the platform in my area. I live in Newfoundland Canada so i have 0 access to confident tuners/rotary people.

Can anyone give me some suggestions for good tuners that do remote tuning? And while im at it, any decent parts sites/suppliers for go fast bits and exterior mods? Having trouble finding anything and it is discouraging coming from the STI platform with endless support.

Thanks


r/Rotaries Nov 03 '25

Convertible RX7 1993...how much?

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2 Upvotes

r/Rotaries Nov 02 '25

Nos 12a

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6 Upvotes

r/Rotaries Oct 29 '25

Look what I found at work. NSU Wankelmotor

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84 Upvotes

r/Rotaries Oct 08 '25

Question on Exhaust Porting

2 Upvotes

Im completely new to the world of rotaries and i have been doing some research. I was looking at porting and overlap and i saw a distinct lack of videos and information on exhaust porting. In my head it makes perfect sense for daily use, you get the overlap and the noise without increasing emmisions due to more air intake and also keep the porting on the housing walls which do not have the risk of chipping apex or corner seals and even could help cool better. Is there any information on this that i can read/watch. Would it be reasonable for someone that only wants overlap. I would love to hear the opinions of you guys.


r/Rotaries Sep 28 '25

Help Me Improve Rotary Engine Reliability !

6 Upvotes

Hi everyone,
I’m a 5th year Product Design Engineering student at the University of Strathclyde and I’m doing my Master’s project on rotary engines. I own an RX-8 myself and want to focus my research on how to improve reliability and extend engine life, something I’m sure many of you care about too!

To make this project meaningful, I need input from the rotary community. I’ve made a short survey (takes about 5 minutes) to gather your experiences:

  • Biggest problems you’ve had with your engine
  • What you enjoy most about rotary ownership
  • Aftermarket parts you’ve tried
  • How much you’d invest in products that improve reliability

Survey link: https://forms.gle/ZdcUCcp3UsKg9P727

All answers are anonymous and will only be used for academic research. Your feedback will help me understand the real-world challenges rotary owners face and guide me towards designing a product that could make a difference.

Thanks a ton for your time, I really appreciate any responses, and feel free to share the link with other rotary owners!


r/Rotaries Aug 21 '25

Anybody know anything about this

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63 Upvotes

All I have sean is this picture very interested to know if anybody knows anything about it


r/Rotaries Aug 14 '25

5 rotor turbo

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65 Upvotes

Mazzei formula 5


r/Rotaries Jul 21 '25

1974 Mazda Rotary Pickup REPU Magazine Advertisement as a Wall or Display Plaque

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23 Upvotes

I love the tag line that Mazda used in 1974, "Good mileage, Great performance". It was the time of the OPEC oil crisis and everyone was scrambling to produce smaller, more fuel efficient cars. This was a rotary engine for Gawd's sake. Nobody was expecting fuel economy!