Photic

I tried searching, but I got a butt-load of results.
Since rotors can be stacked together. Would there be the possibility of adding 2 extra rotors to the current engine design, then having 2 seperate ECU's? (since the current controls 2, and there are so many threads on how hard it is to crack)..
I know there would be a lot more work involved then just bolting them on, such as new crankshaft etc.
It was just something that popped into my head a couple days ago. thought I would search and then ask about it.

ZoomZoomH

iTrader: (1)

search '787B'

ZoomZoomH

iTrader: (1)

better yet, search 'Mazda Le Mans 787B' on google :D

Photic

Yeah, I know about that one, but what about the renesis itself?
I know acosta (i believe) also fit the 3 stage 3rd gen into the rx8.
But being that the renesis is so much more advanced, I thought that stacking 2 more stages, and 2 ecus would be an interesting solution..

Icemastr

Your answer = no.

Photic

See wasn't that simple

rotarygod

Back in the early rotary development days, Mazda had tried using eccentric shafts that were able to be pieced together for each rotor in a modular fashion. They did this on the early racing engines. This way all they had to do was to essentially stack another rotor and housing on and add an extension to the eccentric shaft. Of course the orientation of each rotor would have to be changed depending on how many rotors you wanted. The problem wasn't that this didn't work or couldn't be done. The problem came from the fact that the keyway linking device they were using was weak and could break or warp, throwing the entire assembly off or worse, destroying an engine. I'm sure technology and metallurgy are at the point today that these issues can be solved but Mazda just chose to stick with the current setup. Even the 20B eccentric shaft has the 3rd lobe of the shaft slide on but the main part itself still has 2 out of 3 lobes and is one long piece. It was stronger this way. Is it possible from an engineering standpoint? Yes. Is it possible to do with existing engines? No.

zoom44

how about a V rotary 4 then? 2 Renesis side by side eshafts turning a central output shaft? wasnt threre a rear engined car at 7stock like that?

rotarygod

It had 2 13B Turbo II engines that ran to a common custom made transmission. That's spreading the weight out over a very large area.

IcemanVKO

What about a front and rear engine each running two fo the wheels, then you could have 4 wheel stearing, and two drivers!!

rpm_pwr

There are several 13b based custom four rotor motors getting around Australia and NZ. Most are still 'in the build' but a couple are already out running. For example the BARB BMW drag car.

There are also 4 rotor 12A based cars getting around, one belongs to Scoot (runs 2 PFC's) and another is in the US.

The e-shafts for nearly all the 13b based 4 rotor engines are made by Jeff Bruce in NZ. But before you get any ideas, 4 rotor engines are BIG $ to build let alone install.

All custom 3 or 4 rotor engines run 2-piece e-shafts.

rotarygod

If you build a 4 rotor engine in the same way that the 787B engine is built, you can get away from using complex computer and ignition systems. The 787B engine would be equivalent to a flat plane crankshaft on a piston engine. The traditional way to fire a 4 rotor is the way Scoot and other racing rotaries were done. Each rotor fired 90 degrees off from the next one. The 787B was different though. It fired rotors 1 and 3 at the same time and rotors 2 and 4 at the same time. Maybe is was 1,4 and 2,3? No matter the point is still the same. By doing it this way, the standard 2 rotor ecu can be used. This really saves alot on the complexity side of it and is also cheaper since the ecu isn't as problematic. A 4 rotor firing this way sounds very different from a conventional 4 rotor. Anyone at Sevenstock heard 2 different 4 rotor cars fire up. One was an old 2nd gen RX-7 4 rotor and the other was the 787B. The RX-7 had the traditional 90 degree firing order and the 787B had the 180 degree firing order. They sounded totally different. The RX-7 had a much lower tone. The 787B sounds more like a Formula 1 car at full throttle. Obviously the eccentric shafts are different between the 2 setups. Both of these engines had 3 piece eccentric shafts.

rpm_pwr

Not true. Taken from the R26B SAE paper:

rotarygod

Yep, double checked that one. You're right. Maybe I had it backwards but one of them had it done the other way.

magixpuma

HYpothetically. with no money involved. Imagine 2 renisises engines both woulkd be powerin the same drive shaft and powering both wheels would that mean almost twice the power?

dragula53

If you just slap 2 rotary engines together (I'm simplifying), each rotor would be 180 degrees from the previous, and 1 and 3 would fire at the same time, as would 2 and 4.

If they were at 90 degrees, 1 would fire (with 3 at the peak of it's exhaust stroke), 2 would fire (with 4 at the peak of it's exhaust stroke), and 3 would fire while 1 was at the peak of it's exhaust stroke, 4 would fire while 2 was at the peak of it's exhaust stroke.

So, I can't see how having 90 degrees between rotors can follow the pattern the SAE suggests, unless it means that 1 is 90 degrees out from 3, 2 is 90 from 4. (in which case they don't fire at the same time, they just fire sequentially). Surely there is a simpler way of stating this.

Whoops, I just got dizzy thinking about it.

But I agree that an engine that has 4 distinct combustions per revolution would sound different than one that fired 2 at the same time, twice.

CERAMICSEAL

As far as I know a 26B and R26B have the same firing frequency as each other although they have big differences between them including overall length. The biggest thing separating the sound of the GTO RX7 and the 787B is exhaust design although they both sound orgasmic.