I was pondering in boredom one day when I thought of this. I figured if you could increase the displacement by reshaping the rotor it would make a lot more power. I did my best to try to draw my idea on "paint" to try to show you guys online. The red lines are the new rotor, inside of the outline of a normal one. Sorry if it's a little blurry, but you should still be able to make out the idea. The apex seals stay in the same positions, and the side seals would simply invert the other direct. The rotor would be lighter, and I would imagine it would have a lot more bang with that much more compression room and angle. I doubt this would really work, I think someone that actaully knows what they are doing can tell me why it's a stupid idea. Feel free. I'm still learning so anything is helpful. Thanks for any input, Evan

 

it would lower compression way too much

 

The rotors are shaped the way they are for a reason. Maximum compression. Remember, an internal combustion engine isn't just burning crap, it's compressing crap nice and tight and then burning it. That design wouldn't compress the air/fuel mixture very much at all, and although rotational inertia would be reduced, the engine simply would not make much power, if it worked at all.

 

Pondering in boredum is good, I do it all the time so what I miss a lot, it's that one good hit that I'm looking for, so now there is some one I heve to race to the finesh with.

 

I think you might have to change the eccentricity of the eccentric shaft to change the displacement. That would increase the "stroke". "Bore" seems like it might be determined by the rectangle you see when staring a rotor right in the face. It isn't clear that your design changes either of these dimensions, so it isn't clear that the displacement would really be any different. Just lowering the compression ratio does not change displacement.

It is an interesting idea, but I think you need to go all the way and show how the geometry would still work with the new rotor shape (perhaps do an animation for the full combustion cycle). And then make sure you change the "bore" and/or "stroke" to adjust the displacement. Displacement is the difference in volume of the combustion chamber at its smallest versus its largest.

It is possible that it would allow the eccentricity to be increased (though I have some doubts), but it is hard to imagine the whole thing without actually "seeing it work" for the full cycle.

-Max

 

The design change wouldn't have to be that severe. I just wanted to see if the general idea of reshaping the rotors could get any where. Piston engines are so good today becuase they've had 100+ years for their developement. Compared to that the rotary is still young, so I think a lot of ground can be made, not that I can do it or anything. But it's great to see what people think about improving it. Thanks again it's been really helpful, Evan

 

Mazda experimented with heaps - I have a pic here, just can't post it at the mo, will keep trying

 

This time?

 

Thats a neat pic, I would like to see how some of those other rotors performed. Thanks again

 

Looks like what piston engines do with domed or dished pistons. Wonder what kind of power improvement or whatnot that would give. I know a lot of times piston engines use dished pistons for FI applications.

 

i believe there isn't all that much difference in how the section is cut out and how the rotor performs, and so they just kept it simple and made it symetrical...

 

I would disagree, I think that a lot of testing and thought has gone on... when you line up lots of rotors from over the years there is some variation... I have found three completly different 10a rotors, two 12A twin dizzy, at least 3 standard 12A etc... not all symetrical.

Depends on what Mazda were trying to achieve - fuel economy was one of the reasons..

The other thing that vary's slightly is where the spark plugs are located in the rotor housing.

I have heard of people successfully screwing inserts into the face of the rotor to change the combustion chartisitics and raise compression. Not sure how long the motor survived

 

i was watching speed channel and there was a mazda ad, there was a rotor shape similar to the one on the first post, how did that work

 

it was probably a section through a rotor ... with the pockets on each face the centre section of the rotor looks similar to the image in the 1st post. IIRC mazda have used that X-section image in some of their advertising for the rotary.