What do you guys know about rotary engines? What are the advantages? I am having trouble really grasping how they work, and why people use them? Can anybody help me out? I know Mazda has one in their new RX-8, why? Anyway, just trying to expand my horizons. Thanks for any info.

 

Once it's explained it's not too bad of a concept to get. Well you have the block, which is not very large. Then instead of pistons it has a sorta triangular shaped cam. This is the piston. Now on the intake it turns and sucks in the gas and air. it keeps turning building compression and it hits the plug and sparks it. So there is never really a delay lke the lope in good V-8. Then the "rotor" the triangle thing keeps going pushing the exhaust out. So basically it is a very simple engine. IT is just like a one stoke sorta thing. It doesn't have a lope or delay, just a sweep, Gas, spark, exhaust. Oh and they are a Mazda staple in the RX-cars. acctually felix wankle made the engine and mazda grabbed it up. They aren't really fuel efficient, so that is why you don't see them a lot. So I just wonder how the new one is going to size up. Oh and if you want a detailed site for the rotary go to-http://travel.howstuffworks.com/rotary-engine.htm Hope that clears some things up for ya.

 

I understand that they can run on pretty much anything you throw at them. My dad worked on a rotary engine project at John Deere's, and he said that they put one in a tractor, and it worked really well. Well, aside from burning the paint off the hood. They even ran the thing on peanut oil, and it ran fine on it. They never put them in production tractors though. I'd like to find one of those engines and put it in my truck...

 

I understand the basic concept of the engine. How do they compress the mixture if the size of the chamber never changes? Or does it? And what is the advantage? Do they make more horsepower, more torque? If they do, how? And why? Anyway, thanks for the info.

 

Lotsa hp. Lotsa rpms. 22000 of em. Doubt it makes much torque but rpm is the rate of speed that work gets done. So more rpm. More hp. Raced one once. I lost.

 

Visit the web site above and click on producing power and it tells you how it is done and gives a neat little picture showing it. This is my first time looking into them as well so it was nice to have the visual aids!

 

How is displacement determined?

 

displacement is determined by the size of combustion chamber x the number of vanes. Since they just spin on a shaft, there aren't many moving parts to wear out, and the better bearings you use, the more you can rev it. the stock apps redline at about 7K, but with good racing build, 25K is not unheard of. The old rx7s were put out of production due to new epa regs. They pollute like hell, because they have to have oil injected directly into the combustion chamber to keep the vane blades lubed to seal on the chamber walls. Compression is due to variations in the shape of the wall. It's not just a circle. It swells out on the intake. There are actually like 6 seperate sections on a 3 vane setup. Anyway, mazda claims to have reduced emissions by 90% for the rx8. That's what they needed more than anything. They have two engines available, both with good hp and tq numbers. one in the low 200HP range, and one in the high 200HP range in stock trim, I think. Anyway, they don't require much in mods to greatly increase those numbers. Turbos are very popular on these engines, since there is no head gasket to blow, you can pump them up pretty good. They are fairly cheap to have built up, and there is nothing to maintaining them. I had one come in once on an old rx7 with 270K miles on the odometer, with the original distributer cap. It was burned all to hell, but it was running. That was like an '82 model, and that was last year.

 

I think that Mazda has been using them in their RX-7's for a long time. I have never heard anything bad about them. Wonder if labor costs are high for them.

 

I think the new mazda 6 has it.

 

Mazda's been using rotary engines for a long time. Anybody else remember those little pickups they made in the 70's that said rotary power (or something like that) on the tailgate? The big problem with those was that they didn't last too long, all kinds of reliability problems. Notice how you don't see many running these days.

When they finally worked the bugs out and got the rx-7 on the road they continually improved it to be a good performance motor (I think the new rx-8 is rotary powered) Last I heard they still get pretty bad mileage as far as fuel is concerned

 

The only problem I have with these kind of engines is the fact that they really didnt have a whole lot of torque, plus in my area its hard to find people who know and can supply the parts to work on these. Otherwise I would get an rx7 for ****s and giggles.

In motorcycles however they were pretty nice, I cant remember all who ran em, but for the time they ran alright considering the 2 cycle engines they were competing against.