I'm still trying to understand how the RX-8 can use Hydrogen fuel because of it's "compartment" design but a normal engine, say a toyota celica can't.

I've looked online and seen a lot of diagrams but never a good solid "This is how it works to a non engineering major" way.

4/26/2006 9:32:07 PM

For example

http://auto.howstuffworks.com/rotary-engine1.htm

This shows it going in a working .gif... but it doesn't make sense to me at least why it isn't banging on the sides or eventually starts banging and how is it more efficient? I would think normal engines would have a much better radio of power because of the leverage.

4/26/2006 9:35:01 PM

assume you already checked
http://www.howstuffworks.com/rotary-engine.htm
and
http://www.rotaryengineillustrated.com/re101.php

4/26/2006 9:36:23 PM

normal 4stroke engines are more efficient

rotaries can make more power with smaller displacement, but they also use more fuel at the same time, iirc

4/26/2006 9:36:39 PM

Yeah i checked out the first one, and though the second gives me a better idea of the design of the actual rotor it's still a bit confusing to me at how things aren't worn down faster in the Rotary engine. It's one thing to tool a circle hole... but another for the design needed inside the engine.

4/26/2006 9:46:28 PM

I dont know the answer to Raige's question, but a rotary has a power stroke per rev, as opposed to one every other rev for conventional motors. (The rotary actually has 3 power strokes with each rotation of the rotor, but the 'crank' turns three times per one rotor rev, dividing out to one power stroke per rev.) This makes it powerful in a small package (1.3L). But the nature of a rotary has a good amount of combustion force going the wrong way, so the force is not utilized as much as a conventional engine.

I have an 04 RX-8, and the best mileage I can get highway is just above 23, with 18-19 being an average with a heavy foot. Im sure a similar 4cyl (2.3L would be an equivalent, as they would have the same displacement for combustions per rev, and a Mazda 13B has 2 rotors) would be more efficient, but not quite as powerful with the same compression. I know my rotary runs pig rich due to the lovely soot I get on the exhaust tips.

4/26/2006 9:54:16 PM

My understanding is that because piston engines intake and compress their charge in the same area they combust and exhaust that charge; while a rotary engine which intakes at one side, compress at the top, combusts at the opposite side, and exhaust at the bottom, the heat transfer from the engine to the intake charge is greater and as such the compression ratio must be lower in the piston engine to prevent detonation of hydrogen fuel. There may be other more complex factors that I am not aware of, but I am not a mechanical engineer, just a rotary fanatic

4/27/2006 3:48:48 AM

Quote :

"But the nature of a rotary has a good amount of combustion force going the wrong way, so the force is not utilized as much as a conventional engine."

A piston engine has force "going the wrong way" too.

4/27/2006 9:16:57 AM

I spent a while looking last night and finally understand a bit more about the engine components and how the crankshaft works.

What I didn't realize was that not only was the crank turning but there is a orbit of the rotary where it uses a geared connection for the timing. I felt kind of stupid once I figured this out.

4/27/2006 10:10:36 AM

how the hell is the displacement measured? by the size of the combustion chamber?

4/27/2006 11:24:41 AM

Displacement is the volume that the piston sweeps through in its travel. pi*(bore radius)^2 x stroke

For a rotary it would be the theoretical volume of air that the rotor draws in on a stroke, different calculation but same pricipal as a piston engine.

[Edited on April 27, 2006 at 2:56 PM. Reason : d]

4/27/2006 2:55:13 PM