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Does this mean you have to top up the oil at the same time as the fuel (or indeed, mix oil in with the fuel) as with a 2-stroke?

No, the rotary engine is planted firmly in four-stroke land. What the Mazda 13B does is inject a small amount of oil onto the apex seals of the rotors via a port on the inside of the rotor housing. It's really sort of a controlled drip instead of a squirt, so that when the seals go over the oil port, they literally "squeegee" the oil around the interior surfaces of the engine. The oil is sourced from the regular supply of oil used to lubricate the rest of the engine. Yes, it needs to be topped off regularly, but it's on the order of 1L/2000km for an engine in good condition, which is not much different from many reciprocating engines. Take a look at this page for an illustration.

I drive a brand new 2004 Mazda RX-8. It's got a 1.3 liter naturally aspirated rotary engine that generates 238hp @ 8500rpm.

The sticker said it will do between 18 and 24mpg. I've been getting closer to 13. My best was 16 on a roadtrip. It's a fun 13mpg, don't get me wrong, it's just nowhere near the "18-24" that's on the sticker.

Here's the strange part. I can baby the car and shift at 3000-4000rpm and I'll get the same mileage as when I beat the piss out of it and shift at 9000rpm.

The moral of this particular story is...this one likes it rough, so drive it like you stole it.

And some rotary engine animations. This is probably the best one with regard to the reason for the shape. However, when I was a kid at the Mazda dealer they had a nice film projector that showed how the gas intake and compression worked using different colors for the different conditions of the gas (intake, compression, explosion, expulsion, etc).

And some rotary engine animations. This is probably the best one with regard to the reason for the shape. However, when I was a kid at the Mazda dealer they had a nice film projector that showed how the gas intake and compression worked using different colors for the different conditions of the gas (intake, compression, explosion, expulsion, etc).

ceramic, double-rotor two-wheel drive

Couldn't that also mean it's driven by a single, two-rotor rotary engine, where the rotor is ceramic instead of metal, and this engine drives both wheels the way a single engine drives all four wheels in 4-wheel-drive cars and trucks?

You are thinking of apex seals, and it's closer to 100,000 - 150,000 miles.

And I love telling big iron guys they just got stomped by a car with a 1.3 liter engine.

Oh and turbocharging eliminates the tourque problem very nicely BTW...

BTW nice visual explanantions of how a rotary engine works can be found here: http://www.rotaryengineillustrated.com/.

The main reason that none of the big makers are running the rotary engine is that it is very unreliable. That is what the big hub-bub is about at Mazda - they keep saying that they've improved reliability when in actuality they've just reduced combustion pressure and increased speed (thus maintaining power at the sacrifice of torque). So they haven't improved reliability - just reduced stress on the unreliable bits.

If the rotary engine *could* become reliable under the context of "American driving styles", then it would be an amazing technology. There are just a few moving parts in the entire damn engine - its VERY cheap to make them.

On the reliability note, the "apex seals" are the problem in the engine. For more info, see Rotary Engine Illustrated.

Darren

Here's another page that shows how the wankel rotary engine works: http://www.rotaryengineillustrated.com/