Rotary Engines

[mikey4444]

I have just had a good look at a Mazda RX8 sports car, when was parked in Lidls car-park. Its a smashing looking car !

But why are Maxda the only people left that use the rotary Wankel engine ?

I thought that these engines were the bees knees and I am sure I remember Honda using them in the past ( but I may be wrong about that )

Can anyone tell me, in simple layman's terms, why rotary engines are good, or bad ?

[retrocop]

Well Norton made a rotax engined motorcyle for the police market as well as a racing bike.The police version did not operate at all well at slow speed as it was air cooled and overheated.It was a two stroke engine and was an environ mental disaster. I believe the Norton racing team were quite successful but of course those engines were running at max speed and were well cooled.

[BRIGHT SPARK]

A good idea in principle and if set up right will give good power and a great sound....however at a cost ...mpg and oil consumption is always an issue.

[mikey4444]

Thanks guys !

[retrocop]

Certainly true about oil consumption.The Norton I road tested burnt most of it's oil and threw it out in great smelly blue clouds at low speed. Hence my mention of an environmental disaster. And they say diesels are bad!!!! :-)

[Graham-W]

Rotor tips used to be a problem but with modern developments in ceramics is less so now. As others have said, fuel consumption seems to be the main problem. They make a wonderful sound though.

[Khandro]

I think the seals along he edges of the rotor were prone to wear and replacement was a big job in comparison to piston rings.

[retrocop]

Khandro
I believe that indeed was one of the problems.

[Booldawg]

RX8 is always tempting as its a lot of car for not much money. Cheap for a good reason!

My mate is a Mazda mechanic (todays tongue twister!) and says they are unreliable and expensive to maintain. Apparently the RX7 was a better car, if you can get hold of one.

[1ozzy]

In theory they should be great.
But they ain't.
Massive fuel consumption and excessive oil use seem to be the problem.
They create huge amounts of horse power at a high rpm but stuff all torque at a low rpm. Hence not good for general road use.

[Khandro]

Actually though it is often referred to as a rotary engine, it's real name - give the man his due - is a Wankel Engine. A real rotary engine has an uneven amount of cylinders in a circular configuration, used mostly in early aircraft, I was looking at some last year in the science museum, they are gorgeous pieces of machinery!
Felix may be gone, but he's not forgotten, a street in a nearby town to me is called Felix Wankel Strasse.

[retrocop]

Must give the engine a bit of credit.Fewer working parts so less friction wear etc

[1ozzy]

//Fewer working parts so less friction wear etc//

Spot on Retro, but those fewer working parts do so at a much higher Rpm, hence wear out much quicker.

[New Judge]

Since we're straying a bit and as Khandro has mentioned it, there are two types of engines similar to those he describes (with cylinders arranged in a circular configuration around the crankshaft). The radial engine is more conventional in that the cylinders remain stationary whilst the crankshaft (usually with a propellor attached as they were used almost exclusively in aircraft - though some were used in tanks) rotates. The rotary engine is similar in design and appearance but when these are running the cylinders and crankcase (usually with a propellor attached) rotate around a stationary crankshaft.

These rotary engines were not entirely successful and their limitations were soon discovered. Much of the engine's power was lost in simply driving round the crankase and cylinder assembly. When used in aircraft the hefty rotating assembly produced a serious gyroscopical effect making the handling of the aircraft a bit dodgy.

[ToraToraTora]

judge is talking about a radial engine. The engines with a wankel in the are commonly known as rotary. The problems are that they use a lot of fuel and Oil and generally have a shorter life. The probem is the seals on the tips of the rotor continually wear and cause problems. They are also very misleading in terms of CC and are usually understated. When working well they are very good and responsive but will cost a lot of fuel and maintenance in the long run. Only bother if you are a devotee.

[New Judge]

"judge is talking about a radial engine"

No I'm not, 3Ts. As I think I made clear I'm talking about an earlier type of engine similar in appearance to a radial engine, but called a rotary engine. They pre-date the Wankel engine by about 50 or 60 years and in my view are the "true" rotary engine:

http://uk.ask.com/wiki/Rotary_engine?lang=en

[Khandro]

http://en.wikipedia.org/wiki/Rotary_engine

[Khandro]

nj; snap!

[retrocop]

That's why I referred earlier to a Rotax engine and avoided the use of a radial or rotary. :-)
.

[retrocop]

Now these little beauts had a radial engine.Very similar to a rotary from outwards appearance.Douglas Bader lost his legs by crashing this type of aircraft BTW.

http://en.wikipedia.org/wiki/Bristol_Bulldog

[BRIGHT SPARK]

retro...Norton used Rotax (brand name..as in small aircraft,go-carts etc)and a rotary....the Rotax is not rotary.