>The Wankel rotary engine was used for many years in Mazdas (I don't
>think it still is). It had two problems:
>
>
The actual Wankel rotary engine was introduced in 1969 in the Mazda
Cosmo as a 1.1-liter, 2-rotor variety after about ten years of
development after it was purchased from it's original German designer
who falsley pitched it as a ready-to-produce powerplant. It was used in
the Cosmo, the RX-2, -3, -4, and -7 as well as the compact pickups and
overseas in everything Mazda. The later Cosmo got the big one (a
turbocharged 3-rotor) and yes, the engine was sadly retired--but only
for a short time. The new RX-8 has the "Renesis" engine which is a 1.3
liter 2-rotor Wankle with improved porting so that it runs more
efficiently and produces more power...
>1) As implemented, the corners of the three-sided "armature" inside the
>combustion chamber were made of carbon. These wore out over time.
>Naturally, you'd have to tear down the whole engine to replace them.
>This is based on some things I read many years ago, so I don't know if
>they ever changed it.
>
>
Yes, the apex seals are composed of a graphite-aluminum compound and
just as a reciprocating engine's piston rings, they do eventually wear
out, and typically, they last longer than conventional rings. And, just
as with piston rings, the engine must be torn down for an overhaul like
that.
>2) The engine was very smoky. More pollution for a gasoline engine than
>a standard inline or "V" engine.
>
>
There is quite a bit of oil blow-by in a rotary engine due to the nature
of the beast in that unlike a conventional reciprocating engine (inline,
"V" or transversely opposed), there is no structural division between
the crankcase and the combustion chambers per say. However, this was
not a flaw in operation, but a part of the design of the engine that
lended to thorough lubrication of the relatively few moving parts.
There have been other working rotary engine designs that have come
together in other companies that were differentiated from the Wankel
patent. Mercedes-Benz had one that I think made it to pre-production,
but it did not do what they wanted it to. Chevrolet also had a design
that they were thinking of putting in the Corvette, but the rumor has it
that the engine in the test mule was so durable that even after harsh,
long abuse, it was showing such nominal wear that they were afraid of
the ramifications of releasing it to the market. That's what I was
talking about there.
--Michael
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