On Fri, Nov 04, 2005 at 08:59:39PM -0600, michael hast wrote:
>
> >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...
So they're still using them? Hmm. Didn't know that.
>
> >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.
>
Assuming regular maintenance (= oil changes), it takes a loooong time
for rings to wear out, though.
> >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.
>
Anyone ever tried diesel in a Wankel? Is it possible to make the
clearances tight enough to tolerate diesel combustion?
> 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.
>
I'm pretty leery of rumors. These days, auto repair probably has a lot
to do with other things falling off the car, aside from engines. My
car's got nearly 100K miles on it, and I've never had the engine
repaired. Injectors, yeah. Fan belts, yeah. Tranny, yeah. Distributor,
yeah. But not the engine. Same with my last car.
Anyway, could we get more off-topic? ;-}
Paul
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