ArdunBill, John, List,
The rotary fell out of favor more in the US because of Mazda's
unwillingness to release the engine in anything but an RX7, and it's
extensive list of patents, which made the engine uneconomical for anyone
else to produce. Then they priced the RX7 out of most mortals reach, and
had gotten a little over their heads with the sequential turbos. (Not
something you sell the "put gas in it and drive" public.) Last time I was
in Japan ('91-'92) there were rotaries in slick two door sedans, large
(Lincoln Sized) 4 door sedans and the RX7. The three rotor hadn't reached
the tiny island of Okinawa yet, but at 450 HP in stock trim I was hoping to
make another trip after some hit the junk yards. My priority aboard
military aircraft has been degraded somewhat since I retired, but I'm
getting ideas! ;)
Mazda's latest redesign of the Wankel will radically change the exhaust
port configuration, from a peripherial design to a side port, like the
conventional intake. Basically the exhaust will have to go around a corner
instead of blasting straight out into the header. This will also allow the
exhaust to exit from two sides of the rotor, so a much more gradual exit can
be achieved. This will allow fuller combustion and soften the exhaust note
considerably. The possibilities for rotary tuners to alter this new design
are equally exciting, since it will allow greater flexability in where the
power band begins, and where peak HP will be acheived. By altering the
intake and exhaust ports we can change the lift and duration and timing,
just like your conventional camshaft. That's the largest thing rotary
tuners have to play, since we can't easily change the engines displacement
or compression ratio. (Although there are several compression ratios
available for turbo and non turbo applications.) There is little to limit
the port size or configuration as long as you keep all the internal engine
parts from falling out through the holes. Naturally, some ports work better
than others, but the engine can be tailored to the task.
Yep, an altered rotary without all it's factory emission gear is a bit
dirty, but even in the 240 HP range my street driven 13B will get 21 MPG on
the highway. I get something like 4 MPG at Maxton. The latest RX7's and
the earlier (second generation) RX7's were fuel injected and were pretty
clean burning. Mazda had reduced the oil, which is injected into the rotor
housings to lubricate the seals, to almost nothing. Older engines have this
oil injected into their carburetors at a rate of about a cc per minute. New
seal materials being tested by Mazda may eliminate the need for any oil
injection, further reducing emissions. The rotary is also the engine with
the greatest potential for running on alternative fuels, since there are far
fewer parts to corrode or which must be sealed. Don't write the little
round engine off just yet. Remember, this is an engine whose design was
created, and certainly perfected during only the past 40 or so years. Gotta
love that rotary sound!
Chuck "deaf as a post" Rothfuss
ECTA
Pole Cat Hollow, NC
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