Hi Paul,

I enjoyed your site very much.

I am fascinated very much by the wankel concept. I am looking to buy a
cheap 1st
airplane running almost out of engine hours with the plan to replace the
engine by a
Mistral.  But I talked a lot to RX7-8 owners all saying that you need a new
engine every
100.000 km because of wear and tear. Why do you claim then this robustness
and longevity
in a wankel?

thx!

Rudy Berkvens
Wuustwezel
Belgium
Europe.

I can't explain it. Perhaps they are talking about the NSU RO80. Here in
the states the
Mazda's last 300,000 to 400,000 miles (not Km) if the cooling system and
oil supply is
taken care of. Thousands of 20 year old RX7s are still on the road. They
dominated 24
hour endurance racing in the 1980's and won the 24 hour Le Mans outright in
1991. They
are still winning here in the United States in the Rolex GT class despite
severe
penalties on max RPM and minimum car weight.  Many Mazda Wankels installed
in aircraft
running at 75% full power are lasting hundreds of hours and in some cases
over 2000
hours. To my knowledge nobody has worn one out in an aircraft yet.

Yes they burn 5% more gas but that is more than made up for by the ability
to burn car
gas instead of more costly aviation fuel. When somebody builds a turbo
compound version
they will become the most efficient internal combustion engine of all time.

Paul Lamar

I can explain it.
It's mostly true for the 3rd gens.
The fault wasn't with the engine though.
The turbochargers didn't hold up and owners were installing new single stage
ones and boosting the hell out of them.
The 2nd gen N/As ran forever, if you didn't mind a little oil smoke untill
they warmed up.

Ron Freier

The Teflon/silicone oil scraper O-rings solve the oil smoke.
I drove my Cosmo for years with oil smoke every time I started up.
I figured it reduce the wear on the side housing :)

Paul Lamar