"Detonation" is the spontaneous
ignition of the fuel air mixture. This
occurs after the planned ignition event and usually at
a location
remote
from the spark plugs. So, mixture temperature is
usually to blame. So,
the use of intake air coolers and intercoolers on
super charged and or
turbo charged engines. In order to reduce intake air
temperatures.
Also,
additional fuel my be added to help
reduce charge temperature.Also,
lower compression rotors or pistons
may be used. Also ignition advance
may be pulled out as boost is going
up. Flame front speed is largely a
function of cylinder pressure.
So, the higher the cylinder pressure,
the faster the burn, and less
advance is needed to get best
cylinder pressure near 50 degrees after
TDC. Ceramic seals hold up well to
detonation. Steel seals and carbon
seals do not.
"Preignition", is an ignition event
that occurs before the planned
ignition event. Unlike detonation, it
often occurs at or near the spark
plugs. Usually too high a heat range
(plug tip overheats and becomes a
glow plug). Running the ideal mixture
for best power is very popular.
However with best power comes highest
cylinder temperatures and the
least amount of cooling oil. When
leaning to lean of peak operation,
move quickly through ideal and get to
lean. The more powerful the
ignition system the leaner it will
run without missing. Faulty
distributor cap, plug wires too close
together. Primary wires not
shielded from secondary wires. Solid
conductor secondary wire (Use
inductive secondary wires in most
cases).
You can induce both problems at one
time.
One outstanding feature of the
ceramic and the carbon seals is that
they
weight nothing compared to steel
seals.So, they will track the chrome
well up into stupid RPM. For above
stupid RPM, multiple springs can be
installed with still no chrome
damage. Also there is just a one piece
seal, so no pesky corner piece to
overload one iron face. Carbon and
ceramic seals must be fitted to each
housing using a diamond file.
Check
with supplier for specs.
With both carbon and ceramic seals
after years of racing show no
wear at
all on chrome faces. Ceramic seals
stay as new and carbons last about 2
years.
Lynn E. Hanover
This is a piston engine Lynn. What is
the source for this definition.
I would say for an aircraft engine
the extra cost of Iannetti apex
seals
is essential.
For turbo charged Mazda Wankel the
iron seals are marginal.
Steels seal are not to be used if you
expect your engine to last.
Paul Lamar
Lynn,
What material are you referring to
citing 'carbon' for apex seals.
We know ceramics, steel and cast iron.
It could not be plain carbon. It has
to be reinforced with
something to prevent breakage and also
wear.
Please elaborate what you are referring to and who
makes and sells
carbon
seals?
I know that in Germany firms have tried to use carbon
as piston
seals.
It did not make
it to mass production as far as I am aware of. I trust
to much wear
was
an issue. ?
Thank you
Rolf Pfeiffer
Mazda used carbon impregnated aluminum
for a while. Light so it did not
cause chatter
marks on the rotor housing. They also
were not hard on the chrome
housing
for wear.
Dale
Davies
Yes
Dale, I read about that too.
I
just wonder if any carbon based seals or a carbon
compound is in use for apex seals today.
Light
weight also reduces the centrifugal force of the seals
which, besides reducing or eliminating the
tendency to chatter is also beneficial for less wear
and less friction.
So
far it looks that silicon carbide is the best bet. I
would love to use a carbon compound or such
as carbon has self lubricating properties. This may
eliminate the need for oil supply to the Trochoide
and side housings. No fuel - oil mix would be needed
if carbon could be used. However, a bit of oil
also supports a better gas seal. Small amounts of oil
would still be beneficial.
Rolf Pfeiffer
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