"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.
Steel seals are not to be used if you expect your engine to last.

---------------------------------------------------------------------------------------------------------

Detonation is unlikely to occur in a rotary due to the moving combustion
chamber and the high wind.


quotes:

det·o·na·tion
ˌdetnˈāSH(ə)n,ˌdedəˈnāSH(ə)n/
/noun/
noun: detonation; plural noun: detonations


   combustion of a substance that is initiated suddenly and propagates extremely rapidly, giving rise to a shock wave.

   the premature combustion of fuel in an internal combustion engine, causing knocking.

   rapid combustion in an internal combustion engine that results in knocking

https://en.wikipedia.org/wiki/Detonation
The velocity of detonation <https://en.wikipedia.org/wiki/Detonation_velocity> in solid
and liquid explosives is much higher than that in gaseous ones,

"Velocity. The speed of the reaction is what distinguishes an "explosive"
reaction from an ordinary combustion reaction. Unless the reaction
occurs very rapidly, the thermally expanding gases will be moderately
dissipated in the medium, with no large differential in pressure and
there will be no explosion."

End quotes:

We would be lucky if all non premature explosions in the wankel were detonations. Then
the moving combustion chamber and high winds would not affect the BSFC.

Paul Lamar


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