"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
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