wmd wrote:
 >
 > I spoke to a friend the other day who does a fair amount of road racing
and
 > he runs an engine shop. He likes the rotary for its power and size but is
 > critical of it in that it is susceptible to detonation, which if it

occurs

 > damages the seals and ruins the engine---not to the point of catastrophic
 > failure but  a reduction in power immediately and further over time.
 > What steps can be taken to prevent this in an aircraft engine

application ?

 > Has anyone experienced this problem.
 >
 > Comments ?
 >
 > bill

 Only the turbo is affected by this problem. The NA engine rarely detonates.
 With the turbo use 3 mm Hurley Engineering two piece steel apex seals.
 The 2 mm three piece cast iron seals were developed by Mazda to improve
 the low RPM/low HP fuel consumption and emission problem. They have no
 benefits at high RPM and high power in a turbo engine. The two piece
 steel apex seals are much more rugged and less prone to fracture
 under detonation.

 Paul Lamar

I built a periphery port 12A with a crank trigger, and two double ended
coils. One firing both front plugs and another firing both rear plugs. I used
two Chrysler pickups and an aluminum disc/ reluctor wheel with a single
reluctor (a piece of a nail). The pickups drove two MSDs. I ran both pairs of
pickup wires through a length of dash 4 stainless covered hose that I had
grounded. I twisted each pair of leads in opposite directions to avoid cross
firing. It didn't work. It ran fine sitting still. It even ran up to RPM
sitting still. Once on the track, it would fire both front and rear at the
same time. Unfortunately not often enough to stop the engine. The driver was
hopeful that it would clear up, and drove an extra lap just to be sure that
there would be nothing left to work on. It ruined both housings and the front
cast iron, and all of the case bolts. It broke a piece off of the front cast
iron. Never saw that before. The crank, rotors, all of the seals, center and
rear cast iron and the distributor were just fine.

  If the timing is under say, 32 degrees and there is oil for the apex seals,
I don't think you can hurt one. We used to add extra cheap dino oil to the 87
octane fuel to cut the octane down some more. A little extra oil in the fuel
makes even a tired engine run (seal) well. I suspect that detonation is not
the culprit. Just the added heat from detonation causing preignition. We did
run one out of water during a race. We couldn't get it to shut off
afterwards. I thought that the ignition switch had shorted and was supplying
power in the off position. I shut off the battery, nothing. I opened the hood
and snatched both coil wires out of the car, nothing. I had the driver put it
into 4th gear and let the clutch out with the brakes on. That did it. The
spark plugs were acting as glow plugs like a model airplane engine. That
engine lost the rotor housings, the front cast iron and the side seals.
Everything else was running the next weekend.  Detonation? We NA people don't
have no stinking detonation.
Lynn E. Hanover

 
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