Here is a chart showing that detonation is primarily a low
     RPM high
     load
     phenomena.  The white band in the chart is the no
     detonation max HP
     operating range. Cars and airplane engines with variable
     pitch or
     constant speed props are much more likely to suffer from
     detonation
     than an aircraft engine with a fixed pitch prop

running at

     max RPM.

Paul and group,
 One of the few times that there are true differences
between older engines and new ones is this portion of detonation phenomena. The big difference between these
engines is  fuel injection, or more to the point
electronic fuel injection. With carburetors the biggest problem is how to control the portion of the speed range
where RPM is low and the throttle is opened wide. Where
I live we called this lugging the engine. This high load
low RPM situation "fools" the carburetor because the as
the throttle is opened the vacuum can fall to zero just
when the engine needs fuel due to the large opening of
the throttle valve. This lean condition is the detonation devils playground. All sorts of tricks have been played
with carburetors to get them to meter this low vacuum environment. This area is where a large displacement car might "stumble" prior to spinning the tires and speeding
away. Electronic ignition and injection can be a true
demand system, preventing stumbling and excessively lean mixtures during transition. On the rotary we seem more
likely to detonate at higher RPMs. The potential for destruction  seems to come at higher pressures and temperatures, like turbocharging without an intercooler.
We must be careful because the potential for damage is
higher at these speed ranges. Get a really good engine
management system. This is a complex subject that many
books and sae papers have been written about, so I won't
get to involved and just say, hey, "let's be careful out there".
Bill Jepson

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