Paul Lamar
Lets define detonation as an extremely rapid burning of the fuel and pre
ignition as the premature ignition of the fuel relative to TDC.
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Paul Lamar
Detonation is characterized by a rapid increase in pressure. Pre ignition
not necessarily so. Direct fuel injection does not preclude detonation.
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Eric Ruttan wrote:

What an interesting idea!
Let me see if I understand what you are suggesting Paul.  Under certain
circumstances the burn speed of an air fuel mixture can suddenly increase by
an extraordinary factor?

It was always explained to me that the rapid increase in pressure of a
detonation event was a function of the ignition event too far before TDC.

I think that is pre ignition.

The rising piston was increasing the cylinder pressure which, as expected,
accelerated the burn speed.  These two events combined to create the
characteristic steep detonation pressure spike.  It was all expected and
there what no unexpected chemical phenomena occurring.  I believe we even
did the math to show the pressure was correct.

I know of no chemical phenomena that allows the air fuel ratio to
suddenly and unexpectedly increase burn speed rapidly.  Can you point to any
reference that suggests that?

The 500 page Skyranch Engineering Manual explains this well and comprehensively.
They spend about ten pages on the subject. Give them a call and order
a copy. It is a real bargain at $29.95  (916) 421 7672

Paul Lamar

Another good book on the subject is the 800 page  Advanced Engine Technology by Heinz
Heisler.  ISBN 1 56091 7342 Published by the SAE. Not cheap.

Paul Lamar
 
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