Hi Dick,
Thanks for the reply. It appears that most of my confusion came
from lumping pre-ignition, pinging, knock, detonation, everything all
together. Also whats becoming more apparent is that the burning of the
fuel/air is not instantaneous. Things are clearer now, but as you mentioned,
chapters of books have been written, I should probably read some of those if I
really want to get into it any further!
Kendall
----- Original Message
----
From: Sally or Dick Taylor <tr6taylor@webtv.net>
To: Kendall Larsen
<mailkendall@sbcglobal.net>; 6pack List <6pack@autox.team.net>
Sent: Tuesday,
June 17, 2008 12:25:38 PM
Subject: Re: [6pack] [TR] Compression boost
Kendall---Chapters in books have been written about this phenomena, but let's
see if this can be shortened.
PREIGNITION occurs when the charge (air/fuel
mix) fires without benefit of the engine's normal spark event, such as hot
spots somewhere in the combustion chamber.
DETONATION is what gasoline does.
We want it to, as this is what drives the engine. What we don't want is for a
second detonation to take place while the piston is rising.
This other
detonation occurs when excess pressure has built up at the flame front, at the
top of the piston, and creates a "second" flame front. This second front is
usually started at the opposite side (of the piston) from the spark plug. When
the two fronts meet before the piston reaches TDC, a knock occurs. Delaying
the spark timing, either thru a physical setting by the tuner, and/or thru
some automatic device that senses pressure or knock, can reduce or eliminate
this destructive force.
Fuel that has a higher octane is slower burning,
which gives pistons more time to "reach the top" before another detonation can
occur.
Cooling down the (air/fuel) charge is another way to reduce or delay
detonation.. This can be done by lowering the CR, or the temp. of the fuel or
air.
Any help?
Dick
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