AEM 30-71XX Infinity Stand-Alone Programmable Engine Mangement System Full Manual - Manual (Page 288)

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© 2014 AEM Performance Electronics
Infinity User Manual
noticeable combustion and a rise in cylinder pressure and temperature occurs. The chemical
reaction within and on the surface of the initial flame kernel causes energy to be released during
the ignition delay period. When the flame front is at this initial stage of propagation there are
energy losses via conduction, radiation, and convection of heat If too much of this energy is lost,
the mixture will fail to propagate and a misfire will result.
As compression ratio increases the requirement for charge motion in the chamber is reduced.
Engines that have high compression ratios generally require reduced ignition timing
requirements due to the increased flame speed. The design of the combustion chamber in a high
compression engine is necessarily small. The compactness of the chamber imparts its own
charge motion and squish into the mixture.
We have included some sample ignition timing maps for gasoline engines that are typical for use
on a street car. These examples include a naturally aspirated engine, forced-induction engine,
and a high-compression engine. These are conservative samples that should be used as a
starting point only.
The tuner of the engine must use good judgment when selecting the appropriate timing
map for the engine.