Stratified Charge; Emissions Information; Manufacturer's Responsibility - Mercury 15XD Service Manual

Stratified Charge

A stratified charge engine only pulls air through the transfer system. The fuel required for
combustion is forced into the cylinder through an injector placed in the top of the cylinder
(head). The injector sprays a fuel/air mixture in the form of a bubble into the cylinder. Sur-
rounding this bubble is air supplied by the transfer system. As the bubble is ignited and
burns, the surrounding air provides almost complete combustion before the exhaust port
opens.
A stratified charge is hard to ignite, the fuel/air bubble is not evenly mixed at 14.7:1 and
not easily ignited.

Emissions Information

Manufacturer's Responsibility:

Beginning with 1998 model year engines, manufacturers of all marine propulsion engines
must determine the exhaust emission levels for each engine horsepower family and certi-
fy these engines with the United States Environmental Protection Agency (EPA). A certifi-
cation decal/emissions control information label, showing emission levels and engine
specifications directly related to emissions, must be placed on each engine at the time
of manufacture.
90-826883R2 JUNE 1998
EMISSIONS
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