Stratified Vs Homogenized Charge; Homogenized Charge - Mercury 15XD Service Manual

EMISSIONS

STRATIFIED VS HOMOGENIZED CHARGE

DFI engines use a stratified charge inside the combustion chamber to aid in reducing
emissions. All other models use a homogenized charge. The difference between the two
is:

Homogenized Charge

A homogenized charge has the fuel/air particles mixed evenly throughout the cylinder.
This mixing occurs inside the carburetor venturi, reed blocks and crankcase. Additional
mixing occurs as the fuel is forced through the transfer system into the cylinder.
The homogenized charge is easy to ignite as the air/fuel ratio is approximately 14.7:1.
Page 3B-4 90-828883R2 JUNE 1998