Pistons With Cut-Back Top Land as a Measure Against Bore-Polishing? Influence on Engine Characteristics, Exhaust Emissions and Engine Durability

By applying large top land gaps bore polishing can be reduced significantly or avoided entirely. Lube oil consumption is also reduced and remains constant over a long period of time. By means of a suitable lay out of the piston and a minimizing of the air volume in the top land gap, the fuel consumption can even be reduced somewhat versus the standard piston version. With a minor correction of the fuel injection timing the same U.S. 13-mode-cycle emission values of HC and NO_x as with the standard piston can be obtained without any deterioration of the fuel consumption versus the standard version.