Understanding the mechanism of Cylinder Bore and Ring Wear in Methanol Fueled SI Engines

One of the major problems created by the use of methanol fuels in SI engines is the high cylinder bore and ring wear rates observed during operation at low engine temperatures. The objective of the work reported in this paper was to identify the processes controlling the corrosion/wear mechanism in methanol-fueled, spark-ignition engines.

Basically, three different types of experiments were performed during this project. The experiments consisted of:

1. 1.
   Combustion experiments designed to identify the combustion products of methanol at various locations within a confined methanol flame;
2. 2.
   Exposure studies designed to define the specific role of each of the combustion products on the corrosion mechanism;
3. 3.
   Lubricant screening experiments designed to identify the mode of penetration of the oil film, and the location, in the microscale, of the surface attack.

Performic acid was identified as the corrosive agent. It appears that corrosion prevention is best accomplished through additive formulation designed to prevent the accumulation on the metal surfaces of the precursors to performic acid formation and to provide excellent dynamic antiwear characteristics.