14th International Congress on Combustion Engines, Helsinki, 1981. 14th International Congress on Combustion Engines, Helsinki, 1981 / 12th International Congress on Combustion Engines. 10th International Congress on Combustion Engines = 11th International Congress on Combustion Engines. 15th International Congress on Combustion Engines = International congress on combustion engines. Tenth International Congress on Combustion Engines International Congress on Combustion Engines : International Congress on Combustion Engines.