Pistons for 6.7 litre engines - from VIN 8742

Prior to VIN 8742 a short stroke engine was fitted denoted by an engine number starting with SY. This is stamped on the front of the top of the crankcase. These engines were fitted with a 4 ringed piston. At VIN 8742 the long stroke engine was introduced, denoted by the engine number starting with SYL. At this point 3 ringed pistons were introduced.

The table below shows the original application for the piston assemblies (including rings and gudgeon pin) and the piston part number which is stamped (along with the grade of the piston) on the crown of the piston. The VIN references relate to Standard Cars. Coachbuilt & LWB car VINs are slightly different so please contact us with the VIN of your vehicle if you are unsure of the correct applicability.

For further confirmation, the Workshop Manual diagram of piston crowns is shown here.

VIN Region Piston Assembly Piston CR
VIN: 8742-8861 All UE36190 UE36191 9:1
VIN: 9001-14953 All UE38010 UE38011 9:1
VIN: 14954-22117 All except North America UE38010 UE38011 9:1
VIN: 14954-20754 North America with EGR UE38200 UE38199 8:1
VIN: 20755-26700 North America UE39155/39157 UE39154/39156 7:3:1
VIN: 22118-26700 All except North America UE38200 UE38199 8:1
VIN: 30001 onwards All except N America & Japan UE38200 UE38199 8:1
VIN: 30001 onwards N America, Canada, California & Japan UE39155/39157 UE39154/39156 7:3:1
VIN: 39628* onwards All except N America, Japan & Australia UE42757 UE42758 9:1

Given that a range of different compression ratio pistons were originally fitted and that numerous changes have been made in the last 50 years to the cars, fuels and Government restrictions we now recommend two pistons:

UE46305 for customers wanting 9:1 Compression Ratio & UE46310 for customers wanting 8:1 Compression Ratio

These part numbers are the natural Bentley supersession for a number of the pistons listed above. We stock both pistons as OEM Bentley pistons and these are listed in the sections below along with the originally specified pistons where they are still available. Care must be taken when replacing piston rings because although different part numbered piston assemblies are interchangeable some piston rings are specific to a particular piston.