VH45 CHAMBER VOLUME

[VH45 PATROL]

Ive been seaching what little info on this engine about compression ratio mods and found noone has measured the combustion chamber volume. Before decompressing the chamber I measured 46.5cc, after 49.5cc.That works out to be 10 to 1 flat with a piston to deck height 10thou, 1cc valve reliefs in piston,60thou head gasket. Has anyone else checked their combustion chamber volume?Where does this 54cc figure people talk about come from?