by far Id say as an example similar sized engines eg. Ca18de block with main caps and girdle 42kg VS Suzuki M18a with main capas and sump 23kg

Suzuki head has slightly bigger ports than four port Ca18de with even better angles and compact combustion chamber design yet weighs 18.5kg while Ca18de weighs 24.5 kg, ten years later big weight difference!

The numbers are impressive no doubt for the mr16ddt however Id rather a modern flathead motor in alloy with all the latest technology but a four cylinder. Ive always loved the simplicity of Flatties, drop a valve who cares! :)

http://www.uncommonengineering.com/