Production products
PBradshaw’s oil-boilers oking fun, many nickname Bradshaw’s oil-cooled engines ‘oil boilers’ and a few use the term in derision. The former is fun, albeit a joke done to death, but one wonders if the latter souls are equally derisory about the Suzuki ‘oil-cooled’ models, including the successful Bandit range.
While your scribe has no experience of Bradshaw oil-cooled engines, friends (including our editor James) have, and they all report the 349cc Bradshaw oil-cooled engine performs well and its oil doesn’t boil!
It is worth considering oil involved with motorcycle recirculating systems aids engine cooling, albeit heat dissipation isn’t its primary role. An awareness of the assistance oil offers an engine was known to motorcycle race factories before the First World War. For example, early IoM TT riders would manually pump extra oil into their engines on the Mountain Climb and fast straights for both lubrication of stressed engine and engine cooling – period reports confirm this. Some machines were fitted with two oil pumps, often one hand and one foot, and riders carried extra sparking plugs for when they oiled up.
Part of Granville Bradshaw’s aero brief during the First World War involved improving heat dissipation, and his work involved oil assisting air to cool ever more powerful aero engines. He even sited oil pumps into air streams to cool the pumps to help. From his work, he concluded oil cooling engine barrels was more efficient than air cooling with applied fins.
How far Bradshaw got with oil cooling development during the First World War is uncertain, but in 1920 he
