Finally Found the paper again...
Interesting in the viscosity and piston temperature, and how much (little) effect was gained by cutting off access to oil spray under the pistons, indicating that viscous shear on the cylinder walls played more of a part than "cooling" from the oil.
(Yes it's old)
http://naca.central.cranfield.ac.uk/reports/1940/naca-report-698.pdf
Interesting in the viscosity and piston temperature, and how much (little) effect was gained by cutting off access to oil spray under the pistons, indicating that viscous shear on the cylinder walls played more of a part than "cooling" from the oil.
(Yes it's old)
http://naca.central.cranfield.ac.uk/reports/1940/naca-report-698.pdf