Equation 300-3 applies to lubricated cylinders. Non-lubricated cylinders have a lower Ev due to greater piston-to-liner clearances, and other factors. For non-lube applications, change the 97 in Equation 300-3 to 94.
Speed also affects Ev. Equation 300-3 applies to slower speed machines up to 600 RPM. For 1000 RPM machines, Ev is about 3% less, and the Ev determined from Equation 300-3 should be multiplied by 0.97.