Compute CFM for Two-Stroke Engine Air Filter Requirement

[97K15004WD]

I'm looking at a specific two-stroke application and have computed CFM requirements for the air filter to confirm adequate flow. I have several questions, as I would like to confirm my numbers.

Application: chainsaw
Engine: 121.6 cc
Bore: 60 mm x 43 mm
BHP: 8.7 bhp at 8,500 rpm
Max RPM: 11,000
Computed Ve: 0.5841435966524767

I come up with around 28 CFM, but this site comes up with 15.67 CFM
https://strikeengine.com/air-filter-size-calculator-for-power-bhp/

I have 47.2368985 CFM at 11,000 RPM as the maximum possible airflow with the above information.

What am I missing?

 

[wag123]

2-cycle vs 4-cycle. The website is basing it's calculations on a 4 cycle. A 2-cycle takes a gulp of air on every crankshaft revolution, a 4-cycle on every other crankshaft revolution, but it isn't a whole 121.6 cc gulp of air on a 2-cycle like it would be on a 4-cycle due to a 2-cycle's inherent inefficiencies.