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From page 417 of the 2020 HD parts and accessories catalog:
Im looking at upgrading my air cleaner, along with slip ons and the HD pro street tuner. My 2020 Road Glide Special comes with the wedge type air cleaner. I prefer the look of the round style like I had on my Road King.
Screaming Eagle has four options: heavy breather, ventilator, round and wedge.
I find it interesting that from the above 114CI stage upgrade charts, different air cleaners are used. I assumed (probably wrongly) that one model would be the best for all stage upgrades.
HD uses round for stage 1, heavy breather and wedge (torque or power cam) for stage 2, heavy breather for stage 3 and ventilator for stage 4.
I plan on stage 1 with a tuner and, maybe later, a stage 2 torque cam. For discussion purpose, if I upgrade to the extreme flow-round air cleaner, should that provide sufficient airflow to support a stage 2 upgrade or is the heavy breather (from above chart) the correct choice?
As long as the air cleaner flows enough air for your application.... the style, looks, size won't matter..
For example, the stock Rushmore air filter is thought to flow about 175CFM... If your engine needs 160CFM at max flow, then changing that air filter to one that flows 200CFM really won't make a difference...
If your engine needs 200cfm... using an air filter that supplies 220, 240, or 250cfm will all supply enough air. One won't provide better performance than another.....
The air flow of an engine is determined by rpm, VE (volumetric efficiency), and displacement..
I checked my notes (thanks to mkguitar on this forum) and CFM = cubic inch displacement x RPM x VE /3456
Volumetric efficiency varies with RPM. If I remember correctly, VE is at it's max, when the torque peaks, then decreases from there... but I couldn't find that in my notes to confirm it...
As long as the air cleaner flows enough air for your application.... the style, looks, size won't matter..
For example, the stock Rushmore air filter is thought to flow about 175CFM... If your engine needs 160CFM at max flow, then changing that air filter to one that flows 200CFM really won't make a difference...
If your engine needs 200cfm... using an air filter that supplies 220, 240, or 250cfm will all supply enough air. One won't provide better performance than another.....
The air flow of an engine is determined by rpm, VE (volumetric efficiency), and displacement..
I checked my notes (thanks to mkguitar on this forum) and CFM = cubic inch displacement x RPM x VE /3456
Volumetric efficiency varies with RPM. If I remember correctly, VE is at it's max, when the torque peaks, then decreases from there... but I couldn't find that in my notes to confirm it...
It would be helpful if Harley Davidson published the CFM flow ability for each air cleaner in the catalog or on the HD parts website.
I've gone through as many threads on this and other forums to find physical numbers or dyno results. Lot of opinions, not a lot of data.
For instance, from the parts catalog, the round high flow air cleaner flows "more" air than the stock round filter. And the round extreme flow air cleaner flows 11% more than the high flow which flows "more" than the stock.
I'm only going as high as Stage 2 so I've made my choice based on favorite looks and we'll see what the Pro street tuner can do to the performance.
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air cleaner comparison
