Air Filter mod.

[Millwright]

Feeling a little skeptical tonight. Lol tough day at work.

I've read, and you tubed a bit about stock air filter setups being restrictive.
I've always doubted that these clone engines have been engineered to allow just the precise amount of air flow. To suggest that they are on the verge of being choked out, or simply underperforming?

Valve size, valve lift, duration, RPM, smallest choke point, and atmospheric pressure are the key players as I understand it.

Does anybody have any numbers or experiences to indicate that a stock engine, at 4500 RPM would really need, or benefit from a filter upgrade?

My air intake box has 4 inlet holes with a combined area of 2in²
Any other restriction would need to be smaller than 1.6" Diameter. I'm sure the throttle body is smaller. (upgrade carburetor?)

For the "stage 1" build, I'm thinking the jetting is the real hero. Filter upgrade, not so much.
Elimination of muffler, I can see the stock being restrictive, but I'm not sold on any big hp gain.

 

[Millwright]

I removed the big bulky air box, fully exposing the filter element. At this point, is there any reason to purchase adapter kits and choke replacements?

 

[Denny]

No, unless you like having your cylinders honed by fine dust. Put the foam prefilter back on too.

 

[madprofessor]

I'm a firm believer in the venturi effect on a negative pressure space, where the depth of vacuum is constantly varied like it is down the throat of a carburetor. Hence I'm a fan of the engineered venturi billet filter adapters for hi-flow air filters.
That's the adapters that are NOT the flat-face (and flat-rear) adapters. The venturi type have exactly that as their face, a smooth venturi. They start curving inward from the very outside edge of the O.D., and keep curving all the way in to their own backside (carb connection point). That particular configuration will accelerate air into the carb, and draw more air in with it.
It's not how big the outside opening is, it's increasing the airflow through it. You don't have to buy a big expensive hi-flow filter to put on the adapter, but I certainly don't like the small ones that some folks use. Besides, the big ones with the angled neck and a neat color just look better overall on your engine.