Air Filter
HDF Community Team
Joined: Nov 2012
Posts: 6,192
Likes: 2,424
From: USA
A better flowing air filter doesn't do anything unless the engine can use that increase.
Using my 88 engine with a stock 5,800 rpm redline:
88 cubic inches is 0.051 cubic feet. It's a four stroke engine, so it only breathes half the time. 0.051 / 2 = 0.0255 cubic feet.
0.0255 x 5,800=148 cubic feet of air per minute.
That's assuming 100% engine efficiency, at redline.
So a filter breathing that will supply all the air the engine could possibly use. An air filter that supplies more does nothing, other than go longer in service before becoming a restriction from dirt buildup.
Do beware of over oiling the likes of a K&N filter. Many folk do, and that oil gets stripped off the fabric and deposited on things like sensors, which does not do them any good.
Using my 88 engine with a stock 5,800 rpm redline:
88 cubic inches is 0.051 cubic feet. It's a four stroke engine, so it only breathes half the time. 0.051 / 2 = 0.0255 cubic feet.
0.0255 x 5,800=148 cubic feet of air per minute.
That's assuming 100% engine efficiency, at redline.
So a filter breathing that will supply all the air the engine could possibly use. An air filter that supplies more does nothing, other than go longer in service before becoming a restriction from dirt buildup.
Do beware of over oiling the likes of a K&N filter. Many folk do, and that oil gets stripped off the fabric and deposited on things like sensors, which does not do them any good.
Foxtrapper-Most air filters will only feed the engine the air it can use, even a stock filter.
A stock air filter may feed all the air a Stage-I Harley engine can use, but still needs replacing.
I have used K&N filters for over 40 years. The first time it's cleaned & re-oiled, most of
the users learn not to over oil the filter element. On the plus side K&N's are your last air
filter you buy for that vehicle.
John
A stock air filter may feed all the air a Stage-I Harley engine can use, but still needs replacing.
I have used K&N filters for over 40 years. The first time it's cleaned & re-oiled, most of
the users learn not to over oil the filter element. On the plus side K&N's are your last air
filter you buy for that vehicle.
John
Road Captain
Joined: Jul 2015
Posts: 565
Likes: 152
From: Calgary, Alberta
I have vent hoses putting hot oily air directly into my intake. So much so that occasionally I need to pull the cover and clean it up because it will drip. I cannot imagine an over oiled filter doing worse. That is unless it's physically dripping oil as you install it .... maybe then.
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justmealwatts
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Aug 9, 2010 12:24 PM
