A little off topic but not much. I wouldn't anyone to ruin their filter . K&N style fiters you can't use any kind of hp air to blow them out or dry them. It damages the cloth element.

 

I thought of switching to the K&N because of it being an oiled filter; however, with less air flow than the SE filter(if the numbers aboveare right) seems like a waste. I am not too worried about water since most users with open systems say it has never been a problem.

 

I wonder what the engine actually needs to make the most HP/TQ. I would like to see a CFM number for the stock airbox K&N replacement filter HD-1499.

 

Here's a bit of factual information to cloud the issue...

Your 88 cid engine at 6000 rpm only needs 122 cfm of air to make max power. This is assuming a volumetric efficiency (VE) of 80%, which is the standard average for most stock engines.
Even using a VE of 100% (which is fairly impossible with a normally aspirated engine) you still only need 153 cfm.

Since few of us ride around with the engine at 6000 rpm all day, a more usable figure would be CFM requirements for say, accelerating with the engine speed between 2500-4500 rpm. In this instance you'll only need 51-92 CFM for the engine to make its max power in this rpm range. Even a stock H-D element with as much as 50% blockage can easily provide this amount of air.
This is why simply changing the stock air filter with a "high-flow" style rarely provides any power or mileage gains by itself.

The only advantage to a higher flow filter would be extended cleaning/replacement intervals, as it can hold more dirt and still flow the required amount of air. But even then, the felt difference would only be at high rpm and the stock filter would have to be extremely dirty to see any difference.
So ultimately, for most bikes air filter selection is more a matter of bling factor and personal taste than actual operational efficiency...

 

Interesting Observation

Thank You

Ride Em Carry Em

 

good info lost1...i am glad i did not drop alot of coin for an a/c set-up...just a k & n in the stock can for my evo

 

I have the SE air filter, and it's an oiled filter. Possibly the elements were changed out in '02 or '03. I also have the BC Overflow, but I like the narrower SE with the smaller round cover (not the Nostalgic).

 

Interesting. Seems like clean ability is still riding the top of reasons for replacement.

TP

 

Yep, and for those who aren't aware, the stock '07 element (not sure about previous models) is reusable as well. All that's required is to clean it in soapy water & dry it out.
Pretty cool.