Air filter size

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Re: Air filter size

Postby VDF1 » July 7th, 2011, 2:57 pm

I saw no difference in performance on the track is all I can say. Of course, I was sometimes inconsistent and that may have skewed my results. I don't know how many low-profile filters K&N make. It does occur to me that any filter will intefere with an air/fuel charge above the carb so it's a matter of how much interference that can be tolerated, I guess.

BTW, the "respected FV person" was a driver I raced with 30+ years ago when velocity stacks with no filter were in common use and who quit racing 15 or so years ago.
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Re: Air filter size

Postby SR Racing » July 7th, 2011, 7:30 pm

VDF1 wrote:It does occur to me that any filter will intefere with an air/fuel charge above the carb .


True in respect to the gauss filtering. However the filter design internally and base plate especially, usually HELP the flow.

I just stuck a Regional carb on the bench. I tested max flow with the following K&N's

RU-520 Flow about 105.5
RU-510 Flow about 105.5
RC-1200 Flow about 105.5
RU-570 Flow about 105.3 to 105.4. (This is the very low profile one with the offset carb hole that was mentioned here. )

The dimensions and shapes of these filters can be seen here.

http://sracing.com/Store/FV_Stuff/FV_Stuff.htm

With the possible exception of the RU-570 there was no statistical difference in flow. Before I would even swear the RU-570 was down, I would want to do more testing. It it is that close.

The carb upper bowl shape is 80% of the difference between prepped carbs. When choosing an induction system on a vee getting the coolest air to it with the best possible "free" air "boost" is the primary concern. Any good filter will work fine.
We suck air through a tiny venturi and a long garden hose. That is where the pumping losses are. :lol:
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Re: Air filter size

Postby Mystique Racing » July 8th, 2011, 3:55 pm

I saw no difference in performance on the track is all I can say.


The differences are small. Your not going to feel it on the track.

However, you might be able to measure a difference on the track if you are using a data system.

Additionally, in this case I don't think the flow bench results tell the whole story.

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Re: Air filter size

Postby SR Racing » July 8th, 2011, 11:13 pm

[quote="Mystique RacingHowever, you might be able to measure a difference on the track if you are using a data system.

Additionally, in this case I don't think the flow bench results tell the whole story.

[/quote]

Other than potential boost and air temps, I don't see why the flow bench doesn't tell the full story on flow. :lol:

But I certainly agree re: data acquisition on the track for measuring any differences in engine performance. You can look at the rate of acceleration from 70 to 90 (the ET in millsecs) etc. Exactly how long it take to move 1000 feet etc. You can even compute your rear wheel HP directly. And a system to measure all that and much more is under $1000. A tach and all your guages, warning lights etc. and wiring kludge and time to install costs almost as much $.
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