Drop Base Filter Update/closure

[Kevin Johnson]

I believe the screen was mainly intended to keep debris from falling into the carb when the hood was open. (since the filter was mounted to it)

Also, note that as designed the filter rode an inch or so higher on the foam ring, rather than sitting down on the flange. In other words, the flow path is more convoluted if the same height filter sits directly on the base...

some racers ran without a filter in the hood and you need the screen to prevent carb calibration problems. I have tried it with and without a filter and you need the screen when running without the filter element. there is a positive pressure to the carb from the cold air intake caused by the windshield at speed

Possibly, then, there would be a further improvement with a thin array of vertical slats -- like spokes on a wheel -- supporting the small lid. Time intensive to build.

Good project for someone with a printing machine as you would be able to contour the slats and lid in one fell blow.

[Calypso]

Laws of the diminishing returns may apply...

[cv67]

What I keep wondering ^^^^^^
have a hot 383 maybe 500hp +- and have a 10x3 cheapie Edelbrock air cleaner with a paper element. Seems to run Ok wiht it but keep wondering if one of those fancy bases or lids would help or just lighten the wallet. Til I figure out how I want to make a cold air system if any...better than no filter I guess. Tired of throwing money down the drain though think the l88 base would hit my fuel lines which cost a bundle to make or the linkage..maybe not.
Wouldnt speedway motors have something like that?

[MadBill]

That's way small, mostly because of the small diameter. K&N's formula for sizing filters is: Area = (C.I.D. x RPM)/20839, so a 383 @ 7,000 RPM would need 129 "². The effective area of a filter is the diameter x Pi x (height minus 0.75"*) (*to account for the sealing bead top and bottom.) so a 14" filter would need to be 3.5" tall.

You can do a very simple test for air intake restriction. Per David Vizard's How to Build Horsepower Vol. 1., build a simple manometer from 10' or so of clear windshield washer or aquarium hose taped in a U-shape to a yardstick. Fill the U about half way with water (a little food coloring helps) . Position one end of the hose inside the aircleaner base (drill a hole or use a vent line fitting) and the other outside the filter (or at the snorkel entrance if it's a closed housing). Have a helper hold it upright and take readings as you drive.

At WOT and max RPM, the height difference in the liquid from one side to the other should ideally be no more than 1.5". Don't be surprised if it's much more, e.g., sucks water right out the top. My 61", 55 HP Chev Metro pulled over 10" with the stock assembly!

[cv67]

If K&Ns formula is accurate looks like this ones heading for the trash bin
Imagine it could create a rich condition also no?

Maybe Ill hold off on the rejet for a sec

[MadBill]

Absolutely. On top of the size, understand that K&N's flow more per square inch than most paper filters, so the formula probably undersizes a typical paper element.

[dave brode]

Some filter flow data from Mr. Bill Jones.

http://ryanbrownracing.com/Bill_Jones_Page_4.html

[cv67]

Interesting, Dave.

[Lizardracing]

I use a 2" air cleaner spacer for two reasons. The first is too get the filter element above the hood and the second is too straighten the air into the bores. Is there a lenght of spacer benefit in play here? obviously hood clearance is a factor for he OP.

[LnL]

lnl
could you verify which color base goes with which color line
hard to tell with these old eyes
I may be off base
and
thanks for the info

Sorry for missing this question, I've had 4 major surgeries since this was posted!

The blue base is the blue line. The chrome base is the green line. The spun aluminum (rounded) is the red line.

[BOOT]

There was another thread recently but the spun alum is too tight against the filter inside and you can see the blue base has a wider filter seat area, it even has witness marks to show where the filter was.