Hilborn IR filters vs. no filters Dyno comparison

[338Raptor]

Does anyone have dyno results comparing Hilborn/Stack style IR intake running filters vs no filters?
I frequently see engines dyno’d without filters to optimize air flow and power. But in reality how many of those engines get filters once installed in a vehicle. How much air flow is restricted with filters or screens and how much horsepower is lost?
I’m going to use a Hilborn on the street and plan to dyno the engine with filters installed exactly like it will be in my car.

Different style filters that I’m aware of:
1. Individual K&N style air filters
2. Large single K&N style filters (like the dirt track guys use)
3. Bug Dome screen style (I would add outerwear nylon booties)
4. Tube top filters (foam sandwiched between large hole screens)

Basically I’m looking for first hand knowledge of horsepower loss for each filter option.

[CaptCobrajet]

We did it on an 8-stack Hilborn set-up for a GT40 engine that we did a couple of years ago.  Customer supplied the filters.....he had researched media choices.  He made the stacks, very very nicely machined......threaded on the outside to hold the filter in the cap.  The difference between filters and just screens was significant.  Seems like it hurt about 50 hp on a 720 hp engine.  Definitely makes a difference to run the filters.

[338Raptor]

But the screens alone didn’t seem to hurt power?

Any comparison between screens and no screens?

[Barry_R]

Ran screens on a couple IR engines on dyno.  Every time it simply murders power by a ton and drives mixture dead rich.  A necessary evil, but heavy on the evil part.

[338Raptor]

Do IR screens and filters kill power more that a filter on a standard carburetor?

[CaptCobrajet]

I would say yes.  A really good air filter on a Stock Eliminator engine hurts about a tenth of a second, which is +/- 20 hp.  That being a really good filter.  There is much more surface area than the carb top.  With IR, the surface area of the filter is not much more than the open top.......the air cleaner doesn't kill it as bad because of the extra area.

[cammerfe]

Several years ago there was an examination of the effect of putting various kinds of filters on the intake tract for a turbo. It was on a Turbo website. The conclusion was to make the filter as big as possible so as to get very substantial surface area on the filter. K&N-style 'cone' filters seemed to be the best answer, and they are certainly available in a variety of sizes. (Think of the ram-box that came on the High-Riser engine on a T-bolt. Think of the pair of tubes attached, and their size. Now come up with filters to fit the tubes.)

KS