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View Poll Results: Air filter brand?
K&N 12 46.15%
Green 3 11.54%
STi 1 3.85%
Whatever is on sale 3 11.54%
Other (please specify) 3 11.54%
--------------------------- 2 7.69%
Cone 2 7.69%
Flat panel 9 34.62%
Multiple Choice Poll. Voters: 26. You may not vote on this poll

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  #16  
Old 01-20-2005, 02:12 PM
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The Hunter The Hunter is offline
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I use a K&N filter cleaned and recharged every week, if Im driving her. Wich hasnt been lately if you've look at my pictures.
It offers the highest flow and when maintained properly very good filtering. I'm going to try one of those new Air Hog Filters as well as an STi in the furture.
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  #17  
Old 01-20-2005, 02:16 PM
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The Hunter The Hunter is offline
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By the way the K&N is a replacement pannel filter never use a Cone type unless your going to insulate it in some way from the engine heat. Hears some nice info on that.......


The amount of horsepower an engine makes is directly related to the mass airflow of the engine. Mass air flow is determined by volumetric efficiency VE, and the density (pressure-and-temperature) of the air. In turn, if you know the actual efficiency of the engine, and energy content of the fuel used, you can predict horsepower. The SVX service manual shows 97.5% VE at 5400. At standard temperature and pressure (77 degrees Fahrenheit, and 14.53 psi) this equals 22.56 lbs/hour air. Assuming 19000 Btus per gallon of gas and a 0.33 (mechanical x thermal) efficiency the SVX should produce 228 hp. That happens to be really close to what Subaru advertises. Converting the mass flow to CFM = 309CFM. Now, just for grins add a K&N cone filter into the picture. It may positively impact VE due to a lower pressure drop at 309 CFM than the stock filter. Let's say VE goes to 98%. Based on the same calculation, the mass airflow is now 22.68 lbs/hr or 230 HP. However, consider the temperature of the air. Under the hood, without any type of insulation, I am willing to bet the temperature is probably not far from the temp of the thermostat. To be conservative, let's say the new cone filter is breathing in 160 degree under hood air instead of 77 degree air. Using the previous formula, but adjusting the air temperature what is the mass flow rate? 19.64 lbs/hour. That amounts to 199 horsepower. Here are calculations for a couple other temps at 98% VE:

temp
mass airflow
predicted hp

40
24.36
247

77
22.68
230

100
21.75
220

120
21.0
213

140
20.3
206

160
19.64
199

180
19.03
193



Think about this before buying a cone filter that breathes hot engine air. Of course, they produce an extra 15hp. Why would the manufacturer lie?

Leading to the air filter canister is a circuitous, plastic resonator housed in the right fender whose job is to quiet the induction system. Although I'm not convinced this causes any serious restriction to airflow, if you want a more aggressive intake sound, the resonator can be removed. If you do this, do NOT cut a hole in the bottom of the fender cover in the hopes that more air will fill the fender. A high-pressure area builds up in front of the radiator when the car is at speed. This air flows around the radiator into the fender cavities to create a source of high-pressure ambient air for induction. This is an old hot-rodder's trick and is done on purpose by Subaru and other manufacturers. Air passing over a surface creates a low pressure area on the surface, so if you then put a hole in the bottom fender, you are in fact creating a low pressure area. This will actually pull air OUT of the fender, not into it. If you don't believe the manufacturer knew what they were doing, go ahead and cut a hole, but fashion some sort of scoop facing the high-speed air stream.

Hope this is informative

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  #18  
Old 01-20-2005, 02:31 PM
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SilverSpear SilverSpear is offline
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wait and see the mods I am doing to my car which will be unveiled in a couple of months: the super hood, the engine external mods, the remodified clear smallcar heads and corners, and the totally HEAT INSULATED air filter and intake....
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1994 Silver SVX in hybernation, awaiting for the monsterous awakening (Lebanon)
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2013 Mercedes-Benz SL350 Euro Specs, White/Red. Mint... Another step into SL Collection.
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