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Old 07-23-2008, 02:32 AM   #1 (permalink)
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Join Date: Mar 2008
Location: WV
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Pequod - '17 Subaru Outback
90 day: 22.79 mpg (US)
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Subaru Outback Hot Air Intake Results

Had some free time tonight, decided to test a hot air intake as well as I could. Interesting results.

I did the test on the flattest straightest road in town, over a 1 mile stretch.

I sat cruise at 45 mph with the cruise control, then turned it back off with the brake pedal, resuming it with the resume switch. I used the scangauge II to do the reading. Reset it at a marker then read it each way.

Did a total of 12 runs, A-B-A-B-A-B Then with the variable changed.

The cold air intake was sucking air out of the fender well, while the hot air was sucking off the top of the intake manifold. This was done with an ultra high tech variable intake pipe. (Dryer hose)

Run with Cold:

1. 38.5
2. 36.5
3. 36.4
4. 37.1
5. 35.6
6. 36.0

Average: 36.68

Run with Hot:

1. 37.0
2. 36.8
3. 37.0
4. 34.8
5. 36.4
6. 35.1

Average: 36.18

A .5 mpg decrease overall at 45 mph. While this would be acceptable if there was another benefit, there isn't. The power is NOTICEABLY gone from the engine. With the hot air intake, its choked.

With the cold air coming in, the torque converter locks up quickly. It locks up way more than I'm used to, it can lock up in 4th and still climb a moderate hill at 45 mph without a problem.

Food for thought. Just thought I'd share my results, I encourage everyone to do their own testing.

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