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  #21  
Old 10-07-2022, 05:04 AM
RViator60 RViator60 is offline
 
Join Date: Nov 2019
Location: Southport, NC
Posts: 132
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Quote:
Originally Posted by RV6-KPTW View Post
Very interesting.

Did you make the ram air appliance?

I assume there is a control for switching back and forth, yes?

Did you make any other adjustments - injectors, timing, exhaust etc to accommodate filtered vs ram air?

Thanks for sharing.
I purchased the double-butterfly Y-valve from Airflow Performance and the hose adapter to the filter off Amazon. I used an Airflow Performance bracket to run the controls under the engine and ran the air control cable to the panel. The induction scoop is also something I built. I did all this to make room for the A/C compressor where the standard snorkel normally goes, but was also motivated by the ability to achieve higher MP using RAM air. I can get quite close to the same results Scott reports (171 kts at 2300 rpm/23 in, 7500 ft MSL) but at a slightly higher fuel flow (9.2 gph). I'm about 100 lbs heaver with the A/C installed and the induction scoop probably increases the drag slightly.
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Marty Guinn
Based at KSUT, Southport, NC
- 1973 PA28-180 (N55087) sold
- 2021 RV-14A (N818PP) finished 12/21. 150 flight hrs so far.
RV14A Build Log: https://eaabuilderslog.org/?s=MartysRV14A
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  #22  
Old 10-07-2022, 09:21 AM
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DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
Posts: 11,075
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Don't put too much weight on the difference between Marty's filtered and unfiltered performance.

The filtered system is crippled, taking its air from inside the lower cowl volume. That volume has already suffered a large pressure drop across the engine cooling fins. It is being fed with little more than freestream pressure, unlike the standard snorkel filter, which is at freestream plus 70 to 80% of the available dynamic pressure (q).

In addition, the filter is in the cooling air outflow from #2, which is quite hot, so air density is low....effectively the same as a big jump in density altitude, and pro-detonation too.
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Dan Horton
RV-8 SS
Barrett IO-390
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  #23  
Old 10-07-2022, 07:10 PM
RViator60 RViator60 is offline
 
Join Date: Nov 2019
Location: Southport, NC
Posts: 132
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Dan,
I donít know who you are and donít know why you think you are an authority on my set-up. I chose this route after much discussion with known experts, and after 200 hrs have had very satisfactory performance. Out of respect, I would appreciate it if you would direct any comments to my post directly to me and I would be glad to answer any questions you have about my airplane. This forum is a platform for sharing learnings and ideas and not to discredit another user. If you canít do that, I would prefer you didnít comment further on a post of mine.
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Marty Guinn
Based at KSUT, Southport, NC
- 1973 PA28-180 (N55087) sold
- 2021 RV-14A (N818PP) finished 12/21. 150 flight hrs so far.
RV14A Build Log: https://eaabuilderslog.org/?s=MartysRV14A
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  #24  
Old 10-07-2022, 11:12 PM
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DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
Posts: 11,075
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Sorry to hear you're unhappy Marty. Instrument the installation for temperature and pressure and you'll find the commentary is accurate. Taking intake air from a hot place stripped of dynamic pressure results in reduced performance. The HP loss here is 8.4%. It's just the facts.

It is entirely possible to build a full time filtered system with very small pressure loss, or a Y-system offering choice of unfiltered ram or filtered air...with the filtered air being supplied from a cool, high pressure location.

https://vansairforce.net/community/s...d.php?t=175589

https://vansairforce.net/community/s...ad.php?t=49556
Steve's photos here:
http://www.hpaircraft.net/rv8/100_1801a.jpg
http://hpaircraft.net/rv8/p1010163b.jpg

Chris Zavatson's work:
http://www.n91cz.net/airbox/airbox.htm
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Dan Horton
RV-8 SS
Barrett IO-390

Last edited by DanH : 10-09-2022 at 09:32 AM.
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