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  #11  
Old 08-23-2017, 01:02 PM
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1001001 1001001 is offline
 
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Quote:
Originally Posted by rleffler View Post
I have a Rod Bower RAM air mod for my RV-10

http://www.ramairforhomebuilts.com/

I typically don't open it until I get about 5,000 ft. Although, I usually don't close it on the descent. It yields about a 1" MP increase.
Glad you posted this. I was getting close to sending a message about it! I remember when I came out to look at your airplane and we talked about it, but I was drinking from a firehose and forgot so many things you told me, including who made the ram air for your bird.

Are you still satisfied with it? I remember looking at your build log and not seeing too much in the way of plan modifications to install it. Is that really the case, or did it require a lot of fiddling with the cowl and such?
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  #12  
Old 08-23-2017, 01:15 PM
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Most of the Harmon Rockets have the Y for Ram or Filtered air. I only use the filter when in dirty environment like taxiing on grass or dirt and also when shutdown. Nothing unusual in oil analysis. Unfiltered for start in case of fire belch in intake!

Russ
HRII
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  #13  
Old 08-23-2017, 01:31 PM
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Russ McCutcheon's RV4, horizontal induction, no filter. He has flown it that way for many years. I do not know how many hours but a bunch. Perhaps he will chime in.
My '42 Aeronca L3 didn't even have provisions for a filter. It had 1000 hours on it when I got it and I put 600 more in the ten years I owned it. It ate a lot of bugs and never seemed to mind.

So, plenty of examples running without filters but I don't think you will find any real data on engine life comparisons filter vs not.

I agree with DH. There is no reason not too given the small, perhaps insignificant, gain going naked.
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  #14  
Old 08-23-2017, 02:31 PM
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Quote:
Originally Posted by rleffler View Post
I have a Rod Bower RAM air mod for my RV-10

I typically don't open it until I get about 5,000 ft. Although, I usually don't close it on the descent. It yields about a 1" MP increase.
As compared to pulling air from inside the lower cowl, through the plastic flap valves. The rise is large because it's so badly choked with the butterfly closed. It is definitely not an optimized filter system.
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  #15  
Old 08-23-2017, 03:06 PM
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I put one of these 4" O.D. K&N filters (with that rubber fitting on the left end cut off) in my ram air intake. It keeps the bugs out of the carb.

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  #16  
Old 08-23-2017, 03:10 PM
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13brv3 13brv3 is offline
 
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Thanks for the excellent comments. Sounds like I'm probably worrying too much about the unfiltered air, but I'm pretty sure I'll change the system at some point to include a low loss filter full time. The engine didn't have an oil filter either, and they were routinely going well past 25 hours on the changes, so that probably did more harm than the unfiltered air. I've already added a filter.

As the 4th owner of this plane, there have been some changes through the years, and plenty of things I need to make right. Dan was right on the money about the RAM air though, the second owner did race it at Reno. I kinda figured he was responsible for the RAM air.

Anyway, thanks again, at least the unfiltered air is not an immediate concern.

Cheers,
Rusty
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  #17  
Old 08-23-2017, 03:12 PM
Tom Martin Tom Martin is offline
 
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I use a Bower airbox on my rocket for winter use only. With the snow potential where I live I do not like the possibility of plugging the filter with snow. With the ram air closed you lose about 2" of manifold pressure. It is sort of like using carb heat as you are now drawing air from the hot lower pressure area of the plenum. Good for snow conditions though. The system does work well in the summer with the ram air open but I do not like unfiltered air. My engine has a fresh rebuild, ECI cylinder problems, but after that big expense I will use filtered air as much as possible.
I built a custom filter that fits in the same spot as the Bower box. It has a much larger filter and MP are very similar to the Bower set up with the ram air open. It is a clean simple filter box with no moving parts.
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  #18  
Old 08-23-2017, 03:13 PM
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13brv3 13brv3 is offline
 
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I had another question about the Rod Bower system. They don't seem to show a lot of details on their web page, but in looking for info online, I could swear I've seen his system with a filter, and then later it looks like the filter was eliminated. Does his current system have a filter or not?

Thanks,
Rusty
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RV-8, SN-80587, built, flown, sold.
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  #19  
Old 08-23-2017, 03:30 PM
SJordan SJordan is offline
 
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Hey gusy don't forget Air Flow Preformance makes a alternate air "Y" with nice filter. It's honestly a pice of art work it's so nicely made. Much cheaper than than Rods system and much simpler. I agree ram air is probubly more work than it's worth and filtered air is best but if your like me and have to have ram air check out the Y from Don at Air Flow Preformance.
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  #20  
Old 08-23-2017, 03:46 PM
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Quote:
Originally Posted by snopercod View Post
I put one of these 4" O.D. K&N filters (with that rubber fitting on the left end cut off) in my ram air intake.
John, the cone filters are relatively restrictive, as compared to the flat panel K&Ns. The pleats on the flat filters tend to be 7/8" to 1" deep, while the pleats on cone filters are quite shallow. Imagine cutting the media from the filter body and stretching it out flat. BIG difference.
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