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02-15-2013, 06:46 PM
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Join Date: Oct 2005
Posts: 1,516
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Thanks Allan for posting some answers.
Looking at my installation pictures I may be just around 45 degrees and "puddling" was what I was hoping for.
By puddling I understand collecting the one or two drops of oil that make their way down the tube and end up on the hangar floor after shut down. I thought that the reed valve would capture these after shut down and burn them off again when the exhaust system is hot. Having put a few hours on before installing the reed valve I can say there was no oil getting on the floor as opposed to the standard installation without the oil separator.
Maybe you can explain what you mean by puddling and why I would not want that.

__________________
Ernst Freitag
RV-8 finished (sold)
RV-10 Flyer 600 plus hours
Running on E10 mogas
Don't believe everything you know.
Last edited by N427EF : 02-16-2013 at 06:45 PM.
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02-15-2013, 06:51 PM
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Join Date: Mar 2006
Location: Newport, TN
Posts: 7,496
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Just an observation here...that brace you have on there to the engine mount will most likely cause more harm than good....The engine mount is stationary, that exhaust is tied to the motor which will move around a bunch! The brace is going to put some high stress on that tube.
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02-15-2013, 07:44 PM
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Super Moderator
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Join Date: May 2005
Location: Locust Grove, GA
Posts: 2,627
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Exhaust brace
No, not really. That is a standard brace for all of the Vetterman exhaust systems. The rubber hose allows for support without a "hard" connect that would cause the stresses you mention. Look at my pictures a few posts earlier.
Vic
__________________
 Vic Syracuse
Built RV-4, RV-6, 2-RV-10's, RV-7A, RV-8, Prescott Pusher, Kitfox Model II, Kitfox Speedster, Kitfox 7 Super Sport, Just Superstol, DAR, A&P/IA, EAA Tech Counselor/Flight Advisor, CFII-ASMEL/ASES
Kitplanes "Unairworthy" monthly feature
EAA Sport Aviation "Checkpoints" column
EAA Homebuilt Council Chair/member EAA BOD
Author "Pre-Buy Guide for Amateur-Built Aircraft"
www.Baselegaviation.com
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02-15-2013, 07:49 PM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Quote:
Originally Posted by PerfTech
....In theory that is correct, but if you do as we do and install a temporary gauge on the crankcase you will see that this is not the case. The pressure fluctuates considerably when the engine is running. If you crank your engine over with the starter (mags off) and place your hand over the breather you will feel the engine suck and blow on your hand as described.
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I'm sure a fast response sensor on an ordinary open breather will record pressure oscillation pretty close to a sine wave, for at least two reasons, maybe more. However, it will be all or mostly an oscillating positive pressure, with little or no negative component when running....blow-by is always adding to the crankcase gasses.
Your previous statement was "The major portion of the pressure reduction is accomplished via the pumping action of the crankcase as it volume changes throughout the rotation of the engine. The valve allows air to exit but not enter, thus creating a pressure drop.
Crankcase volume does not change. There is no driver for a negative case pressure merely by placing a reed valve in the breather line, as there would be with a single or opposed twin. Here the negative pressure source is external.
It's easy to prove or disprove, in the field, with an old mechanical gauge or with a transducer. Tap the breather line for pressure measurement. Record breather pressure with the reed valve connected to the exhaust pipe. As previously measured and posted here, the average will be negative. Now remove the reed from the exhaust tap and cap the tap fitting. Leave the reed connected to the breather hose, with the end formerly connected to the exhaust open to the atmosphere. Make another identical run. If your assertion is correct the mean pressure will be only slightly less negative. I say it will be positive. Care to wager a ten spot presented on bended knee at the next RV beer social?
__________________
Dan Horton
RV-8 SS
Barrett IO-390
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02-15-2013, 08:12 PM
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Join Date: Mar 2006
Location: Newport, TN
Posts: 7,496
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Quote:
Originally Posted by vic syracuse
No, not really. That is a standard brace for all of the Vetterman exhaust systems. The rubber hose allows for support without a "hard" connect that would cause the stresses you mention. Look at my pictures a few posts earlier.
Vic
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While the 10 looks different, my Vetterman braces hook to the engine. Looks like the 10 uses some sort of flex cable to minimize the stresses.
The brace in question is "inline" more or less with the rotational axis of the engine. I still say that ain't a good idea but hey you guys are the experts....
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02-15-2013, 10:50 PM
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Join Date: Feb 2009
Location: San Jose, CA
Posts: 164
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Quote:
Originally Posted by Brantel
While the 10 looks different, my Vetterman braces hook to the engine. Looks like the 10 uses some sort of flex cable to minimize the stresses.
The brace in question is "inline" more or less with the rotational axis of the engine. I still say that ain't a good idea but hey you guys are the experts....
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This is a little off topic for this thread, but I called and spoke with Larry Vetterman about this exact issue when hooking up the supports for the 4 pipe exhaust on my RV-7. He said that some of his systems are designed to be supported from the engine and some from the engine mount and was adamant that I follow his recommendation to support my system from the engine mount.
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02-16-2013, 05:40 AM
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Join Date: Mar 2006
Location: Newport, TN
Posts: 7,496
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Quote:
Originally Posted by beav
This is a little off topic for this thread, but I called and spoke with Larry Vetterman about this exact issue when hooking up the supports for the 4 pipe exhaust on my RV-7. He said that some of his systems are designed to be supported from the engine and some from the engine mount and was adamant that I follow his recommendation to support my system from the engine mount.
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Not talking about Larry's intended purpose for what he provides. He obviously knows what's best.
I am talking about how this mount is being used to "brace" that stub that has been welded to the exhaust.
Anyway, my opinion is worthless in this matter so back to the regular scheduled program... 
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02-16-2013, 06:31 AM
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Join Date: Oct 2005
Posts: 1,516
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Brantel,
The brace you are talking about was part of the installation before the stub was added. As you can see from the brown mark on the white engine mount it was merely moved over a bit to provide space for the reed.
Like Vic pointed out, it's a flexible connection where the stainless tubes on each side of the flexible hose are used only for attach points and serve as
an anti rotation brace that can be adjusted to different lengths.
The main support is the flexible steel cable attached to a flexible support from the top down.
The entire muffler installation moves around about a half inch in all directions
and is installed as per Vetterman instructions, hope that helps. 
Back to harnessing crank case vacuum.
__________________
Ernst Freitag
RV-8 finished (sold)
RV-10 Flyer 600 plus hours
Running on E10 mogas
Don't believe everything you know.
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02-16-2013, 07:27 AM
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Join Date: Sep 2006
Location: Townsend, Montana
Posts: 3,179
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I'm with Brian concerning the mount.
The mount itself does a good job of supporting stuff and still flexing. But by attaching the support between the engine mount and the reed valve tube, you are transferring all the load from the exhaust and heat muff to the tube weld.
Could be wrong. Give us a report in 100hrs.
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Retired Dam guy. Life is good.
Brian, N155BKsold but bought back.
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02-16-2013, 07:57 AM
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Join Date: Oct 2005
Posts: 1,516
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I don't have a picture from the other side but there is a ring clamp around the exhaust pipe hidden from view.
You can see the rusty little stub coming out from the right, that is the attachment flange. The stub is attached to it with yet another somewhat flexible stainless clamp to accomodate heat expansion.
__________________
Ernst Freitag
RV-8 finished (sold)
RV-10 Flyer 600 plus hours
Running on E10 mogas
Don't believe everything you know.
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