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Std vs. Aerobatic Engine Vibration Mounts

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Matt Dralle
Site Admin

Joined: 08 Nov 2005
Posts: 25858
Location: Livermore CA USA

Posted: Wed Aug 05, 2009 3:50 pm Post subject: Std vs. Aerobatic Engine Vibration Mounts

Dear Listers,



I've got an IO-390 to mount on the RV-8.  What are the pros and cons and opinions regarding the use of the "Standard" vs. "Aerobatic" engine vibration mounts?  I have a set of both and can't decide which to use.  Will there be more sag with the Std version over time?  Is the different in vibration noticeable?  Does having the larger engine make any difference in the selection?  What other gotchas are there between the two different types.



One other question.  Do they have a shelf life?  Does a set sitting in the box, on a shelf for 15 years have any noticeable reduction in "performance"?



Thanks for your feedback!



Matt Dralle

RV-8 #82880 N998RV

FWF Starting This Weekend!

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Matt Dralle
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Vanremog(at)aol.com
Guest

Posted: Wed Aug 05, 2009 6:50 pm Post subject: Std vs. Aerobatic Engine Vibration Mounts

Matt-

  

 One wearout mode besides compression set (sag) in these isolators is loss  of elastomeric properties over time due to outgassing of the natural  oils/emollients in the rubber compound.  This increases the durometer of  the compound over time and increases their transmissibility.  Aerobatic  mounts are naturally stiffer than standard isolators from the get-go.  IMO  you should buy fresh standard isolators and immediately coat them in DC4, then  you should dynamically balance your engine/prop combination.  They then  should last until engine TBO.

  

  N1GV (RV-6A  Flying 924TTAE Silicon Valley, CA)



  

  In a message dated 8/5/2009 4:51:38 P.M. Pacific Daylight Time,  dralle(at)matronics.com writes:

  	  Quote: 	
		  One    other question.  Do they have a shelf life?  Does a set sitting in    the box, on a shelf for 15 years have any noticeable reduction in    "performance"?

    

    

	


 

  [quote][b]

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martin(at)gbonline.com
Guest

Posted: Thu Aug 06, 2009 5:12 am Post subject: Std vs. Aerobatic Engine Vibration Mounts

---

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martin(at)gbonline.com
Guest

Posted: Thu Aug 06, 2009 5:20 am Post subject: Std vs. Aerobatic Engine Vibration Mounts

Listers,

I now have 1000 hours on my 390 installation.  I will be happy to comment 

via telephone (at)920 619 6968.

Dick Martin

RV8 N233M

---

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martin(at)gbonline.com
Guest

Posted: Thu Aug 06, 2009 5:21 am Post subject: Std vs. Aerobatic Engine Vibration Mounts

I now have 1000 hours on my IO-390 from Barrett Performance AC.  I used the 

aerobatic mounts because I noticed on my old  IO360 on my RV8 that there was 

some sag.  As of this date their is no sag with the aerobatic mounts.  Also 

there is no descernable difference in vibration etc.  The alignment of the 

engine within the cowl shows no difference.

I did use a shim washer under one of the mounts to achieve perfect alignment 

of the engine within the cowl.

Note, I also use a Aerocomposites 74" Carbon fiber prop with  a Sam James 

cowl and plenum.  More speed and less weight.

Dick Martin

RV8 N233M

If you want to discuss, call me (at)9206196968

---

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JohnInReno

Joined: 08 Sep 2007
Posts: 150

Posted: Thu Aug 06, 2009 6:44 am Post subject: Std vs. Aerobatic Engine Vibration Mounts

What is DC4? 

 

 John

 

 Vanremog(at)aol.com (Vanremog(at)aol.com) wrote: [quote]            Matt-

    

   One wearout mode besides compression set (sag) in these isolators is loss of elastomeric properties over time due to outgassing of the natural oils/emollients in the rubber compound.  This increases the durometer of the compound over time and increases their transmissibility.  Aerobatic mounts are naturally stiffer than standard isolators from the get-go.  IMO you should buy fresh standard isolators and immediately coat them in DC4, then you should dynamically balance your engine/prop combination.  They then should last until engine TBO.

    

      N1GV (RV-6A Flying 924TTAE Silicon Valley, CA)

   

    

   [b]

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John Morgensen
RV-9A - Born on July 3, 2013
RV4 - for sale

Vanremog(at)AOL.COM
Guest

Posted: Thu Aug 06, 2009 8:34 am Post subject: Std vs. Aerobatic Engine Vibration Mounts

http://www.aircraftspruce.com/catalog/cspages/dc4.php

  

  

  

  In a message dated 8/6/2009 7:45:18 A.M. Pacific Daylight Time,  john(at)morgensen.com writes:

  	  Quote: 	
		  What is    DC4? 



John



Vanremog(at)aol.com (Vanremog(at)aol.com) wrote:     	  Quote: 	
		            Matt-

      

     One wearout mode besides compression set (sag) in these isolators is      loss of elastomeric properties over time due to outgassing of the natural      oils/emollients in the rubber compound.  This increases the durometer      of the compound over time and increases their transmissibility.       Aerobatic mounts are naturally stiffer than standard isolators from the      get-go.  IMO you should buy fresh standard isolators and immediately      coat them in DC4, then you should dynamically balance your engine/prop      combination.  They then should last until engine TBO.

      

          N1GV      (RV-6A Flying 924TTAE Silicon Valley, CA)



      





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  [quote][b]

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AV8ORJWC

Joined: 13 Jul 2006
Posts: 1149
Location: Aurora, Oregon "Home of VANS"

Posted: Thu Aug 06, 2009 9:04 am Post subject: Std vs. Aerobatic Engine Vibration Mounts

It is silicone in a tube and often used when installing O rings.  

   

John  

       

From: owner-rv-list-server(at)matronics.com [mailto:owner-rv-list-server(at)matronics.com] On Behalf Of John Morgensen

 Sent: Thursday, August 06, 2009 7:42 AM

 To: rv-list(at)matronics.com

 Subject: Re: Std vs. Aerobatic Engine Vibration Mounts  

  

  

   

What is DC4? 

 

 John

 

 Vanremog(at)aol.com (Vanremog(at)aol.com) wrote:     

Matt-  

    

   

    

One wearout mode besides compression set (sag) in these isolators is loss of elastomeric properties over time due to outgassing of the natural oils/emollients in the rubber compound.  This increases the durometer of the compound over time and increases their transmissibility.  Aerobatic mounts are naturally stiffer than standard isolators from the get-go.  IMO you should buy fresh standard isolators and immediately coat them in DC4, then you should dynamically balance your engine/prop combination.  They then should last until engine TBO.  

    

   

      

N1GV (RV-6A Flying 924TTAE Silicon Valley, CA)  

  

    

   

  

   [quote]  [/b][/b][/b][/b][/b][/b]http://www.matronics.com/Navigator?RV-List[/b][/b][/b][/b]http://forums.matronics.com[/b][/b][/b][/b][/b]http://www.matronics.com/contribution[/b][/b] [b]

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Dale Ensing

Joined: 11 Jan 2006
Posts: 571
Location: Aero Plantation Weddington NC

Posted: Thu Aug 06, 2009 4:26 pm Post subject: Std vs. Aerobatic Engine Vibration Mounts

DC4 is Dow Corning 4 compound. 

  

 see : http://www..aircraftspruce.com/catalog/cspages/dc4.php

 [quote]   ---

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