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SJ Cowl with Standard baffles

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robin1(at)mrmoisture.com
Guest

Posted: Sat Oct 17, 2009 12:53 pm Post subject: SJ Cowl with Standard baffles

Is there anyone out there flying the Sam James Cowl but using standard baffles in place of a plenum? If so can you please share your comments / results?  

I have committed to the James cowl on my 8A but don’t want to deal with a Plenum (again).  

   

Thanks,  

Robin  

   

RV-4      Sold  

RV-6A   Sold  

RV-10    Flying  

RV-8A   Engine hung  

   

      [quote][b]

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pitts_pilot(at)bellsouth.
Guest

Posted: Sat Oct 17, 2009 1:46 pm Post subject: SJ Cowl with Standard baffles

I plan on a plenum for my -10.  What was so terrible about your 

experience???

Linn

do not archive

Robin Marks wrote:

 	  Quote: 	
		   Is there anyone out there flying the Sam James Cowl but using standard 

 baffles in place of a plenum? If so can you please share your comments / 

 results?

 

 I have committed to the James cowl on my 8A but don’t want to deal with 

 a Plenum (again).

 

  

 

 Thanks,

 

 Robin

 

  

 

 RV-4      Sold

 

 RV-6A   Sold

 

 RV-10    Flying

 

 RV-8A   Engine hung

 

  

 

 *

 

 

 *

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robin1(at)mrmoisture.com
Guest

Posted: Sat Oct 17, 2009 4:18 pm Post subject: SJ Cowl with Standard baffles

Linn,  

      If you plan on using a plenum with your standard Vans cowl then I have no data for you but if you plan on installing a James Cowl & plenum then be forewarned that there are significant cooling issues for both the cylinders & oil that may be extremely time consuming to resolve while receiving no additional speed benefit. The issues stem from not having enough pressure on the upper deck driving down the cooling air to the lower section of the engine and out to bottom of the cowl. There are a number of us James/Plenum owners working on these cooling issues as well as trying to fly LOP. Because of the pressure issues flying LOP is all but impossible and we as a group are considering adding expensive & complicated Turbo Pressure rails to counteract the pressure issues plus a few other small fixes. None of us is able to fly LOP right out of the box like many if not most standard cowl/baffle builders.  

      As you asked specifically about the Plenum I have to also say that it seems an airtight plenum is a requirement. No sloppy work can be allowed around here. With a well sealed plenum you have basically no access to the top of your engine w/o both removing the top cowl and then the plenum. It takes me a minute or two to remove my top cowl. Probably 15 minutes to remove and another 15 minutes to install the plenum. Plus what seems like a lot of additional wear & tear. I was considering an all aluminum plenum for my 8A with a hinged center column so I could have quicker access to the cylinders but after much thought I was soooooo much happier with my 4 & 6A and standard baffles. AKA the good old days. As I have already sold my 8A cowl and committed to buy the James cowl I was thinking of trying a James cowl w/o the plenum and wanted input from anyone that may have gone down this path before.  

      One last word for you Linn as a -10 builder. I am flying now with most of the construction behind me and a beautiful airplane to enjoy but the whole James Cowl & Plenum has been a huge mistake FOR ME and I am strongly considering replacing it with a Vans cowl. That is a drastic step for a flying (and painted) plane. I would never consider this if I could control my temps and fly LOP. I have not made a final decision so please take this as another data point before you commit one way or the other. Feel free to contact me off-list if you have further questions.  

   

Robin  

Robin (at) painttheweb.com  

   

   

   

--

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pitts_pilot(at)bellsouth.
Guest

Posted: Sat Oct 17, 2009 5:28 pm Post subject: SJ Cowl with Standard baffles

Robin Marks wrote:

 	  Quote: 	
		   Linn,

 

       If you plan on using a plenum with your standard Vans cowl

I am.
	


  then I

 	  Quote: 	
		   have no data for you but if you plan on installing a James Cowl & plenum 

 then be forewarned that there are significant cooling issues for both 

 the cylinders & oil that may be extremely time consuming to resolve 

 while receiving no additional speed benefit. The issues stem from not 

 having enough pressure on the upper deck driving down the cooling air to 

 the lower section of the engine and out to bottom of the cowl. There are 

 a number of us James/Plenum owners working on these cooling issues as 

 well as trying to fly LOP. Because of the pressure issues flying LOP is 

 all but impossible and we as a group are considering adding expensive & 

 complicated Turbo Pressure rails to counteract the pressure issues plus 

 a few other small fixes. None of us is able to fly LOP right out of the 

 box like many if not most standard cowl/baffle builders.

I want the plenum so that ALL the cooling air goes through the cylinders 
	


and oil cooler, not around them.  Cowl seals are poor at best when new, 

and go downhill fast with age.

 	  Quote: 	
		   

       As you asked specifically about the Plenum I have to also say that 

 it seems an airtight plenum is a requirement. No sloppy work can be 

 allowed around here. With a well sealed plenum you have basically no 

 access to the top of your engine w/o both removing the top cowl and then 

 the plenum. It takes me a minute or two to remove my top cowl. Probably 

 15 minutes to remove and another 15 minutes to install the plenum. Plus 

 what seems like a lot of additional wear & tear. I was considering an 

 all aluminum plenum for my 8A with a hinged center column so I could 

 have quicker access to the cylinders but after much thought I was 

 soooooo much happier with my 4 & 6A and standard baffles. AKA the good 

 old days. As I have already sold my 8A cowl and committed to buy the 

 James cowl I was thinking of trying a James cowl w/o the plenum and 

 wanted input from anyone that may have gone down this path before.

I'm aware of the access problem ..... but I tend to only want access to 
	


the top of the engine during the conditional inspection ..... unless 

something breaks.

 	  Quote: 	
		   

       One last word for you Linn as a -10 builder. I am flying now with 

 most of the construction behind me and a beautiful airplane to enjoy but 

 the whole James Cowl & Plenum has been a huge mistake FOR ME and I am 

 strongly considering replacing it with a Vans cowl. That is a drastic 

 step for a flying (and painted) plane. I would never consider this if I 

 could control my temps and fly LOP. I have not made a final decision so 

 please take this as another data point before you commit one way or the 

 other. Feel free to contact me off-list if you have further questions.

I will be in touch further on.  Thanks for the comments.
	


Linn

[quote] 

  

 

 Robin

 

 Robin (at) painttheweb.com

 

  

 

  

 

  

 

 --

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