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  #1  
Old 05-22-2011, 10:37 AM
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miyu1975 miyu1975 is offline
 
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Default fabing my Plenum

Thought I would share the beginning of my plenum building..Last night I cleaned and waxed the mold (made from upper interior cowl) and layed 4 layers of S glass. I just got finished pulled the dried epoxy/glass and I am pretty happy with the initial results. It will need a little modifying, but all in all, very good so far....more to come...

the Mold.



While pulling out of the mold...it released very easily and I only cut myself a few times on the edges






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  #2  
Old 05-22-2011, 10:40 AM
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Default

Looks great!
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  #3  
Old 05-23-2011, 01:38 PM
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miyu1975 miyu1975 is offline
 
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Default

thanks Bill..

I little more progress here. Cleaned up the edges and fitted it to the baffle...mostly.. Still some work to do on the left side rear, there is a gap and I have not decided how I am going to handle this yet. Also, I need to rework the inlets and widen them about an inch.. Haven't decided the best plan of action there either yet.

Left side rear gap.





I am thinking possibly to cut on the line here and move the outer piece where I need it and then lay glass over the gap.. ??





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  #4  
Old 05-23-2011, 01:51 PM
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Default

Ryan,
I'm very interested in following your methods and progress on this project. Please keep the details coming! Do you have a website or more pics somewhere online?
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  #5  
Old 05-23-2011, 02:09 PM
scsmith scsmith is offline
 
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Default just scarf the edges and lay on more glass

Your idea for the inlet widening is fine. Just grind the edges down to a thin edge, creating a tapered lap joint with the new glass.

Same thing for the gap in the back. You can tape a piece of cereal-box cardboard inside to form the shape a little bit, cover it with packing tape, and build up glass over it to extend the edge of the plenum out to where you need it. Again, just grind a scarf angle on the original glass to bond to.

The tricky part is going to be making the rubber boots to seal the plenum to the cowl intakes. Dan Horton has made some interesting reinforced rubber parts, you might check out his postings
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  #6  
Old 05-24-2011, 03:26 PM
Pilottonny Pilottonny is offline
 
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Question Benefit??

Hello,

Can anybody explain to me what the benefit of this is?? To me it looks a lot more work, more weight and less access to the top of the engine than the standard setup with rubber baffle seals against the inside of the cowling.

Regards, Tonny.
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  #7  
Old 05-24-2011, 03:56 PM
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Quote:
Originally Posted by Pilottonny View Post
Can anybody explain to me what the benefit of this is??
The elimination of leakage, which has a host of benefits.

Quote:
To me it looks a lot more work, more weight and less access to the top of the engine than the standard setup with rubber baffle seals against the inside of the cowling.
All true......there's no free lunch.
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  #8  
Old 05-24-2011, 04:08 PM
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Default Very cool

Love using the top as the mold! I am one step behind and now rethinking the project to mold my top the same way.

Great work!
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  #9  
Old 05-24-2011, 04:23 PM
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hevansrv7a hevansrv7a is offline
 
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Default A further question

I think I understand the purpose. I have a SJ plenum under my SJ cowl. However, if I understand both the principles and the design of the SJ version, there is more to it than just reducing leakage.

As I understand it, as the air enters the volume above the cylinders, it is expanded because of the difference in intake area versus volume, taking into account speed. The speed is thus reduced. As I understand that, reducing the speed increases the pressure. The increased pressure is supposed to aid in the transfer of heat from the aluminum to the air. And so on.

In addition, the SJ version is gradually greater in volume toward the rear, an apparent technique for managing cooling rates of the individual cylinders. On mine, it seems to work quite well.

So my question is whether or to what degree that whole subject was applied to this design. To my unpracticed eye and taking the description of the use of the cowl and the mold, it was not. Lost opportunity?
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  #10  
Old 05-24-2011, 04:30 PM
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Default

Quote:
Originally Posted by Pilottonny View Post

Can anybody explain to me what the benefit of this is??



... also locks all baffles preventing cracks in oil cooler corner by stiffening it


Looking good Ryan just watch that gap between the cowling and plenum by the prop.
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