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  #1  
Old 09-29-2015, 10:59 AM
BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
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Default Sam James RV-7 Builders- need feedback

I built a replacement plenum cover for my SJ cowl (long). It uses epoxy with a Tg over 300F. The cooling inlet areas are increased by over 40% at the head, and the area flow diffusers are much smoother. It has a perimeter flange for attachment, can be removed without cutting a lot of RTV, the oil cooler can sit up high, and it weighs less than the rubber baffle material in the standard kit. A core material was added to the center section to substantially stiffen the structure.

It took way to much time and money just to make one. The question: would you be interested in buying one to help me offset the cost of the materials of development? If you are interested, send me a PM-Email and I will send a draft report with more details, and answer any questions. The plenum cover is very smooth on the top side as it is a female mold and vacuum infused with resin. The inlets are on bucks, and hand layups. The exterior would need bodywork to look as nice as the cover. I think your installation time of fitting to perfection would be very short. Parallel valve only, though. I have materials for 4-5 sets, and wish to do this while skills are still fresh.



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  #2  
Old 09-29-2015, 11:04 AM
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N941WR N941WR is offline
 
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Default

That is very nice!

I would order one but I have a short cowl on my -9.
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  #3  
Old 09-29-2015, 11:33 AM
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cka357 cka357 is offline
 
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Default

Bill,

This looks very nice. I wish I was far enough along to need one.

Chuck
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  #4  
Old 09-29-2015, 11:44 AM
BillL BillL is offline
 
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Default Hmmmmm

Quote:
Originally Posted by N941WR View Post
That is very nice!

I would order one but I have a short cowl on my -9.
Well, you have the 360, so probably already used the 7 engine mount, but the baffles?

I thought this might come up and don't have a ready answer as I am not aware of the geometry changes, the question . . is it closer to the engine or further? Also, do you already have the SJ plenum cover? If so and you have already cut down the baffles, would you be making some new pieces?

If you are serious, I could make some patterns of the side baffle profiles and send to you to check. If that works out, then I would send an early development piece (if you promise not to take a picture of it.) to see if it will fit. If the cover fits, then the next steps are the inlet transitions. My cowl is already 7/8" shorter. It might be that you could make a set of DanH style inlets from rubber and eliminate another 1.5 inches from the transition. Maybe the shorty could work just fine.

Gee - already sounding alike a bit of work, but could make a nice change.
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Lord Kelvin:
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and express it in numbers, you know something about it; but when you
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  #5  
Old 09-29-2015, 01:04 PM
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DanH DanH is offline
 
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Default

Quote:
Originally Posted by BillL View Post
I built a replacement plenum cover for my SJ cowl (long). It uses epoxy with a Tg over 300F. The cooling inlet areas are increased by over 40% at the head, and the area flow diffusers are much smoother.
And that, boys and girls, is what the inlet diffusers should look like.
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  #6  
Old 09-29-2015, 01:24 PM
aerhed aerhed is offline
 
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Default

Sure looks righteous. Are the angles on the starter ring temporary cowl supports?
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  #7  
Old 09-29-2015, 01:48 PM
BillL BillL is offline
 
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Default

Quote:
Originally Posted by aerhed View Post
Sure looks righteous. Are the angles on the starter ring temporary cowl supports?
Right you are! - - they allowed me to use the bolts as touch points for the upper cowl. That way it could be installed w/o the lower with some assurance of position for marking baffles, checking clearances etc.
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Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
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  #8  
Old 09-29-2015, 02:18 PM
JakeLewis22 JakeLewis22 is offline
 
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Default Nice job!

Bill,
Very nice work and as someone who had to rework a Sam James plenum, I can understand why you took on this task. The only thing I see that you may want to reconsider is the gap between the rear of the inlet ring and the front of the inlets on the platinum. When the engine shuts down it twist quite a bit and I think that your gap is not enough to allow for this movement.
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  #9  
Old 09-29-2015, 03:19 PM
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N941WR N941WR is offline
 
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Default

Quote:
Originally Posted by BillL View Post
Well, you have the 360, so probably already used the 7 engine mount, but the baffles?
...
Nope, I have the -9 engine mount. The -9 has longer gear legs than the -7 and they come out at a different angle. That is required to get the wing stalled in the three point position.

I could buy new baffles but the transition is so short it probably wouldn't make any difference as there isn't enough room for the air to slow down before it hits the cylinders.

I cut off the front of my plenum and fiberglassed it right to the nose of my engine so it is a perfect fit. That said, I like your solution.
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  #10  
Old 09-29-2015, 08:49 PM
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Default Interested

Bill,

I'm intersted, but VAF says you've exceeded your private message limit. Contact me offline.

David
ddalton536@gmail.com
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