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  #11  
Old 08-17-2021, 02:43 PM
Bob Martin's Avatar
Bob Martin Bob Martin is offline
 
Join Date: Jan 2005
Location: Charlottesville, Virginia
Posts: 1,272
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Quote:
Originally Posted by motodave View Post
Thanks for the note Bob.

I wasn't sure if more volume above the engine is desirable or not and as you know the instructions are lacking... I'd like to avoid cooking my engine on the early flights. The intake holes look manageable (will need to cut a slit and bend upwards) but sealing the front of the plenum to the engine looks like a science project. I plan to get the standard baffles fitted and then see how the plenum fits that... then cut the hole for the oil cooler which per your post probably sets everything else.

How are your temps with the James Cowl/Plenum? Any pics of yours you could share?
Pretty sure the Vans baffeling has the cut out established, with the reinforcement doubler ring.
The first one I did rubbed in the center....so the shaking of the engine was not an issue in the rubbing department.
The front needs several fiberglass cloth layups to make it fit the baffels and create places to screw it on.
Yes I can send pictures....PM me with your email.
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RV-6, 0-360 Hartzell C/S, Tip up, 1200+TT
James extended cowl/plenum, induction, -8VS and Rudder. TSFlightline hoses. Oregon Aero leather seats.
D100-KMD150-660-TT ADI2- AS air/oil seperator. Vetterman exhaust with turndown tips.
Louisa, Virginia KLKU N94TB
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  #12  
Old 08-17-2021, 06:41 PM
motodave motodave is offline
 
Join Date: Dec 2018
Location: Littleton, CO
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PM sent...

The opening for the oil cooler is left to the builder.
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Dave
RV7 Slider N732DH reserved
I(O)360-M1B Thunderbolt
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Wiring 40% done
Was QB wings now will be slow build...
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Photo log: https://flic.kr/ps/9jjZz
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  #13  
Old 08-17-2021, 06:51 PM
BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
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Quote:
Originally Posted by motodave View Post
VAF,
I'm installing a Sam James plenum on my 7 with a I(O)360, James cowl and using the standard Vans baffles (I know that I need to modify these to adapt) to mount the plenum with screws/nut plates to secure it.

Question I'm not clear on is how high above the engine should it be, i.e. what is the clearance between engine and plenum? Should I just make this as high as possible? And, yes I will be mounting the oil cooler to the baffles at #4.

Appreciate any "experiences"!
There are different generations of the James plenums. The original was based on the RV4 so it has a hump in the center, this is the limit how high it will fit. Also being one piece, the angle of how it fit across the front may define the rake to the rear. This may push your oil cooler quite low. If that happens you may be better off remounting the oil cooler off the aft baffles, like on the mount or firewall.

Some of these constraints can be reduced with modification of the plenum. Pictures as you begin fitting would help with more accurate assistance.
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Last edited by BillL : 08-17-2021 at 06:54 PM.
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  #14  
Old 08-18-2021, 04:12 AM
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Capflyer Capflyer is offline
 
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Location: Gaithersburg, MD
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Set the height by lining up the inlets with your cowl which will set the height above the two front cylinders. Then the rear is set by keeping the height about the same over the rear cylinders. The oil cooler will either need to be angled down when attached to the rear baffle or remote mounted. Plenty of pics online to get a visual idea.
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  #15  
Old 08-18-2021, 07:19 AM
rockwoodrv9 rockwoodrv9 is offline
 
Join Date: Dec 2011
Location: Meridian ID, Aspen CO, Okemos MI
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Dave,
Bill built mine for me and I modified it to fit my engine and the James inlets. Here are a couple pics. PM me if you want more info. I am flying the next 2-3 days depending on weather so may not get back to you or I may have lots of time waiting weather to get across the Rocky’s!
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  #16  
Old 08-18-2021, 08:25 AM
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DanH DanH is offline
 
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Take a good look at the above photos. There are significant technical differences between this one (from Bill Lane) and most of the James plenums I've seen.

A plenum lid is fundamentally a sealing device, but it also has to satisfy the requirement to convert available dynamic pressure to increased static pressure. Good installations have a measured coefficient of pressure above 0.8, and I'm pretty sure that is true for Rockwood's above. Believe me, not all installs meet that criteria. The optimum case slows the incoming air to near stagnation with little turbulence. High velocity flow past humps and bumps and sharp changes of cross section is unlikely to meet that criteria. Here note the steady expansion and clean transitions.
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  #17  
Old 08-18-2021, 09:15 AM
motodave motodave is offline
 
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Location: Littleton, CO
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Rockwood's photos are very helpful.

Here's the plenum I have from James:
Untitled by [url=https://www.flickr.com/photos/daves_photo_log/]

My untrimmed baffles:
Untitled by [url=https://www.flickr.com/photos/daves_photo_log/]

And the plenum setting inside the baffles, obviously sits too low. Only good fit is around nose of engine. If I tip the back up then the center is way to high and inlets too low. If I align the inlets then the back is only a few inches from the #2 & #4 cylinders and no room for the oil cooler opening:
Untitled by [url=https://www.flickr.com/photos/daves_photo_log/]

I think I only have a couple of options: 1.) build from scratch (UGH!) or 2.) really hack up the plenum and re-glass the parts back together. I want to keep the oil cooler on the #4 baffle and want the plenum as high as possible. Thinking I need 1/2" clearance on top and at least that over the cylinders for engine shake. First step (today) will be to trim my Vans baffles so the top cowl just fits. Before any cutting I will call James and see if they sent the wrong one to me. <update> called Mona at James, based on pictures it sounds like I have the wrong plenum and they will correct it.

More pics to come....
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RV7 Slider N732DH reserved
I(O)360-M1B Thunderbolt
Empennage 100% Complete
Slow build Fuselage 95% done
Wiring 40% done
Was QB wings now will be slow build...
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Photo log: https://flic.kr/ps/9jjZz

Last edited by motodave : 08-18-2021 at 11:20 AM. Reason: James is helpful and going to fix it
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  #18  
Old 08-18-2021, 11:30 AM
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wirejock wirejock is online now
 
Join Date: Oct 2005
Location: Estes Park, CO
Posts: 4,671
Default Plenum

Keep us posted Dave.
I have a RV Bits plenum to install soon.
Any tips would be appreciated.
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Estes Park, CO
wirejock at yahoo dot com
Donated 01/01/2021, plus a little extra.
RV-7A #73391, N511RV reserved (2,000+ hours)
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Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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  #19  
Old 08-18-2021, 12:43 PM
scsmith scsmith is offline
 
Join Date: Jan 2008
Location: Ashland, OR
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Quote:
Originally Posted by motodave View Post
Rockwood's photos are very helpful.

Here's the plenum I have from James:
Untitled by [url=https://www.flickr.com/photos/daves_photo_log/]
.
Based on your pictures and BillL's comments above, it looks like this plenum is for the RV-4 with the hump in the middle. This is not a very good starting point for your application. I would see if you can find a different plenum that is more flat on top.

Also note, relative to DanH's comments about the shape of the inlet diffusion, that the plenum you have pictured has a rather abrupt diffusion rather than the gradual one that BillL made for RockwoodRV9.

Big picture, I think you want the upper plenum volume as big as you can make it without risking interference with the cowl. The large area (and assuming good inlet diffusers) leads to low flow velocities and high pressure in the upper plenum, which is what you want.
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  #20  
Old 08-18-2021, 09:23 PM
rockwoodrv9 rockwoodrv9 is offline
 
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Location: Meridian ID, Aspen CO, Okemos MI
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I can say that all temps are very close to each other with this plenum and cooler now that the mags are correctly timed. All green. My plenum is very close to the cowl. It doesnt touch, but about as close as you can get.
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Last edited by rockwoodrv9 : 08-18-2021 at 09:26 PM.
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