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  #21  
Old 09-08-2021, 08:48 AM
IowaRV9Dreamer's Avatar
IowaRV9Dreamer IowaRV9Dreamer is offline
 
Join Date: Jan 2005
Location: Marion IA
Posts: 1,116
Default my so far failed attempt

I've been trying to implement a leak free connection between front cowl and airbox using some of the ideas in this thread. My lower cowl snout is separately removable so it can be slid on to the cowl using a horizontal front-to-back motion. My thought was to attach a flexible hose to the lower cowl snout and it would fit into a closely shaped duct on the front of the FAB.

My first attempt used a 2.75" SCAT tube (wire removed for flexibility) that was clamped onto the snout. No pictures because cause it is too rough, and I had trouble getting good alignment between the two parts which would cause the tube to be wrinkled.

My question is - is 2.75" too small? The cowl snout inlet is about 4.25 x 2.2 inches, but with large radius corners, so something under 9 in2, maybe 8 in2? A 2.75" SCAT is only about 6 in2. Going up to 3" SCAT increases the area to 7 in2.

So my question is: does it matter? I don't want to go thru all this work and make a restrictive inlet.

I was wondering if going round was a dumb idea... maybe stick with a more rectangular shape on the flexible duct/sock.
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  #22  
Old 09-08-2021, 04:34 PM
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Bill Boyd Bill Boyd is offline
 
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Nothing wrong with "going round" IMO

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  #23  
Old 09-08-2021, 06:56 PM
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9GT 9GT is offline
 
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Default

I made my snorkel removable and extended the snout about 3", making a 3" round opening with an embedded 3" round aluminum tubing inside to accept 3" Scat. I also have a highly modified standard Van's FAB to accept the other end of the Scat. I don't have a photo of my FAB, but in the second picture, you can see the 3" aluminum tube in the snorkel snout.
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  #24  
Old 09-08-2021, 07:46 PM
wawrzynskivp wawrzynskivp is offline
 
Join Date: Feb 2018
Location: Incline Village Nv
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Default Rubber induction moldings

Edit: Should title this rubber molding of induction path. This wasn't induction molded.

My challenge was with a FM-200 on a Superior sump. Using the K&N filter yields very little room for anything. So my answer was to lay-up a kevlar/urethane filter body connecting the FM-200 to the inlet ring.

I suspect that there may be some collapse at high power and low airspeed. This seems evident by some oil imprints from the K&N on the inside of the cone. This could also be happening at/caused by high engine torque.

I did some estimates of airflow at high engine power and low DA then used a shop vac to try to produce that flow x 1.5. I did not see any cone collapse doing that test so I cannot be sure where the soft filter body-filter contact may be coming from.

If I were to be doing it again I would definitely lay some reinforcing rings into the circumference of the cone to stiffen against collapse without affecting lateral flexibility.
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  #25  
Old 09-09-2021, 03:47 PM
Jslow2 Jslow2 is offline
 
Join Date: Dec 2020
Location: Cement City
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Default

Would using the 90 degree elbow airflow performance sells beteeen the sump and the servo be an option?
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  #26  
Old 09-09-2021, 06:47 PM
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BlackhawkSP BlackhawkSP is offline
 
Join Date: Jun 2011
Location: Indianapolis
Posts: 299
Default

Quote:
Originally Posted by IowaRV9Dreamer View Post
I've been trying to implement a leak free connection between front cowl and airbox using some of the ideas in this thread. My lower cowl snout is separately removable so it can be slid on to the cowl using a horizontal front-to-back motion. My thought was to attach a flexible hose to the lower cowl snout and it would fit into a closely shaped duct on the front of the FAB.

My first attempt used a 2.75" SCAT tube (wire removed for flexibility) that was clamped onto the snout. No pictures because cause it is too rough, and I had trouble getting good alignment between the two parts which would cause the tube to be wrinkled.

My question is - is 2.75" too small? The cowl snout inlet is about 4.25 x 2.2 inches, but with large radius corners, so something under 9 in2, maybe 8 in2? A 2.75" SCAT is only about 6 in2. Going up to 3" SCAT increases the area to 7 in2.

So my question is: does it matter? I don't want to go thru all this work and make a restrictive inlet.

I was wondering if going round was a dumb idea... maybe stick with a more rectangular shape on the flexible duct/sock.


The Rod Bower set up I have uses a ring of roughly 1/4 inch neoprene (I think wet suit material) sewn together to make the flexible connection between an AL transition from the filter inlet to the front ring on the removable lower cowl inlet. It works great.
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