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  #21  
Old 10-05-2021, 06:06 PM
bjdecker's Avatar
bjdecker bjdecker is offline
 
Join Date: Jun 2005
Location: Georgetown, TX
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Quote:
Originally Posted by Kyle Boatright View Post
Check the link I posted earlier in the thread. There's a picture on that page which shows how to eliminate that hose.
Ahhh yes -- thanks Kyle.

Unfortunately that would interfere with the exit radius material. Also, it would seem that would impart more movement (read: stress) to the exhaust stacks as it is fixed to the firewall instead of hanging off the engine...
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  #22  
Old 10-05-2021, 06:20 PM
Kyle Boatright Kyle Boatright is offline
 
Join Date: Aug 2005
Location: Atlanta, GA
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Quote:
Originally Posted by bjdecker View Post
Ahhh yes -- thanks Kyle.

Unfortunately that would interfere with the exit radius material. Also, it would seem that would impart more movement (read: stress) to the exhaust stacks as it is fixed to the firewall instead of hanging off the engine...
Did you read the description on the web page? You still suspend the pipes from the engine or engine mount with flexible mounts. But you firmly mount the exhaust exits to hold the lateral spacing. The slip joints handle the relative movement.

Vetterman is pretty smart.

To make your exhaust fairing work, you'd just need to cut a couple of slots in it for the clamps.
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2001 RV-6 N46KB
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  #23  
Old Yesterday, 01:22 PM
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bjdecker bjdecker is offline
 
Join Date: Jun 2005
Location: Georgetown, TX
Posts: 884
Default Performance update...

Ok, I've had some time to fly with the modified cowl exit ramp and I am happy to report a pretty substantial decrease in CHT's, and modest increase in TAS/IAS.

Aircraft:
RV-7
Lycoming IO-360-A1B6 stock except for Dual Lightspeed PIIIs @ 20
Hartzell 7497-2 (72")

Flight Test Parameters:
6500Ft MSL, 30.05InHg
~17C OAT
2500RPM
~24"MAP (WOT)
9.8 GPH
60F LOP

--

Before:
CHT F 1: 312, 2: 340, 3: 312, 4: 294
Oil Temp: 190F
TAS 161Kts

After:
CHT F 1: 297, 2: 322, 3: 311, 4: 278
Oil Temp: 186F
TAS 165Kts

--

Your mileage may vary, but I'm liking the results and temperature margin that this widget provides.

Next changes(s):
Remove and replace horizontal exhaust stack brace with NACA 0024 shape -or- similar.
It's been suggested that using Vettermen's alternative firewall mount for exhaust stacks is the way to go, but I respectfully disagree; there's just too much lyco-shake going on and I fear the ball joints don't have enough range or ease of motion to absorb it.
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  #24  
Old Yesterday, 06:22 PM
scsmith scsmith is offline
 
Join Date: Jan 2008
Location: Ashland, OR
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Nice!

How did you get the 'before' data? It does not appear to be the same as the 'before' data you reported on with the original narrow aluminum prototype. Did you remove the first one, fly, then install the second one, and fly again?
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