REFLECTOR: IO550-N intake

[Bob Jackson]

Don,

 

We have only ~1/8" clearance between our IO-550N 5 & 6 intake tubes and the
plenum, and the plenum top barely rubs against the bottom of the top cowling
in flight.  We did not have to bubble our top to achieve this clearance.  If
you aren't already flying maybe you should check the placement of the engine
mount on the firewall, or consider shimming it down.  

 

Also, over time if your installation is like ours, the engine will slowly
sag at the rear an 1/8 or 1/4" -- so we've had to shim our engine mount
bottom legs on the firewall up/out a couple of times over 500 hours to keep
the prop perfectly centered in the cowling hole.  You might be able to shim
the engine mount angle down (probably 1/8" aluminum shims under the top two
engine mounts will bring your #5 & 6 intake tubes temporarily below the
upper cowling) -- then in a couple of hundred hours, as the engine sags on
the mounts, you can take the shims out and still have the prop centered.  

 

We haven't been able to detect the effect of the change in angle of the
thrust vector caused by an 1/8" shim and tilt change (up or down) has on
cruise speed -- cruise speed doesn't seem to be particularly sensitive to
small tilt changes like that.

 

Bob Jackson

Turbo 'Cross Country' XL/RG

N2XF

 

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From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Don Johnston
Sent: Friday, October 07, 2011 6:47 PM
To: reflector at tvbf.org
Subject: REFLECTOR: IO550-N intake

 

The intake tubes on my IO-550N cylinders 5 and 6 are just barely keeping my
upper cowling from closing completely. Rather than create a couple of
bubbles in the cowling, does anyone know if it's possible to get custom
intake tubes? Or if it's possible to modify the existing tubes.

Don Johnston
XL-RG (with an installed engine!) 

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