REFLECTOR: Continental info

[Bob Jackson (Jax Tech)]

Hello Don,

 

The Continental 550N has been a great engine for us.  We've got 400 hrs on
ours now and it's always run very smooth and very strong.  Even after two
years we're still tweaking the cooling, though, particularly because our
goal is to cruise at up to 85% continuous power (LOP) settings at up to 25
kft cruising altitudes.  Currently we can do that at low altitudes but only
up to about 65% power settings at 25 kft.  

 

Our (self imposed) cruising limitation is 380 deg CHTs which we're trying to
strictly observe for engine longevity.  We're having more trouble with the
2-4-6 co-pilot cylinder side (especially #2 which is right above the CP
turbo and right behind the oil cooler), and I think its because of the prop
airflow direction and how it creates a relative high pressure area under the
engine cowling on the CP side relative to the pilot side.  At 25 kft, 65%
and 380 deg for our hottest CHT, our oil temps are around 190 deg F .

 

Here are some shots of our cooling plenum.  Originally, we had a separate
little plenum built between the oil cooler and cylinder #2 (barely visible
in the third photo), to be fed from intercooler scoop fresh air.  But, we
couldn't get enough air in that way to keep the oil temperatures down.  So
instead, we cut the top out of that little oil cooler plenum so that it is
now fed directly from the CP-side plenum cooling inlet runner along with the
rest of the engine.  It is still important, however if you provide cooling
air to the oil cooler this way to make sure you also create an airtight seal
with fiberglass walls along the bottom and outside gaps between the oil
cooler and cylinder #2, so you don't lose top down cooling air pressure and
airflow between the cylinder fins.  In the third photo, you may be able to
see where we've cut away the top and the side of the oil cooler plenum that
used separate it from cylinder #2.

 

Overall engine cooling plenum with runners installed



 

Cooling plenum without inlet runners



 

Bottom and outer space between Cyl #2 and Oil Cooler must be blocked --
originally our oil cooler had a 'private' plenum, separately vented



 

Bob Jackson

Custom turbocharged IO-550N

N2XF

 

  _____  

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Don Johnston
Sent: Sunday, May 15, 2011 9:26 PM
To: reflector at tvbf.org
Subject: REFLECTOR: Continental info

 

Looking for some info on Continental IO550-N installs.

Specifically, pictures of cooling plenum installations and in particular,
the oil cooler ducting.

As for finished/flying aircraft, what kind of CHTs and oil temps are you
seeing?

Thanks!

Don Johnston
 

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