|
Today I finished installing the firesleeve on the
remaing fuel lines, made some stand-offs so that the fuel lines would not be
right up against the engine, and finished hooking up and securing a few other
items. With the top cowling off, I ran the pumps for a minute, then
checked for leaks...none found. Then I started the engine and ran it for
20 or so seconds and shut it down and reinspected for fuel leaks. None
found. I restarted and taxiied away from the hangar a bit so as to not be
as loud for others in and near the hangar and did a full power runup. I
hit 5600 static rpm's. In the past, the best I could hope for was 5200, most of
the time settling for 5100 rpm's. I taxiied back in and installed the top
cowling....max rpm's 5100. Took the top cowling back off....max rpm's
5600. One more try....5100 with the cowling back on. It is beginning
to become more clear to me, that one of two things are affecting rpm's.
Option one is that with the top cowling on the engine is ingesting heated air
and just cannot develop the same power as when it ingests outside unheated
air. Option two is the muffler bearing may be worn. I'm kinda
leaning toward option one.
I was thinking of
installing two small NACA ducts on the bottom of my cowling with two hoses
coming up to feed air to my TWM throttlebody. The NACA ducts I purchased
from Van's RV (made for cowling ventilation) already have a male outlet already
molded in the assembly, so you just slide a hose over it and secure with a
clamp. Very simple installation.(Works well for my cabin ventillation) If I
recall correctly, they are about the same size as my throttle body bore. I
wonder if I will loose much efficiency as the air goes through the corregated
hose, and if the Van's RV ventillation NACA ducts will provide a sufficient
volume of air. Of course while flying, I would have the advantage of a little
bit of ram effect as well as the ability to suck in fresh outside air that has
not been heated inside the cowling during taxi/takeoff run. Any
opinions/suggestions would of course be much appreciated. I will discuss
the vapor lock issue in the next post, so as to not complicate responses,
etc. Thanks to all who reply. Paul Conner
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.300 / Virus Database: 265.8.8 - Release Date: 2/14/2005
|