In a message dated 11/6/2004 8:28:35 PM Central Standard Time,
twobarons@saber.net writes:
I really do appreciate all the posts in
the last month or so on cooling and insight gained from Ada. However, I did
find it all a bit disjointed but was able to pull bits a pieces of info from
all the posts. This subject is very hard to verbalize, but I will
try.
Cyl.# 1- Always has been very cool (170
C)[340F] ,so it is a non issue.
Cyl# 2-The hottest (200[390F] to 210
C[410F]) in cruise. I actually had to replace it at 850 hours due to it being
"out of round".From the List I learned that you have to drive the air down
thru the FRONT on # 2, at the flat spot, where there are very small to
no cooling fins. This was very easy to do by cutting 3/4" off of the 45
degrees ramp that is actually touching the cylinder. This opened up a gap
about 1/4" directly in the front center of # 2. No air was going over the
front lower quarter of # 2. Now air is going over and under # 2. The result is
a 10 to 15 degree C drop in temp. The piece that I cut off has no structural
value to the baffling and looks like it was designed to force the air
up into the plenum area.
Cyl # 4- Always ran cool like # 1 ( I
need 4 ahead of 3 as a reference)
Cyl # 4 has a curved baffling
piece about 1/2" from the flat spot in the very rear of the engine
that allows air to be forced downward at the very place it needs the most air.Again, a
flat spot with very small if any cooling fins.
Cyl#3- Always hot like # 2. Looking at
the rear of # 3, you can see how the air cannot go through the top rear
of 3 # (guess what, the flat spot).It should be a fairly simple matter to make
the rear of # 3 look like the rear of # 4 ( a curved piece that stands off
from the top rear of # 3)
I'm sorry that this is so wordy, but
that is the nature of conversation. Also, I really love my airplane, but feel
that Lancair let us down in the design of the baffling. I will report on
the progress of # 3 next week.
Sincerely, Fred N. Baron, Lancair 9BF
(Don't fly like my brother)
Fred,
Verrrrry Interrrrresting!
I have slowly been attacking cooling and cooling drag forever.
So......
The latest configuration includes the use of silicon baffle seals instead
of the thin black weinie stuff Lancair supplies and expanding air intake ramps
to avoid the turbulence surrounding sharp cutoffs while slowing down the air.
Yesterday's flight was at 6500 ft(9800m) [6000 ft palt (1830m)], 40F
(4C), 30.44 Hg (1031mb). Ok, you have got to do the conversions (except
temp) from here on out. 180 KIAS (194 KTAS), 25.2" MAP, 2500 RPM,
172F (78C) oil temp.
The cooling air exit temperature was 126F (52C) for a rise of 86F
(48C). Upper/lower plenum pressure difference was 9.7" H2O and the lower
plenum/ambient pressure difference was about 2" H2O.
Other considerations:
1) Cyl #1 - has about a 4"x4" deflector on the front to raise the
temperature near to other cylinders.
2) Cyl #2 - has the leading edge deflector cut off, the lower fin wrap
moved fwd 1/4" (drilled new holes) and a deflector added to route some air down
below the "flat spot". This dropped the temp about 15 - 20F.
3) A separate ram air is supplied to injector shrouds (all
injectors are .022) that matches or increases the air pressure over
the manifold pressure to assist in equal atomization of fuel. This
maintains a less than a .3 gph spread between cylinders operating at peak
(so called "lean test").
4) I use a small oil cooler with a separate NACA duct supply although the
exit air is dumped into the common lower plenum.
After Cyl #1 peaked at 1370F, the mixture was enrichened to 10.3 gph and
the following stabilized temperatures were observed:
CHT EGT / CHT EGT in C
1 360 1260 182 682
2 370 1270 188 688
3 370 1280 188 693
4 390 1290 199 699
Note also I currently use the LASAR ignition system and ECI Cerminil
Cylinders which are finned slightly different than Lycomings (about 210 hrs of
use).
I now want to reduce the temperature of the new hot cylinder, cyl #4.
Is #4 running lean? It used to be the first to lean. I am looking at
exhaust shields (I have the type IV exhaust, front mounted throttle body),
although the cabin heat muff is on the #4 exhaust pipe. Maybe I will
forcibly direct some air over #4.
I also wish I had a more accurate engine monitor - more accurate than
the jumps reported by VM's EPI 800.
Scott
Krueger AKA Grayhawk
N92EX IO320 Aurora, IL (KARR)
Some Assembly
Required
Using Common Hand Tools and
Probes to Answer Burning Questions.