for the heat muffs and his thought was the heat may escape there as well.
They probably screw up the positive pressure situation more than anything.
That said..YES his dimensions are still working just fine all these years
later.
We also opened Bob White's O-360 Elite cowling up to be basically the same
size this spring and his is working great hauling Clamar 2200 amphibs around
the back country of Ontario.
Wayne
----- Original Message -----
From: "Gary Gustafson" <gargus@adelphia.net>
To: <rebel-builders@dcsol.com>
Sent: Tuesday, January 16, 2007 5:23 PM
Subject: [rebel-builders] Speed cowl exit air
I am currently working on my speed cowl and modifying it to increase
the amount of exhaust air. I have an O320 (160 HP) and it will be on
wheels,
but would like to plan for eventual floats. In that regard, back in July
2002, Wayne O'Shea wrote the following in an email:
"Rule of thumb!? Cut 'till the temps are right! But yes I have read in
many
places one and a half times the inlet. Didn't do any calcs when we did
Howard's. We just slit the MAM scoop down the sides and kept putting in
larger pieces of aluminum until the temps dropped to an acceptable limit.
It
was then glassed in at this size and the aluminum removed."
"Howard's main outlet is 4 1/4 x 14 1/2 = ~62 sq inches and then there is
about 12 square inches around each exhaust pipe, plus he added the two 1
1/2" x 5" shark gills for another 15 sq inches for a total of ~ 101 square
inches. Don't have a speed cowling here to measure the inlet size, but
I'll
guess at about 5" x 7" each side for a total of 70 sq inches. 101/70 =
1.44
ratio. If you have the measurements, what is the actual inlet square inch
number and the out/in ratio." (I measured and it is about 68 sq in.)
"On Bob's I just cut it out from one exhaust pipe to the other and forward
to about an inch behind the carb heat dump pipe. This is most likely a
good
200 square inches of outlet and seems to do the trick overly well.."
My questions are:
1) Does anyone know where to get ready made "shark" gills? It
would make increasing the exhaust flow a lot easier without making a big
exhaust plenum hanging down underneath the cowling as I have seen in some
pictures.
2) Did Howard's configuration provide sufficient cooling for his flying?
3) Has anyone had any over temp problems with about 100 sq in of exhaust
area?
4) Is it necessary to have an external carb heat dump pipe or am I
misreading the quote?
Thanking any and all for your assistance.
-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------
-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------