lml@lancaironline.net Mailing List Archive

Randy,

I have a very similar layout to yours, yet have no problem with temperatures. All winter I run with the oil cooler air naca duct mostly plugged with a piece of foam. My oil temp seldom reaches 200 degrees. Oil cooler outlet dumps to lower cowl area like yours. See picture on my web page. http://home.comcast.net/~rbelshe/

I measured the air inlet and outlets from my cowl. I have no trouble with CHT, seldom see 375 degrees, even in climb. Cruising is 325-350 normally, lower on cold days.

Here is breakdown of my air portals.

Front air inlets 2.75x6.25x2 =34.4 sq in

Nose strut slot 4x8 =32 sq in

rear bottom outlets 2.5x5x2 =25 sq in (partially obstructed)

slot for exhaust pipe 12x0.4x2 =7 sq in

slots on top of mags 1x4x2 =8 sq in

outlet area total 72 sq in.

the "rear" bottom outlets and the slots on top of mags are reversed NACA ducts. I don't believe that NACA ducts work in reverse, but of course they do let some air out.

I have never seen another Lancair with slots over the magnetos like mine. I guess they help but don't know how much. Here is a picture.

This picture shows the air outlet area.

Bob Belshe
Moraga, CA
Lancair 235/320
http://home.comcast.net/~rbelshe/

From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of randy snarr
Sent: Friday, March 06, 2009 4:54 PM
To: lml@lancaironline.net
Subject: [LML] oil cooling

All,
I am looking for suggestions on how to lower my oil temps. I am running an IO 320 on the original 235 frame. On warm days in a climb I have trouble keeping them below 220. I usually have to flatten out the climb to cool things down if they get up to 230 or so. Once in cruise it is not a problem and they will settle around 210. I would like to get them down to 190 if possible. The problem is on a 75 plus degree day when the airplane is already warm from flying and I need to go again. I am picking up outside air on a naca vent on the left side of the cowl. There is a 6" length scat tube (4"diameter) connecting the cowl inlet to a glass expansion section that is connected to the cooler.(see pics). It just dumps in the lower cowl area.
I am running a Stewart Warner oil cooler that many have had success with.

I have tried larger hoses to the cooler now using -8's and also removed the 90 deg fittings I used to have to improve flow.
I suspect my ducting and or connection to the cooler could be improved. I am looking for suggestions that could be done without cutting the cowl.

Thanks in advance!

Randy L.Snarr

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