lml@lancaironline.net Mailing List Archive

[ photos re-compressed -Rob ]

-------- Original Message --------

Subject:	Baffling solved?
Date:	Tue, 7 Sep 2004 11:36:27 -0700
From:	Carl Cadwell <CarlC@Cadwell.com>
To:	<lml@lancaironline.net>

Baffling solved?

<<baffling 003.JPG>> <<baffling 004.JPG>> <<baffling 009.JPG>> <<baffling 010.JPG>> <<baffling 013.JPG>> <<baffling 014.JPG>>

I listened with great interest to the baffling questions, saw the posts, read Walter’s responses, understood what was taught at the Advanced Pilot’s Seminar, looked at the current baffling in my engine, drew some conclusions and tried some changes. I am greatly appreciative of all the discussion and participants. Disclaimers: I am not an engineer, have no vested interested in anything but my Lancair and have not bones to pick.

I have a TCM TSIO 550 E with Lancair firewall forward kit from late 2000 on a IVP with 620 hours.

I had already upped my fuel flows at WOT to 43 gph. I also see 32 gph at 2500 rpm and 31” MP. (This is a critical part of keeping the engine cool as the TCM settings are most likely too low of fuel flows to keep the engine cool. I learned this from George Braly.)

Problem: Number 2 and 5 run hotter. Can’t climb at full power more than a 4-5 minutes before the head temperatures start climbing excessively, esp. #5.

Problem: The barrels come to the edge of the cooling fins on all cylinders at the biggest finned area about 2” wide.. This is a problem on number 2 and 5 where the baffling is tight against cylinders blocking airflow over the 2”.

Solution: Get more air around the front side of #5 and the rear side of #2.

Picture 003 and 004 shows the swaging of the baffling of #2 cylinder. 003 is the cylinder side and 004 is the inside of the oil plenum. I did not want to cut a hole and violate the plenum for the oil cooler. If I had cut a hole as seen on an earlier post I had no clue what this would have done to the airflow or my ability to control the oil temp. The swaged area is 2.125” wide and 3.5” tall and ¼” in depth at the center. Picture 009 is the pattern used in creating the cavity to shape in a board. I pounded the aluminum with curved oak piece of hand railing. Note also that I beveled the walls and clamped the baffle to the board with angle iron.

Picture 010 shows the hole I cut in the front baffle of #5. The hole shown is 1” x 2.125” and is too big. I subsequently covered ½ the hole so it is now ½” by 2.125”. This seems to be about right, perhaps still a little cooler than it needs to be. If you are wondering how I cut this, I did not remove the baffle or the alternator. I used a dental high speed handpiece with a fluted carbide burr. (Nice to have a dentist/son in the family.) About 10 minutes to make this mod. Picture 013 Now look at what Lancair has done on their production baffling for the last 8 months. Their hole on #5 is higher than mine. The top of the hole is just at the point where the barrel of the cylinder closes off the air from the cooling fins. I like their solution better. Picture 014 They have also moved the oil plenum behind #2 rearward about ¼” and modified the other attached baffling to reposition it back to the cylinders. I suspect that this is a very good solution also. Maybe someone on the list flying with these mods can share how these work.

Results: I can now climb full power to 13,500 with the highest CHT at 340 degrees. 150-155kts IAS, 1800-2000fpm (This is as high as I have climbed since the mods last week.) I will test this to FL 240 in a trip later this week. In cruise at 8500’ 32”MP, 2470 rpm, 17.2 gph, OAT 10C, TIT 1522