David-aviator
Well Known Member
On a recent cross country flight I recorded some engine numbers just to stay awake and maybe learn something about what was going on. That data indicated #1 and #4 CHT's were running about 20°F warmer than 2 and 3, wonder how come?
An oil change was due after that flight so things were checked over.
In front of #1 cylinder is an air deflector as per Van's baffle plan. It is about 2" tall and a similar device is installed at #2. I decided to trim the #1 deflector .75" from the top and see what gives. It is now about 1.25" tall and more air is available for direct cooling of #1.
Yesterday I finally had a chance to fly to see if it made a difference. It did. #1 CHT is down about 12F. The CHT's were 352,346,346,363 across the board.
OK, so what's going on with #4 now riding high compared to its neighbors?
It is the oil cooler stealing air from it. I have a remote oil cooler ducted with 4" scat as per the RV-10. When air flow to the cooler is shut off oil temp rises, like from 170 to over 190 and #4 CHT begins to drop.
For a change it all makes good sense, at least in stable cruise.![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
An oil change was due after that flight so things were checked over.
In front of #1 cylinder is an air deflector as per Van's baffle plan. It is about 2" tall and a similar device is installed at #2. I decided to trim the #1 deflector .75" from the top and see what gives. It is now about 1.25" tall and more air is available for direct cooling of #1.
Yesterday I finally had a chance to fly to see if it made a difference. It did. #1 CHT is down about 12F. The CHT's were 352,346,346,363 across the board.
OK, so what's going on with #4 now riding high compared to its neighbors?
It is the oil cooler stealing air from it. I have a remote oil cooler ducted with 4" scat as per the RV-10. When air flow to the cooler is shut off oil temp rises, like from 170 to over 190 and #4 CHT begins to drop.
For a change it all makes good sense, at least in stable cruise.