#2 was also my hottest cylinder.  First I installed the cupped insert that was listed in one of the on-line articles that allows the air to flow around the shallow fins on the oil cooler side of #2.  I learned that TCM cylinders have asymmetric depths on the fins on the left vs right sides.  The left sides have very deep channels between the fins, while on the right side the cylinder barrel comes right up to the top of the cooling fins.  This means that the oil cooler box effectively blocks the cooling air from going around to the lower right side of the cylinder. 

However, even with the cupped insert, #2 was still my hottest.  At that point I remembered that my engine, which I got from a salvage of Adam aircraft inventory, came with a piece of baffling for the oil box that had a scoop installed inside the oil box that directed air around to the lower right side of the cylinder.  The scoop was ¾” deep at the top and flush at the bottom, and about 3” wide.  I moved this scoop from the discarded Adam baffling piece onto the Lancair oil box (the hole was nearly the same size as the previous dished shaped part I had installed before).  Not only did this solve my #2 CHT problem (it is now one of my coolest cylinders), but it did not noticeably affect oil temps.  A win-win.

Looking for advice for this problem.  Oil cooler door may help a little but the trade off of oil temp increase vs CHT increase is a trap at high power climb and in slow flight.  Two hours of flight time and problem is consistent up to about 8,000 or 9,000 ft.  One idea suggested is to fair the inside top of the intake cowl on the left side because turbulence here will decrease the airflow to the top left side of the engine.  One person indicated he did this with a IVP and achieved a 20 degree drop in EGT by doing this. 

Anyone else have experience with that?

Thanks in advance and to those who have sent congratulatory emails.

Regards,

John Barrett, CEO

Leading Edge Composites

PO Box 428

Port Hadlock, WA 98339

www.carbinge.com