Butch:

There seems to be no issue with running CHTs cold.  Lycoming says that the minimum operational CHT is 150dF.  That's pretty low.  The issue is the oil temp.  Getting the oil temp up is, in fact, important.  The problem is that altering the airflow into the cowl with anything has unexpected results and they are not even.  The changes in airflow and the creation of hot and cold areas around cylinders is very unpredictable and can cause serious problems.

I do not alter the airflow into the cowls and let the CHT's run cool. I put a little tape over the oil cooler to bring the oil temp up.  Based on the science and the testing, this properly addresses both even CHTs and adequate Oil temp.

Walter

Bill:

I have noticed that the standard, old, stand-by grey duct tape leaves a minimal residue upon removal.  I've started using the aluminum tape and it seems to come off a little cleaner.  What has been your experience?

Walter

Walter,

I read with interest your description of your research on CHTs. I own a Bonanza (E225 engine) and noted that you stated that Bonanzas are OK except for two cylinders. Which cylinders are those? I have noted several patterns in CHTs and am curious to hear which cylinders  are most affected by poor cowling and what cowling changes may diminish the problem.
Thanks in advance.