Question... Scott, have you looked at the "automatic" alternate air system
specified in the IV construction manual and found it deficient?

Answer... YES, it's deficient.  The alternate air door does open if
operating correctly; however the hot cowl air causes hot CHT's even at full
rich in most installations.  So unless you want to toast your engine you
have to pull back on the power, not what you want when you're taking on ice
in the soup.  I've been there many times.

Larry Klaas

Larry, I'll defer to your experience, but this doesn't make sense-from an
engineering perspective-to me.

Bob Pastusek