Boots and cooling

Been having both cylinder and oil cooling issues.

The middle cylinders (3 and 4) were warm and getting into the yellow regularly on climb out.  I added some fins attached to the underside of the plenum top to push air down into the middle cylinders.  Worked extremely well.  Google Gemini helped me with this and was spot on.

The deflector is 2.5" wide, 2" long and bent on a 2" radius.

Gemini did such a great job, figured I would see what it would recommend for my oil cooling.  Gemini recommended building a diffuser.  So I spend a day and built what I felt it recommended.

The basic principle is the keep the air moving at high velocity and not just have it spill out into the lower pressure area inside the cowl.

Did not work.  Oil temps were hotter.  Luckily I attached it with screws, so taking it out what not a huge job.

But during the process, I discovered that the January 2026 version of the operations manual has increased the upper green limit for oil cooling from 212 F to 230 F (from 100 C to 110 C).  If this is the case, then I really dont have an oil cooling problem, but I would still like to get it better.

The plan for this week was to head to the Glasair Flyin at Smiley Creek Idaho.  The weather does not look good.  But, I wanted to get the rubber boots on the horizontal stab before going.

The local AMO where I sourced the boots educated me how they adhere them, so I followed that to the letter.  It did pain me to scuff sand my paint job, but it had to be done.

Last step is to edge seal the boot using PRC.  That is today's job.