Here is a technique that we have used for years to improve cooling on various aircraft. It is fairly time consuming but if you do it yourself to avoid the labor it is very inexpensive.
Keep in mind that the baffle components are intended to serve two purposes. First is to direct the flow of cooling air to the items you want cooled (cylinders, fuel pump, alternator, oil cooler, etc.) and second is to create a high/low pressure differential inside the cowl. Any air flowing from the upper deck (air inlet side) to the lower deck (cowl flap/outlet side) that is not routed properly is not only providing limited cooling, it is also evening the pressure differential, impacting overall airflow and cooling. In addition to using optimized baffle parts like the #3 baffle mod that is the topic of this thread, here is the process that we have had a great deal of success with.
1) Remove the cowl.
2) Get a flashlight.
3) Turn off the lights.
4) Using the flashlight, work your way around the engine looking down from the top while shining the flashlight up from the bottom. Any small (or large) gap or hole that air can escape through will be easy to spot and make note of.
5) Repeat looking up from the bottom with the flashlight on top. Make note of all of the places the light leaks through.
6) Use RTV silicon to plug up all of the holes that do not contribute to cooling the parts that need cooled. Common places are between the baffle and engine block, corners where the baffle makes turns, inter-cylinder baffles between 1-3 and 2-4, down where the baffle meets the engine block, and near the prop governor controls.
7) Place the upper cowl on the plane.
8) Looking in through the inlets at the front of the cowl, use the flashlight to identify any place where the silicon baffle does not press against the cowl.
9) Sometimes cutting a slit is enough to close up the ruffles potato chip style wrinkles.
10) For gaps that can not be easily sealed, apply enough RTV silicon to slightly over fill the gaps.
11) Put a layer of saran wrap over the RTV, then re-install the cowl.
12) Wait for the RTV to dry and peal the saran wrap off. The cowl should now have a perfect fit to the baffle.
13) Ensure that anywhere the silicon baffle overlaps it overlaps in a direction that will not cause it to flap open in flight.
If you aren't used to working with RTV in this way it can end up looking awful. Once you get used to working with it the result can be both very effective and very tidy.
