Here are some more pics that show it better I hope. All I really did was add and extension with a bit of a drop to the rear of the cowl. I stole the idea from some of the Cub guys here in Alaska. I'm not a Cub guy but apparently for one of the mods of float installs there is a similar cowl extension required.
I am not an engineer either, but the cowl airflow depends on both the ram air at the front and the exit flow. If you have a cowl that does not allow good flow at the exit as I did then an extension may help. With my cowl in it's original configuration It stopped about 3 inches short of the firewall and I suspect that was creating some back flow and relatively high pressure, By adding the extension with the sweep down as well the air flows smoothy over the bottom cowl and and, more or less like a wing, creates a lower pressure behind it.
Anyway, that seemed to greatly increase the flow of air through the engine compartment and over the oil cooler without much if any loss of airspeed.
Hope this helps,
Scott
