oilsardine a écrit :
But in my case things would be much
easier (and streamlined) if I would feed the pressureized air from below and
let the hot stuff exit through the top cover of the cowling. It will be an
aluminun cowling, so heat is not such an issue.

Assume you mean tractor engine.
"Reverse" cooling has already been done. It can work, but the air is
pre-warmed when passing the exhaust pipes before reaching the cylinders
and heads. See for instance the Eze family.

NACA and NASA studies (Miley) have shown that this method generates a
little more drag than an equally engineered "normal" cooling.

So, unless you look for ultimate performance, you can do as you want.
BTW, where will the exhaust discharge ?

Best regards,
--
Gilles
http://contrails.free.fr