Here it is.
-- 
Paul Lamar ...No rotor no motor.

Paul,
  What is the size of the radiator in this drawing.

TIM Holt

The core frontal area is 470 square inches. If it is 2 inches thick
it would give a core volume of 940 cubic inches. About right for
a 300 HP 3 rotor. If you want to go to a 360 HP p-port 3 rotor you
night have to increase the height of the rad to about 20 inches
from the 16 inches shown which I think should still fit in
the stock cowl. An RV10 with 360 HP at sea level would be
a real nice 250 HP cruiser at 12,000 feet.

Make sure you plan for cowl flaps.