Here are some V6 powered Velocities. Timothy England's C-FUFM is flying, and Kurt Winker's N11LW will be flying soon.
N11LW Aluminum block 4.3L chevy. Aluminum heads & PSRU. Same weight (minus radiators) as an IO-360, but with a more forward CG. 340 HP, almost 700 ft/lbs of torque at the prop.
Upper & lower cowl after mods. It took quite a bit to make it fit & smooth. still waiting to finish off the aft end.
Upper Naca scoops are "XL" size on my 173. Lower NACA is slightly larger than the ones on the XL. Also shown are Hinge type cowl attach Mod. Very smooth and strong.
Lower Naca designed as a torque box through the firewall and gear bulkhead. Much stronger that without it. Fuel drain flush with the surface of the scoop.
(2) Aluminum radiators. 12"x6.5" core area. Shock mounted. Plenums allow air to expand w/minimal directional change along a smooth laminar curve. The connections between the radiators also use aluminum piping for additional cooling.
Link to Winker Velocity run video: http://www.youtube.com/watch?v=MT-0zHmcp9o