the benifit is worth the trade-off. It is better to have a flat plate forceing the air to flow over or around the vehicle (somewhat predictable and managable flow path), rather than having that air go under the vehicle where all the unpredictable mess/drag/turbulence can occur.
My thoughts precisely! In my circle track days that was a major upgrade. We would form sheetmetal panels around the important parts to increase pressure/ala efficient volume and direct the heat out the back under the car. We also would panel in the underside of the engine compartment to help in this area. More directing less scooping.
Mike, I still need to make an access area for tech to verify the carby and I think I am going to fly it the way it is. On the test bench the engine would come into a rich setting after about two minutes and pick up 3-500 rpm. I have plenty of practice time for the next race.