University of Cincinnati Supermileage: Bye Bye Fins

With emphasis on dropping weight, we were considering milling most of the Briggs block (cooling fins and valve assembly). This would make our block run hotter since we wouldn't be dissipating as much heat. Now how would that affect our engine performance? Let's think about this...
We know that the amount of air passing through the carburetor determines how much fuel will be drawn per engine cycle. Warmer air is less dense than colder air, so warm intake air should draw less fuel than cold intake air. If this is true, we would actually want warm air for sake of reducing fuel consumption rate. The trade off for consuming less fuel is the smaller power output (cold air will expand more than warm air).
This theory was the basis of this engine test. In the North Lab at OCAS, we used the Otto Cycle Lab test stand from Thermodynamics class (with Muthar's permission, of course!) to change the intake air temp and measure the time to consume a fixed amount of fuel. We found that it took 35 seconds longer to consume 25 mL of fuel when the intake air temp was 94 F vs 77 F. By removing the cooling fins we will drop some engine weight AND have a lower fuel consumption rate. Bye bye cooling fins!

Our Briggs setup on the test stand