For the SAE Supermileage competition, a 3.5 hp Briggs & Stratton engine must be used. The rules state that any modifications are allowed, however the cylinder and crankcase must be identifiable as components of the base engine. Our intentions were to determine the performance characteristics of the engine, along with performing minor modifications, to maximize the efficiency of the vehicle.

Performance plots were made with the assistance of a Go-Power dynamometer. The dynamometer measures torque and rotational speed (RPM) of the engine, allowing the horsepower of the engine to be determined at any RPM. We used a hand-held digital tachometer to measure the RPM, since the existing analog tachometer couldn't be calibrated.

Test procedures were created to standardize the data collection. A test throttle was implemented for precise control of the engines RPM. With no load on the engine and varying the RPM, the corresponding torque output was recorded along with the rate of fuel consumption. These tests were repeated with the addition of a varying load, in order to simulate actual driving conditions.

This is a picture of our engine with the new carburetor: