IC Engine Displacement Reduction


Created on 10/20/2015

This week, we will be switching away from our immediate goal of conquering #SEM2016 and going back to our traditional competition, SAE Supermileage and the Internal Combustion engine. An IC engine mixes air and fuel in an enclosed cylinder which are then compressed and ignited. This results in expanding gases that force the piston down which in turn, turns the crankshaft which drives the wheels. When an engine is running at a set throttle position and a set load, the fuel to air ratio in the cylinder is constant. In turn, this means that the amount of fuel being used is dependent on the constant volume of the cylinder.


One of the issues that we have with our current IC engine is that it produces much more power than is required for our car. While this may not seem like an issue, it is a large waste of energy (aka fuel). The fuel-air ratio has already been tuned to be as efficient as possible already so there is only one option remaining: reduce the volume of the cylinder.

For the next two semesters, a group of Mechanical Engineers are taking this project on. Their goal is to insert a piston sleeve into the cylinder to reduce the engine displacement. This will allow the air to fuel ratio to remain the same while overall using less fuel. This will allow our engine to use less fuel, while at the same time having enough power to continue to operate our car. To complete this project, a number of parts will need to be remachined/resized. The overall engine block will not need to be modified but the engine head along with the piston, connecting rod, piston rings, valves, and valve springs will need to be rebuilt. The exhaust and intake systems may need to be modified as well.

Obviously, the goal of this enterprise is to build a car that can get the best fuel economy. This project will be a huge stepping stone for us as we push towards that goal. Hopefully, these modifications will increase our mileage even further and propel the Supermileage Systems Enterprise even closer to the top.