A fairly common statistic used to describe how inefficient a car engine can be is how much energy is lost as heat. Even more energy is lost due to the heat though as it warps the cylinders the pistons are in and increases the friction on them. Researchers at Fraunhofer-Gesellschaft however have developed a way to counter this thermal distortion and improve fuel efficiency by as much as 2-3%
Cylinders suffer from two kinds of distortion. One is a static distortion that comes about from the pistons not moving perfectly up and down. Auto manufacturers figured out how to counter that by honing the cylinders to match that movement, and the researchers have figured out how to do the same for thermal distortions. By simulating the cylinder at 90 ºC, which is the operating temperature for the engine they used, the researchers determined what the distortions would be. To incorporate this data into the engine design, the researchers created a special honing tool with small electrically-driven actuators in it. These actuators allow them to precisely shape the cylinder to be perfectly smooth when it is running at high temperatures.
The prototype of the honing tool has already been tested to prove that it can be used without disrupting the assembly of the engine by much. To the end of the year they will be running multiple tests on this technique, including some concerning the lifespan of an engine with cylinders bored like this. After these test, the researchers plan to work on a product for industry use.