An engine's compression ratio is actually a theoretical number. This ratio compares the cylinder volume of the piston at bottom dead center (BDC) versus top dead center (TDC).

In Two Stroke Spark Ignition engines the thermal efficiency increases with increase in compression ratio. Also, with higher compression ratios the lean burning limit increases because of the reduction ...

Read the tech article on an Engine Compression Guide, brought to you by the experts at Chevy High Performance Magazine.

In an effort to both increase engine efficiency and generate new, consistent, and reliable data useful for the development of engine concepts, a modern single-cylinder 4-valve spark-ignition research ...

Variable Compression Ratio Engines have been some sort of a Holy Grail, and now Porsche proposes a viable solution for this ...

Variable compression engines, as the name suggests, can alter their compression ratio, i.e. the volume of the combustion chamber when a piston is at the bottom of the stroke compared to when it ...

That's because Infiniti is planning to roll out the variable compression ratio engine for its next generation of cars.

Here's a fascinating example: Infiniti is about to unveil the world's first production-ready variable compression ratio engine at this year's Paris Motor Show.

But too high a ratio causes knocking—premature detonation of fuel-air mixture during the engine's compression stroke caused by high cylinder temperatures.