Piston ring gap.
Clearance volune
The rings seal the space between the piston and the walls of the combustion chamber, so that there is enough compression of the fuel-fair mixture. They also prevent engine oil from being sucked up into the chamber, which is why blue smoke is a warning sign of bad rings.
Combustion chamber
The age of the tree
The answer is Compression Ratio. You should try reading the Study Unit it really helps!
The space between your eyebrows is called the "Glabella."
The space between the vocal cords is called the glottis.
In a cell the empty space is filled with a gel like substance called cytoplasm. Cytoplasm holds all things within a cell. ^CELL If the space is empty, then it's called Empty Space. Space around the nucleus where electrons move is called Electron Cloud.
Saturn
There is a gap between the spark plug and the top face of the piston called the clearance volume. It serves 2 purposes. 1. The fuel before and after combustion has to occupy some volume and this is small gap is for that space for it to burn. 2. To avoid unnecessary contact between the piston head and the spark plug.
There are only asteroids, there are no planets in the region between Jupiter and Mars. There is however a large asteroid called Ceres which is commonly referred to as a Dwarf planet.
A cylinder is the central working part of a reciprocating engine, the space in which a piston travels.
The space between letters in printing (or typography) is called tracking.