Igneous Rock is formed when a magma cools underground and crystallizes or when it erupts unto the surface of the ground, cools and crystallizes. Magma that erupts onto the surface is called lava. When magma cools slowly underground the crystals are large enough to see.
Readings for compression tests usually vary between 175 to 250 PSI (Pounds per Square Inch). A higher reading generally indicates better engine performance; however you should check your vehicle manual to find out what the ideal reading should be for your vehicle.
The compression ratio in short is the amount of air that an engine can squish ready for the bang phase of combustion.A 9:1 compression ratio simply means that 9 units of air will be compressed into the space of just 1 unit.he compression ratio in short is the amount of air that an engine can squish ready for the bang phase of combustion.