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.
Factors that affect battery requirements are listed below: 1  Engine size-Engine size is the single greatest determining factor in CCA requirements. 2  Cylinder head compression ratio-Compression ratio is a measure of how much fluid and gas pressure is generated inside the engine cylinders when the engine turns over.