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.
With this test. you will know beyond doubt if there is low compression in one or more cylinders. Relative Compression testing is useful to diagnose a rough running, or misfiring engine is to. see if the compression in any one cylinder is substantially lower than compression in the other. cylinders.