An important test that will assess the health of any Subaru engine. We perform this test to any turbo charged Subaru before a client purchases a Subaru, or as a pre-dyno inspection / pre tune inspection. 

This test measures

• Amount of compression each cylinder and piston are creating 

• How much pressure each cylinder and piston can hold over a period of time (leak down) 

• If the forced induction system holding pressure under boost

The engine being essentially an air pump needs to create pressure in its cylinders to function. When our tests show an uneven reading of pressures amongst the cylinders or an abnormally low pressure readings across the board we know the engine is either worn, meaning the piston rings aren’t sealing, or in some cases with Subarus it can signify a piston ring-land failure.

The Turbo charging system works by compressing air and feeding into the cylinders. The system is made up of various components that need to be air tight under high pressures. The entire system will malfunction in the case of a leak. In extreme cases if the system malfunctions it can cause engine damage. We test this system by simulating boost conditions and checking for leaks. 

This procedure is very important before any dyno tuning is done, and every Subaru must pass before being tuned on our dyno.