Compression Check

The 4.8-litre V8 naturally aspirated engine has a compression ratio of 12.5 : 1. The 4.8-litre V8 turbo engine has a compression ratio of 10.5 : 1.

The 4.8-litre V8 naturally aspirated engine has higher compression values than the 4.8-litre V8 turbo engine. They are not comparable.

The measurement of two comparable V8 naturally aspirated engines can produce different pressure ranges. This is not a sign of wear or a defect.

Test values =>
The compression values are heavily dependent on: Amount of deposits in combustion chamber, state of the combustion chamber seal (valves, piston rings, etc.), starter speed, engine temperature, engine mileage etc.

No absolute pressure values displayed as these would not be meaningful.
expected pressure ranges of 4.8-litre V8 naturally aspirated engine = approx. 18 to 25 bar (no wear limits). It is not a sign of wear or defects if the pressure exceeds or drops below these values.
expected pressure ranges of 4.8-litre V8 turbo engine = approx. 15 to 18 bar (no wear limits). It is not a sign of wear or defects if the pressure exceeds or drops below these values.
maximum difference between the cylinders in bar overpressure (within one measurement) = 3.0 (single permissible criterion for suspected wear). Further tests, such as pressure loss test or endoscopy, should follow. For example: a V8 naturally aspirated engine with 20.6 bar at cylinder 2 and 16.9 bar at cylinder 8 (wear suspected).