We walk you through a compression test, a great way to determine the condition of your valves and piston rings.

Compression test kits do just what they say: measure the ability of each cylinder of your engine to combust the fuel/air mixture without losing any of the resulting energy.

There's a fair bit of science behind how engine turbochargers do what they do (air pressure, compression, fuel burn efficiency, etc.), but basically it will improve an engine's power by around 30 ...

But without verifying the combustion chamber volume on the cylinder heads, it's impossible to be sure of the engine's true compression.

An engine's compression ratio is actually a theoretical number. This ratio compares the cylinder volume of the piston at bottom dead center (BDC) versus top dead center (TDC).

Late-model engine designs have come a long way in the engineering of pistons and cylinder heads to improve combustion efficiency, allowing higher-compression engines to run on regular gas.

The fruit of their labor is the VC-Turbo engine, and the 2019 Infiniti QX50 SUV is the first vehicle to feature the world’s first production variable compression engine ever.

CHECK OUT: Audi looks back at 40 years of 5-cylinder engines When you want power, the compression ratio drops and the turbocharger makes use of more boost.