What is a variable compression engine?

Engine manufacturers have been faced with a difficult task for decades. How to make an efficient motor that also satisfies drivers’ needs for speed. Over the years, we have seen new engine technologies like electronic fuel injection, direct injection, turbocharging, and variable valve timing. While those are all great, they don’t compare to the latest breakthrough from INFINITI. The 2019 QX50 crossover SUV is the first production vehicle to feature the new variable compression engine. Keep reading to learn more. 

You might also like: 2019 INFINITI QX50 design features 

How does a variable compression engine work? 

Engine compression is far from simple if you’re not an engineer. Fuel and air are taken into the cylinders of the engine. That mixture gets squished together (this is compression) when the bottom of the engine’s piston rotates around the crankshaft. That causes the piston to rise, and when it is at the top of its designated path, your car’s spark plugs ignite the fuel and air in the cylinder. The small explosion that occurs creates the engine power needed to move. When the piston moves back down, the process repeats. 

Also read: INFINITI Q Inspiration concept car 

What is compression ratio? 

Your compression ratio can be found by measuring how much empty space is leftover in the cylinder when the piston is at the bottom of the cycle. You compare that to the amount of empty space in the cylinder when the piston is at the top. If the piston holds 1,000-cc of fuel and air at the bottom and 100-cc at the top, the compression ratio is 10:1. This may be confusing, but it’s important to know to understand how engines work. 

This new INFINITI variable compression engine is turbocharged. With turbocharged engines, more air is forced into the cylinders during the intake process. A high-compression engine requires the piston to squeeze extra air into a smaller-than-necessary space. That gives the engine more power and efficiency, but also more stress.

The variable compression engine, meanwhile, lives in the best of both worlds. If a driver wants more power, the engine shifts to a lower compression ratio and the turbocharger activates at the same time. The added turbo power more than makes up for the change in compression ratios. Those ratios can range between 14:1 and 8:1. 

We hope this has made sense, but we understand that some wordage may be taken as jargon. Please contact us for any clarification and we will happily answer your questions.

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