Hyundai Wants Your Gasoline to Act like Diesel

Is this a GDCI engine or did we play a trick on you? They look about the same, and we’re not telling.

Hyundai is making a concerted effort to push automobile technology into the 21st century. In the past, the OEM has been working on better integrating wearable technology into its cars. Now, the Korean automaker has shifted its attention to the underpinnings, specifically the gasoline engine. That’s where the GDCI comes in.

GDCI stands for Gasoline Direct Injection Compression Ignition (that other “I” must have gotten lost on its way to the party). It combines the spark-free operation of a compression-ignition diesel engine with the benefits of operating on standard-octane pump gas.

Diesel engines can get away without using spark plugs, thanks to an insanely high compression ratio. When the piston compresses the combustion chamber during the compression stroke, the pressure inside the chamber generates enough heat to ignite the mixture of air and fuel. 

Hyundai believes the GDCI powertrain could improve gas-engine efficiency by nearly 25 percent.

Hyundai is using that principle alongside gasoline direct injection to create the same effect with pump gas. The compression ratio is not as high as it is with a traditional diesel engine, but Hyundai has developed a way to create ignition at that level. When the piston is at the tail end of the compression stroke, the fuel injectors shoot the gasoline directly into an indentation built into the piston. There’s enough heat at that point to ignite the gas, and Bob’s your uncle.

Did we mention that it’s also twin-charged? That means it utilizes both a supercharger and a turbocharger in tandem. At low engine speeds, the belt-driven supercharger provides enough exhaust flow to spool up the turbo’s turbine. Twin-charging isn’t used very widely on factory-built machines; rather, they are used for custom, high-horsepower applications. However, since the GDCI engine needs the turbocharger to function, and since the engine is highly efficient, it needs a little something extra to get going.

That indentation in the piston is what helps pressure alone combust the air-fuel mixture.

There’s also the matter of cold starts. In the event of a cold start, diesels will utilize glow plugs to warm up the combustion chamber prior to starting the engine; otherwise, too much heat will be lost to the metal comprising the chamber walls, and ignition won’t happen. At this stage, the GDCI engine will only start at room temperature, and Hyundai hasn’t added glow plugs or anything else to aid in warming the engine up. So Hyundai will need to address that, unless it plans on selling the cars exclusively in Boca Raton.

It’s actually a very promising development, despite sounding overly complicated. Gasoline is cheaper, buyers are more familiar with it, and Hyundai believes the GDCI powertrain could improve gas-engine efficiency by nearly 25 percent. It could end up cheaper than diesel, as well, because the compression ratio would be lower, requiring less strengthening of surrounding materials.

GM’s tinkered with this theoretical method of propulsion in the past, but judging by the zero compression-ignition gas engines currently installed in production vehicles, nothing really panned out in that regard. This gives Hyundai the advantage, and if the technology gains a solid foothold, it could pull some of the increased attention that diesel’s been receiving lately. However, since the gains still aren’t equal to the diesel engine, it will likely stand as a solid replacement for a traditional gasoline engine instead. Either way, it’s about time we focused on moving past the century-old technology we’re still working with.