Could the Variable Compression Mechanism be a Game Changer for Piston Engines?

The automotive and aerospace industry is always looking for ways to improve engines. It could be from environmental needs or economic reasons, but the goal is to chase fuel-savings and higher efficiency regardless of the carmaker and manufacturer. Of course, newer technologies such as spark-controlled compression ignitions can have original equipment manufacturers jumping for job because they tend to focus on streamlining what is already there. However, many engine developments are thanks to individuals who took the time to think differently.

One start-up company based out of Pennsylvania is working on developing an internal combustion mechanism that offers an infinitely variable compression ratio for the four-stroke and two-stroke piston-driven engines. This mechanism uses a gear-pin assembly, mirror-image planetary-gear assembly, and piston-connecting rod assemblies to alter the top center position of the piston, which invariably changes the compression ratio of the engine itself.

Nothing Currently Like It

When the start-up mogul thought about the current prototype in college, he realized that the compression-ignition stroke was the power of the piston traveling to the point of compression but no farther, which extracts the energy that still remains.

Because most piston-driven engines use a fixed compression ratio, he realized that all he had to do was increase that ratio to improve efficiency. However, to-end operations can cause detonation or engine knock. Therefore, his prototype focused on using a control to rotate the gears of the mirrored assembly slightly, which ultimately changed the compression ratio.

The mechanism can use a higher compression ratio at low-end power or a low-compression ratio at the top-end of power to be more efficient. The functionality here sidesteps the high-compression limit and reduces knocking.

The working prototype was placed in a four-stroke, overhead-valve, 212 cubic centimeter gasoline engine and it could almost instantly change compression ratios from 7:1 all the way to 39:1. It also uses an intake manifold vacuum, allowing the engine to self-adjust compression ratios automatically.

As reference, the Variable Compression engine for Nissan vehicles can shift from 8:1 all the way to 14:1.

When you search for VC options, everyone has looked into it, and many carmakers utilize it, but no one has an IVC engine, which is called an infinity variable compression engine.

Along with such, four-stroke engines using the mechanism can have two piston stroke lengths within one engine cycle.

The combination ensures that you get exhaust and power strokes of up to 50 percent longer than compression and intake strokes. The more power that is extracted means that the exhaust temperatures are significantly reduced, as well. The current prototype was constructed using 40 percent more exhaust and power strokes.

In a sense, this prototype is an IVC with Atkinson, the dual-stroke that was created in 1888. The levers that came out created the variable compression mechanically, though people never built high-speed engines with that until now.


While things are still being tested, the mechanism could be used in both aerospace and automotive domains or in any instance where internal combustion engines are utilized. That can include gasoline-powered lawnmowers, hybrid-electric propulsion systems, and much more. This new mechanism can also easily integrate with current internal combustion engine options without too much expense. Also, the design is modular, which means multiple pistons can stack on top of each other.

The benefits are plentiful with more engine efficiency, less pollution, and the ability to have fuel capabilities, such as natural gas, gasoline, propane, alcohol, jet fuel, and blends.


Could the Variable Compression Mechanism be a Game Changer for Piston Engines?

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