3 of the World’s Most Unusual Engines

January 30, 2017

Getting from one place to another fast and with minimal effort is a human specialty. Generations of automotive innovation and the human desire to do things faster and more efficiently lead to the transportation empire which humans continue to use and rely upon. There are millions of types of vehicles designed to take someone or something to one place or another, though they all rely on one critical component, the engine. As new technologies emerge and resources deplete, engineers continue to adapt by modifying and totally redesigning thousands of different engines; here are the top five most bizarre engines on the planet.

Evaporation engine [Image Source: ExtremeBio]

Free-Piston Engine range extender technology

In principle, electric cars are fantastic. However, it is difficult to manufacture battery stores large enough to support transportation over long distances. Many electric vehicles are hybrids allowing them to extend their range by implementing a combustion engine to power the car or the battery.

Previous hybrid models simply used a regular piston engine to provide power to a separate generator while simultaneously providing direct power to the wheels. While there are many variations of the hybrid, most require multiple components to direct power, ultimately causing a reduction in efficiency.

Now, engineers are looking to combat the issue by disconnecting the engine from the drive shaft entirely. Instead of the power being directed to a generator, the piston engine itself will be the generator in of itself.

The crank in between the pistons holds a strong magnet which passes through a series of coils, thus creating an electric current as electrons are pushed back and forth through the spiral. The electricity is then directly transported and stored in batteries.

Ideally, the engine will reduce the number of batteries required. Fewer batteries will need to be recycled making it an economical and environmentally sound solution.

Unfortunately, the design of the engine produces a lot of vibrations as the pistons oscillate from side to side. While the principle of the engine remains sound, the vibrations will need to be significantly reduced before the engines are integrated into real motor vehicles.

The SABRE Skylon

SABRE – Synergetic Air-Breathing Rocket Engine- is a revolutionizing engine targeted towards propelling both high-speed aircraft and spacecraft.

The SABRE is a collection of many propulsion mechanisms integrated into one machine to provide hypersonic transport. Essentially, the engine is the integration of a jet and rocket engine designed to propel a vehicle as a jet to about MACH 5 before the engine transforms into a rocket to provide the propulsion necessary to escape Earths gravitational vice.


The engine breaks down into five main components; the supersonic air intake, ramjet, compressor, rocket engines, and finally, the pre-cooler.

At speeds of about MACH 5, the air entering the engine is about 1000 degrees Celsius, much too hot for any jet to function. An air intake slows the air to a reasonable speed where a ramjet can function at a reasonable temperature. Hydrogen fuel also enters the engine to both cool and provide fuel. The ramjet generates the thrust by mixing the air from the intake with the evaporated hydrogen.

A ramjet functions similar to a turbine jet in that a gas is compressed, injected with fuel, then combusted to accelerate air through an engine. A compressor then helps convert heat absorbed from the precooler to useful work. Both systems work together to provide enough thrust to allow the aircraft to reach an altitude high enough for the engine to change into rocket mode.

Once it reaches a fast enough velocity, a conventional LH2/LOX rocket engine provides the final push into space.

Evaporation Engine

The ExtremeBio evaporation engine is unlike any other engine. Developed by Columbia University, the engine does not rely on a conventional fuel, instead, it relies on bacteria.

In nature, bacterial spores remain dormant until they come into contact with humidity. Researchers placed the spores onto plastic tapes to take advantage of the bacteria’s ability to absorb and evaporate water very quickly.

The engine is made by securing hundreds of bacteria infused pieces of tape onto the side of a wheel. Using a dome to create a difference in humidity, as the tape passes through the air it readily absorbs humidity, causing it to expand. On the opposing end, the tape passes through the dome which has less humidity. The water evaporates, causing the tape to contract. The difference in weight distribution causes the wheel to be heavier on one side, creating rotation.


The technique is remarkably fascinating. However, while researchers were able to power a light car, the engine will not be powering any human-carrying vehicle any time soon. Nevertheless, the principle remains functional.

As times change, so do the technologies which will carry humans from one point to another. Currently, there are hundreds of engines undergoing development. While some may seem incredibly bizarre, it is through outlandish innovation which will propel humanity into the future.

SEE ALSO: Top 10 Largest Engines in the World

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