INNengine's e-REX motor offers highly-efficient, 1-stroke engine technology

The motor is 55 percent smaller and 70 percent lighter than any four-stroke ICE, making it an ideal choice for range-extender applications.
Jijo Malayil
INNengine's e-REX motor
INNengine's e-REX motor


Numerous startups across the globe are devising technologies that empower the global transition to electric forms of mobility. 

In this regard, Spain-based firm INNengine believes the future of sustainable motoring should be a mix of both electric and ICE, as the former is cleaner and more efficient, while the latter is lighter, more power dense, and provide autonomy/protection against hazards. With the tagline, "The Future is Eclectic," the firm is offering an efficient solution with e-REX, a 1-Stroke engine technology, which it claims offers 4 times more power events per revolution than a conventional 4-Stroke and twice more than a 2-Stroke ICE offering.

According to it, "instead of looking only at tailpipe emissions, we need to conduct a full life cycle assessment of such solutions if we really want them to be sustainable. Doing otherwise is irresponsible and sooner rather than later reality will catch up," said the blog post by the firm.    

The firm says that an e-REX equivalent to a traditional 2000cc engine weighs just 77 lbs (35 kg). "This allows you to have a full range extender powertrain (including motors, alternators, batteries) within the same space and weight of a traditional engine saving energy cost by up to 40%."

A novel technology that is highly efficient

The e-REX is 55% smaller and 70% lighter than any 4-stroke ICE, thanks to a design that is devoid of crankshaft, valves, camshaft, or cylinder head.

This is made possible by an opposed-piston design with four pistons on each side for eight. The opposing pistons share a combustion chamber and are held together by fixed rods. These rods press on plates with an oscillating wave-like shape, allowing the rods to push and release the pistons in a smooth, synchronized action. Having a variable compression ratio on demand means that the "engine and its combustion chamber does not have to be optimized for a particular fuel’s energy release conditions but can be configured to work with many different ones."

The engineering on e-REX also makes sure that the users are greeted with a smooth running motor as "moving parts do so reciprocally and in equilibrium at all times in all 3 planes, canceling out one another."

Wide range of applications

e-REX is an ideal option for range extender applications that would combine the economy and low emissions of a cutting-edge four-stroke engine with the simplicity, versatility, and power of a two-stroke engine. As battery resources are scarce and expensive, and with 90% of the daily mileage of light-duty vehicles being under 62 miles (100 kilometers), combining it with an option like e-REX can make such offerings more sustainable in the long run.

The team is "currently working with the CMT of the University of Valencia to develop the e-REX to satisfy EU7 European emissions standards when they are implemented in 2025." The team is also looking to make the e-REX the perfect green hydrogen engine to achieve true zero emissions. 

Its size, weight, power capacity, and lack of vibration also make it ideal for powering both light/medium aircraft/drones or as an APU in bigger aircraft, eliminating the need for an additional turbine. Other possible applications can be as a power generator or in the maritime industry. 

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