For those who love them, two-strokes hold a special place in many a gearhead’s heart. However, even the fondest two-stroke fanatic can’t deny the truth of that two-smoke nickname. It’s simply a fact of life—and whether you love or hate that smell, it’s also hardly a low-emissions proposition.
Then, there are four-strokes. Generally speaking, those are more efficient at utilizing fuel, but are more complex, weigh more, and are comparatively less powerful than their two-stroke counterparts. Still, plenty of enthusiasts—both old- and new-school—have their favorites. Soichiro Honda famously despised two-strokes with a passion, which is why he was all-in on four-stroke technology from the beginning.
What if there was another way, though? That’s what Spanish company INNengine has been asking since it was founded in 2011. It’s based around engineer Juan Garrido Requena’s vision: One-stroke engine technology with opposed pistons. It fires every 180 degrees, or twice each revolution—which means that it fires twice as often as a two-stroke and four times as often as a four-stroke engine.
So far, the company has patented two engine variations using this unique technology. Both the e-REX and the REX-B are one-stroke engine concepts that INNengine envisions as helping to power a future populated with zero-emission vehicles. The e-REX is particularly small and lightweight, coming in at just 38 kilograms, or 83 pounds—and yet, it’s powerful enough for use in automotive and aircraft applications.
That’s why INNengine sees it in hybrid hydrogen electric vehicle scenarios, across a spectrum of vehicles. It’s small and lightweight, which means there’s more room for electric motors and batteries. Now, INNengine’s zero-emission plans revolve around the possibilities of green hydrogen, which is still unfortunately in the “wouldn’t it be nice if?” stage of development. Still, no one gets anywhere without a vision, and if INNengine can help make it happen, that would obviously be a net positive for both the environment and gearheads alike.
If INNengine’s one-stroke engine tech isn’t wild enough for you, the company also claims that the e-REX engine gives off zero vibrations in operation. We’re not engineers, so we can’t offer that level of expertise in analyzing their claims—but they’ve certainly given us something fascinating to contemplate.
