This radical 85-pound engine cranks out 120 horsepower and just found its way into a Miata

Ever wondered what happens when engineers throw conventional engine design out the window? A Spanish company just answered that question with a revolutionary opposed-piston engine that weighs less than most motorcycle engines yet delivers serious power.

The INNengine from Granada represents everything we thought we knew about internal combustion turned upside down. No cylinder head. No crankshaft. No camshaft. No valves whatsoever. Yet this 30.5 cubic inch powerplant somehow manages to squeeze out 120 horsepower while tipping the scales at just 85 pounds.

How does this engine actually work?

Picture this: instead of pistons pushing against a fixed cylinder head, each piston faces off against another piston in the same cylinder bank. The opposed-piston configuration creates four combustion chambers using eight pistons across four cylinder banks. Sounds complex? It’s actually simpler than traditional designs in many ways.

The real magic happens with the timing mechanism. Forget connecting rods (well, traditional ones anyway). These pistons ride on rollers that follow a lobed circular plate – think of it as a sophisticated cam that controls everything. When the lobe peaks, pistons rush toward each other, fuel gets injected directly into the compressed space, and a spark plug does its thing.

What’s really clever is how the exhaust works. One piston reaches the bottom of its stroke slightly before its partner, uncovering the exhaust port first. This creates a vacuum that sucks out spent gases while fresh air rushes in through the intake port. No valves needed – the pistons handle both jobs.

The Miata connection nobody saw coming

Why stuff this experimental engine into a Mazda Miata? Because sometimes the best way to prove a concept is to actually drive it around. The lightweight nature of this engine makes it a natural fit for a car that’s all about power-to-weight ratios.

The dual power output design means you could theoretically connect transmissions to both ends of the engine. Imagine the packaging possibilities (though your mechanic might have some choice words about maintenance access).

Is it really a “one-stroke” engine?

Here’s where things get a bit misleading. The company calls it a single-stroke combustion cycle, but technically it operates on a two-stroke principle with compression and exhaust phases. The “one-stroke” branding apparently came from an external engineering institution and stuck because it sounded catchy.

Unlike traditional two-stroke engines that mix oil with fuel, this design keeps lubrication separate. That’s a big deal for longevity and emissions – two areas where conventional two-strokes typically struggle.

Will we see this engine in production cars?

Don’t expect to walk into a dealership and buy a new car with this engine anytime soon. The automotive industry moves slowly, and we’re already racing toward electrification. Even revolutionary designs like the Wankel rotary engine struggled to gain widespread adoption despite their innovations.

The most realistic application? Range extenders for electric vehicles. Think about it – a compact, lightweight engine that could efficiently charge batteries without taking up much space or adding significant weight. For EVs trying to shed pounds and extend range, this could be a game-changer.

The timing might actually work in favor of this technology. As automakers scramble to make EVs more affordable and practical, a super-light range extender could solve multiple problems at once. Weight reduction means better efficiency, and the compact size opens up new packaging options.

The bigger picture for engine innovation

This engine represents something we don’t see often anymore – genuine innovation in internal combustion. Most engine development these days focuses on incremental improvements rather than fundamental redesigns.

The opposed-piston architecture offers inherent balance advantages that could minimize noise, vibration, and harshness without heavy counterweights or complex balancing systems. For range extender applications, where the engine might cycle on and off frequently, smooth operation becomes even more valuable.

Will this specific design make it to market? Maybe, maybe not. But the willingness to completely rethink how engines work – that’s what keeps automotive engineering interesting. Sometimes the most important innovations aren’t the ones that immediately succeed, but the ones that inspire the next breakthrough.

Whether you’re a die-hard internal combustion fan or eagerly awaiting our electric future, there’s something undeniably cool about engineers who refuse to accept “that’s how we’ve always done it” as an answer.