The three-cylinder has become a performance engine
The auto industry is in the midst of a monumental transition. As regulations demand that gas mileage be a thing of the past, automakers are pledging for an all-electric future. Of course, we are not there yet. But the industry must strike a balance between emissions compliance and the relentless demand for ICE-powered machines. As a result, we’ve seen turbocharging, hybridization, and outright engine reduction take hold. Perhaps the most extreme example of the latter is the large number of three-cylinder engines on sale today.
That said, not all of these three pots are built for efficiency alone. In fact, some of these three online offer a lot more performance in their small packages than you might think.
The Ford Fiesta ST gained a reputation as one of the greatest hatchbacks of all time, but sadly left the American shores in May 2019. Luckily for our friends across the pond, Ford didn’t cut the baby ST in Europe, releasing an all-new model that same year. The refreshed and improved sporty Fiesta received a new engine known as the Dragon. This 1.5-liter three-cylinder is an evolution of Ford’s smaller 1.0-liter EcoBoost, but don’t let its size disappoint – it puts out 197 horsepower and 236 lb-ft of torque. For reference, that means the little EcoBoost puts out over 131 horsepower and 157 pound-feet of torque per liter of displacement. For comparison, the hottest version of BMW’s 3.2-liter S54 inline-six produces 103 hp per liter.
To produce that kind of power, Ford’s 1.5-liter uses both direct injection and direct injection, variable camshaft timing, and an integrated exhaust manifold. However, as Gareth Maxwell, Ford’s powertrain manager for the Dragon engine, explains in an interview with Road & Track, the real secret of the 1.5-liter is its radial-axial turbocharger design. Compared to a traditional turbo, a radial-axial unit has significantly less inertia and therefore reacts much faster to throttle inputs with reduced lag. Working in tandem with that slick camshaft, the small 1.5-liter is capable of delivering both low-end torque and high-end performance. While the Dragon was admittedly created with extreme attention to fuel economy, Maxwell says this turbocharged design legitimized the 1.5-liter as a performance product.
A three-cylinder engine is generally more powerful than a four-cylinder engine of the same size. Maxwell notes that this is because fundamental components such as combustion chambers, pistons, and retaining pins are all larger in a three-cylinder engine of equal displacement. This allows automakers to run higher internal pressures and develop more horsepower while ensuring reliability.
“I think there is a bit of a perception historically that more is better,” says Maxwell. “And there’s this perception that if you have more cylinders, you have better reliability. I think, from an engineering perspective, we are completely questioning that. More is not always better, and from an engineering perspective, less is actually better. It’s simpler and lighter, and there is less friction.
Ford isn’t the only company turning to a three-cylinder to power a hot hatch for this reason. The glorious Toyota GR Yaris is also powered by a three-pot, although the Yaris unit measures a slightly larger 1.6-liter. For the Japanese GR Yaris market, Toyota claims output figures of 268 hp and 273 lb-ft of torque, figures one would expect from a bigger four-cylinder. Rated at 166 hp per liter, the GR Yaris’ G16E-GTS engine has the highest specific horsepower per liter of any Toyota road car ever made; even the glorious 4.8-liter V-10 in the Lexus LFA puts out just 115 horsepower per liter. In fact, GM’s more modern 755 horsepower LT5 V8 is good for just 122 horsepower per liter.
Toytota’s decision to use a three-cylinder wasn’t all about fuel efficiency. The GR Yaris is a true homologation stage, and its powertrain was a staple in motorsport. In fact, Toyota had to file a petition with the FIA to be allowed to run a three-cylinder in the World Rally Championship. The team fought for the three-cylinder because of its simple and compact design and its ability to produce great power thanks to the absence of interference from the exhaust gases. Like the 1.5-liter Ford, the G16E-GTS uses both direct injection and fuel injection, but racing engines receive a more serious kit, like a ball-bearing turbo and sprayers. oil for the pistons. Even in the on-road specs, Toyota says there isn’t a 1.6-liter turbo engine more compact or lighter than the G16E-GTS.
The three cylinders are no longer reserved for hatchbacks. In fact, small engines have even found their way into the bays of seven-figure machines. The all-new Koenigsegg Gemera is a four-seater hybrid hypercar with over 1,700 hp at its disposal. Unlike other exotic hybrids with V-8 and V-12, the Gemera’s gasoline engine has only three cylinders. Known as the Tiny Friendly Giant (TFG), this 2.0-liter twin-turbo engine is an absolute engineering marvel. The TFG features Koenigsegg’s Freevalve technology, which allows the car’s ECU to independently control the intake and exhaust valves, without camshaft, depending on engine load parameters. With the ability to adjust the timing on the fly based on these parameters, this system allows the car to adapt to driving conditions and actively increase its efficiency. The engine can even run the Miller cycle, allowing high power output and fuel economy at the same time. Texas-based artificial intelligence company SparkCognition is helping the automaker develop AI engine management software to work with Freevalve.
Koenigsegg claims that all of these technologies allow the TFG to be 15-20% more efficient than a typical 2.0-liter four-cylinder engine. Impressive stuff, especially when you realize that the TFG makes 600 horsepower and 443 lb-ft of torque. No other engine in production rivals the TFG, with an output of 300 hp per liter, in terms of specific power. Even if you were to remove the sequential turbo system from the TFG, Koenigsegg believes around 280bhp would still be possible.
So it’s not hard to say that the TFG is one of the most extreme engines we’ve ever seen, regardless of the number of cylinders. As the fuel allowance continues to be reduced each year, this type of material could help extend the life of the enthusiastic market for ICE vehicles. As Ford is embarked on an all-electric future, Maxwell noted that he believed combining three-cylinder engines with hybrid systems was the next logical choice for automakers looking to retain ICE powertrains. If that first crop of hot triples is anything to go by, there could still be some exciting gasoline offerings ahead.
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