May it be a big ol’ V8, or a tiny 3-cylinder, Toyota’s performance preference has long been natural aspiration over forced induction. This is especially true when it comes to turbocharged motors, which for the longest time were not made available to American buyers.

While the iconic 2JZ and 1JZ Supra engines of old continue to fetch the average automotive enthusiast’s attention (and a premium price point), there hasn’t been much in the way of forced induction since the older generation of the sports car was sacked.

Sure, there were a few other Toyota vehicles sporting boost back in the day, with the turbocharged MR2 perhaps being the second most recognized behind the Supra GT. But outside of those two throwbacks, a handful of underperforming turbocharged 4-cylinder pickups in the mid-1980s, and the utterly awesome, but equally unobtainable Celica All-Trac, Toyota vehicles were all N/A all the way.

It would not be until July 6th of 2014, a full 12 years since the Mark-IV Supra’s retirement, that Toyota would announce that it had come out with a new turbocharged car intended for the North American market. The vehicle was the 2015 Lexus NX 200t luxury compact CUV, and it was actually the first vehicle I ever test-drove and reviewed for an automotive publication. Oh, the humanity…

So when Toyota announced that it would hop back into the fray that is the World Rally Championship the following year, we had high hopes that 2015 would be the year of the return of the All-Trac in some form. Unfortunately, it would be another half-decade or so before anything came of it.

Rally Race Engineering With a Catch

The turbocharged vehicle that emerged was the GR Yaris, and it took everything that Toyota learned from its experiences in WRC from those years, and the race team’s big win during the WRC manufacturers’ championship in 2018. These lessons were then applied to a platform that the automaker referred to as, “…a new road car that is also suitable for competition driving, and an affordable proposition for customers.”

As the first sports car made 100-percent by Toyota in more than 20 years, the GR Yaris was crafted from scratch and engineered to compete at the highest levels. Working closely with former Formula 1 champion, Fernando Alonso, as well as 4-time rally car championship driver Tommi Mäkinen and other members of his Toyota Gazoo Racing World Rally Team, Toyota’s engineers began to apply professional driver input to prototype models.

We preferred this engine due to its lightweight and compact size making it simple to install, while the lack of exhaust gas interference made it easier to obtain power.—Atsunori Kumagaya, Lead GR Yaris Project Developer

But here’s the funny thing: Toyota didn’t make this 3-cylinder hot hatch just for fun. It needed something that was also somewhat affordable. Remember that statement from Toyota talking about how they needed to build a car that could provide “…an affordable proposition for customers…” to go with all that performance?

As a Japanese automaker, Toyota needed to produce a platform for buyers on its own home turf that was justifiable from an ownership expense perspective. For Japan is the land where you are not only taxed on the overall size and weight of your vehicle but on its engine size as well.

Plan on Driving in Japan? Please Hand Over All of Your Yen

For those of us who live in Japan (like myself), the biggest issue with driving has nothing to do with driving itself, but the act of owning an automobile.

Here in Japan, automotive-oriented taxes are measured on an annual basis and increase a staggering 20 percent once the vehicle reaches 13 years old, and crest 50 percent once your car reaches the legal age of 18. Due to the extremity of these taxation laws, the Japanese have long been known to upgrade to a newer vehicle sooner than the average American. For there is no worse feeling than realizing that you owe more in taxes than your craptastic 1998 Toyota Camry is actually worth.

But it’s the damn engine taxes that piss us performance enthusiasts off the most. For over here, they are based upon overall engine displacement and therefore make owning anything with more than four cylinders a rich man’s folly. This explains why so many people in Japan drive tiny cars that weigh less than a pack of rice cakes, with engines that fire on as few cylinders as possible.

Do you see where I’m going with all of this driver fatigue-inducing taxation mumbo-jumbo? Toyota sure did, and that’s one of the primary reasons why the GR version of the Yaris was bred for the Japanese market before being homologated for the rest of the world.

Toyota Cuts Corners, Rallies, and Wins

Toyota knew that constructing a high-output turbocharged car based upon its existing 2.0-liter four-banger would have cost Japanese consumers considerably more in taxes. This would potentially have posed problems for the lightweight little Yaris chassis as well, so the engineering team decided to take the smallest engine in its lineup and over-engineer the hell out of it.

Badged as the G16E, this 1.6-liter turbocharged three-cylinder offered loads of performance potential on paper, and in competition use/testing, proved to be extremely lightweight and reliable. Upon its debut in 2020, the G16E-GTS motor was heralded as “…the world’s most powerful three-cylinder engine and also the smallest and lightest 1.6 turbo.” Producing 257 horsepower and 265 pound-feet of torque, the engine launched GR Yaris drivers to 62mph in just 5.5 seconds, and onward to an electronically limited top speed of 143mph.

The fundamental requirement for the GR Yaris engine was a sports unit that would deliver outstanding, powerful acceleration and exhilarating sense of continuous power, in keeping with the car’s ‘GR’ designation.— Toyota

From a taxation standpoint, this engine was also quite appealing, as it sat right in the sweet spot where performance fans could justify the additional expense of shelling out an additional few months of pay to get the hot hatch they craved. When buying a new vehicle in Japan, a staggering three years’ worth of those aforementioned taxes are due upon taking possession of the vehicle, and every last cubic inch counts to your overall upfront cost.

The Science Behind the G16E-GTS Engine

When it first launched, the GR Yaris had the most powerful three-cylinder engine in production, as well as the title of being the smallest and lightest 1.6 turbo engine on the market. This was eventually surpassed by the Yaris hatchback’s GR Corolla big brother, whom we shall discuss here shortly.

To get all 257 horsepower to slam you back in your seat at 6,500rpm, and that torque to hit from 3,000 to 4,600rpm, Toyota’s engineers had to adopt a plethora of motorsports-oriented technologies to achieve their goals. A few of which stand out as automotive engineering overkill in its purest performance form, and were well thought-out to boot.

Start at the Bottom

For performance to safely find a home in something so small, Toyota knew that its G16E engine needed to be reinforced to be as strong as possible, while still being ultra lightweight. And so a 3-piece block was constructed, with one giant bearing girdle holding it all together. 

The thickness of the open deck block’s outer wall was reduced, and the forged steel crankshaft was revised for less rotational mass and greater strength, and sits offset from the cylinders by ten degrees. Being that this is a 3-banger, Toyota installed balance shafts to help offset vibration. 

Piston skirts received a low-friction surface treatment as well, and the main bearing was optimized to reduce the risk of oil starvation and overheating issues. Meanwhile, high-strength forged connecting rods, hydraulic lash adjusters, lightweight pistons with a 10.5:1 compression ratio, and a hollow camshaft assembly with a slightly concave radius and VVT-i replaced the conventional cast and machined VVL design.

Add Some Straightforward Turbocharged Tenacity

The engine’s single-scroll turbocharger may perform best at a higher rev range, but neither is it a lagging monster snail either. This design was selected because there is only one bank on a 3-cylinder motor, so a twin-scroll snail would have been completely counterintuitive. 

As with many modern turbocharged vehicles, the snail itself is integrated into the exhaust manifold, which aids in reducing weight, while better controlling wastegate bypass gases for faster catalyst warm-up times. Meanwhile, a cross-flow style intercooler reduces low-pressure loss and boosts cooling capacity. An air-cooled intercooler with a cooling-spray function was also made standard on the high-performance “RZ” model.

Utilizing something Toyota calls “wear-resistant abradable seals,” and a ball-bearing design to improve the compressor’s efficiency and reduce friction. Since this is an exhaust manifold integrated turbocharger, Toyota found that placing the wastegate control valve nearby could further eliminate lag when the exhaust gas flowed down the turbine side.

Level-Up Your Lubrication & Cooling

As for the cooling portion of the engine, that all starts with two cooling jackets inside the head, instead of just one. there’s also a water-cooled oil cooler made from aluminum for high heat-exchange efficiency and dissipation. The unit is installed upstream of the main oil filter to reduce the risk of bearing seizure due to debris in the oil and is located inside the water pump outlet, which further improves cooling performance and efficiency.

A total of nine oil squirters were also installed for additional peace of mind, and a belt-driven, large-capacity water pump was added to the mix to accommodate additional loads and cooling.

Don’t Forget Fueling

A combo of direct and port fuel injection systems come in a high-pressure (22MPa) D4-S configuration for finer spray atomization and combustion. There’s a high-tumble design handling airflow within the combustion chamber, and the six-hole spray inlet design Toyota’s engineers came up with eliminates interference with valves so that the car can pass lower emissions and still remain performance-packed.

Port injection is delivered via a series of long-nozzle, 10-hole injectors, with each intake port being extensively machined to reduce fuel adhesion along the walls. Toyota claims that every moving part and magnetic circuit within this upper portion of the engine was designed with rally racing temperatures and performance needs in mind. Coincidentally, this has made the vehicle far less thirsty when driven on the street and lowers emissions even further when ignited by those bespoke high-energy ignition coils.

Breath Deep

Due to the G16E’s insane performance aspirations, both the entire air induction and exhaust ends of the engine had to be redesigned. CNC ported and polished intake ports, with increased valve angles for greater tumbling, eccentric valve seats, and larger, sodium-filled exhaust valves all made the cut, while a free-flowing exhaust reduced back pressure. Remember, this is a 4-valve design, hence it only having a dozen valves all told.

Relocating the battery to the rear of the vehicle allowed a much larger air induction system for reducing low-pressure losses, which according to Toyota is rated at having a maximum capacity of 10.8 liters of air. Sound-absorbing materials, a few sheets of proprietary paper, and an ultra-fine fiber compound construction form the filter itself, thus preventing tiny particulates and debris from ruining the party. Being that this is a rally-inspired automobile, a “hydro-lock filter” sits inline as well, serving as a rally-ready air-liquid separation safety check.

Make Sure You Mount Her Just Right

When it came time to slap this all-new engine into the heavily reinforced Yaris chassis, Toyota used a completely redesigned mounting system. The right-hand mount was a hydraulic type, lowering NVH during heavy throttle and at idle. By changing the rubber’s spring rate, Toyota’s engineers discovered that acceleration responsiveness and feel could be improved without adding too much vibration, all while still reducing the risk of engine roll when the accelerator was pushed to the floor.

A duo of aluminum torque rods were also introduced to serve as structurally sound mounts that reduced both weight and rigidity. This allowed the motor to be moved further back into the engine compartment, further adding to the car’s weight distribution, balance, and lower center of gravity.

The GR Corolla Power Play

While there seems to be little sign of the GR Yaris reaching American shores anytime soon, its larger GR Corolla brother is available. And while the engineering that went into constructing that 5-door hot hatch is not nearly as transparent as that of the GR Yaris, many of the same attributes and overall engine architecture are shared betwixt the two.

Rumor has it that the GR Yaris’ power figures will increase in 2024 to match its slightly larger GR Corolla sibling being sold in America. While precise figures from Toyota remain undisclosed, we can foresee the Yaris receiving the same 300 horsepower and 273 lb.-ft. of torque. That’s 185.4 horsepower per liter for those of you looking to crunch a few figures while on your lunch break.

Unfortunately, there is no word of the “Morizo Edition” of the GR Corolla returning, which was widely regarded by critics and enthusiasts as the best version, as the regeared and retuned drivetrain combo easily achieved 295 lb-ft anywhere from 3,250 to 4,600 rpm.

So while driving a 300-horsepower street-legal rally car with the curb weight of a piece of popcorn sounds like loads of fun, there is little hope of obtaining one of these machines in America. So for now, learning how Toyota makes the GR Yaris will have to suffice because this is a pretty impressive little piece of engineering, and one that comes loads with rally-grade revs.