During January's Tokyo Auto Salon, the mid-engine TGRR GR Yaris M concept was unveiled as the number-one item in "Morizo's Top 10 News Stories." At the recent Super Taikyu race in Okayama, the midship model finally took to the track.
Going compact with a new 2.0L turbo engine
As for the engine itself, the GR Yaris M concept sports Toyota’s compact G20E 2.0L turbocharged engine, first unveiled at the Multipathway Workshop in May 2024.
Compared to the existing 2.4L turbo engine, the G20E delivers substantially more power while being 10% smaller in terms of both height and volume, making it suitable for a wide range of vehicles that require high output, from sports cars to trucks and other heavy-duty vehicles.
Project General Manager Mitsuto Sakai, who develops engines at Toyota’s ICE Development Division, provided an overview of the G20E engine.
Project General Manager Sakai
Since the Technical Workshop, it has gotten even smaller. Though it’s still a work in progress, and there’s no guarantee of success, we are constantly pushing to make it more compact.
Our primary focus is figuring out how to design a powerful unit to be as compact as possible.
With the initial concept, we sought to make the engine smaller by looking at aspects such as the bore/stroke ratio (the ratio between a piston’s diameter and the distance it travels), but we’ve also challenged ourselves to shave millimeters from the dimensions of various parts, while trying to strike a balance with reliability.
We’ve also used CAE (Computer Aided Engineering, the use of simulations to assist development) and other technologies to boost output by drawing in more air. We spend our days doing such fine-tuning and testing all kinds of ideas through trial and error.
By pursuing a compact design while refining combustion efficiency, we are developing this engine to contribute to ever-better carmaking.
The task is far from simple, but this last practice session helped us identify various areas to work on, such as controlling the amount of air. Feeding these insights back into the vehicle, we will continue striving for new heights.
As a variation, right now we are racing a car with the engine mounted horizontally in the rear, while exploring the possibility of using it in a vertical position.
For the future, we are also considering things like modifying the engine’s specifications slightly to tune it for low-speed torque.
President Takahashi
When we showed this at the Multipathway Workshop, our key message was that, even as we pursue carbon neutrality, we are continuing to build engines.
Similarly, our goal here is not to build a race engine, but ultimately to improve combustion and clean up exhaust emissions toward a commercial release.
By combining improved efficiency with carbon-neutral fuels, in the future, we will create carbon-neutral engines.
The team is taking on these challenges as regulations on exhaust emissions and other aspects continue to grow ever more stringent. I believe that overcoming them will allow us to one day bring smiles to our customers.
What about the sound?
At the Okayama International Circuit, the TGRR GR Yaris M concept’s somewhat high-pitched engine sound stood out from the rest of the field of racing cars. Sakai was asked whether his team would continue refining the sound moving forward.
Project General Manager Sakai
As you improve performance, I believe there’s a trade-off in sound quality. Although it may be technically challenging, we are looking to control how the sound is transmitted from the engine by regulating the speed of combustion.
We want to analyze and effectively control such aspects. Ultimately, I believe developing the right sound is a crucial part of the car, and we will continue tuning the sound not only from the engine but in coordination with components throughout the entire vehicle.