Rear aero modifications for the 2022 Toyota GR Yaris Rally1

The development testing season for the 2022 Rally1 cars is reaching its climax as the end of the year approaches, with the design phase almost complete and the teams have already started the homologation process. Now it’s time to test the final designs, so we can discover some of the new solutions for the cars. This week, it was Toyota who tested the 2022 GR Yaris Rally1 car on some gravel roads of Central Catalonia. And the car used in these tests showed significant aero modifications at the rear that are worth reviewing.

K.Rovanperä/J.Halttunen, Toyota GR Yaris Rally1, Development tests, Central Catalonia, November 2021

The redesign of the hybrid cooling system is one of the main modifications in the car seen in the test. On one side, the size of the side air intakes has been reduced, as shown by the image below.

Toyota GR Yaris Rally1 in September (left) and November (right) tests – pictures by Louka Sorriani (left) ad llluis555 (right)

The reason behind the size reduction can be due to a smaller airflow required (less requirement than expected from the rear radiator) or to reduce the interference of the intake on the air flowing towards the rear wing. Both explanations are reasonable: the maximum typical temperatures in electric propulsion are typically around 60ºC, while normal operation temperature is 35ºC, that is, a cooling requirement considerably smaller than for an internal combustion engine (ICE). On the other hand, the upper part of the original air intake was located ahead of the side wing. Even though this is probably not the final wing design, it seems logical to eliminate any potential disturbance on the air flowing to the rear.

K.Rovanperä/J.Halttunen, Toyota GR Yaris Rally1, Development tests, Central Catalonia, November 2021

On the other side, the rear vent has been relocated to a more elevated location, and the new design of the vent allows to clearly see two fans (in opposition to one in the case of the Puma) to remove hot air exiting from the hybrid system radiator.

K.Rovanperä/J.Halttunen, Toyota GR Yaris Rally1, Development tests, Central Catalonia, November 2021

This design is significantly different from the previous design, where the vents were located at the bottom of the rear bumper, thus allowing to add energy to the air flowing under the car, to facilitate removing it.

Old (top) and new (bottom) design of the rear end of the Toyota GR Yaris 2022 – images by Rourebel (top) and llluis555 (bottom)

With the new design, the rear vent has been moved upwards, thus preventing it from adding energy to the air flowing from under the car (kind of exhaust blown effect). But it has now another purpose, as we will see later.

The second big modification in the car seen in the test is the redesign of the rear fenders. The wing shape on the top profile has been removed (as shown in the images below), making it less prominent, possibly to allow a cleaner flow under the rear wing, as well as reducing drag (due to the reduction of front area).

But the most significant modification in the rear fenders would be the introduction of a new orifice to act as a vent, by removing air from the wheel space, in substitution of the famous Yaris rear fender vents, now forbidden. For this purpose, there is an orifice in the inner of the wheel arch, connecting with the rear of the car, to allow air to be removed from this space (as shown by the yellow arrow in the image below).

Wheel arch air intake (top) and rear vent (bottom) n the new Toyota GR Yaris 2022

The air is conducted across the rear fender towards the rear orifice. The orientation of the pipe and vent forces air to the center of the car, where it interacts with the airflow coming from the fans. The result is that air is pushed by this stream to the car’s wake, and this effect travels upstream, increasing the efficiency in air removal from the wheel space. Air has to be removed from there or it will flow under the car, increasing the pressure and reducing downforce. With the removal of the rear diffuser and rear fender vents, any solution oriented to improve downforce in this area is more than welcome.

K.Rovanperä/J.Halttunen, Toyota GR Yaris Rally1, Development tests, Central Catalonia, November 2021

In summary, the new modifications seen in the test allow Toyota to increase rear downforce by removing air from under the car with the new rear fender design, while the potential exhaust blown effect generated by the hybrid system cooling is probably lost due to the relocation of the rear vent. Step by step, the new car is been defined, a process that should be completed in the next weeks.

This post includes the opinions of the author, which are certainly not always right. If you detect any error or you disagree, do not hesitate to contact us, by sending an email to wrcwings@gmail.com. We love to learn!

2 thoughts on “Rear aero modifications for the 2022 Toyota GR Yaris Rally1

  • 2021-11-13 at 06:51
    Permalink

    Hello Lluis

    Thank you for your article, still discovered with passion.
    A question calls out to me; The rear is particularly designed to cause the maximum aerodynamic thrust, but only on the rear! On the WRC2021s, the front of the car had a lot of aero accessories. Have they become banned? Do cars not risk being out of balance? Also, during the jumps.
    Jean Luc.

    Reply
    • 2021-11-13 at 10:19
      Permalink

      Hi Jean Luc,
      You’re very kind, thanks, also for us continues to be amazing and challenging to try to understand any new solution.
      That’s a very good question: yes, the new regulations seem to forbid the front appendages (dive planes, winglets) in addition to the rear diffuser. On paper, the impact on downforce at the front and rear should be similar, but we have seen during the last years how difficult was to achieve enough front downforce to balance the excess at the rear. We have not seen the whole aero package of the new cars yet (only for the Puma and it may still change), so new solutions for the front, pseudo-diffuser and rear wing could be introduced for a better balance, based on the experience gained in previous years. But the risk of unbalance is high, because of the new regulations, and if they don’t succeed with that, most probably the next jokers will be spent at the front of the cars, as it happened in 2017/2018.

      Reply

Leave a Reply

Your email address will not be published. Required fields are marked *