Updated with images of the real car on June 22th, 2024 (at the end of the article)
The upcoming Rally Poland will bring a technical first: the introduction of the first non-hybrid Rally1 car. This new category was introduced by the FIA end of last year to help bridge the gap between Rally2 and Rally1, providing cheaper and simpler top cars for young drivers, and allowing Rally1 cars to compete in regional rallies.
The debut of the non-hybrid Ford Puma fielded by M-Sport in Poland will be performed by Latvian duo Mārtiņš Sesks and Renārs Francis, who already took part last Monday on the team’s pre-event test held in Estonia. There, they drove the same car used by Muntser and Fourmaux the days before, at least externally, but possibly with the hybrid unit out of operation, to get the driver used to driving such a specific car.
M.Sesks/R.Francis, Ford Puma Rally1, 2024 Rally Poland pre-event test, Estonia – image by Emīls Grintāls (IG @e_grintals)
The concept of a non-hybrid car seems clear: a Rally1 car without the hybrid unit. That is, without the extra 134 hp that the hybrid unit is able to supply at some acceleration points. But how will it be materialised? And how will it affect aerodynamics?
As usual, it’s good to start with regulations. FIA defines a non-hybrid Rally1 car in article 12.1.3 of the 2024 WRC Sporting Regulations. According to this article, the hybrid unit must be replaced by either:
1) the existing (bullet-proof) carbon housing with ballast replacing internals, or
2) a dummy hybrid unit with identical size and dimensions, made of any material (but one face of the dummy must be removable for checking internal ballasts). It will be located in compliance with the Rally1 Homologation form and ensuring that the center of gravity/height must be equal or higher to the one of the hybrid car.
The minimum mass is set at 100 kg, 90kg for the dummy unit plus an additional 10 kg, to be fitted either in the cockpit or the boot of the car, in compensation for the removal of other internals related to the operation of the hybrid unit: the shaft between the hybrid system and rear differential, sensors, actuators or the cooling system.
A steel panel must be added to close the openings for accessing the hybrid electrical connections, and a cover plate or bung to cover the space left by the disassembled shaft, but no other modifications are permitted on the rear differential.
M.Sesks/R.Francis, Ford Puma Rally1, 2024 Rally Poland pre-event test, Estonia – image by Emīls Grintāls (IG @e_grintals)
What about the exterior of the car?
Removing the hybrid unit means there is nothing to cool down at the rear of the car (brakes and transmission apart). Thus, regulations allow the removal of the ducts and, even better, the removal of the homologated trim, which can be replaced by body panels with a continuous surface.
Does it mean that the side air intakes will disappear from the Puma? As always, it will depend on the cost. If it is only a one-off appearance (as it seems to be, as the car will only be aligned in Poland, AFAWK), it might well be that air intakes are simply blocked. Preventing air from entering the car is already a way to get a (modest) drag reduction, as air is forced to flow around the intake instead of entering into a pressure-drop duct.
But, if the (upper) side intakes are finally removed, the gain in drag will be even higher. The reduction in front area, combined with a smoother shape of the car will result in a significant air resistance reduction. As the Puma is the Rally1 car with the most prominent side intakes, such a modification would have a big impact on the car’s performance… and who knows if it could lead to modifications in the hybrid car if it proves beneficial enough…
Non-hybrid Ford Puma Rally1 potential configuration: blocked or removed upper intake, while the lower intake remains intact – image by Emīls Grintāls (IG @e_grintals)
Regarding the lower side intakes (those ahead of the rear wheels), they are expected to remain in place, as still used for brake and transmission cooling.
On the other hand, no cooling air entering the car means no air will be expelled at the rear. The rear radiator and cooling fan will be removed and replaced by ballast. The disappearance of the jet of air expelled by the rear fan (which helped accelerate the air coming from under the car) means losing the advantage of removing more air thanks to this element, as shown in the left side of the image below. This means that pressure under the car will be higher, that is, less rear grip will be generated due to the removal of the rear fan.
Ford Puma Rally1 with (left) and without (right) hybrid cooling system: the rear fan contributes to removing air from under the car, thus increasing grip – image by MSport WRT
The car will be identified by inserting a 45 mm diameter sticker over the green/red lights of hybrid cars, representing “HY” in red on a white background and crossed and surrounded in black.
In summary, a car with some similarities with the hybrid version (similar weight/weight distribution/center of gravity), some important downsides (less power and less rear grip) and even some small benefits, in the form of less drag. All in all, a less competitive car but a good first contact with the top category for young drivers, who are released from the pressure of helping their team (as, by regulation, they cannot be nominated for scoring manufacturers’ points) so they can concentrate on their learning process.
IMAGES OF THE REAL CAR RELEASED BY M-SPORT
The images of the car released by M-Sport on June 21st confirm the disappearance of the upper side air intake and the blockage of the rear outlets, as suggested in our article.
M.Sesks/R.Francis, non-hybrid Ford Puma Rally1, 2024 Rally Poland – image by M-Sport WRT
The car includes the latest design of the rear wing used by the official cars since Croatia, while still missing the stickers showing the non-hybrid character of the car.
M.Sesks/R.Francis, non-hybrid Ford Puma Rally1, 2024 Rally Poland – image by M-Sport WRT
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