High-performance turbocharged engines generate significant thermal load, especially in compact platforms such as the Toyota GR Yaris and GR Corolla. When driven hard—on track, mountain roads, or in high ambient temperatures—heat accumulation inside the engine bay becomes a limiting factor for consistency, reliability, and aerodynamic stability.
Hood vents are not cosmetic components. They are engineered airflow devices that influence two key parameters: thermal evacuation and aerodynamic pressure management. When correctly positioned and structurally integrated, they improve cooling efficiency and reduce front-end aerodynamic lift.
At PIRAS Motorsport, our PIII GR Yaris Rally 1 WRC-style, PIII GR Yaris Rally 2, and PIII GR Corolla TRACK ATTACK HOOD VENTS Kit were developed as functional solutions validated through testing and precise geometric integration.
These kits are now installed on hundreds of cars worldwide, and all customers have been incredibly satisfied with the performance achieved!
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Heat Extraction and Pressure Differential
As the vehicle moves, high pressure builds at the front bumper and radiator inlet. The cooling stack relies on a pressure differential: air must enter through the grille, pass through the radiator and intercooler, and exit efficiently. If hot air accumulates in the engine bay, internal pressure increases and reduces cooling effectiveness.
Strategically placed hood vents create an extraction path in a low-pressure zone on the hood surface. The CAD top-view diagrams in the installation manual (pages 8 and 18) show how the vents are positioned specifically for extraction efficiency.
With improved evacuation, the engine bay retains less heat. As stated in the Important Notes section (page 4), the vehicle will take slightly longer to reach operating temperature due to improved cooling efficiency . This is a moderate and predictable consequence of reduced heat retention.
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Reduction of Front-End Aerodynamic Lift
Cooling is only half of the equation. The other half is pressure management.
At speed, high-pressure air trapped under the hood contributes to front-end aerodynamic lift. Lift reduces the effective vertical load acting on the front tires, which directly reduces available grip. By extracting that high-pressure air through controlled exit zones, hood vents lower internal engine bay pressure and reduce front-end lift.
Because aerodynamic forces increase with the square of speed, the effect becomes progressively more noticeable as speed rises. In real-world driving, the benefits typically become clearly perceptible from approximately 100 km/h onward, where aerodynamic loads begin to meaningfully influence vehicle dynamics.
Reducing front lift increases front axle grip during high-speed braking, cornering, and fast directional changes. The car feels more planted at turn-in, more stable under threshold braking, and more precise during rapid direction changes. On track, this translates into improved consistency and measurable lap time gains through increased stability.
As noted in the installation manual (page 4) , aerodynamic balance shifts toward the front axle. Suspension setup should account for this shift, particularly on OEM configurations where rear damping is relatively soft. Lowering the rear end and stiffening the rear low speed damper rebound may be of help if corner-entry oversteer is experienced. Of course, a rear wing would balance the aerodynamic package further.
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PIII GR Yaris Rally 1 (WRC-Style) Hood Vents
The Rally 1 configuration provides maximum extraction surface area for the GR Yaris platform. Its vertical strake architecture promotes strong evacuation from the upper engine bay and rear radiator region.
The kit includes left and right vent assemblies, aluminum mesh grilles, and an ECU harness protective liner. The liner must be installed as described in Step 10 (page 7) of our instructions to protect the harness located beneath the extraction area while still allowing service access.
All hood vent kits — Rally 1, Rally 2, and TRACK ATTACK — are manufactured using PA11 with HP Multi Jet Fusion technology. This material provides high thermal resistance, structural rigidity, and dimensional stability suitable for engine bay environments exposed to heat cycles and mechanical stress.
Due to its more complex and open strake geometry, the GR Yaris Rally 1 version is by design more delicate than the other configurations. The architecture maximizes extraction efficiency but requires careful handling. For this reason, we advise that the Rally 1 vents be used primarily on track-only cars that are maintained and handled with specific care, rather than on vehicles exposed to regular daily-use conditions.
Our Rally 1 hood vents are used, among others, by André Krutrok, Swedish Time Attack Category Champion, on his GR Yaris. In competitive environments, aerodynamic stability and cooling consistency directly influence performance repeatability and lap time results.
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PIII GR Yaris Rally 2 Hood Vents
The Rally 2 version applies the same engineering principles in a more robust and visually restrained configuration. The CAD positioning references (pages 18–19 of our instructions) confirm placement in defined extraction zones.
Like the Rally 1 and TRACK ATTACK versions, the Rally 2 vents are produced in PA11 using HP Multi Jet Fusion technology, ensuring identical material properties, structural integrity, and thermal resistance across the entire product range.
Installation involves accurate template positioning, controlled cutting of the aluminum hood skin, structural adhesive bonding along integrated paths, and mesh integration: we strongly recommend to have our hood vents installed by a good body shop.
While subtler in appearance and more tolerant of mixed-use conditions, the Rally 2 vents still reduce internal pressure, improve heat evacuation, and contribute to reduced front-end lift and improved high-speed grip.
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PIII GR Corolla TRACK ATTACK HOOD VENTS Kit
For the Toyota GR Corolla, PIRAS Motorsport developed the PIII GR Corolla TRACK ATTACK HOOD VENTS Kit using the same airflow and pressure-management principles adapted to its specific hood geometry.
Although the powertrain is shared, the GR Corolla is a totally different package from the GR Yaris, therefore we went back to the drawing board to design a new, bespoke extraction layout. Given the relative position of the GRC’s radiator package, we added a third – central vent in order to guarantee both the best heat dissipation and best aerodynamic performance.
By evacuating high-pressure air from defined extraction zones, the kit improves cooling efficiency while reducing front-end aerodynamic lift. As speed increases, the reduction in lift improves front axle grip in braking and high-speed cornering, enhancing overall stability and driver confidence.
The TRACK ATTACK vents are manufactured using the same PA11 HP Multi Jet Fusion process as the GR Yaris versions, guaranteeing identical material characteristics, thermal resistance, and structural durability.
Correct installation and structural bonding remain essential to ensure airflow effectiveness and long-term durability.
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UV Protection and Surface Finish Quality
All PIRAS Motorsport hood vents are supplied in black OEM-grade UV protection paint. Surface protection is treated as a durability requirement, not merely an aesthetic feature.
We conducted accelerated UV exposure testing and verified that, under normal operating conditions, the finish can exceed 10 years of sun exposure without degradation. This ensures long-term resistance to fading, surface breakdown, and coating failure.
All vents are painted by the same manufacturer responsible for painting body components for an Italian supercar manufacturer, ensuring consistent process control and high-quality surface finish that lasts in time.
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Engineering Development and Fitment Accuracy
The GR Yaris kits were developed using OEM-grade 3D scanning of hood geometry to ensure curvature conformity and precise placement. The kits underwent three product revisions and more than 12 months of real-world testing prior to validation (page 3) .
Extraction efficiency depends on positioning accuracy. The supplied templates ensure correct alignment within defined zones so that aerodynamic and thermal benefits remain predictable and repeatable.
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Durability and Use Considerations
Washing and High-Pressure Water Automatic car washing has been tested, but exposure should be minimized after installing the GR Yaris Rally 1 Hood Vent Kit (due to its complex strake architecture, concentrated pressure can stress the central fins and compromise structural integrity), therefore direct jet cleaning must be avoided or used with extreme caution.
The GR Yaris Rally 2 and GR Corolla Track Attack kits are not subject to this limitation.
Rain and Water Exposure
Rain does not create operational issues. Testing has shown no problems related to humidity or water ingress. The fuse box area beneath is OEM-grade insulated, and the supplied ECU harness liner provides additional protection in the extraction area.
The under-hood paint is the same you find on your car’s exterior, therefore it will not suffer from exposure to rain.
Driving in wet conditions does not compromise reliability or electrical safety.
Snow and Environmental Exposure
In heavy snow conditions, accumulated snow should not be forcibly removed from the vent area. Engine heat will melt accumulation during operation. As with any exterior component, protection during hailstorms is recommended.
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Final Perspective
Hood vents influence engine bay temperature, internal pressure, and front-end aerodynamic lift. By extracting hot, high-pressure air, they slightly increase engine warm-up time, stabilize cooling under load, reduce front lift, and increase front axle grip as speed rises.
On performance-oriented vehicles, improved stability under braking and in high-speed cornering directly supports more consistent lap times.
The Rally 1, Rally 2, and PIII GR Corolla Track Attack HOOD VENTS Kits, developed by PIRAS Motorsport, are engineered airflow systems designed not only to enhance performance, but to sustain it under demanding conditions.
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