Uncovered: The genius behind Red Bull’s short-lived exhaust-blown diffuser

Uros Radovanovic
Sebastian Vettel in action for Red Bull at the 2010 German Grand Prix.

F1 2010: The start of Red Bull's first dominant spell

To become the fastest team in F1, you must think more creatively and differently than the rest.

That’s exactly what helped the Red Bull team clinch the Constructors’ and Drivers’ championship in 2010.

We will explore the exhaust-blown diffuser – an invention that, like many brilliant ones, was short-lived but had a significant impact on the F1 world.

An unsolvable problem in F1

The period from 2009 to 2012 was an exhilarating time for all engineers in the F1 industry. In 2009, the double diffuser was first seen, which has since received even more aerodynamic enhancement, especially by Red Bull.

The 2010 RB6, in addition to the double diffuser, had interestingly positioned exhausts. Adrian Newey, one of motorsport’s most brilliant minds, worked on this car. However, he faced significant challenges in solving some of the biggest aerodynamic issues.

Specifically, the unresolved aerodynamic problem was the dirty air created behind the front wheels. This turbulent air negatively affects all aerodynamic components it flows over. Keeping this dirty air away from the car remains a completely unsolvable issue.

As previously mentioned, the invention of the double diffuser shifted engineers’ focus to the rear of the car. They wanted to extract the maximum level of downforce with the help of a loophole in the rulebook that was discovered the previous year. But the mentioned problem caused them great difficulties, which did not allow them to realise the full potential of the double diffuser.

Moreover, turbulent airflow would enter the diffuser space, disrupting its efficiency. This happens because the space under the car forces air to move faster, creating a low-pressure field. However, Red Bull engineers thought to revert to designs from the 80s and 90s to solve this problem.

Say hello the exhaust-blown diffuser

In the 90s, McLaren-Honda tested interesting exhaust designs. They placed exhausts on the lower surface of the diffuser, “feeding” it with additional air. Note that exhaust air is at high temperature and speed, meaning it carries a lot of energy. From an aerodynamic standpoint, such air makes aero components highly efficient.

Red Bull’s team of engineers reinvented and implemented this system on the RB6. Initially, Red Bull used the old exhaust system from the RB5, until the last day of testing when they tried different exhaust positions. They even used stickers on the old exhaust pipe to hide their secret from other teams.

However, they were quickly discovered and became a main topic among F1 engineers.

The previous generation of cars had high-positioned wishbones that allowed the exhaust to be practically under them. This system had several aerodynamic advantages, increasing their performance that year.

The hot air exiting the pipes at high speeds served as a boundary between the dirty air and the diffuser, preventing turbulent air from disrupting the diffuser’s airflow. Therefore, the diffuser functioned much more efficiently, generating more downforce.

One of the myths at the time was that the new exhaust position was used to better control the temperature of the rear tyres. While it might have had a small impact, it was certainly insufficient to drastically change the performance of the rears.

The drawback of this system was that it only worked when the driver was at full throttle because that’s when the exhaust airflow is at its maximum. Therefore, Renault, along with Red Bull, had to find a solution for this problem.

Blowing hot and cold

Engineers from the power unit section came up with brilliant solutions quickly adopted by other teams. There were two solutions: cold blowing and hot blowing.

Both solutions involved continuous maximum operation of the power unit. This means it spins at high revolutions even when the driver is not pressing the accelerator.

The first idea was for the engine to continue at maximum revolutions even when not under full throttle, essentially turning the motor into an air pump and pushing air through it, known as cold blowing.

Hot blowing worked under similar conditions but maintained combustion of fuel, giving even more energy to the exhaust air. Engineers created a specific engine map that demanded it delay the injection of air when the driver isn’t pressing the accelerator, leading to late reactions and fuel burning in the exhaust branches behind the engine.

Of course, this solution significantly impacted fuel consumption and brought new challenges.

Firstly, temperatures and engine loads were much higher, so Red Bull couldn’t use this race strategy throughout the entire race. What was more important to them was the advantage created during qualifying.

For us fans observing from the sidelines, the hot blowing system brought an incredibly loud sound from the cars, which we surely miss now.

Other teams quickly saw the positive aspects of the exhaust-blown diffuser and developed their versions.

The war with the FIA

Before the start of the 2011 season, the FIA changed the rules and defined the position of the exhaust system differently. However, this only inspired ingenious minds to find their way around the rules.

The most interesting concept came from the McLaren team, which placed the exhaust pipe right at the edge of the car’s floor.

The goal of this design was to create a barrier between the airflow passing under the car and the external air, isolating the floor and diffuser and making them work more efficiently by creating a lower pressure area.

However, this project never made it to testing due to significant temperature management problems.

Meanwhile, Red Bull created another version of its ingenious system. This time, the exhaust pipe was wide and low, positioned on the top surface of the floor. Like the previous year, its main role was to prevent dirty air from entering the diffuser.

Red Bull dominated that year, winning 12 out of 17 races. Sebastian Vettel secured his second championship title, and the RB7 car went down in history as one of the most dominant.

Of course, the exhaust system wasn’t the only reason for their championship win, but it certainly contributed as much as other components.

Such stories are true examples of how creativity in high-tech sports like F1 can pay off.

Read next: F-Duct uncovered: The banned McLaren innovation that gave birth to DRS

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