When F1 Used Exhausts to Make Cars FASTER

Summary

After the double diffuser was banned following the 2010 season, Formula 1 teams needed to recover rear downforce. Red Bull found a way to use exhaust gases to improve diffuser performance, and other teams soon followed.

The diffuser creates low pressure beneath the car by expanding and accelerating airflow under the floor. That airflow can be disrupted by tyre squirt: air pushed sideways by the rotating rear tyre, which can interfere with the diffuser.

Red Bull repositioned the exhaust outlets so fast-moving exhaust flowed along the floor, between the tyre and the diffuser. The exhaust flow drew surrounding air with it, helping move more air through the diffuser and increasing downforce. It also helped push tyre squirt away from the diffuser, allowing it to work more effectively.

The main limitation was that exhaust assistance normally depended on the driver pressing the throttle. Teams developed two ways to keep exhaust flowing when the driver lifted off:

• Cold blowing

  • The engine’s throttles remained open even when the driver lifted off the pedal.
  • Fuel and ignition were reduced to slow the car, while air continued to pass through the engine and out of the exhaust.
  • This maintained some diffuser effect, but not as much as full-throttle operation.

• Hot blowing

  • The throttles stayed open, and fuel continued to be injected, but ignition was delayed.
  • Combustion occurred late, with fuel burning in the exhaust and producing hot, fast-moving gases even while the driver was off throttle.
  • When successfully implemented, this could sustain a stronger diffuser effect through corners and give drivers more confidence, particularly at low speeds.

Exhaust-driven downforce also produced the cars’ distinctive rasping sound. The FIA eventually tightened the rules on exhaust positioning at the end of 2013, bringing the blown-diffuser approach to an end.

Speakers and Sources Featured

• Driver61 narrator — introduces and explains the technology.
• Scarbs — provides the technical explanation of cold blowing and hot blowing.
• Red Bull — identified in the narration as the team that developed the exhaust-layout solution described.