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Racing Refresh Tech Tuesday: INDYCAR Push-to-Pass

Updated: Jun 22, 2022

(Photo Credit: INDYCAR)

In this new series brought to you by Racing Refresh will be a weekly, in-depth review of the engineering and technological advancements in auto racing. From the leading edges of performance and innovation in Formula One, IndyCar, and NASCAR. Each Tuesday will be something new for new fans to understand more about the cars they see on their televisions, so they have a deeper understanding of the things they see on a weekly basis.

In our first installment of Tech Tuesday, we will be looking in the world of the NTT INDYCAR SERIES is the Push-to-Pass system that was brought to IndyCar in the 2009 season. To start, there are many forms of this system in open-wheel racing that is used. In Formula One it was originally called the Kinetic Energy Reserve System and now just the Energy Reserve System. In Formula E it is called Attack Mode, and in the former Champ Car days it was called "The Button." Each of these features preforms in the same way. To add a boost of power for a limited time to help facilitate passing or help with defending a position.

In INDYCAR, all cars in the field use a 2.2 liter, V6 turbo-charged engine that is supplied by both Chevrolet and Honda respectfully. Each engine puts out 700 hp and can rev up to 12,000 RPM. What sets IndyCar and Formula One apart is the fact that the former has no restrictions on how much fuel could go through the engine to create power.

Much like Formula One; IndyCar had a problem. The problem was with how powerful the engines are, there is a significant power loss from an internal combustion engine in the form of exhaust and heat transfer. (If we remember the Law of Conservation of Energy that energy cannot be created nor destroyed, only transferred to one form or another.) Unlike the MGU-H in F1 (which we will talk about in next Tuesday's article), IndyCar does not have that component on the car which means some energy is lost at low revs. To counteract this in IndyCar is the use of push-to-pass. In the instant the driver pushes the button, the exhaust air is pushed through a turbine and into a compressor which is then passed through back towards the engine.

For each road and street course race on the IndyCar schedule, each driver has the ability to use the push-to-pass system for 200 seconds per race and is accessed by a button on the drivers steering wheel. With each press, the driver has 10 seconds of use with a brief 10 second cool-down period between uses. Once activated it gives the driver 50 additional horsepower and 200 additional revs to either attack a driver for position or defend himself from people behind. As of writing this, there is no push-to-pass at ovals. (But that might change with the new power units being delivered in 2024.)

In our next installment of Tech Tuesday, we will be looking at components of the Formula One power unit called the MGU-H and MGU-K.


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