Ask Soylent: Implementing Hybrid Engines in NASCAR
"dalek" writes:
As recently as less than a year ago, NASCAR stated it planned to implement hybrid engines in 2024. Although rumors indicate that this timeline may have changed, IndyCar has successfully tested the hybrid engines it will begin using in 2024, and NASCAR probably won't be too far behind. A hybrid engine simply means that it's powered from more than one source of energy, usually a combination of gasoline and electricity.
Formula 1 began using hybrid power units in 2014, which are powered both with gasoline and electric power, and use fuel more efficiently than cars without hybrid components. F1's experiences with hybrid power units and their mistakes could provide some guidance for how other racing series might switch to hybrid engines. Chain Bear provides an excellent discussion of how F1 power units work. They still contain an internal combustion engine, but the efficiency is increased and energy is recovered in a few ways.
F1 engines are turbocharged, meaning that energy from exhaust getting expelled is used for forced induction. This means that the air in the intake is compressed, and the combustion is more efficient than in a naturally aspirated engine. However, the turbo requires a high exhaust pressure, meaning that there is a lag between when the car accelerates and when the turbo can operate efficiently, which is known as turbo lag. One of the hybrid components is the MGU-K (K for kinetic energy), which captures energy through regenerative braking. Instead of energy being lost as heat during braking, the energy is used to charge the energy store, which is usually a capacitor or a battery. Another component is the MGU-H (H is for heat), which captures energy from the exhaust as it goes through the turbo, and can charge the energy store. The MGU-H can also put energy into the turbo during acceleration to avoid turbo lag.
The last time F1 ran a points race on a true oval track was the 1960 Indianapolis 500, only going to street circuits and road courses since then. These tracks usually have hard braking zones, providing frequent opportunities to capture energy during braking. Even without the MGU-H, F1 cars have many opportunities to capture energy during a lap.
NASCAR runs a few races each year on road courses, and some short ovals like Martinsville and Gateway also have hard braking zones. This is a combination of high speeds on relatively long straights and much slower speeds through corners with small radii and low banking. Regenerative braking would work well at these tracks. However, most other oval tracks do not require nearly as hard of braking, limiting the opportunity to capture energy through regenerative braking. For hybrid engines to have an effect without hard braking zones, energy will need to be captured in other ways these tracks. Despite the lack of a turbo, the obvious solution would seem to be capturing energy from exhaust heat while on throttle.
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