At the time of writing, IndyCar was on the verge of its hybrid era, with the Mid Ohio event on July 7 scheduled as the first race for the modified cars. The series continues to exploit a spec Dallara chassis design that is now 12 years old, powered by either a Honda (HRC) or Chevrolet (Ilmor) V6 twin turbo of equal vintage. Tight, original design and ongoing development rules mean the two very similar engines produce comparable outputs.
To hybridise the IndyCar, the choice was made to instal a spec system between the clutch on the existing engine flywheel and the spec Xtrac gearbox. Thus packaged into a revised bellhousing is an MGU geared to the gearbox input shaft, and a super-capacitor for storing electric energy harvested by the MGU in generator mode and for deploying it in electric motor mode.
Thus, the key electrical elements are all packaged into a modified bellhousing, including the inverter, which is integral with the MGU. This hybrid bellhousing is larger than the previous item and the Xtrac transmission has been repackaged to mate with it. Water is used to cool the MGU/ inverter and super-capacitor, with a single electric water pump mounted on the outside of the bellhousing.
A water/air cooler is provided within the right-hand sidepod, where there was scope to add one alongside the existing engine and gearbox oil. The other pod with its engine-coolant radiator is unchanged. Other limited modifications to accommodate the hybrid elements include changing the clutch from a push to a pull type and relocating the air jacks outside the bellhousing.
The MGU is from Empel Systems, while the super-capacitor pack is from Skeleton Technologies. This combination will add power boosts of up to 60 bhp, as controlled by the driver. However, while the MGU may be deployed at any time, not only will the amount of energy harvested be a constraint, but there will also be a limit on the amount of electrical energy deployed per lap.
The amount of energy that can be stored in the super-capacitor pack will be insufficient to run the MGU for many seconds at a time. It will be used for short bursts, perhaps sometimes as a torque-fill off of slow corners while the V6 turbos are still spooling up.
