Chip Ganassi Racing’s six-time IndyCar champion Scott Dixon was driving for Honda around the 14-turn 2.439-mile course, while Team Penske’s two-time and reigning champion Will Power took the wheel for Chevrolet.
Although the test was for 2024 – when IndyCar will introduce a hybrid system mated to the 2.2-litre, twin-turbo V6s – the event was shrouded in secrecy.
Representatives from IndyCar, Chevrolet and Honda all refused to speak either on- or off-the-record about the purpose of the track time.
A Chevy spokesperson insisted to Autosport that it was “not a hybrid test”, Honda stated that it may choose to comment on the progress of the company’s 2024 power units within the next two weeks, while IndyCar was unwilling to pass statement on what was a manufacturer-led test.
However Autosport has learned that, as Chevy stated, this was not a strictly hybrid test. Power and Dixon were trialing all systems other than the MGUs themselves, checking that other new-for-2024 components in the system – including the supercapacitors – are capable of withstanding the stresses of racing as well as trying out a proposed new gearbox.
The current IndyCar, which has its roots in the DW12 introduced 11 years go, is already considered by most teams and drivers to be overweight thanks to the regularly improved safety systems, not least the aeroscreen introduced from the start of the 2020 season.
This problem will be exacerbated by the arrival of the hybrid system in 2024, which appears set to increase the weight of an IndyCar by around 100lbs. The Penske and Ganassi cars in the IMS test are believed to have been ballasted to replicate that weight gain.
To slightly offset this increase, IndyCar has proposed a lighter magnesium casing for the gearbox, and these were on the Ganassi and Penske cars for the last two days.
Although the test was heavily rain affected, there was a plentiful supply of Firestone wet tyres on hand, so Power and Dixon were able to plow through the programme and an assiduous observer believes that between them the two IndyCar champions clocked up almost 600 laps. There were few if any major reliability concerns, and stoppages appeared to be confined to those caused by weather alerts for lightning in the area.
Given this amount of running at IMS over the past two days, it suggests that progress with the hybrid system – a collaboration between Chevrolet and Honda, since the original 2.4-litre engines were put on ice and the proposed Mahle hybrid system was dropped – has been notably swift.
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Two major caveats are that the MGUs were not being utilized in the test, and that the bad weather meant that the systems that were in place were put through far less strain than if the track had been dry. Lower grip levels of course mean lower G-forces – lateral in cornering, and longitudinal in acceleration and under braking – but they also mean that the drivers generally stay away from the kerbs, so the vertical forces and subsequent vibrations are considerably reduced.
The next 2024-spec test for Honda and Chevrolet will include the full hybrid system, and is likely to be held again at IMS, this time in late June, after the Road America race.
