One of the first DPi Mazdas was delivered to Joest’s workshops in Germany, and work immediately began in turning it into a competitive car. That process included a general tidying of the cockpit and particularly focussed at the rear of the car in terms of cooling and suspension layout. ‘I saw the very old car that came to the workshop in Germany and is still there,’ says team manager Ralf Juttner. ‘It was a shock to see that. This is still not what a racecar should look like; that was a nightmare. Looking at our situation now, hats off to SpeedSource that they ran with two racecars at all, but why didn’t they use the second half of the year to clean up what was obviously a ‘get it ready somehow’ car? There was no cleaning up process. For example, they had a drinks system in it, welded aluminium. [Drivers] Jonathan [Bomarito] and Tristan [Nunez] were in Germany with us, and I asked how much are you drinking in the stint? They said not much, because it doesn’t work anyway. It looked like a small nuclear power plant!’

But now Multimatic has taken on sole development of the chassis, and put former Lola designer Julian Sole on the case.
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The overheating issue on the original racecar Sole mentions above had led to some rather unusual solutions. The radiators were stood up in the sidepods, with a reduced size compared to when the engine ran in a Lola. So the first job was to improve the internal design and airflow. ‘I heard even with temperatures like this [speaking at a freezing cold Daytona at the ROAR before the 24 test in January], they would have struggled with the old cars,’ says Juttner. ‘They ran that engine in the Lolas, and they were on the limit, and then Riley made the radiators 70 per cent the size of the Lola. We have gone for bigger radiators. The radiators were standing on the left, and behind that was the big inlet for the turbo, so 60 to 70 per cent was blocked. The car that we received in Germany, they had a constantly blowing ventilator for the radiator to survive somehow. Now they are angled, bigger, and the inlet configuration is different.’

All four DPi manufacturers have been hit with Balance of Performance changes ahead of next weekend’s IMSA WeatherTech SportsCar Championship round at Long Beach.

There have been boost reductions across the board for the three teams running turbocharged prototypes.
The Acura ARX-05, Mazda RT24-P and Mobil 1 Twelve Hours of Sebring-winning Nissan Onroak DPi have all had their boost levels affected for the first sprint race of the year.

Cadillac’s DPi-V.R, meanwhile, will run with a 0.6 mm smaller air restrictor than it had at Sebring, while the Joest-run Mazda DPis have also been been hit with a 10 kg weight increase.

No aero changes have been made to the Prototype category, which has 14 cars listed for the third round of the season.

All four DPi manufacturers, however, will have reduced fuel capacities, with Acura and Nissan losing 3 liters, Cadillac 2 liters less and the Mazda getting handed a considerable 7-liter decrease.
The changes come amid a dominant run from DPis at Sebring, which saw the global-spec LMP2 cars, which are not subject to BoP adjustments by IMSA, struggle to match the pace in the 12-hour race.