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50 REPORT : 24-HOUR PROTOTYPE ENGINES 2020 The Mazda DPi car is based on the Riley LM P2 car, with aerodynamic development by Multimatic, as described in our sister publication 24 Hour Race Technology 2019 . As in the two previous years, at Daytona the two examples of the RT24-P (#55 and #77) were campaigned on behalf of the factory by Germany’s Joest Racing team from a US base in Georgia. However, it had already been agreed that later in the 2020 season, Canadian company Multimatic would take over the running of the Mazda DPi campaign. At Daytona, AER had a practice engine for each car that was changed just prior to qualifying. The replacement was then used for the rest of the event, plus there were two spares on hand that were not called upon. As in 2019, the #77 took pole for the 24 Hours, this year lapping in 93.711 s, just 0.026 s slower than its all-time lap record from the previous year. It then had a race devoid of any issues aside from one penalty, but it didn’t quite have the pace of the winning Cadillac, which overcame two penalties and a few niggles to beat it by just over a minute. Nevertheless, this was the first Daytona finish for a Mazda DPi car, and the close runner-up spot was well-deserved. The #55 also came through to the finish, 10 laps down after sustaining bodywork damage early on and then a loss of boost pressure, owing to a wastegate mechanical failure. 24-hour marathons, Wilson said, “The base specification remained unchanged but there were numerous very small changes, all focused on addressing reliability weak points. There were some minor changes around the pumps. There were also some detail casting changes where we had identified the potential for cracking. “Those were from observations we had made when an engine was rebuilt after more than 5000 km. There were some things that hadn’t necessarily stopped it from running but were found upon inspection during strip-down. We are robust about the process by which we identify improvement opportunities.” The detail changes embraced engine installation. “Since it is an I4 it shakes a lot,” remarked Wilson. “We had a car fire in testing as a result of a bent tube fitting failure. That was a knock-on impact of the vibration; it can be significant as to whether you use a bent tube aluminium fitting on a fuel rail or a forged stainless steel fitting instead. “So nothing was fundamentally different for Daytona 2020; it was an accumulation of very small, detail changes. It was really grasping the change in culture around quality, reliability and continuous improvement. It was almost more of a culture change than the sum of its parts. “It was getting the quality and process sides right. That is where the real differences were [between the engine raced at Daytona in 2019 and the one in 2020]”. Wilson said that, ahead of Daytona 2020, “We did some long runs to support our confidence in our technical package. We did three 24-hour race simulations on the dyno in the months leading up to the event. There was also a concerted effort on endurance testing on track. The team ran a 24-hour simulation, albeit not all in one chunk – they split the miles across Daytona and Sebring tests. That was primarily looking for any Achilles heel in terms of overall car reliability.”  Going into 2020, 5500 km remained AER’s mileage target. The IMSA-imposed boost curve was unchanged from Daytona 2019, as was the compression ratio and other such details, including the maximum of 9000 rpm. MAZDA AER AT DAYTONA AER P91B 2.0 litre 16-valve, DOHC I4 turbo AER owner/managing director: Mike Lancaster AER technical director: Michael Wilson AER global project manager: Andrew Saunders P91B project manager: Karam Kundi Daytona 24 Hours 2020 track support lead engineer:  Andrew Saunders Daytona 24 Hours 2020 track support #55: Boris Poullain Daytona 24 Hours 2020 track support #77: Oli Poyser 77 Mazda DPi (Xtrac/Michelin) 2nd – 833L 2nd DPi 55 Mazda DPi (Xtrac/Michelin) 6th – 823L 6th DPi “We had a car fire in testing as a result of a bent tube fitting failure. That was a knock-on impact of the vibration” Joest again ran a pair of Mazda DPi cars – this #77 car finished second overall (Courtesy of IMSA) t