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Toyota's Peak performance
Toyota sent a revised version of its EV P002 to the 2013 Pikes Peak International Hill Climb after a six-week program to update the car
by Rachel Evans
On the back of its EV record-setting success at the 2012 Pikes Peak Hill Climb, Toyota decided to enter the 2013 competition with a revised version of its all-electric race car. A six-week program to update the TMG EV P002 was carried out by both Toyota Motorsport in Cologne, Germany, and Toyota Racing Development (TRD) in Concord, North Carolina. While TMG concentrated on the powertrain, a small team of four engineers from TRD was responsible for aerodynamic upgrades as well as testing. Says TRD’s technical director, Steve Wickham, “Most of our time at TRD is spent working on NASCAR. This was a little bit of a side project for us!”
Changes to the car included a new aerodynamic package, revised brakes and more power. In addition, the position of the driver was changed and a bigger steering wheel fitted.
The revised aero package featured a new front and rear wing, which increased the downforce of the car threefold. Wickham says, “This increased the lateral performance and also the rear-end grip out of the medium-speed corners.” The components were manufactured by DJ Cars from the UK, under design direction from TRD.
TRD was responsible for their mountings. Wickham says, “They put a lot of load into the car so we needed to change the structure underneath the skin from the standard radical-based structure to support the additional loads at the front and the rear.”
The car has a 60:40 weight distribution front/rear and produces 1,800 lb of downforce at 100mph. As part of the new aero package, Wickham explains, “Extensions were placed around the wheel arches to encourage air out from underneath the vehicle, creating low pressure.”
The new structure at the rear included the new cooling system; the radiator was moved into a vertical arrangement with bigger fans to extract the heat.
To increase the performance, “We rebuilt the electric motors and changed the specification so we could increase the rpm,” Wickham verifies. “We also changed the gearing to make it more suitable for the hillclimb, where top speed is only in the region of 140mph, not [the Nürburgring-spec maximum of] 160mph.” Toyota’s electric car produces 400kW of power.
TRD moved the driver to the middle of the car, which also increased its performance by increasing the airflow to the rear wing and improving weight distribution. It also enabled the squad to put a bigger steering wheel in.
With just six weeks to prepare, there was little time for testing. TRD regularly uses Windshear’s wind tunnel in its NASCAR program and, Wickham says, “I managed to persuade the manager of that program to let us have a day there!”
The team spent one day in the rolling-road tunnel on a 12-hour shift testing the front and rear wings. “We ran through all the aerodynamics and all the sweeps of the positions of the wings so that we knew what we had in terms of an aero map,” explains Wickham. “This meant that on the mountain we could adjust the front and the rear syncronization without having to guess.”
Due to limited resources, TRD was unable to do any CFD on the resulting design. However, an FE analysis of the rear-wing structure ensured the design was safe.
There was no time for pre-event testing at altitude, but the team performed two shakedown tests in the Charlotte area, close to its base, at around 220m above sea level – a world away from Pikes Peak, which reaches altitudes of 4,302m. These early tests were designed to get driver Rod Millen familiar with the car and conduct system checks before it was packed up and shipped to Pikes Peak.
Once at the event in Colorado, teams are only allowed limited track time before the actual race: only one or two runs a day, and never the full course. TRD performed three days of tire testing before the main race week.
Initial testing revealed the need for almost no changes to the vehicle. The cooling capacity of the power electronics cooling system was increased with what was essentially a dry ice bucket in front of the radiator. “At that altitude, the air is 30-40% less dense, so although you don’t need the air for the engine, it is needed for the cooling system.” Wickham confirms, “Your cooling needs to be 40% more efficient than at sea level.”
Come race day in June 2013, bad weather meant the team was unable to improve on its 2012 record – however it did take 16th overall, fourth in class. But for Wickham, the exercise was about much more than just the result.
“One of the main reasons I pushed for this program to happen was to give our engineers a different way of looking at things,” he explains. “For many years, they’ve been working with a NASCAR frame of mind, but being able to work on this car with a limited budget and very few rules, was a breath of fresh air.”
Dimensions: 4,100 x 1,040 x 1,790mm
Wings: DJ Cars
Electric motors: Evo Electric
Inverters: 2x TMG inverters
Battery: Lithium ceramic