Engine 2.4-litre, twin-turbo, V6 (petrol)
Hybrid system twin-axle KERS, battery storage
5 Sébastien Buemi, Anthony Davidson, Kazuki Nakajima
6 Stéphane Sarrazin, Mike Conway, Kamui Kobayashi
“We understood after Spa last year that we should have changed engine concepts for 2015.”
Toyota Motorsport technical director Pascal Vasselon offers a candid appraisal of the Japanese firm’s unsuccessful defence of its 2014 WEC crowns. His words also explain why this year’s new Toyota TS050 Hybrid has a twin-turbo V6.
A turbocharged engine to replace the normally aspirated V8 that powered the TS030 and TS040 had been scheduled for 2017. Toyota’s technological road map called for a switch from its super capacitor energy-storage system to a battery in 2016, to be followed one year later by the arrival of a new petrol powerplant. The poor performance at last May’s Spa WEC round resulted in a rethink.
“We kicked off a global feasibility study to see how far the changes could go,” says Vasselon. “We understood at Spa that the development potential of turbos was a bit higher [than a normally aspirated engine].
A turbo gives you peak efficiency in a much wider range of revs, atmospheric pressure and temperature. Overall you operate at a higher average fuel efficiency over a season.”
An additional consideration was the reduction in fuel available to the factory LMP1s for 2016. The final call by the rule makers to go for the maximum reduction of 10MJ of energy measured over the long Le Mans lap, roughly equivalent to 7.5 per cent, was made after Toyota’s decision, but it was on the table. Vasselon describes this as a “consideration” but not “the driving factor”.
The green light was given to the turbo programme immediately after Le Mans last June. Little existed at that stage at Toyota’s Higashi-Fuji technical centre in Japan, but by mid-September the first 90-degree 2.4-litre engine was running on the bench. A V6 was chosen because, says Hisatake Murata, general manager of Toyota’s motor sport development unit, it “achieves the best balance of power and efficiency” with the latest regulations.
Toyota might have opted for a turbo engine and the switch to a battery, enabling it to move up into the 8MJ hybrid class, but its concept remains distinct from that of Porsche. The reigning world champions retrieve from the front axle and a turbine driven by exhaust gases. Toyota has retained the twin-axle kinetic energy recovery system of the TS040.
Murata points out that recovering kinetic energy “is for free”, but using exhaust gases to drive a turbine comes with a penalty on engine performance. Vasselon concedes that a twin-KERS is heavier than Porsche’s set-up, but “you get more performance out of it”.
Toyota admits it is still learning about its 2016 Le Mans challenger and can improve on a Silverstone weekend during which it was outpaced by rivals. “We still have the possibility to make big steps, which Porsche doesn’t,” says Vasselon, “but they have room to improve.”
Toyota again runs two cars at Le Mans. Former champions Davidson and Buemi continue with Nakajima, who joined them in 2015 (with the exception of Spa, where he sustained back injuries in practice), while ex-F1 driver Kobayashi has graduated from a test and reserve role to take the retired Alex Wurz’s seat alongside Mike Conway and Stéphane Sarrazin.
Toyota claims it has had no major problems during its endurance tests for Le Mans.
“We have had no issues affecting long-lead parts, so no gearbox or engine problems, things we would struggle to fix before Le Mans,” says Vasselon. One more 30-hour simulation was planned between the Silverstone and Spa WEC rounds, at Motorland Aragon in Spain.
“We absolutely need this session, but it should be enough to validate all the solutions to the problems we have had,” adds Vasselon. “We should be able to close our winter test season.”
Toyota’s belief that it didn’t extract the maximum from the TS050 Hybrid at Silverstone seems plausible. There were times when the new twin-turbo LMP1 was quick, but it wasn’t consistently so. Toyota wasn’t sure it was optimising its hybrid system and had concerns that it wasn’t getting the most out of its Michelin tyres after going off-line in traffic. It was still early in the development curve for a car that undertook the first of its two tests at the beginning of the year with the previous normally aspirated V8 in the back. That learning process was most evident in qualifying at Silverstone. Its two cars were dramatically off the pace in a session held on a drying track, conditions it had not encountered before. What we can say with some certainty is that Toyota has made some giant gains – it was more than a second and a half faster at Silverstone than 12 months before – and will be closer to the front of the field than in 2015.