Chevrolet: 2018 IndyCar aerokit makes torque, driveability critical
Rob Buckner, Chevrolet’s new IndyCar program manager for 2018, says that the heavily reduced downforce of the 2018 universal aerokit has placed renewed emphasis on engine power characteristics on corner exits.
Buckner, who was Chevrolet’s engineer at Ilmor Engineering for three seasons 2013-15 developing the 2.2-liter V6 twin-turbo used in IndyCar, says that the ability to get power down efficiently has become the panacea for all drivers in this year’s car which has lost up to 40 percent of its downforce.
He told Motorsport.com: “We’ve been working hard over the winter – I’m sure Honda has too – because the new car requires some new focus on driveability. The last three years, with the manufacturer aerokits, from the power delivery standpoint you could get away with certain things with that extreme downforce level.
“Now our drivers are going to criticize our power delivery more, and rightfully so, because the corner exits are going to be much more difficult and more critical. You’ll have more time at part throttle, less wide-open. Everyone’s been talking about how much longer the brake zones are now, but the part-throttle and acceleration phase will be longer too.
“So making sure we have strong and consistent power delivery across the torque range is vital, and across all the turbo boost levels – 1.3-bar [superspeedways], 1.4-bar [short ovals] and 1.5-bar [road and street courses].”
By the second half of last year, there were rumors that Honda Performance Development’s engine was creating up to four percent more horsepower than the Chevrolet – that’s 28hp at the very rough (and too low) approximation of 700hp in road/streetcourse form. The theory was that Honda’s advantage had been neutralized by the drag caused by its overly complicated aerokit.
“I don’t think Honda had a huge advantage,” says Buckner. “Everyone wants to latch onto something, crazy numbers like 40 or 50 horsepower, or whatever. But I suspect it’s gains everywhere – one or two of their teams did a really good job, they were allowed extra modifications to their aerokits the year before, and so on. It’s never just one thing, a huge advantage in one area.”
Gearing, said Buckner, was also important to driveability but admitted that teams are steered by what Chevrolet supplies them.
“Gearing is up to the teams, but it’s influenced by our power curve,” he said. “We’re always in communication with the teams on how we can shape our power curve to be the best performing.
“So we’ll make changes this year regarding our torque curve and power delivery.”
Focusing on the Indy 500 and Detroit
Although Chevrolet has powered five of the last six IndyCar champions and has won all six manufacturers’ titles since the current engine regulations were introduced for the 2012 season, it has won only two of the last six Indianapolis 500s. Buckner admits that this is a statistic that Chevrolet’s top men are desperate to change.
“We’re not going to hide from the fact that we need to do better at the Speedway,” he said. “Mark Reuss [president of General Motors] and his whole group of executives, they made it pretty clear that in 2018 we need to make our focus on the Indy 500 and Detroit [Rahal’s Honda-powered RLLR entry won both races in GM’s home city last year].
“At the same time, we haven’t ever purposely given up anything in the Month of May to chase improvements in other events. So we want to try and work on our power curve for all types of track, but certainly not give up anything at the Speedway.
“We’ll know when we get there where we’re at in terms of our competition, but I expect it to be very close, and the Fast Nine will probably be a good mixture between the engine suppliers. I mean, it’s the seventh year on these engines so they’ve been fine-tuned and the days of finding really sizable gains are over. Everyone’s looking at a half a percent or one percent gain.”
IndyCar set the 2017/18 offseason as one of the more restrictive years in terms of what areas were/weren’t allowed to be modified.
“Yeah, a lot of the parts were homologated, so this winter it’s been more about spending time on the dynos and making sure the calibrations are optimized. Our group does a tremendous job – and yeah, our guys have been working on speedway stuff a lot. So I think when we get to Indy we can be pretty confident.”