Plot twist: The turbocharger ruled the road before the race track

From disc brakes to multi-valve engines to electronically shifted transmissions, the list of technologies that migrated from race cars to street-legal vehicles is long. Rarely, however, does technology pioneered for regular production cars move from the road to the track.

The turbocharger is an exception. The technology that made turbochargers an ultra-sophisticated, high- performance device for cars, SUVs and even pickups also has benefited vehicles that are raced, both on road and off.

Suppliers such as Garrett Motion, BorgWarner and Valeo have spent billions of dollars on turbocharger research and development over the last 20 or so years. Those investments have yielded breakthroughs that have made turbochargers lighter, more responsive, and most importantly, more reliable.

"Turbos now are kind of a fit-and-forget thing now," says Stephen Eriksen, COO of Honda Performance Development, American Honda's racing entity. "It does need attention, because it is a critical component of the powertrain infrastructure, but it's not a big worry bead. It's a piece that has become very, very reliable."

That's a notable achievement for the industry considering the superheated temperatures the turbo endures and the speed of the engine, the car and the turbo's inner components. Eriksen said a typical Indianapolis 500 car runs at 230 mph, the engine runs in a range of 11,500 to 12,000 rpm, and the turbine and compressor wheels spin at upward of 90,000 rpm for 500 miles.

And while many of the turbo's most recent innovations first saw action in motorsports, a few improvements made their debuts on more humble stages: dealership showrooms.Cross-pollination in turbo technology between street cars and race cars has been going on for years, says Mike Moyer, global motorsports manager for Garrett Motion.

"There is a lot of cross-sharing," Moyer said. "It's not always from motorsport to road cars; it's not always from road cars to motorsports. The way we as a company use it is as another tool to help our engineering organization to act fast and understand the automotive landscape well."

He cited the electrification of the turbocharger, either as a means to generate electricity to quickly spool up a turbo or to route to the vehicle's electrical system, as a recent example of how racing and street turbos are evolving in tandem. A turbine wheel, he said, can spin up to 150,000 times per minute. A generator can be used instead of a wastegate to manage its speed and to create electricity.

John Norton, a BorgWarner engineer for turbo systems, innovations and new concepts, said the company's Gamma Ti titanium-aluminum alloy turbine and compressor wheels saw limited use in passenger vehicles first, such as the 2008-10 Ford Super Duty diesel pickup. The wheels weigh 50 percent less than the standard nickel-alloy wheels on most cars' turbos. The reason they are not standard on such vehicles as the Ram Heavy Duty or Mercedes-Benz GLC 300 is price. The lightweight wheels cost at least twice as much as the standard nickel-alloy wheels.

"Cost is king. We're often in a competitive situation where we have to meet all the customer's targets for a budget," Norton said. "We have to come in with a very low cost." But exotic car manufacturers prioritize performance over cost, and those lightweight wheels enable the turbochargers to reach extremely high speeds quickly, which gives the driver instant throttle response.

Two more areas where race cars benefitted from turbocharger technology developed for street cars, Norton said, are the bearings that the turbine shafts and wheels run on and the design of the turbine blades.

Some electronic controls started in street cars and are now used in motorsports, Norton added.

"Another piece that comes to mind is the compressor wheel geometries," he said. "The aerodynamicists developed extended tip technology for passenger cars, but they've got benefits for motorsports as well. The outside diameter of the wheel could be either straight down to the back disc or they can be extended tip at a largest diameter tapering down to back disc. It transferred from passenger cars to motorsports."

In 2017, 27.6 percent of light vehicles sold in the U.S. were built with turbocharged engines, up from 5 percent in 2010, according to Wards Intelligence.

The rise of the turbo started in Europe in the early 1980s, when taxes favoring diesel fuel led to a diesel-engine boom. Small turbodiesel engines delivered plenty of torque at low speeds and offered excellent fuel economy. In the U.S., turbochargers were mostly confined to diesel engines in Detroit 3 heavy-duty pickups, and high-performance cars.

Ford's EcoBoost engines debuted in 2010 in the Taurus SHO.

As internal-combustion engines shrink and hybrid powertrains become mainstream, engineers are now working to carve out a role for the turbocharger on gasoline or diesel engines mated with electric motors.