Building a Better Turbocharger

We look at how turbocharger technology keeps improving to boost vehicles' power, efficiency, and driveability.

Dan Carney, Senior Editor

October 19, 2020

3 Min Read
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This BorgWarner Variable Turbine Geometry turbocharger is optimized for 1.0-liter gasoline engines and can withstand operating temperatures of 1,800 degrees F.BorgWarner

Forced induction wrings the final efficiency gains available from internal combustion engines, so the automotive industry is moving toward universal use of turbochargers on gasoline engines, as already happened with diesels previously.

Turbochargers have historically suffered from some characteristics that turned drivers off, most especially the lag time it can take for a turbo to spin up to speed when the driver opens the throttle abruptly and catches the turbo at low boost pressure.

Turbocharger manufacturers are addressing that issue with a variety of techniques designed to deliver power, efficiency, and satisfactory driving experience.

Design News talked to BorgWarner’s director of engineering, Douglas Erber, to hear about the direction of turbocharger technology.

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The 2021 Porsche 911 Turbo features BorgWarner VTG turbochargers.

DN: Are combustion engines likely to all be turbocharged in the future, and if so, why?

Douglas Erber: Absolutely!  Turbocharging is an essential technology to meet OEMs’ targets for fuel economy, emissions, transient performance, and peak power.  All new combustion engines are being designed with very specific turbocharging needs in mind.

DN: What are the critical technologies exhibited in today’s state-of-the-art turbochargers?

Douglas Erber: Variable Turbine Geometry (VTG) and Dual Volute Connect (DVC) will play an even bigger role in future light-duty segment vehicles as both technologies enhance the operating range of a turbocharger.  Electric actuators (rotary or linear) will become the standard for controlling wastegates, variable geometry vanes and volute connect valves.

Related:BorgWarner 4x4 Parts Plant Reopens After Tornado Damage

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Doug Erber, BorgWarner engineering director.

 

DN: What are the emerging technologies that we will see to make turbos even better?

Douglas Erber: Ball bearings will be used in both passenger and commercial vehicle applications due to reduced friction (improving efficiency) and superior transient characteristics.

The next step in the innovation will be the industrialization of eTurbos.  An eTurbo is a turbocharger with an electric motor located between the compressor and turbine stages.  Electricity can either be applied to or harvested from the eTurbo. 

When electricity is applied, the eTurbo rotor group provides an instantaneous boost response.  Or, under certain operating conditions, electricity can be harvested from the eTurbo and used to re-charge vehicle batteries. 

DN: What role will things like variable turbine geometry, two-stage turbocharging, electric turbochargers, and dual volute turbos play?

Douglas Erber: Gasoline VTG and Dual Volute Connect will play a larger role over the next few years in the passenger vehicle market.  eTurbos will first be used in high-performance niche markets before becoming more mainstream.  Two-stage turbocharging has barriers in cost, weight, and complexity and will primarily be used in high-pressure ratio commercial vehicle applications.

Related:Garrett E-Turbo Jumps from F1 to Mercedes-AMG Production

DN: What are the most difficult challenges facing improved turbochargers, such as materials used, or cost, or whatever it might be?

Douglas Erber: At BorgWarner, the innovation never stops.  Every single individual turbocharger component is continuously being optimized with CAE tools to find the most suitable design and material to meet performance, durability, and cost targets.   

About the Author

Dan Carney

Senior Editor, Design News

Dan’s coverage of the auto industry over three decades has taken him to the racetracks, automotive engineering centers, vehicle simulators, wind tunnels, and crash-test labs of the world.

A member of the North American Car, Truck, and Utility of the Year jury, Dan also contributes car reviews to Popular Science magazine, serves on the International Engine of the Year jury, and has judged the collegiate Formula SAE competition.

Dan is a winner of the International Motor Press Association's Ken Purdy Award for automotive writing, as well as the National Motorsports Press Association's award for magazine writing and the Washington Automotive Press Association's Golden Quill award.

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He has held a Sports Car Club of America racing license since 1991, is an SCCA National race winner, two-time SCCA Runoffs competitor in Formula F, and an Old Dominion Region Driver of the Year award winner. Co-drove a Ford Focus 1.0-liter EcoBoost to 16 Federation Internationale de l’Automobile-accredited world speed records over distances from just under 1km to over 4,104km at the CERAM test circuit in Mortefontaine, France.

He was also a longtime contributor to the Society of Automotive Engineers' Automotive Engineering International magazine.

He specializes in analyzing technical developments, particularly in the areas of motorsports, efficiency, and safety.

He has been published in The New York Times, NBC News, Motor Trend, Popular Mechanics, The Washington Post, Hagerty, AutoTrader.com, Maxim, RaceCar Engineering, AutoWeek, Virginia Living, and others.

Dan has authored books on the Honda S2000 and Dodge Viper sports cars and contributed automotive content to the consumer finance book, Fight For Your Money.

He is a member and past president of the Washington Automotive Press Association and is a member of the Society of Automotive Engineers

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