History of the VNT Turbocharger

Honeywell VNT™ – Creating History Through Innovation

In the history of turbocharging, few innovations can rival Honeywell’s development of VNT™ architecture in terms of technological advancement and industry reach. The company was the first to develop variable geometry turbine turbocharging – the concept underpinning the VNT range – and the first to launch it on both gasoline and diesel powertrains. Since its mainstream release in the 1990s, more than 40 million VNT™ turbochargers have been manufactured, boosting performance and contributing to better fuel efficiency and lower emissions in passenger cars and trucks on every continent of the world. From 1.2L to 13L engines, VNT is specified by all the world’s major auto manufactures. It’s a turbo technology perfectly aligned to the needs of the 21st century.

VNT – Before Takeoff
It’s hard to believe, but it was in 1951 when a Garrett engineer Ted von der Nuell first advocated the controlled variable nozzle as a solution for a turbocharged earthmover. The concept, though ahead of its time, was later embraced by Honeywell Garrett engineers, who spotted its potential for the passenger car sector and introduced it to the market in 1990 on the gas-powered Chrysler Dodge-Shelby Daytona Turbo-Z – the first car in the world to utilize variable geometry turbocharging. However, what truly changed the trajectory of VNT technology were the transformations underway in Europe in modern diesel engines.

The beginning of this European diesel renaissance can be traced to the 1991 launch of Honeywell VNT turbo on Fiat Croma’s 1.9L direct-injection diesel engine, and shortly afterwards on Renault Espace Matra 2.0L. Both production runs were limited, but this trial hinted at the symbiotic fit between turbo and diesel engines and the impending stratospheric take-off of this the VNT turbo innovation.

VNT – The First Generation
It was in 1995 that VNT really came of age. This was the year that the VNT Multivane, with a new vane design and improved aerodynamics, was developed for a Volkswagen-Audi 1.9L direct injection diesel engine. The turbocharged VW Golf was unveiled to rave reviews at the Frankfurt Motor Show, with the boost provided by the then state-of-the art GT15 platform, a much smaller VNT model than had previously been developed.

VW was interested in using engine boosting technology alongside a high pressure rotary injection system to increase the power output of its base 66kW diesel engine, but couldn’t achieve the desired results with wastegate turbo technology. So Honeywell and VW worked closely together to apply VNT technology – and succeeded in uprating the power output from the targeted 75kW to an impressive 81kW at 4000 rpm while lifting the torque from 170Nm to 230Nm at 1500 rpm.

Denis Jeckel, Director of Powertrain Marketing at Honeywell, led the VW project at the time, and in his view, the timing of the introduction of VNT could not have been better.

“VNT technology anticipated the needs of the industry – and we were ready for this market shift when boost management, alongside high pressure injection, became recognized as the major enabler for the success of direct injection diesel engines. OEMs were impressed with VNT’s ability to deliver significant low-end torque, handle exhaust gas recirculation and set new standards for diesel driveability and emissions control.”

In less than one year, VNT technology transformed from a niche technology to one with mass market penetration, as Honeywell invested in large-scale production to ride the growth curve.

VNT – The Second Generation
With diesel engines growing in complexity, the second-generation VNT took turbo performance to the next level, and was adapted to more engine sizes to meet demand from automakers in Europe. It became a mainstay turbocharging technology at VW, and the trend soon spread to Audi, BMW, Ford and Daimler as they saw the variable geometry technology as the perfect fit for their premium V6 and 6-inline engines.

Launched in 1998, second generation VNT turbochargers enhanced the performance and the required precision in controllability required by the improving injection systems. Rotary Electronic Actuation – or REA – was also developed to complement VNT functionality and was first introduced by BMW on its bi-turboV8 in 1998.

Within one year, VNT was exceeding one million units in production annually, as OEMs seized on the benefits of improved aerodynamics and electric actuation to optimize the performance made possible by high pressure injection systems and the broad introduction of common rail injection systems. VNT was also seen as an ideal enabler in emissions compliance thanks to its ability to improve DPF functionality by controlling back pressure and maintaining boost.

Soon, VNT production exceeded that of wastegate as all major global OEMs, including Toyota, Honda and Hyundai in Asia, adopted this Honeywell technology across all engine segments.

VNT – The Third Generation
In 2004, the VNT story reached another milestone, with an all-new innovation that underlined Honeywell’s technological leadership.

Third generation VNT was conceived by Honeywell engineers in anticipation of new EU emission standards (EU 4). The key advance was the ground-breaking way that the variable mechanisms were attached onto the bearing housing through an elastic shroud. This new platform delivered many innovations – a new cartridge design, new cambered vanes, a new generation turbine wheel, improved aerodynamics and better controllability. The result was a unit capable of delivering up to 10% turbine efficiency gains and 130% of second generation VNT boost at 90% of back pressure, which made the turbo an even more important component in helping lower emissions.

The third generation VNT with cast turbine housing was first launched on the BMW One Series and is now specified around the world across an ever-broadening engine range, including the VW Polo 1.2L BlueMotion, launched in 2010, which achieves an outstanding 87g CO2/km while meeting EU5 emission.

VNT – The Commercial Vehicle Perspective
The appeal of VNT goes beyond passenger vehicles. Today, different variations of Honeywell VNT technology can be found on diesel-powered pickup trucks, medium to heavy-duty commercial vehicles and off-highway equipment. The wide adoption of VNT in this segment largely results from the technology’s ability to help deliver superior power and torque while helping improve fuel consumption, as well as its contribution to emissions reduction through Exhaust Gas Recirculation.

Whether it’s AVNT or VNT DualBoost in light trucks, or VNT DutyDrive in medium and heavy-duty vehicles, Honeywell turbochargers are increasingly important in the drive toward a cleaner future in the Commercial Vehicle sector. Just recently – at the end of 2010 – Honeywell successfully launched its VNT DutyDrive turbo technology on a major off-highway application in North America, further extending the reach of VNT technology and helping its customer to meet much more stringent emissions regulations.

VNT – The Future
With its versatility in range and ever-improving capabilities, VNT will remain the leading turbo technology for diesel engines for the foreseeable future. Honeywell engineers are working on scale reduction to fit ever-smaller engines as automakers embrace the downsizing agenda, while at the same time it’s now also a key component in a number of complex two-stage turbocharging systems to deliver superior performance and great fuel efficiency. It’s also increasingly linked to 3 or even 2-cylinder diesel power units.

Comments Pierre Bathelet, Global Product Line Leader for Small VNT: “The success of VNT is testament to the vision of engineers within Honeywell and the ability of the company to apply this breakthrough technology to the global automotive industry. Today it is a perfect fit for an era that requires fuel efficiency and emissions control – but without any performance compromise. It’s clear that the technology has a great future ahead of it, particularly with ongoing advances in aerodynamics, bearing systems and materials science.

“The Honeywell culture of innovation has enabled VNT to remain best-in-class and to continue to deliver competitive advantage for our customers – and there’s even more to come.”