Booster Online

From Niche to Mainstream

Posted 02.18.2010

In the history of turbocharging, few innovations could rival Honeywell VNT™ turbo in terms of technological advancement and industry reach. Since its mass release in the 1990s, more than 30 million VNT™ turbochargers have been manufactured. And today, the technology is equipped on light vehicle engine platforms ranging from 1.2L to V10 engines.

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.

Ever since, the concept, though ahead of its time, intrigued Honeywell Garrett engineers, who in 1990 first introduced the technology to a passenger car, making Chrysler Dodge-Shelby Daytona Turbo-Z the first car to utilize Garrett VNT™ turbocharger with electronic boost control.

However, what truly changed the trajectory of VNT™ technology were the transformations that modern diesel engines began to experience in the early 1990s. And this time, it all happened in Europe.

The beginning of this European diesel renaissance can be traced to the 1991 launch of Honeywell VNT™ turbo on Fiat Croma’s 1.9-liter 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 pending take-off of this new turbo innovation.

VNT™ – The First Generation
VNT™ really came of age in 1995. This was the year that the VNT™ Multivane, with a new vane design and improved aerodynamics, was developed for a Volkswagen-Audi 1.9-liter direct injection diesel engine. The Golf was unveiled to rave reviews at the Frankfurt Motor Show. It’s also worth noting that compared to the previous VNT™ based on T25 model, it was a much smaller VNT™ based on the state-of-the art GT15 platform.

VW were 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 technology. 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 1500 rpm whilst lifting the torque from 170Nm to 230Nm at the same engine speed.

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

“In many ways, our VNT™ technology was anticipating the industry needs, and we were ready when boost management , alongside high pressure injection, turned out to be the major enabler for the success of direct injection diesel engines. OEMs were simply 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 appeal, enjoying the benefits of large-scale production.

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 following its wide adoption by 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, this new generation of turbochargers enhanced the performance and the required precision in controllability demanded by the newer injection systems.
Rotary Electronic Actuation or REA system was also developed to complement VNT™ functionality and was first introduced by BMW on its bi-turboV8 in 1998.

Within a year, VNT™ was exceeding one million units in production annually, as OEMs saw the benefit 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 seen as an ideal enabler in emission 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 technology across all engine segments

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

This generation VNT™ was conceived by Honeywell engineers in anticipation of new EU emission standards (EU 4) that would potentially call for sheet metal housing. It was ground-breaking in the way it attached the variable mechanisms 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 VNT™ Step 2 boost at 90% of back pressure, which made the turbo a key component in emissions control.

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 latest VW Polo 1.2L BlueMotion, achieving outstanding 87g CO2/km while meeting EU5 emission.

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 sizing it down for ever-smaller engines as automakers embrace the downsizing agenda, while at the same time it’s also been adopted in 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 Denis Jeckel: “In many ways, the VNT™ story is one about how important it is to anticipate new trends in engine platforms and emissions regulation and finding opportunity with synergistic technologies such high pressure injection when developing turbocharging technologies. This is how we have been able to deliver, on competitive advantages for our customers – by being the first mover in innovation.”

Photo Credit: Alain Ernoult