Honeywell’s introduced the VNT in early the 1990s. The system use a turbine housing that can change its internal configuration to adapt to variations in the engine’s air boost requirements. This enables the turbocharger to supply greater engine boost at lower speeds than a smaller unit and behave like a larger turbo at higher speeds. VNT turbo also help to control the emission of NO from diesel vehicles by the use of EGR - Exhaust Gas Recirculation in the engine.
This new platform had several high performance innovations – a new vane shape, a new generation turbine wheel and better controllability delivering 130% of second generation VNT™ boos levels at just 90% of back pressure.
To meet the customer’s needs for smaller, cleaner and better performing engines new type of cartridge was developed which doesn’t not use the turbine housing as a mechanism holder, this housing can be more readily made out of sheet metal material.
Dual Stage systems are being applied to passenger cars in serial-sequential or parallel-sequential configurations. In a serial sequential system, a smaller turbo works in high pressure in advance of a much larger turbo. In a parallel sequential system, two small turbos work side by side.
In a typical application of 4 cylinders, a parallel-sequential system creates up to 30 % more torque compared to its 2.2 liter baseline diesel counterpart. The fuel consumption improvement ranges about 5 percent.
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