|Exhaust side of the new 1.4-liter engine. Click to enlarge.|
Volkswagen’s new 90 kW 1.4-liter TSI, introduced at the Vienna Motor Symposium, represents the company’s latest step in developing cost-effective, fuel-efficient gasoline engines. (Earlier post.)
The 1.4-liter 90 kW TSI engine replaces the 1.6-liter 85 kW naturally-aspirated FSI engine in all vehicles while providing improvements in performance and fuel consumption and meeting Euro 5 standards.
The new engine, in combination with the new VW 7-speed dual clutch gearbox with dry clutches, enables a 22% improvement in fuel consumption compared to the predecessor powertrain in the Golf, and hits a 139 g CO2/km target in the European driving cycle.
Features of the new engine include the further development of the combustion process and fuel injection, an optimized turbocharger in conjunction with optimized charge exchange and a newly developed design for water-cooling charge air.
Due to the moderate downsizing—about a 30% reduction in displacement compared to the 4V naturally-aspirated engine with the same torque—the new 90 kW engine can use just a one-stage turbocharger. For the engines in the family that have a higher specific output, VW adds a second, mechanical, charger stage—i.e., Twincharging.
|Torque curve of the 1.4 TSI compared to the 1.6 FSI. Click to enlarge.|
VW reworked the engine to enable doing without tumble flaps (for technical simplification and cost reduction) as well as the use of a one-stage turbocharger with a turbine temperature limit of 950° C.
The new intake port design generates the charge movement necessary for good homogenization of the mixture and fast fuel burn. VW also introduced port masking for the first time in this engine family.
|Injector spray design. The system for the 90 kW engine is at bottom. Click to enlarge.|
The 1.4-liter engine uses a new type of multi-hole, high-pressure injector with 6 fuel jets. The injection spray cone does not have the typical round or oval shape, but instead optimizes the spatial distribution of the spray. (See drawing at right.) The strongest individual stream, formerly directed downwards towards the piston, has been moved upwards into the middle of the spray. This reduces the moistening of the piston during the very early start of injection at full load as well during as late points of injection shortly before compression stroke TDC in the double-injection catalytic converter heating mode.
|Position of spray cones in the combustion chamber. Click to enlarge.|
Consequently, the injection can take place earlier, lengthening the time for forming the fuel mixture and improving the homogenization. Very low hydrocarbon emissions are one result.
The Magneti Marelli injectors enable the construction of individual length-to-diameter ratio (l/d) for each jet so the penetration can be optimized for each spray cone. VW also altered stream direction to avoid undesirable interaction between streams.
|Comparing the 1.4L 90 kW TSI and the 1.6L 85 kW FSI|
|New 1.4L 90 kW TSI||1.6L 85 kW FSI|
|Bore and stroke||76.5/75.6 mm||76.5/86.9 mm|
|Cylinder distance||82 mm|
|Connecting rods||144 mm||138 mm|
|Nominal output||90 kW (121 hp)
@ 5,000 rpm
|85 kW (114 hp)|
@ 6,000 rpm
|Maximum torque||200 Nm (148 lb-ft)
@ 1,500-3,000 rpm
|155 Nm (114 lb-ft)|
@ 4,000 rpm
|Sp. torque||143.9 Nm/L||97 Nm/L|
|Fuel||RON 95||RON min. 95|
|Emissions standard||Euro 5||Euro 4|
“The TSI with 90 kW—the expansion of the Volkswagen family of fuel efficient gasoline engines”; Dr.-Ing. Rüdiger Szengel, Dr.-Ing. Hermann Middendorf, Dr.-Ing. Ekkehard Pott, Dr.-Ing. Jörg Theobald, Dipl. -Ing. Thomas Etzrodt, Dr.-Ing. Rudolf Krebs, Volkswagen AG, Wolfsburg