Audi offers two new 3-cylinder engines in refreshed A1: 1.0 TFSI and MDB 1.4 TDI diesel for A1 ultra

14 November 2014

Audi A1. Click to enlarge.

Since their introduction on the market in 2010, the Audi A1 and A1 Sportback have sold more than 500,000 units worldwide. Audi is now refreshing its A1 models, including the offer of six engines—gasoline and diesel—that are new or that have been intensively further developed.

For the first time, Audi is offering completely new three-cylinder engines: the 1.0 TFSI gasoline engine and the 1.4 TDI diesel. The 1.4 TDI follows the 2.0L 4-cylinder engine as the second engine in the Volkswagen Group’s modular diesel engine platform (MDB). (Earlier post.) Power output—ranging from from 66 kW (90 hp) to 141 kW (192 hp)—has been increased in most engines, while fuel economy has been reduced by as much as 10% percent. The seven-speed S tronic is available for all engines, either optional or standard (with the 1.8 TFSI).

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The new A1 entry‑level engine is the first three-cylinder gasoline engine in the history of Audi. The Audi A1 1.0 TFSI (provisional data) with 70 kW (95 hp) of power has a combined fuel consumption of 4.3 liters fuel per 100 kilometers (54.7 US mpg) (99 g CO₂ per km [159.3 g/mi]).

Audi’s new 3-cylinder 1.4 TDI is the second MDB diesel. Click to enlarge.

The other new three-cylinder in the A1, the 1.4 TDI ultra with 66 kW (90 hp), attains an NEDC fuel consumption of 3.4 liters diesel fuel per 100 kilometers (69.2 US mpg) (89 g CO₂ per km [143.2 g/mi]), which makes it the first ultra model in the Audi A1 and Audi A1 Sportback.

1.4 TDI power and torque. Click to enlarge.

The three-cylinder diesel unit is designed as a transverse engine and has a displacement of 1,422 cc. The stroke of 95.5 millimeters (3.8 in) is taken from the 2.0 TDI; the bore has been reduced from 81.0 to 79.5 millimeters (3.2 to 3.1 in). Cylinder spacing is 88.0 millimeters (3.5 in).

Unlike the predecessor engine used through 2005 in the Audi A2, the new 1.4 TDI has a lightweight crankcase made of an aluminum-silicon alloy—an exception in its competitive environment. The crankcase is produced via gravity chill casting, which enables particularly high strength, density and homogeneity. Targeted ribbing and detailed measures affecting the engine periphery minimize noise emissions.

The crankcase weighs just 17 kilograms (37.5 lb)—12 kilograms (26.5 lb) less than the cast iron block used previously. The engine has a total weight of 132 kilograms (291 lbs). The thin-walled piston sleeves made of cast iron are thermally joined; the weight of the pistons and connecting rod has been reduced. Piston clearance, ring contour and ring pretensioning have been optimized for low friction losses.

A balance shaft rotates in the opposite direction of the crankshaft. Its drive unit has been integrated into the “duopump”: the oil pump and vacuum pump share a common case. The oil pump switches between three pressure levels as necessary. Another efficiency measure is the separation of the coolant loops for the cylinder block and the cylinder head. The block loop can be deactivated during the warm-up phase. Only the head loop, which also supplies the heat exchanger for the cabin heater, is active here. This thermal management concept quickly brings the 1.4 TDI up to operating temperature following a cold start.

Elaborate needle bearings are used in the drive system for the camshafts. The shafts are mounted in a separate frame and joined to it during engine production. The new valve drive module combines high stiffness with low weight.

The common rail injection system produces 2,000 bar of system pressure. Solenoid valves open and close the nozzle needles in the seven-hole injectors. The high pressure enables an even finer atomization of the fuel in the combustion chambers, and thus more efficient, lower-emissions combustion.

The turbocharger in the 1.4 TDI features pneumatic adjustment of the turbine wheel vanes. The intercooler, which is water-cooled via a separate loop, is mounted on the cylinder head. The low-pressure exhaust gas recirculation system (AGR) is also water-cooled and discharges directly upstream of the turbocharger. It reduces NO_x emissions when the engine is hot and at intermediate and high loads, while the uncooled high-pressure AGR is primarily responsible for the phase following a cold start. The new engine complies with the limits of the Euro 6 standard. The entire emissions control system is compact and designed for minimal flow losses.
The new 1.4 TDI produces 66 kW (90 hp) and delivers 230 N·m (169.6 lb-ft) of torque between 1,500 and 2,500 rpm.

The electromechanical power steering system for the A1 is entirely new. It reduces power assist as vehicle speed increases. Its operation can also be modified by the new Audi drive select system. The driver can operate equipment modules such as the adjustable shock absorbers over several modes.

The program of optional features has been restructured. Customers can configure their Audi A1 to be even more customized by choosing one of the new lines: design or sport. Other lines and packages are offered as well. Brand new is the active kit, which highlights the urban character of the Audi A1 distinctively.

The infotainment lineup was specially configured to meet the needs of young customers. The top components are MMI navigation plus and the Audi connect module including car phone. The latter brings the online services of Audi connect into the vehicle and provides a WiFi hotspot.