The Petrol Engines
The new 3.0-litre V6
Audi is also presenting a new top engine in the A4 Avant: the 2,976 cc V6 with five-valve cylinder head and a power output of 162 kW (220 bhp) at 6,300 rpm. Its maximum torque is 300 Nm at 3,200 rpm, enough to accelerate the front-wheel drive A4 Avant with 5-speed manual gearbox from a standstill to 100 km/h in 7.1 seconds and on to a maximum speed of 243 km/h.
The average consumption of this version is a mere 9.6 liters per 100 kilometers (1999/100 EC).
This engine differs from the previous 2.8-litre V6 not only because of the power output and engine size increase by 20 kW (27 bhp) and 0.2 liters respectively. It shares only the basic concept, the 90-degree cylinder bank angle and the identical bore with the smaller V6. The Audi 3.0 V6 engine consequently not only has a very high power output, but is in fact one of the most modern engines of its kind.
The supremacy of this engine is audibly expressed by its carefully tuned, sporty sound. And the new design of the engine compartment, signaling a departure from plastic-shrouded drive units, is a visual reflection of the advanced technical caliber of Audi engines.
The new 3.0 V6 is a remarkable 17 kilograms lighter than its 2.8-litre predecessor, and weighs just 163 kilograms. Choosing aluminum for the engine block has made a significant contribution to the radically reduced weight. But in view of the increased loads resulting from the increased power output and higher engine speeds, it was nevertheless necessary to revise the design radically.
Weight-saving construction principles also dictated the use of new smooth-skirt pistons with small-diameter, short piston pins. Compared with the 2.8-litre engine, the moving masses have been reduced by 71 grams, a measure that enhances the engine's special quality of freedom from vibration.
The new engine has a balancer shaft or, more accurately, a mass equalizing shaft, for optimized smooth running. The balancer shaft is driven from the crankshaft via a roller chain at a ratio of 1:1; the direction of rotation is opposite to that of the crankshaft. This measure suppresses mechanical vibration and greatly improves engine acoustics.
In the 3.0 V6, the inlet camshaft can be gradually advanced by up to 42 degrees by a motor-driven pivoting mechanism; on the exhaust side, the camshaft can be retarded as necessary by up to 22 degrees. The system achieves maximum overlap at an engine speed of only 1,900 rpm, thus generating the highest possible torque. Peak torque of 300 Nm is available at as low an engine speed as 3,200 rpm, but what is surely no less impressive is that 90 percent of this figure is available all the way from 2,200 to 5,200 rpm.
The new Audi 3.0 V6's engine management is supplied by Bosch - the Motronic ME 7.7.1. Electronic accelerator system and continuous oxygen sensing ensure optimum mixture preparation and, consequently, low fuel consumption and excellent exhaust emission quality.
The new 2.0-litre engine
The other newcomer to the range of petrol engines for the new Audi A4 Avant is the four-cylinder inline engine with a displacement of 1,984 cc and an output of 96 kW (130 bhp).
As for the 3.0 V6, the engine block of the 2.0-litre unit is made of aluminum for significantly reduced weight. At 129 kilograms, the Audi's two-liter four-cylinder engine is the lightest in its class, and with a length of a mere 460 millimeters, it is also the most compact.
On the five-valve cylinder head, the entire rear area was designed for installation of a continuously variable camshaft mechanism. The camshafts are located in a ladder frame structure that increases the rigidity of the entire cylinder head and also clearly improves its acoustic vibration properties.
As an undersquare engine, the two-liter unit is ideal for a good torque characteristic at the low end of the speed range. To make maximum use of this potential, there is map-controlled adjustment of the inlet camshaft through 42 degrees. A pivoting motor controlled by the engine management system maintains the necessary pressure in the hydraulic system. A highly wear-resistant toothed belt transmits the power.
A two-stage variable-length intake manifold governs the desired power output and torque characteristic. The 2.0-litre unit reaches its maximum torque of 195 Nm at 3,300 rpm; 90 percent of this maximum value is available across the broad speed range of 2,300 to 5,000 rpm. The changeover from the high-torque to the high-output position is controlled by a mapped characteristic: load, engine speed and temperature are the relevant parameters.
This engine reaches its maximum power output of 96 kW (130 bhp) at 5,700 rpm. It accelerates the front-wheel-drive A4 Avant with 5-speed manual gearbox from 0 to 100 km/h in 10.2 seconds and gives it a maximum speed of 208 km/h. These figures are all the more convincing in view of the low fuel consumption of 8.0 liters per 100 km (1999/100 EC).
To optimize the smoothness of the new 2.0-litre engine, Audi's developers have installed a balancer shaft assembly in the oil sump. As on the 3.0 V6, the die-cast aluminum casing contains the oil pump and the balancer shafts.
Two balance shafts rotating at twice the speed of the crankshaft are used to compensate for the engine's inertial forces. The outcome of these measures is outstanding low vibration for a four-cylinder engine. Perceptible vibration and drumming frequencies under load are both effectively suppressed. It is no coincidence that the engine's idling behavior matches that of a six-cylinder unit.
The fact that the 2.0 easily complies with EU4 exhaust emission requirements can almost be taken for granted.
Plenty of know-how has gone into this, the current entry-level 1.6-litre engine for the A4 Avant. A cylinder head with valve actuation by roller cam followers reduces interior friction considerably. Audi's developers have optimized other components for minimum friction too.
Together with the engine electronics and an optimized exhaust system, these measures have resulted in the exceptionally low fuel consumption of just 7.8 liters per 100 km (overall figure according to 1999/100/EC).
The engine's power output of 75 kW (102 bhp) and its torque of 148 Nm give the A4 Avant 1.6 a maximum speed of 186 km/h. This Avant version accelerates from 0 to 100 km/h in 13.2 seconds; the engine complies with the tough EU IV emission limits.
The 1.8 T
An engine that in successful use thousands of times over is also available at the launch of the new Audi A4 Avant: the 110 kW (150 bhp) 1.8 T four-cylinder unit.
It reaches its peak torque of 210 Nm at just 1,750 rpm. This figure remains constant up to 4,600 rpm, which means that maximum torque is always available in the most frequently used driving and engine-speed range.
Because of this exceptionally good torque pattern, drivers have in effect access to two different power units rolled into one, each with a highly distinctive character. They can either use the lower to medium speed range, with the emphasis on economical, relaxed driving, or they can exploit the entire speed range in order to enjoy the engine's full vigor.
The Audi A4 Avant 1.8 T with front-wheel drive and manual gearbox consumes just 8.2 liters of unleaded Super petrol (95 RON) per 100 km (1999/100 EC). The power output of 110 kW (150 bhp) gives the A4 1.8T a top speed of 219 km/h and accelerates it from 0-100 km/h in a mere 9.1 seconds.
Increased power output and torque: The 2.4 V6
Audi's engine developers have also updated the 2.4-litre V6 engine thoroughly. This has achieved particularly low fuel consumption of just 9.6 liters per 100 km for the manual-shift 2.4 Avant. Moreover, the engine's emission levels are below the EU IV limits.
The modifications result in clearly increased performance: the 2.4's power output is now 125 kW (170 bhp) and its maximum torque 230 Nm. The A4 Avant with this engine accelerates from a standstill to 100 km in 9.0 seconds and has a maximum speed of 223 km/h.