|The 1.8 TFSI is Audi’s first four-cylinder engine. Click to enlarge.|
Audi has introduced a new turbocharged four-cylinder FSI engine with a displacement of 1.8 liters for the Audi A3 and A3 Sportback. The 1.8 TFSI is the first in a new family of engines and combines the evolution of the TFSI concept with an entirely new basic engine.
The TFSI concept brings together the advantages of gasoline direct injection and turbocharging, delivering better performance with reduced fuel usage and emissions. The 1.8-liter TFSI develops 118 kW (160 hp) of power and high peak torque of 250 Nm (184 lb-ft).
Audi refined its existing TFSI concept—represented by the 2.0 TFSI engine, available since September 2004—for the 1.8 TFSI by increasing the injection pressure to 150 bar and applying new six-hole injectors to guarantee highly homogeneous mixture preparation and efficient combustion.
A new type of high-pressure pump supplies this injection pressure. The pump is driven by a four-fold cam on the exhaust camshaft. This reduces the operating forces required and boosts precision, thus improving the emissions.
The high-pressure lines through which the fuel reaches the injectors at maximum pressure are made entirely from stainless steel. Dual injection—the distribution of the fuel quantity between the admission stroke and the compression stroke—brings further advantages for the homogenization of the mixture and heating of the catalytic converters after a cold start.
The integrated turbocharger and a new engine management system bring a further improvement in responsiveness and help the torque to build up even more smoothly.
|Power/torque curves for the 1.8 TFSI. Click to enlarge.|
The watercooled turbocharger K03, from Borg Warner, maintains optimum cylinder filling. An optimized turbine wheel improves the aerodynamics inside the charger, as a result of which responsiveness lower down the engine range is further enhanced. In the intake system, the redesigned charge movement flap reduces flow losses and simultaneously assures a very homogeneous distribution of the mixture.
Audi also re-engineered the continuous adjusting mechanism of the intake camshaft; this vane-type system now responds much more swiftly than previous concepts and promotes a spontaneous response from the engine even starting at low engine speeds.
The peak torque of 250 Nm is available across a very wide engine speed range extending from just 1,500 rpm all the way to 4,200 rpm.
The new engine is available initially in the A3 and A3 Sportback, both in combination with the six-speed manual gearbox and with the optional S tronic, the dual-clutch gearbox for lightning-fast gearshifts without any perceptible interruptions to the flow of power.
With a top speed of 220 kph (137 mph) and acceleration from a standstill to 100 kph in 7.8 seconds for the 3-door A3 with S tronic, the A3 with the 1.8 TFSI consumes 7.3 liters per 100 km of fuel (32 mpg US).
By comparison, the A3 2.0 FSI model uses a 2.0-liter engine that develops 115 kW/150 hp at 6,000 rpm and maximum torque of 200 Nm at 3,500 rpm, and accelerates from 0 – 100 kph in 8.9, all with the same fuel consumption (7.3 l/100 km) as the more powerful and smaller 1.8 TFSI.
The first 1.8 TFSI-equipped vehicles will be available in January 2007.