The All New Subaru Impreza | Part Three

Subaru Impreza

Subaru Impreza

New 2.0 Litre Engine In Detail

The new Impreza 2.0R and RX enjoy substantial revisions to their 2.0 litre ‘boxer’ engines which result in stronger low and mid-range pulling power, enhanced flexibility and improved fuel economy with lower exhaust emissions.

And while power drops from 160 to 150 PS at the same 6,400 rpm, torque is 7.4 lb ft (10 Nm) greater, recording 144.6 lb ft at 3,200 rpm.

The result is an improvement of more than 2 mpg on the Combined cycle with the manual now recording 33.6 mpg and the automatic even better at 34.4 mpg. Urban and Extra Urban figures are 25.4 and 40.9 mpg for the manual and 25.4 and 43.5 mpg for the automatic. Exhaust emissions are also down, now standing at 199 g/km for the manual (was 214 g/km) and 194 for the automatic (was 207 g/km).

The 0-60 mph time for the manual is 9.2 seconds while the automatic records 11.3 seconds. Maximum speeds have yet to be confirmed.

Common to all new Impreza engines are twin overhead camshafts per bank (DOHC), four valves per cylinder and an Active Valve Control System (AVCS) which is a form of variable valve timing. This enhances low-speed pulling power and high-rev power.

For the new Impreza 2.0R and RX, the combustion chambers have been redesigned for increased tumble gas flow, enhanced tow-speed torque and reduced fuel consumption. Also for improved efficiency are a revised intake system, cooling system and catalytic converters.

The new 2.0 litre four-cam ‘boxer’ engine retains the same 92 mm bore and 75 mm stroke as before but with a lower 10.2:1 compression ratio.

New 2.5 Litre (WRX) Turbo Engine In Detail

The renowned 2.5 litre turbocharged ‘boxer’ engine fitted to the new Impreza WRX receives meaningful revisions to improve efficiency and provide much gutsier throttle response in ‘real world’ driving conditions.

Maximum power for the standard WRX is an identical 230 PS to the previous model but now at a lower 5,200 rpm instead of 5,600 rpm.

Torque (pulling power) is also the same as before at 236 lb ft but now at a more accessible 2,800 rpm instead of 3,600 rpm.

Significantly, torque at 2,000 rpm is now 221 lb ft instead of around 150 lb ft. This translates into much livelier acceleration from low engine speeds and an effortless seam of power in everyday driving. Power is also considerably greater from idle until 3,500 rpm.

These major improvements have been achieved thanks to a new turbocharger and intercooler with the oil pump, sparking plugs and tumble generating valve all being revised for greater efficiency.

On the transmission front, 1st, 2nd and 3rd gears have been revised and despite the lower overall gearing – top now pulls 22.6 mph at 1,000 rpm instead of 23.5 mph – fuel economy is unharmed.

The new Impreza WRX also enjoys a 30 kg weight saving and lower drag coefficient of 0.35 Cd instead of 0.37.

It has an identical 0-60 mph time as the old model at 5.4 seconds. Maximum speed has yet to be confirmed.

Fuel economy is now 19.8/34.4 and 27.2 mpg on the Urban/Extra Urban and Combined cycles while the CO2 emissions are 246 g/km.

Published 23 August 2007 Melanie Carter

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