Citroen has released the first details of a new twin turbo diesel engine that will join its Australian range in early 2007, boasting 125 kW and 370 Nm of torque from just 2.2 litres, making it uniquely light and powerful, delivering outstanding performance, economy and, thanks to the standard particulate filter, significant environmental benefits.

This new Citroen engine features several innovations:

• A parallel sequential dual turbo, a world first on a 4-cylinder diesel engine, designed to boost engine response at low speeds and minimise the response time of the turbocharging system. Maximum torque of 370 Nm is available from 1,500 rpm
• A new combustion chamber, the ECCS (Extreme Conventional Combustion System), which optimises the air/fuel mix, and a third-generation common rail system, in which pressure is increased to 1,800 bars for a finer fuel spray. This combination cuts pollutant emissions and fuel consumption while improving performance.

The parallel sequential dual turbo delivers significant torque at low engine speeds, doing away with turbo lag. Maximum torque of 370 Nm is available from just 1500 rpm. In third gear, driver alone, the C5 accelerates from 30 kmh to 60 kmh in 3.6 seconds for the hatchback and 3.7 seconds for the saloon. This is 20 per cent quicker than the existing C5 HDi.

This system is based on two fixed geometry turbochargers of identical size. Each one supplies around half the air input required at high engine speeds. This design principle extends the operating range of the turbocharger and improves engine performance at both high and low speeds, particularly during transient conditions.

At low engine speeds, below 2,700 rpm, only one turbocharger is operational. This low inertia turbocharger delivers instant engine response, as well as providing up to 40 per cent more torque than the existing engine.

At engine speeds of more than 2,700 rpm, the second turbocharger kicks in to supply the increased air intake required at higher engine speeds. The system is so smart that it starts spinning up the second turbocharger before plumbing it into the air take system, ensuring both instant power and a smooth transition to twin turbo operation.

Thus, the twin turbos only work when required, saving fuel and emissions.

The new engine even looks after pedestrians. It is 40 mm shorter than the existing engine and this has been used to remove hard spots on the bonnet, which are critical in making cars safer for pedestrian accidents.

Full specification and pricing for the new C5 HDi Twin Turbo will be announced when it goes on sale in Australia in early 2007.

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