The 1.3 Multijet 16v (whether 75 or 90 bhp) therefore represents a real leap forward in technological terms, and this translates into lower fuel consumption and emissions for the customer. Without even considering the increased quietness (due to the multiple injections), the enhanced comfort (fewer alternating masses mean less vibration), the smoothness and enjoyment of driving it (due to the extremely smooth torque delivery, that comes from better control over combustion), elasticity and the prompt response of a diesel unit which resembles a petrol engine because of the vast rev range (for example, the driver is no longer aware of the 'fuel cut-out' just above 4000 rpm), the environment-friendly features that enhance the diesel's great quality on the environmental front (consumption) and keep its main defect (particulate emissions) to a minimum.


The 120 bhp and 130 bhp 1.9 Multijet

Both engines have 4 cylinders in line, and two valves per cylinder, with a bore of 82 mm and stroke of 90.4 mm. The first delivers 120 bhp (88 kW) at 4000 rpm and torque of 28.5 kgm (280 Nm) at 2000 rpm; the second delivers 130 bhp (96 kW) at 4000 rpm and torque of 28.5 kgm (280 Nm) at 2000 rpm. Several changes were made to the two engines to increase performance and engine torque at low speeds, and to reduce noise and vibration. For example, the "Common Rail" system envisages two automatic control strategies for the setting and balance of the injected diesel fuel, which reduces noise and vibration. The turboboost is provided by a variable geometry Garrett VGT 17 turboblower with electronic control that helps to improve the power delivery, but also generates very high torque at low engine speeds. In fact, 90% of peak torque is available between 1750 and 3250 rpm. These figures translate into extremely enjoyable driving and brilliant performance: powered by the 120 bhp 1.9 Multijet engine, Fiat Grande Punto Emotion has a top speed of 190 km/h and accelerates from 0 to 100 km/h in 10 seconds (the values for the Sport version with the 130 bhp 1.9 Multijet engine are 200 km/h and 9.5 seconds). Brilliant performance, but in spite of this, fuel consumption remains low: 7.5 l/100 km in the urban cycle, 4.5 out of town, and 5.6 in town (the values for the 130 bhp 1.9 Multijet are 7.6, 4.6 and 5.7).

Last but not least, both the 1.3 Multijet and the 1.9 Multijet mounted on the Grande Punto respect Euro 4 legislation and offer a particulate trap (DPF), a 'for life' system that eliminates fine dust and does not need additives to regenerate it.



The Multijet system on the second generation JTD engines

The Multijet turbodiesel engines mounted on Fiat Grande Punto are jewels of modern engineering which confirm Fiat Auto's leadership in this field. When it developed the Multijet system, the Fiat Group set an important new record in the field of diesel engines, made possible by the huge amount of expertise accumulated since 1986, when the Croma TDI was launched, the world's first direct injection diesel-engined car. For those years it was a brilliant result, the first important step forward towards more efficient combustion in the field of diesel engines for cars. Thanks to this technology, which other manufacturers soon adopted, diesel-engined cars were able to guarantee both better performance and lower consumption. One problem remained: the excessive noise made by the engine at low speeds and in 'speed transients'. This is where the history of the Unijet starts, or rather the search for a more evolved direct injection system, which could drastically reduce the problem of noisy combustion. After a few years, this research produced the Unijet, but it also brought other advantages in terms of performance and consumption. There were only two possible ways of solving the problem: passive acceptance, isolating the engine to prevent the sound waves from spreading, or working actively to eliminate the problem at source, developing an injection system that could reduce combustion noise. Having chosen the second strategy, the Fiat engineers immediately concentrated their research on the 'Common Rail' principle, excluding other high pressure injection systems after careful analysis. The other systems did not allow the pressure to be managed independently of the rpm and the engine load, nor did they envisage pre-injection, the two strengths of the Unijet. The theory that the engineers started to analyse was both simple and ingenious, the fruit of work done by researchers at Zurich University, which had never been applied on a car. By continuing to push diesel fuel into a tank, pressure builds up inside the tank, which thus becomes a hydraulic accumulator, or 'rail', in other words a reserve of pressurised fuel, ready to use.

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