The new 1.9 JTD 16v Multijet motor

Alfa Romeo proudly presents the second generation of Common Rail power units, i.e. 16v JTD engines with Multijet technology. The first member of this new family in the world was the 1.9 JTD unit with 140 bhp which was fitted into the Alfa 147, 156 and Sportwagon, it was fitted in conjunction with a rather sporty 6-speed gearbox. The unit is derived from the 1.9 JTD 8v Common Rail unit and takes the form of a 4 cylinder in line unit with a bore of 82 mm and a stroke of 90.4 mm.
The 4 valves are driven directly by a twin overhead camshaft. The new unit has undergone various technical improvements that were designed to reduce noise and vibration, increase performance and torque at lower speeds. The Common Rail used on the 1.9 JTD 16v unit includes two new strategies for automatically calibrating and balancing the injection to reduce the noise and vibration. Many components of the new unit are brand new, for instance the cylinder head: here we have hydraulic tappets, steel con-rods and crankshaft, a piston with an internal channel to carry oil to the mains and small ends. The intake and exhaust manifolds are also new: the former is made from a special high-strength material whilst the latter is made from pressure cast aluminium. The electronic EGR and exhaust gas cooling systems are also new. The lubrication sytem also features a new oil pump as well as a new external exchanger, air/oil, for cooling the oil, this system also includes a new coolant pump. With these improvements it has turned the 1.9 JTD into a unit with more relialability, lower fuel consumption and more power.

The Multijet System:

The intoduction of the Multijet system makes the 1.9 JTD the first second generation Common Rail power unit in the world. It is based on the same Unijet Common Rail principles, i.e. high injection pressure and electronic injector control, but with a slight difference: the number of injections increases from the current two during each cycle. This allows the motor to use the same amount of diesel but in smaller quantities, this achieves a smoother combustion. The benefits are lower running noise, a reduction in emissions and an increase in performance of between 6% and 7%. This result is extremely impressive, particularly in a motor that not only represents a great technological jump forward compared to the prechamber diesel units, but it is also miles ahead of the first generation of JTD motors. The secret of the Multijet system lies in the control unit that gouverns the electronic injector opening and closure system, as well as the injectors themselves. The crucial part of the motor is the electronic control unit in itself, due to its ability to deliver a series of injections in a very closely-spaced window.
Alfa's researchers have developed the part, together with the injectors, specially for this application. It is designed to deliver the multiple injections and to assure that the designer has more accurate control of pressures and temperatures that develop inside the combustion chamber and also a more efficient use of the air intake. This enables further improvements: quieter combustion, reduced emissions and most of all increased power. :-)

The benefits of the multivalve technology:

The rather large power reserves (103 kW) and the rather generous torque (31 kgm) of the new 1.9 JTD 16v unit are achieved through: a new motor contol setting; an increase in the direct injection pressure from 1300 to 1400 bars; a new turbocharger setting. The power units are charged usind a Garrett turbocharger with a variable geometry turbine which helps to improve power delivery by allowing high torque delivery at low revs.There is 90% of maximum torque between1750 and 3250 rpm. These statistics enable us a very pleasnt drive and rather sparkling performance for the Alfa 147, Alfa 156 and Sportwagon. In fifth gear for example, the Alfa 147 accelerates from 80 to 120 km/h in 7,9 seconds.It reaches a top speed of 206 km/h and accelerates from 0 to 100 km/h in 9.1 seconds. All this is accomplished with a low fuel consumption. At constant speed in sixth gear, the Alfa 147 gives us the following results: 4.5 l/100 km at 90 km/h; 6.0 l/100 km at 120 km/h; 7.5 l/100 km at 150 km/h. Lastly, the Alfa 156 reaches a top speed of 209 km/h and accelerates from 0 to 100 km/h in 9.3 seconds. The Sportwagon on the other hand, takes 9.7 seconds to accelrate from 0 to100 km/h. Even here the fuel consumption is reasonable. At constant speed in sixth gear we have the following results: 4.5 l/100 km at 90 km/h; 5.9 l/100 km at 120 km/h; 7.3 l/100 km at 150 km/h.