On the road, the Lancia Thesis provides the performance one would expect from a large, luxury saloon. The performance of its engines is excellent, and from today it is going to be even better, thanks to the new 2.4 24 valve JTD engine.

The new engine is more powerful than the 10 valve unit of the same size. It delivers 175 bhp (129 kW) at 4000 rpm, in other words 16% more power. And above all it guarantees a significant increase in peak torque: 380 Nm (38.7 kgm) at 2000 rpm for the version with a manual gearbox (compared to 305 Nm-31 kgm at 1800 rpm for the 2.4 JTD 10v); the version fitted with the self-adaptive sequential automatic transmission delivers 330 Nm (33.6 kgm) at 1750 rpm.

Such a generous torque reserve even at low engine speeds means that the Lancia flagship is even more enjoyable to drive. The elasticity and driveability of the car improve (particularly with the automatic transmission, which makes the car even smoother to drive), thanks to a new setting of the electronic turbo control. And performance also improves. 

The numbers speak for themselves:

- 30.8 seconds to cover a kilometre from a standing start, with the mechanical gearbox (31.2 with the automatic)
- a top speed of 225 km/h (220 km/h with the automatic transmission); 
- 9.8 seconds to accelerate from 0 to 100 km/h (10.2 with the automatic converter).

Better performance does not mean higher consumption. On the combined cycle the flagship records 7.5 l/100 km with the manual gearbox and 8.8 for the Comfortronic version, 9.8 l/100 km on the urban cycle (12.1 with automatic transmission) and 6.2 and 6.9 l/100 km respectively on the out-of-town cycle.

In addition to these advantages the car generates practically no noise during warm-up, something that is particularly noticeable when the weather is very cold. And the new engine produces even lower emissions, even without sophisticated exhaust gas treatment devices.

The new engine refutes the prejudice of those who still say that diesel engines are noisy, smoky and cumbersome with an absence of noise that is the best in its class (the articulation index at 120 km/h is 82%), great respect for the environment and superb acceleration. Even smoother, rounder and more elastic than the previous JTD, it makes the Lancia Thesis not only a great car for long distances but also an agile car that handles superbly. Characteristics that are not exactly common in this type of car. It is the ideal engine for people who travel a great deal and want a car that is comfortable and luxurious for long hauls but as enjoyable to drive as a petrol model. 

the structure

The basic constructional features of the new 2.4 JTD 20v are the same as on the 10 valve versions, but numerous technical changes have been made to increase performance and to reduce noise and vibration even further, without affecting the engine's reliability.

The engine still has five cylinders in line, with a bore of 82 millimetres and stroke of 90.4 mm. The capacity is 2,387 cc, and the compression ratio is now 18.1 : 1. There are 4 valves per cylinder, making 20 in all, and they are activated directly by twin overhead camshafts with roller rocker arms (to reduce friction) and hydraulic tappets.
The new engine belongs to the second generation JTD Common Rail family of Multijet engines. They adopt the same principles as the Unijet Common Rail, i.e. high injection pressure and electronic injector control, but with an added feature: during each engine cycle it generates more injections than the two possible today. The quantity of fuel burned inside the cylinder is therefore the same, but it is broken down into more parts, and burns more gradually. The advantages include quieter operation, lower emissions and consumption, and greater efficiency that further enhances driveability.

These are significant results, because they are achieved on an engine which, as well as representing an incredible technological leap forward compared to pre-combustion diesels, also achieves huge improvements compared to the first generation of JTD engines. The secret of the Multijet lies in the control unit which governs the electronic opening and closing of the injectors (and in the injectors themselves). The key element is the electronic control unit itself, which can generate a very rapid series of injections. Developed by Fiat Auto research technicians to this end, the component controls the individual injectors singly (with the injectors) making possible the 'multiple injections' which ensure greater control over the pressure and temperature developed in the combustion chamber, and better exploitation of the air in the cylinders. This allows other milestones to be reached: a reduction in combustion noise, lower emissions and boosted performance.

Multiple injections, a different engine management setting and direct injection pressure increased from 1350 to 1400 bar. These are the main novelties of the 2.4 JTD 20v. But other components have also been changed to guarantee maximum reliability even with the new improved performance: the con rods, the cylinder head with hydraulic tappets (which eliminates the need for periodical maintenance to check and recover play), the piston with an internal duct to circulate the cooling oil, and the use of new materials for the journal and con rod bearings. 

The exhaust and inlet manifolds are also new; the former is made of a special highly resistant material, while the latter is made of pressure die cast aluminium.
The turbo setting has been modified. The engine is turbocharged by a Garrett variable geometry turbo (with electronic control and an intercooler) which improves the power delivery and guarantees prompt acceleration at low speeds.

The electronic EGR (Exhaust Gas Recirculation) system that cools the exhaust gas has also been modified, as has the lubricating circuit, which has a new oil pump and external air/oil heat exchanger to cool the oil, and there is a new water pump on the cooling circuit.