Wednesday, February 25, 2009

World preview: 1.75 Liter 200 HP Turbo Gasoline Engine and 2.0 Liter 170 HP JTDM Engine

Beneath their attractive and characterful lines, all Alfa Romeo cars conceal a structured range of excellent, technically advanced engines which are unstinting in performance. They are the best confirmation of the "sporting heart" which has always distinguished the Alfa Romeo brand. And today it is the turn of two new products to bear witness to this motoring tradition renowned throughout the world:
the 1.75 200 HP Turbo Gasoline Engine (Euro 5). This engine reverts to the 1750 capacity used on earlier successful Alfa Romeo sedans. In fact, at the end of the 1960s, the 1.75 liter Sedan was launched, followed by the 1.75 liter GT Veloce, both fitted with a 1779 cc engine producing 118 HP (the output of this Alfa Romeo engine put it at the top of its category);
the 2.0 liter 170 HP JTDM Engine (Euro 5) Common Rail Multijet, the technology developed by the Fiat Group in collaboration with Bosch, which revolutionized the world of diesel engines at the end of the 1990s.
The new engines produced by FPT – Fiat Powertrain Technologies – and coupled to a 6-speed manual transmission, will be available from April on the Alfa Romeo Brera, Spider and 159 (sedan and Sportwagon) models.

Alfa Romeo 1.75 Liter Turbo Gasoline Engine

The new 1.75 Liter Turbo Gasoline engine brings together the most advanced technologies in the field of spark ignition engines, including direct gasoline injection, continuous variable valve timing, turbocharging and a revolutionary management system. The result is an engine with performance comparable to that of a 3.0 liter engine while consumption is maintained at moderate levels appropriate to a 1.75 liter engine.

“Scavenging” technology
The exceptional performance of the engine is the result of applying “Scavenging” technology, which maximizes torque at very low engine speeds, thereby providing incredible speed of engine response to driver demands.
“Scavenging” is achieved by instantaneously (moment by moment) monitoring and optimizing engine parameters such as fuel measurement, the position of the two phase variators, spark advance and injection timing; in practice, it is possible to define with extreme accuracy the angle and times of valve overlap in order to generate an airflow direct from the inlet manifold to the exhaust manifold and thereby activate the turbocharger very quickly. This allows optimum exploitation of the turbocharger compared with conventional turbocharged gasoline engines. The system is managed by a new engine management computer, containing ultra-modern software which manages all the parameters. The results obtained are astonishing: maximum torque at 1500 rpm is increased by 70% compared with a traditional turbocharged engine and the response times are more than halved, approaching those of a normally aspirated engine.

Direct injection
Direct injection reduces the temperature in the combustion chamber through the evaporation of gasoline which considerably lowers its propensity to detonation. This allows excellent performance to be achieved even in the presence of a relatively high compression ratio (9.5) and provides low consumption at “throttled” speeds.
Direct injection is essential to reduce emissions with an advanced double injection strategy. And with direct control of the fuel, during the scavenging process it is possible to prevent some of the gasoline ending up in the exhaust with harmful effects on catalytic converter operation. Finally, the second generation injection system has a new high-pressure pump (able to handle gasoline pressures of 150 bar) and new 7-hole injectors which guarantee perfect vaporization under all engine operating conditions.

Dual variable valve timing (VVT)
The two continuous phase variators on the inlet and exhaust camshafts optimize the phases at all speeds and engine loads, minimizing consumption and emissions. In addition, by coupling the two variators to the turbocharger, the “Scavenging” strategy is managed, by defining the correct overlap during the transitions. In response to a sudden torque request from the driver it is therefore possible to speed up engine response, even from very low rpm levels, as quickly as possible.

The engine has a new generation turbocharger linked to an innovative exhaust manifold of the “Pulse Converter” type which optimizes exploitation of the exhaust pressure waves to increase torque at low engine speeds. Both the manifold and the turbine are made of microcast steel which allows them to withstand very high operating temperatures (up to a maximum of 1020°C), which is extremely important in reducing consumption during motorway driving at medium/high speeds.

Thermal fluid dynamics
The inlet ducts have been designed and optimized using single and three-dimensional computational technologies allowing the correct high level of turbulence to be achieved. This results in correct mixing of air and gasoline (in addition, combustion is speeded up and fully stabilized even at low engine speeds). The combustion chamber has been optimized for this turbocharged engine by using large “squish” areas and minimizing the surface to volume ratio with beneficial effects on combustion efficiency. Finally, the exhaust pipes have been designed to work in synchrony with the exhaust manifold and to maximize its “pulse converter” effect.

The whole engine been designed to reduce losses through friction. The pistons have elastic rings to limit tangential load and advanced materials have been used to reduce wear to a minimum. In addition, the cylinder head design incorporates roller rockers which reduce losses through sliding contact by 65% at 2000 rpm compared with those in the cylinder heads of Twin Spark engines.
Mechanical optimization, with a very long connecting rod coupled with a relatively short stroke, has minimized typical vibration in four-cylinder engines when operating at high engine speeds. This has given the option of not using balance shafts, further improving the fuel consumption of the engine.

The “Scavenging” strategy, combined with the new management system, has achieved new “benchmark” levels for engine performance. The specific torque (185 Nm/l) is very high and is among the highest for currently available engines. It can also be asserted that the maximum torque value (320 Nm) achieved at an engine speed of 1400 rpm represents a point of absolute excellence. This value guarantees excellent pick-up performance and allows driving without frequent use of the gear change by the driver. Finally, the high specific power of 115 HP/l is achieved at the relatively low engine speed of 4750 rpm, remaining constant up to 5500 rpm.

As a result of the double injection and “high pressure start” the emissions value meets the Euro 5 limit with a relatively small catalytic converter, with positive effects on performance.

Alfa Romeo 2.0 Liter JTDM Engine, 170 HP and 360 Nm (Euro 5)

The 2.0 liter 170 HP JTDM engine (Euro 5) is a natural development of the 1.9 liter JTDM engine from the point of view of both performance (with an increase in torque and power) and emissions, satisfying the limits of the Euro 5 directive and achieving CO2 emission values (in the combined cycle) of a minimum of 136 g/km and a maximum of 142 g/km for the Alfa Romeo 159 (sedan).
The increase in cylinder capacity has been obtained by increasing the bore from 82 mm to 83 mm: this solution, together with a new variable geometry turbocharger, positions this engine at the top of the market. And with a reduction in fuel consumption: for example, the Alfa 159 Sedan in the combined cycle recorded 5.4 liters/100 km. In addition, the compression ratio is reduced from 17.5:1 to 16.5:1 (giving a consistent reduction in NOx) while, compared with the 1.9 liter JTDM engine, the new engine uses a “low voltage” glow plug which allows starting with minimum preheating times. Last but not least, compliance with Euro 5 emission limits is ensured by the use of a close-coupled diesel particulate filter (CCDPF) and an advanced exhaust recirculation system (EGR), in which all the sub-components are packed into one small component (the EGR module).
Finally, on the Alfa 159, a special equipment package is available (green tires, modified gear ratios, etc.) further reducing fuel consumption and emissions of CO2 without penalizing the driving pleasure and sportiness typical of the brand, in respect of both the 2.0 liter 170 HP JTDM engine and the 1.9 liter 120 HP JTDM engine. The values obtained (respectively 136 g/km and 138 g/km on the Alfa 159 sedan version) result in car tax benefits in the main European markets where taxation is based on CO2 emissions (for example France, Belgium, Holland and the UK).
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