|The 200 HP 1.8 Di TurboJet. Click to enlarge.|
Fiat has launched a new 1.8-liter, four-cylinder turbocharged gasoline direct-injection engine—the 1.8 Di TurboJet—in the Lancia Delta. Produced by Fiat Powertrain Technologies (FPT) and coupled with a six-speed automatic transmission, the 1.8 Di delivers maximum power of 200 hp (147 kw) at 5,000 rpm and a maximum torque of 320 N·m (236 lb-ft) at 1,400 rpm.
A new scavenging strategy combined with the engine control system contributes to a specific drive torque (185 Nm/L) that is one of the highest currently available. The 200 HP 1.8 Di Turbo Jet E5 drive torque is comparable to the one of an aspirated V6 engine which is almost twice its displacement, according to Fiat, but with significant efficiency gains through the downsizing.
|Lancia Delta 1.8 DiTurbo. Click to enlarge.|
Equipped with the 200 HP 1.8 Di TurboJet, the Lancia Delta can reach a maximum speed of 230 km/h (143 mph) and accelerates from 0 to 100 km/h in 7.4 seconds, with fuel consumption of 7.8 liters per 100 km (30 mpg US), 185 g CO2/km and a Euro 5 homologation.
Scavenging. FPT uses a scavenging scheme to maximize drive torque at very low rpm. Scavenging can be obtained by controlling and optimizing engine parameters such as dosage, position of the two phase transformers, ignition advance and injection timing. The system defines the angle and overlapping time of the valves with precision in order to generate direct air flow from the intake to the exhaust manifolds and start the turbocharger in very short times. This allows the engine to make better use of the supercharging when compared to standard turbocharged gasoline engines, according to Fiat.
The system is managed by an engine management control unit integrating software which manages all parameters. Maximum drive torque at 1,400 rpm increases by 70% compared to traditional turbo engines and response times are halved, getting close to those of aspirated engines.
Direct injection. Direct injection reduces the temperatures in the combustion chambers through the evaporation of fuel and lowers the knock sensitivity. This enables the engine to achieve great performances even for a moderately high compression ratio (equal to 9.5) and ensures limited fuel consumption at partial speed.
The direct injection system uses an advanced strategy of double injection to reduce emissions. Due to the direct control of fuel, it is possible to avoid some of the gasoline getting directly to the exhaust manifold during the scavenging with negative effects on the catalytic converter’s functionality. The second generation injection system uses a new high pressure pump capable of managing gasoline pressure of 150 bar (15 MPa) and 7-hole injectors to optimize evaporation for all operating conditions.
Double phase transformer. The two continuous phase transformers on the intake and exhaust camshafts enable phase optimization at any speed and engine load by reducing fuel consumption and emissions as much as possible. Moreover, by combining the two transformers with the turbocharger, it is possible to manage the scavenging strategy by defining the correct overlapping during the transitory phases. In this way it is possible to respond to a sudden driver request by maximizing the engine’s response speed at low rpm.
Turbo. This engine is provided with a new-generation turbocharger connected to a “Pulse Converter”-type exhaust manifold which optimizes the use of exhaust pressure waves to increment the driving torque at low speeds. Both manifold and turbine are made of microcast steel so that they can reach very high working temperatures (up to a maximum of 1020 °C). This is important for reducing consumption while operating at medium/high speed—i.e., on the highway.
Thermal Fluid Dynamics. The intake ducts were designed and optimized by using mono and three-dimensional calculation technologies through which it was possible to obtain a correct and high turbulence level. The combustion chamber was optimized by using wide squish areas and by minimizing area/volume ratios with clear benefits in terms of combustion efficiency. Lastly, the exhaust ducts were designed to work in tune with the exhaust manifold and maximize its pulse converter effect.
Friction losses. The entire engine was made with the aim of minimizing friction losses. The pistons are provided with piston rings with a reduced tangent load and are made of advanced materials to minimize wear and tear. The engine cylinder head was designed with two roller rocker arms placed on the valve control which reduce losses by friction of 65% at 2000 rpm compared to direct command.
Very long rods combined with a moderately short travel has resulted in a drop of vibrations which are typical of four cylinder engines operating at very high speeds. As it wasn’t necessary to utilize balancing countershafts, the weight was further optimized and consequently, the fuel consumption was reduced.