|The 1.4-liter MultiAir Turbo. Click to enlarge.|
At the Los Angeles Auto Show, Fiat unveiled the 2012 Fiat 500 Abarth—a performance variant of the 500—featuring the first application of the new 1.4-liter MultiAir Turbo engine. The turbocharged, twin intercooled and MultiAir-equipped (earlier post) 1.4-liter engine delivers an estimated 160 hp (119 kW) and 170 lb-ft (230 N·m) of torque.
The addition of the turbocharger, coupled with MultiAir technology, delivers a 70% increase in engine rpm torque and a 59% increase in power over the base 1.4-liter engine. (Earlier post.)The 2012 Fiat 500 Abarth is also fitted with a heavy-duty five-speed manual transmission with Torque Transfer Control (TTC) system.
Structurally, the 1.4-liter MultiAir Turbo engine starts with a cast-iron block and an aluminum bedplate. Bore is 72 mm (2.83 inches) and stroke is 84 mm (3.31 inches) for a total displacement of 1368 cm3 (83.5 in3). At the bottom end, a forged-steel crankshaft with select-fit main bearings is supported across four main journals. The crankshaft has been designed with lightened counterweights to reduce overall mass for high engine rpm operation.
The use of lightweight forged-steel connecting rods that have been designed with a unique cross section to minimize the longitudinal and lateral bending of the rod enhances durability.
Lightweight pistons contribute to the overall strength of the reciprocating assembly and the engine’s high rpm capability. Full-floating piston pins are used for added strength. Piston cooling jets, located at the bottom of each cylinder, contribute to fuel economy by squirting oil on the bottom of the pistons to help maintain cylinder temperatures and reduce the possibility of hot spots along the cylinder walls or at the top of the piston that could lead to detonation.
The compression ratio of the Fiat 500 Abarth’s 1.4-liter MultiAir Turbo engine is 9.8:1. For optimum fuel economy and performance, fuel with a 91 octane rating is preferred; regular 87 octane is acceptable.
This high-performance 1.4-liter engine also is fitted with a structural aluminum oil pan. Crankcase capacity is 4.0 quarts with a dry filter. Synthetic 5W-40 engine oil is recommended, due to higher overall temperatures with the turbocharger. To maintain a lower ownership cost for the Fiat 500 Abarth, oil change intervals are set at 8,000 miles.
The valve train for the 1.4-liter MultiAir Turbo engine features Fiat’s exclusive MultiAir fuel delivery technology. Unlike engines that rely on direct action from fixed lobes on the camshaft to control intake valve opening and closing, MultiAir is an electro-hydraulic system that can control intake air, cylinder by cylinder and stroke by stroke depending on the demands from the standard electronic throttle control (ETC) system.
Actual opening of the valves is controlled by hydraulic fluid running through a narrow passage that is controlled by a dual-action solenoid. When the solenoid is closed, under highway speeds or full acceleration, intake valves are fully open much like a traditional engine for maximum power. At lower speeds, the solenoid opens, allowing oil to bypass the passage, decoupling the valves. This allows for infinite control of the valves and controls the amount of fresh air into the cylinders, reducing wasted energy that is common with fixed intake lobes on a camshaft.
Spent exhaust gases are released through traditional lobes on the camshaft and exit through a cast stainless steel exhaust manifold.
Ignition is through a single output, coil-on-plug system. Spark plugs are dual precious metal for durability.
Fuel delivery is sequential, multi-port, electronic, with injectors located to direct the fuel spray at the intake valves in a wide spray pattern that increases fuel atomization and enhances complete combustion for a smooth driving experience.
MultiAir technology on normally-aspirated 1.4-liter engines provides 15% increase in low engine rpm torque, 7.5% improvement in fuel efficiency and a 10% reduction in CO2 emissions.
Compared with the Fiat 500’s natural-aspirated 1.4-liter MultiAir engine, the boost to an estimated 160 hp on the new 2012 Fiat 500 Abarth is largely due to its single turbocharger that operates off engine exhaust and utilizes energy that would normally be wasted through the tailpipe.
The turbocharger spins up to 230,000 rpm to convert exhaust heat and pressure to a rotational force that drives a compressor. The compressor draws cool air and pumps it into the intake manifold at increased pressure that results in a greater amount of air in the cylinder and hence more power.
The 1.4-liter MultiAir Turbo’s induction system includes two intercoolers located behind the driver- and passenger-side air inlets of the Abarth-styled front fascia. The intercoolers are designed to remove heat in the air charge that the turbocharger generates while compressing incoming air (higher air density for more power). Reducing heat provides a cooler, denser air charge that helps increase the potential for more power. A cooler air charge also reduces the potential for engine knock.
The new 2012 Fiat 500 Abarth also features several engine system component upgrades needed for high-performance driving.
On the intake side, the 1.4-liter MultiAir Turbo features an Abarth-designed fresh-air intake system with high-flow air filter, redesigned air box for improved air flow and smooth-flowing plumbing for maximum power and low induction noise.
An Abarth-designed concentric “double tip” dual-exhaust system delivers a high-performance look with Abarth-tuned sound and minimal exhaust gas restriction for maximum power.
An Abarth-tuned powertrain control module (PCM) integrates all of the MultiAir Turbo’s engine control functions. The PCM provides specific engine calibrations to maximize horsepower and torque in “Sport” mode, and syncs with the LED-illuminated shift light for additional driver notification at the redline.
An upgraded electrical system includes a high-output 140-amp alternator and 500 amp cold-cranking maintenance-free battery for increased vehicle system charging.
The Fiat 500 Abarth is equipped with the heavy-duty C510 five-speed manual transmission. Proven on the European 500 Abarth models, this transmission features a 3.35 final-drive ratio for quick acceleration and faster top speed, while maintaining fuel efficiency.
Designed to handle the increased torque loads, the Fiat 500 Abarth’s C510 transmission includes an intermediate shaft with equal-length half shafts to mitigate torque steer. Compared with the Fiat 500, the 500 Abarth features 23% larger half shafts (28.1 mm diameter vs. 22.8 mm diameter in the Fiat 500) for increased strength and to reduce torsional stress in the driveline during performance driving on the road or track.
To handle the increased power and torque of the new 1.4-liter MultiAir Turbo engine, larger constant velocity (CV) joints with 53% greater torsional strength (2600 N·m vs. 1700 N·m in the Fiat 500) deliver added durability and refinement. Maximum track handling with Torque Transfer Control (TTC) system Helping the driver to utilize the power of the new 1.4-liter MultiAir Turbo engine is an Abarth-tuned Torque Transfer Control (TTC) system. TTC is designed to control and transfer the engine’s torque to the drive wheels for performance and improved at-the-limit handling.
The TTC system in the 2012 Fiat 500 Abarth features a differential locking system that uses the mechanical differential in the C510 transmission to control torque via the electronic stability control (ESC) system. Utilizing ESC enables the 500 Abarth to transfer torque from a front wheel that slips, to one that grips.
In addition, when the Fiat 500 Abarth is in “Sport” mode, TTC automatically adjusts the degree of differential locking depending on dynamic factors, including vehicle speed.