The engine used in the Fiat 500 is jewel like. It is based on a ground breaking design originating more than twenty-five years ago. Smooth, lively and full of character, it delivers as many smiles per mile as miles per gallon. In this post, we will look at the construction of the Fiat 500's engine with the help of some never before published images and specifications for the North American 1.4L MultiAir engine.
The engine block (1) is made from cast iron. The crankshaft is supported by five main bearings. The thrust bearings are attached to the center upper main bearing. To keep the pistons cool, the cylinder block has four piston cooling jets located under the main bearing shells. The cylinders are formed directly into the engine block. A knock sensor is located on the left side of the block.
- form the load carrying structure with the engine block support the crankshaft
- allow return of the engine lubrication oil to the pan support the engine oil pan
The crankshaft is made from induction hardened forged steel. Eight counterweights at 180° balance the crankshaft rotary mass. The main journals are crossed drilled for rod bearing lubrication. The crankshaft is supported by five select fit main bearings with the center bearing serving as the thrust washer location. Both the front and rear seals are a single piece design and are mounted to the oil pump and cylinder block.
The pistons are a lightweight design with low tension piston rings that improve fuel economy. The pistons are made of a high strength silicon aluminum alloy and the piston skirt has a Moly® coating. The piston pin is a press fit into the rod. The connecting rod is forged steel with a bolted cracked cap design that provides more precise crankshaft bearing geometry than the traditional procedure in which rods are sawed in two.
The vacuum pump supplies vacuum to the brake booster and is mounted to the rear of the cylinder head, driven by the camshaft.
The lubrication system consists of the following components:
- Oil pump pick-up tube attached to the oil pump
- Oil pump that is directly coupled to the crankshaft and is mounted to the front of the engine as part of the oil pump housing
- Pressure relief valve in the oil pump that controls system pressure
- Oil filter housing that supports the oil filter and oil cooler
- Oil cooler mounted to the oil filter housing
- Oil filter located in the oil filter housing
- Four piston oil cooler jets mounted to the engine block
- Filter screen mounted in the variable valve actuation assembly
- Variable valve actuation assembly that uses pressurized engine oil to open the intake valves
- Oil pressure switch located on the oil pump housing
- Oil temperature sensor located on the variable valve actuation assembly
The oil pan in the Fiat 500 is made from aluminum with a threaded oil drainage opening and a threaded port for an oil viscosity sensor.
The 1.4L engine has four engine blocked-mounted oil jets (1) installed to cool the underside of each piston. The oil jets are fed by the main oil gallery, and spray upward on the bottom of the pistons and cylinder walls. Each jet has a check valve which closes to maintain ample oil pressure at idle. All four oil jets are identical and are a press fit to the engine block.
Pressure @ Curb Idle Speed* > 0.7 bar > 10 psi
Pressure @ 4000 RPM* > 4.0 bar > 58 psi
*At Normal Operating Temperatures
The 1.4L aluminum cylinder head features four valves per cylinder with pressed in metal valve guides.
Cylinder head specifications:
Valve sizes: Intake 26.75 - 27.05 mm, Exhaust 22.25 - 22.55 mm
The 1.4L engine uses a Single Over Head Camshaft (SOHC) to provide valve actuation but the camshaft is in the standard position of an exhaust camshaft in a Double Over Head Camshaft (DOHC) engine. The camshaft has five bearing journal surfaces and three cam lobes per cylinder. The camshaft is built up on a hollow tube with cam lobes, bearing journals and end caps pressed into position. The front end cap includes the camshaft sprocket mounting and front bearing journal with end play thrust walls. The rear end cap is the camshaft position sensor pick-up wheel and also drives the vacuum pump.
VALVE TIMING - MULTIAIR PUMPING ELEMENTS Specification Opens 11° (BTDC) Closes 58° (ABDC) Duration 249° Centerline 125° Note: Units are in crank degrees.
VALVE TIMING - EXHAUST VALVES Specification Opens 34° (BBDC) Closes 2° (ATDC) Duration 216° Note: Units are in crank degrees.
- Single camshaft
- Standard and hydraulic exhaust tappets
- Intake tappets integrated in the MultiAir actuator
- Brake servo vacuum pump
- Reduced fuel consumption
- Reduced CO2 emissions
- Increased power and torque
- Increased driver responsiveness
- Less pollution
- Easier start-up
The MultiAir system consists of a hydraulic-mechanical actuator fitted inside the MultiAir engine. MultiAir also includes hardware and software electronic components, built into the powertrain control module (PCM) to manage the engine intake valve motion. At each engine cycle, the MultiAir system controls the quantity of fresh air entering each cylinder by managing intake valve motion.
Type SOHC I-4 16-Valve MultiAir
Compression Ratio 10.8:1
Lead Cylinder #1 Timing Drive End
Firing Order 1 - 3 - 4 - 2
Displacement 1.368 Liters 83.5 Cubic Inches
Bore and Stroke 72 mm x 84 mm 2.83 in. x 3.31 in.
Maximum Power (EEC) 75 kW @ 6500 rpm 101 HP @ 6500 rpm
Maximum Torque (EEC) 133 N·m @ 4000 rpm 98 ft. lbs. @ 4000 rpm
With thanks to Chrysler LLC and Fiat SpA