The Chrysler World Engines: 1.8, 2.0, 2.4 ... and Tiger Shark
Tiger Shark to the rescue
The “World Gas Engine” spawned a more powerful new generation, dubbed “Tigershark,” in 2.0 and 2.4 liter versions. Expected TigerShark production was set at 600,000 per year; the engine is used in Cherokee, 200, Dart, Patriot, Compass, Journey, and likely a small Jeep (and was used in Caliber and Avenger). A new generation of turbocharged engines, “Hurricane,” is due “soon.”
The VVT system on the 2.0 and 2.4 was reworked for a broader power band, with the intakes swapped and the valvetrain upgraded to roller cam followers, doing away with the buckets on the valve springs.
According to an industry analyst, the 2.4 is a surprisingly “beefy” engine, with cast steel main bearings; the three middle bearings have a bridge connecting them for added stiffness. The forged crank is unusual, and the oil pump is “massive,” partly, it seems, to get the flow and pressure needed for MultiAir actuation. The engine appears to have been redesigned either to allow for extra power, or to reduce vibration and noise.
|1.8 liter||148 @ 6,400 rpm||no engine||125 @ 4,400 rpm
124 @ 5,500 rpm
|2.0 liter||158 @ 6,400 rpm||160 @ 6,400||135-141 @ 5,200||145 @ 4,800|
|2.4||172 @ 6,000 rpm||
184 hp @ 6,250
|165 @ 5,200
||171 @ 4,800|
|2.4 SRT||285||no engine||260||no engine|
Thanks, Kerryman, for the gas mileage numbers! WGE MPG is from FWD Caliber for 1.8, 2.0; AWD Caliber for 2.4.
Refinement was a key consideration in the redesign of the engine from the original “sewing machine” World Engine to TigerShark, from its fully isolated aluminum head cover with integrated oil-separation system, to its high-pressure, die-cast aluminum block. Sandwiched between the block and the steel oil pan is a lightweight, aluminum ladder frame with integral oil filter and oil cooler adapter for extra rigidity. Acoustic material is sandwiched between the oil pan’s outer and inner stampings.
The Tigershark’s polymer-coated piston skirts and tighter piston-to-bore tolerances contribute to reduced noise and vibration. The cast-aluminum piston, combustion chamber, and ports align with the MultiAir2 system; the compression ratio is 10:1.
Each bore has squirters that spray oil on the bottom of the pistons and bore walls to maintain cylinder-wall and piston temperatures. The forged-steel crankshaft connects with new powder-forged-steel connecting rods with full floating piston pins with diamond-like carbon coating. This further reduces friction and improves fuel efficiency.
The Tigershark has a two-stage oil-pressure relief system that reduces engine-oil pumping loads at low engine speeds, while maintaining high pressures when needed. It also has:
- 360-degree engine-to-transmission attachment
- Coil-on-plug ignition with dual precious-metal spark plugs
- Front-end accessory drive with automatic tensioning single-belt drive
- No scheduled maintenance for the cam drive, cam phasing, and valve-train components
MultiAir (2.4 engines only)
MultiAir is Fiat’s variable valve timing and lift technology; it has separate timing for each cylinder. MultiAir uses electro-hydraulic valve actuators; a solenoid, energized with each rotation of the camshaft, regulates the amount of oil sent to the actuator, which controls the amount of lift, from completely closed to completely open, and the timing of the lift. A single pair of wires leads to each MultiAir actuator (the actuators and most other parts for the system are made in the United States.)
|Block w/frame||70 lb|
|Head (bare)||39 lb|
|Head (w/valves)||42 lb|
TigerShark 2.4 engines use MultiAir, which replaces the usual mechanical link between cam and valves with a column of oil; it alters lift and timing for each cylinder individually, maximizing intake manifold pressure and reducing pumping losses. MultiAir2 goes further, controlling both valve opening and closing to ensure optimal compression and efficient internal exhaust-gas recirculation (EGR) for improved fuel economy.
The World Engines
The “World Engines” (later dubbed “World Gas Engines,” of “WGE”) replaced Chrysler’s existing, 1994-debut 2.0 / 2.4 liter four cylinder engine family starting in 2006; the last of the old engines was used in the final PT Cruiser. The new WGE had dual variable valve timing and a flow-control valve intake manifold; the blocks were designed jointly by Chrysler, Mitsubishi, and Hyundai, and were used by all three, with completely different heads, fuel delivery, and other systems. Reviewers generally praised the Hyundai version, and put the Chrysler version last of the three, calling it rough, peaky, and noisy. It was, though, reportedly cheaper to build than the prior 2.0 / 2.4 liter engines.
The Chrysler engines were made in three displacements: 1.8, 2.0, and 2.4 liters. The 2.4 was rated at 172 horsepower and 165 lb-ft of torque. All had continuously variable phasing of both the intake and exhaust valves (“dual VVT”), with wedge-shaped heads. Chrysler was the first company to offer dual VVT in the United States on entry-level vehicles.
The engines were designed to be turbocharged and supercharged, with large water jackets and metal areas around each siamesed cylinder.
Noise, vibration, and harshness were addressed through an isolated valve cover and damped oil pan, a variety of select-fit parts, and the flow control valve ("variable") intake manifold. The bell housing is designed for a tighter than usual connection to the transmission, hopefully eliminating the oil leaks that often come to high-mileage engines.
The engine was built in a new joint-venture plant in Dundee, Michigan (south of Ann Arbor); blocks were made by J.L. French of Wisconsin. The older 2.4 liter engines made in Mexico continued for a Russian venture making vehicles closely based on the Sebring/Stratus (using the tooling that was retired in May 2006). Starting in 2013, production of the new TigerShark version began in the “old” Trenton Engine Plant in Michigan.
The photos with blue backgrounds (or no backgrounds) are courtesy of Chrysler; these are from the first generation.
The plastic intake manifold has equal-length runners with electrical flow control valves that, when closed, increase air tumble by blocking over half the intake port. Over 3,200 rpm, the valves are opened to allow full airflow. The valve cover is also composite (plastic) and has a variety of vibration-reducing seals.
The basic block was designed by Hyundai. Chrysler and Mitsubishi modified the design to make it more efficient and adapt it to their uses. The main reason for developing engines with competitors is that Daimler, which owned Chrysler at the time, assumed that it would also own or control Mitsubishi and Hyundai. This plan fell through, leaving Hyundai with much stronger engine capabilities than before the dalliance.
The variable valve timing used by Chrysler was developed by Mercedes and tuned at Auburn Hills. The system, used in the original 2.4 and in all the 2.0s, used oil under pressure to adjust timing using cam phasing, so that timing was continuously variable. There was little overlap at idle and more overlap at speed, to permit built-in exhaust gas reburning without a pump.
The exhaust cam could move through 35 degrees; the intake through 40 degrees. The cams rode on tappets that come in four dozen very similar thicknesses; the tappets were matched to the individual heads during assembly, eliminating the need to adjust valve lash.
The 1.8, 2.0, and 2.4 engines used the same block; displacement is changed by shortening the stroke or using thicker piston liners. The pistons had short skirts and friction-reducing graphite patches. The crankshaft was forged steel, drawing oil from the oil pan, with an integrated pump. Key components such as pistons and bearings were matched to individual engine blocks to reduce machining and noise.
GEMA President Coventry wrote, “Flexible machining centers in a hospital-clean manufacturing environment are the basis to the GEMA business model. ... .this model incorporates part recognition and automatic changeover features to allow different products to flow down the line seamlessly; even allowing for a batch size of one.”
GEMA never built engines for anyone but Chrysler, and eventually was absorbed back into the company. The million-square-foot GEMA plant cost over $700 million; each of its two plants had capacity of 420,000 units per year. One was idled, with assembly lines for making the engines placed in Trenton (Michigan) and Saltillo (Mexico) during 2013-14.
Chrysler World Engine specifications: 2.4 liter (in 2009 Chrysler Sebring trim)
|WGE (Sebring)||TigerShark (Dart, 2015 200)|
144 cu. in. (2360 cu. cm)
144 cu. in. (2360 cu. cm)
Bore x Stroke
3.46 x 3.82 (88 x 97)
3.46 x 3.82 (88 x 97)
Chain-driven DOHC, 16 valves
|Valve Timing||Cam phasing||MultiAir|
|Tappets||Shimless mechanical buckets||Rollers|
Sequential, multi-port, electronic, returnless
High-pressure die-cast aluminum block with dry iron liners, cast aluminum heads and ladder frame, forged steel crankshaft
172 bhp (129 kW) @ 6,000 rpm
184 bhp (138 kW) @ 6,250
165 lb.-ft. @ 4,400 rpm
171 lb.-ft. (200 N•m) @ 4,800
5.0 qt. (4.7L) SAE 5W-20
7.2 qt. (6.8L)
Assumed: 7.2 qt. (6.8L)