Volkswagen of America is introducing the Group’s third-generation EA888 1.8-liter TSI four-cylinder engine in the 2014 Jetta and Passat, followed by the 2014 Beetle. The 1.8-liter unit produces 170 hp (127 kW) and 184 lb-ft (250 N·m) of torque as early as 1,500 rpm. The horsepower is the same as the outgoing 5-cylinder 2.5-liter engine, but it delivers 7 lb-ft more torque at 2,750 fewer revs (see chart at right).
Mated to an automatic or a manual transmission, the new EA888 offers up to a 17% decrease in fuel consumption while providing even better acceleration. In a presentation at Volkswagen of America’s 2014 line drive in St. Helena, California, Hubertus Lemke, Head of Technical Project Management for Volkswagen AG, described the advances in the new third-generation engines. (The 2.0-liter version of this engine has already made its debut in the 2013 Beetle and Jetta GLI, delivering a 10 hp improvement.)
|Generational progress with the EA888. Key advances for Gen 3 are in weight reduction, friction reduction, and the internal exhaust cooling system. Click to enlarge.|
Volkswagen first launched the EA888 engine generation in spring 2007 (Gen 1). In 2009, Gen 2 introduced a number of measures to optimize friction. The goals of the current Gen 3 were to:
significantly improve the engine’s already good power, torque and fuel efficiency;
reduce the weight of the unit, while maintaining at least equivalent comfort attributes; and
to conform to future emissions standards, particularly the stringent EU6 standard which will be mandatory in Europe in 2015.
|MQB and MLB|
|The 1.8-liter engine, which can be mounted either transversely or longitudinally—it is part of the MQB (transverse) as well as the MLB (longitudinal) assembly kits (earlier post)—has already been applied in the Audi A4 in Europe in a longitudinal mounting.|
|“[The EA888] is an engine family that can serve many purposes. It can be the extra thrifty one, but also be one you can use it in motorsports. It is important that it’s not two developments, but the same engine family, the same development.”|
—Christian Buhlmann, Volkswagen Product Communications
|In the A4 with a manual transmission, the 1.8 TFSI with 125 kW (170 hp) has a combined fuel consumption of 5.7l/100 km (41 mpgUS), or 134 grams CO2/km (216 g/mile). The A4 of model year 2000 with a 1.8 T engine that produced 110 kW (150 hp) of power was emitted 197 grams CO2/km (317 g/mile).|
|Improvements contributing to this better fuel economy come from many areas. However, they primarily involve engine optimizations.|
Designed to be lighter and more efficient, the new EA888 Gen 3 turbocharged and direct-injection four-cylinder powerplant features a number of refinements, including a novel cylinder-head-integrated exhaust manifold with exhaust gas cooling. This is the first implementation of such a system in a turbocharged direct-injection four-cylinder gasoline engine, noted Lemke.
While the actual fuel economy varies by model, the Jetta equipped with the 1.8T now can get up to 36 mpg (6.5 l/100 km) on the highway, up from 31 mpg (7.6 l/100 km) for the 2.5-liter engine. At the same time, the city mileage improves from 24 to 25 mpg (9.4 l/100 km), and the overall EPA estimated combined fuel economy is now 29 mpg (8.1 l/100 km) compared with 26 (9.0 l/100 km)) on the outgoing five cylinder.
As well as offering better fuel economy, the new engine’s additional low-speed torque has enhanced the performance of the cars fitted with the engine: the manual transmission Jetta 1.8T now goes from 0 to 60 mph in a manufacturer estimated 7.3 seconds, an improvement of 0.7 seconds over the 2.5-liter model.
One of the keys to this improved performance and fuel economy is the reduction of internal friction. Several innovations contributed to this reduction including; the use of a new piston coating; the two balance shafts that counteract the second-order inertial forces run in roller bearings; utilizing a low-energy oil pump; and using a highly precise electric system to control the oil-jet cooling for the piston crowns.
Like its predecessor, the engine has a cast-iron cylinder block and an aluminum-alloy cylinder head which now has the exhaust headers cast integrally. The cast-iron crankshaft runs in five main bearings. The twin overhead camshafts are chain driven, and there is variable cam phasing on the intake side.
|Weight and friction reduction in the Gen 3 EA888. Click to enlarge.|
Weight Reduction. A primary development goal of the new EA888 Gen 3 engine family was to reduce weight. Numerous improvements have contributed to a significant reduction including changing the casting process from the conventional flat pouring to upright pouring. Nominal wall thickness has been reduced from 3.5 ± 0.8 mm to 3.0 ± 0.5 mm.
Volkswagen engineers reduced the main bearing diameters of the crankshaft from 52 mm to 48 mm in order to cut friction, and reduced the number of counterweights from eight to four. Additionally, the balance shaft concept has been changed to roller bearings.
The pistons in the new EA888 feature a newly developed, strength-enhanced alloy. Piston play was enlarged to optimize friction and piston wear was adapted based on a wear-resistant piston skirt coating with nanoparticles.
Other features include a new, lighter turbocharger/cylinder head assembly; the use of lightweight polymers for the oil pan, and use of aluminum for various screws and fasteners.
The oil circulation system reduces the power consumption of the control oil pump through a number of measures, including optimized pressure losses in the pressurized oil ducts and a reduction in oil pressure level in the low pressure stage
|Intake and injection. Click to enlarge.|
Intake manifold and injection system. Volkswagen engineers further optimized the TSI combustion process in a number of aspects.
Maximum system pressure for the fuel injection system is increased from 150 to 200 bar. The fuel supply to the high-pressure injectors is provided by way of a high-pressure rail which is isolated from the intake manifold and bolted directly onto the cylinder head. For high-pressure control, the system includes a pressure sensor with an adapted pressure range.
The engineers improved robustness in terms of knocking and spark advance at mean pressures increased up to 22 bar. The new integrated exhaust manifold enables operates at λ=1 at full load across wide ranges; the team optimized combustion stability under these changed conditions.
Integrated exhaust manifold with cooling. Volkswagen integrated the exhaust manifold within the cylinder head for the first time in these turbocharged direct-injection four-cylinder gasoline engines. The exhaust manifold is water-cooled, resulting in the elimination of the use of full load enrichment—i.e., enriching the air/fuel mixture at high loads—for cooling the exhaust gas. This results in a reduction in fuel consumption of approximately 20% when driving at highway speeds, according to Volkswagen.
|Design of the integrated exhaust manifold. Click to enlarge.||Cylinder head integrated exhaust gas cooling. Click to enlarge.|
As a result, fuel consumption can be reduced both in normal customer driving and, especially, when employing a more sporty driving style.
The integrated exhaust manifold also aids rapid heat-up of the coolant and so is a key component of the thermal management system.
Achieving thermodynamically and thermomechanically optimized gas ducts and integrated exhaust manifold cooling ducts package posed a particular challenge during the development of the cylinder head, Lemke noted, especially with regard to castability. The cylinder head places extremely high demands on the casting process, uses a die with 12 sand cores in the bottom casting method.
To design the basic gas and water cores, Volkswagen used CFD (computational fluid dynamics) simulations and combined these with FEM (finite element methods) to thermomechanically optimize the cylinder head.
As there is intensive coupling between the exhaust gas and cooling water flows and heat transport in the aluminium within a very tight space involving extreme temperature gradients, for this project all three areas (gas, water, aluminium) were also calculated in a single simulation model for the first time.
Lemke said that this approach enables the more accurate simulation of the retroactive effects of the component temperatures on the fluid temperatures and the resultant heat flows.
|New turbocharger. Click to enlarge.|
Turbocharger and direct injection improvements. The turbocharger in the EA888 is an all-new Volkswagen design that develops a relatively high boost pressure of up to 19 psi (1.3 bar). Key features of the turbocharger include:
a turbine wheel made from a new alloy that can withstand exhaust temperatures of up to 1,796 °F (980 °C) ;
a pulsation damper;
the addition of an oxygen sensor mounted directly upstream of the turbine wheel;
use of a compressor wheel machined from solid; and
a new electric wastegate actuator that adjusts the boost pressure, when power is not needed, to help reduce fuel consumption.
Thermal management. Thermal management is key to helping ensure maximum efficiency. The thermostat keeps coolant temperature between 185 and 225 °F, influenced by load and engine speed, to achieve the ideal balance between minimal internal friction and temperature management. By directing exhaust gases through the water-cooled exhaust manifold, they are approximately 160 degrees cooler by the time they reach the turbocharger.
Under full load, heat is significantly reduced thanks to the integrated cylinder head and water-cooled exhaust manifold.
The 2014 Jetta. The Jetta remains Volkswagen’s best-selling car, three years after the sixth-generation car was introduced to the US market as a 2011 model. The new Gen 3 EA888 1.8L turbo, when mated to a six-speed automatic transmission delivers EPA estimated fuel economy figure of 26 mpg in the city and 36 mpg on the highway (manual transmission)—an improvement of 5 mpg on the highway over the outgoing 2.5-liter engine. The new engine runs on regular unleaded gasoline.
On the cars fitted with the available 1.8T engine, the hydraulic power-assisted rack-and-pinion steering has been replaced by an electric-assist system, in line with the TDI and GLI models.
All Jetta models are fitted with a strut-type front suspension with coil springs, telescopic dampers, and an anti-roll bar. For 2014, the torsion-beam rear suspension that was fitted to the 2.0L S, 2.5L, and TDI models has been replaced by a sophisticated multilink independent arrangement that features three transverse and one longitudinal link per wheel.
This enables the longitudinal and transverse dynamics to be precisely configured almost independently of each other. The result is more agile, responsive and precise handling. All Jetta models have an anti-roll bar as part of the rear suspension.
Although the 1.8-liter engine is the smallest displacement engine in the Jetta line-up, it is not the current entry-level model on sale; that position falls to the older 2.0S, with a starting MSRP of 16,720.
The 1.8T SE comes next, with an MSRP of $18,895, followed by three addition 1.8T models (SE with Connectivity, SE with Connectivity and Sunroof, and SEL), the last of which has a starting MSRP of $25,590.
Jetta also offers its range of diesels and the Jetta hybrid (more on this below).
Driving impressions. We drove a 1.8T SE with six-speed automatic over a short course featuring winding roads and some hill climbing. The 1.8T is incredibly responsive in the Jetta; with the high torque delivered as early as it is, there is no perceptible lag between pushing down on the accelerator and the car shooting forward.
There was plenty of power for overtaking, and accelerating on a hill climb seemed effortless.
The combination of the lighter engine and the new steering and chassis elements give the Jetta good performance and feel on the winding roads.
All that said about how much fun it is to drive the 2014 Jetta with the 1.8-liter engine, it is not the most fuel-efficient of its competitive set, although it is the most powerful.
|Comparing fuel economy (FE) for select MY 2014 models (mpgUS)|
|VW Jetta 1.8T||Chevy Cruze 1.8||Chevy Cruze 1.4T||Toyota Corolla 1.8||Toyota Corolla 1.8 Eco||Ford Focus 2.0|
|FE city (manual/auto)||26/25||25/22||28/26||28/27/29*||30||26/28|
|FE hwy (manual/auto)||36/35||36/35||42/39||37/36/38*||42||36/38|
|* Third entry is for Toyota’s CVT option.|
For Jetta buyers looking for more fuel economy, Volkswagen will steer them either to the popular TDI diesel versions, or the Jetta gasoline-electric hybrid.
The 2.0-liter turbocharged inline four-cylinder TDI Clean Diesel engine produces 140 hp (104 kW) and 236 lb-ft (320 N·m) of torque. With either the standard six-speed manual transmission or the DSG automatic, the Jetta TDI can, according to EPA estimates, average 30 mpg in the city and 42 mpg on the highway. (The diesel with the manual is also extremely fun to drive.)
Next year will see a significant update to the TDI engine comparable to the update on the gasoline side with the 1.8T EA888 unit, Volkswagen said.
2014 Jetta Hybrid. With EPA estimated fuel economy ratings of 42 mpg city, 48 mpg highway, and 45 mpg combined, the Jetta Hybrid is the most fuel-efficient vehicle in the current Volkswagen lineup. (Earlier post.)
The hybrid powertrain combines a 1.4-liter turbocharged four-cylinder gasoline engine with a 20 kW electric motor. The gasoline engine is one of Volkswagen’s latest EA211 series of small engines. This features many improvements over the previous EA111 generation, including lightweight aluminum construction; an integrated (into the head) exhaust manifold; and a toothed-belt drive for its double overhead camshaft valvetrain that incorporates variable intake timing.
The only aspect to be carried over from the EA211 was the 82 mm cylinder spacing. The cylinder bore was decreased by 2 mm (to 74.5 mm) while the stroke was increased to 80mm, a change which not only helps compactness, but also increases torque.
The 1.4-liter TSI engine in the Jetta Hybrid features a 10.5:1 compression ratio, direct fuel injection, and turbocharging to produce 150 hp (112 kW) at 5,000 rpm. This engine’s turbocharging system offers strong boost response due to the design of the intake manifold, which enables the use of a small, single-scroll compressor. The intercooler is integrated directly into the injection-molded induction pipe. This design generates maximum torque of 184 lb-ft (249 N·m) at 1,600 rpm.
The hybrid module is a single, integrated unit that incorporates both the electric motor and the clutch that connects it to the engine. This water-cooled motor can add 20 kW (27 hp) to the mix, as well as a constant 114 lb-ft (154 N·m) of torque.
Combined, the system puts out 170 hp (127 kW) at 5,000 rpm and 184 lb-ft (250 N·m) of torque at a low 1000 rpm, giving the car incredibly smooth acceleration. (The maximum torque is limited by the transmission.)
In other words, the Jetta Hybrid’s power and torque matches that of the 1.8T.
The Jetta Hybrid SE starts at $27,260—representing a 44% premium over the $18,895 starting price for the 1.8T SE. The hybrid also offers a 61.5% improvement in city fuel economy over the 1.8 and a 33% improvement in highway fuel economy.