About half the new cars sold in western Europe have diesel engines under their hoods. Diesels have enjoyed a decade of relentless growth and development encouraged by their less-aggressive appetite for fuel and favorable taxation. Now some European automakers are trying to convince a skeptical motoring public in the U.S. that diesels are the future. Ironically, this latest push, conducted in the name of carbon-dioxide (CO2) reduction, comes at a time when the diesel engine may have passed its peak. The technology required to meet ever-tightening emissions regulations — especially for oxides of nitrogen (NOx) and particulates — will make diesel engines so expensive that gasoline engines with new refinements will likely look more attractive. It seems the diesel revolution is ending and the gas engine is starting to fight back.
Volkswagen, a longtime leader in diesel cars, is now offering the first of a new generation of gasoline engines that could replace the diesel. The idea behind the “twincharger” TSI engine is that by outfitting an engine with a supercharger and a turbocharger — supercharger for low rpm, turbocharger for high rpm — a direct-injection, small-displacement, gas-burning engine can be made to produce the equivalent power and torque of a much larger unit but with less CO2 emissions and fuel consumption. Jan Brockman, VW’s head of powertrain development, predicts the company will be downsizing its gas engines in the near future.
The first TSI engine is now available in Europe in the Golf GT, a car that, aside from its engine, is quite similar to the GTI. (Incidentally, the Golf GT will not be coming to the U.S.) Instead of the GTI’s 200-hp, 2.0-liter direct-injection turbo four-cylinder, the GT uses a 1.4-liter direct-injection supercharged and turbocharged four-cylinder that produces 170 horsepower and 177 pound-feet of torque. Turbo lag is effectively erased by the high compression ratio of 10.0:1 and the low-end boost provided by the supercharger. Below 2400 rpm, all the boost comes from the supercharger; at 2400 rpm, both the supercharger and the turbocharger provide boost; and beyond 3500, the turbo works alone as the supercharger is disengaged by an electromagnetic clutch. The transition, controlled by the engine management computer, is seamless and undetectable.
On the road, it’s hard to believe the Golf GT is powered by a 1.4-liter. It feels like a larger 2.0-liter engine. With fuel consumption that rivals that of diesel engines, the only downsides to the TSI mill might be a slightly rough engine note and a bit more vibration than one might find in VW’s 2.0-liter engine.
Interestingly, the Golf GT is also available with a 2.0-liter turbo-diesel (TDI) that also makes 170 horses. According to European Union carbon-dioxide figures, the gas version puts out only eight-percent-more CO2.
The critical point is whether the extra cost of the TSI technology is less than the cost of the equipment that comes on the latest diesels. VW is tight-lipped about the cost of building its engines, but in Germany the Golf GT equipped with the TSI engine is roughly $3100 less than the diesel TDI version. The GT’s optional diesel engine has an expensive, highly precise fuel-injection system, four valves per cylinder, a variable intake manifold, twin balance shafts, and several pricey exhaust-treatment systems such as a particulate filter. In comparison, the gas TSI engine has a turbocharger and a supercharger, but the turbo is small and lacks variable vane technology. Also, the gas engine can meet emissions standards without the complex devices that diesel engines require.
There will be larger and smaller versions of the 1.4-liter TSI. The next will likely be a 1.6-liter engine making perhaps 190 horsepower, and a smaller 1.2-liter version with about 150 horses should follow. The 1.6-liter could replace the current 2.0-liter turbo engine, but VW’s Brockman is doubtful that a four-cylinder will ever replace a six-cylinder engine, or if a twincharger V-6 will ever replace a V-8: “America, in particular, isn’t keen to give up its V-8s.” As much as we enjoyed our first encounter with TSI, we know he’s probably right, as a premium is usually paid for a V-6 or a V-8.
Vehicle type: front-engine, front-wheel-drive, 5-passenger, 3-door coupe
Estimated base price (Germany): $22,500
Engine type: turbocharged, supercharged, and intercooled DOHC 16-valve inline-4, iron block and aluminum head, direct fuel injection
Displacement: 85 cu in, 1390cc
Power (SAE net): 170 bhp @ 6000 rpm
Transmissions: 6-speed manual, 6-speed manual with automated shifting and clutch
Wheelbase: 101.5 in
Length/width/height: 166.0/69.3/57.7 in
Curb weight: 3150 lb
Manufacturer’s performance rating:
Zero to 62 mph: 7.9 sec
Fuel economy:
European urban cycle: 29 mpg
extra-urban cycle: 46 mpg
combined: 38 mpg
Volkswagen, a longtime leader in diesel cars, is now offering the first of a new generation of gasoline engines that could replace the diesel. The idea behind the “twincharger” TSI engine is that by outfitting an engine with a supercharger and a turbocharger — supercharger for low rpm, turbocharger for high rpm — a direct-injection, small-displacement, gas-burning engine can be made to produce the equivalent power and torque of a much larger unit but with less CO2 emissions and fuel consumption. Jan Brockman, VW’s head of powertrain development, predicts the company will be downsizing its gas engines in the near future.
The first TSI engine is now available in Europe in the Golf GT, a car that, aside from its engine, is quite similar to the GTI. (Incidentally, the Golf GT will not be coming to the U.S.) Instead of the GTI’s 200-hp, 2.0-liter direct-injection turbo four-cylinder, the GT uses a 1.4-liter direct-injection supercharged and turbocharged four-cylinder that produces 170 horsepower and 177 pound-feet of torque. Turbo lag is effectively erased by the high compression ratio of 10.0:1 and the low-end boost provided by the supercharger. Below 2400 rpm, all the boost comes from the supercharger; at 2400 rpm, both the supercharger and the turbocharger provide boost; and beyond 3500, the turbo works alone as the supercharger is disengaged by an electromagnetic clutch. The transition, controlled by the engine management computer, is seamless and undetectable.
On the road, it’s hard to believe the Golf GT is powered by a 1.4-liter. It feels like a larger 2.0-liter engine. With fuel consumption that rivals that of diesel engines, the only downsides to the TSI mill might be a slightly rough engine note and a bit more vibration than one might find in VW’s 2.0-liter engine.
Interestingly, the Golf GT is also available with a 2.0-liter turbo-diesel (TDI) that also makes 170 horses. According to European Union carbon-dioxide figures, the gas version puts out only eight-percent-more CO2.
The critical point is whether the extra cost of the TSI technology is less than the cost of the equipment that comes on the latest diesels. VW is tight-lipped about the cost of building its engines, but in Germany the Golf GT equipped with the TSI engine is roughly $3100 less than the diesel TDI version. The GT’s optional diesel engine has an expensive, highly precise fuel-injection system, four valves per cylinder, a variable intake manifold, twin balance shafts, and several pricey exhaust-treatment systems such as a particulate filter. In comparison, the gas TSI engine has a turbocharger and a supercharger, but the turbo is small and lacks variable vane technology. Also, the gas engine can meet emissions standards without the complex devices that diesel engines require.
There will be larger and smaller versions of the 1.4-liter TSI. The next will likely be a 1.6-liter engine making perhaps 190 horsepower, and a smaller 1.2-liter version with about 150 horses should follow. The 1.6-liter could replace the current 2.0-liter turbo engine, but VW’s Brockman is doubtful that a four-cylinder will ever replace a six-cylinder engine, or if a twincharger V-6 will ever replace a V-8: “America, in particular, isn’t keen to give up its V-8s.” As much as we enjoyed our first encounter with TSI, we know he’s probably right, as a premium is usually paid for a V-6 or a V-8.
Vehicle type: front-engine, front-wheel-drive, 5-passenger, 3-door coupe
Estimated base price (Germany): $22,500
Engine type: turbocharged, supercharged, and intercooled DOHC 16-valve inline-4, iron block and aluminum head, direct fuel injection
Displacement: 85 cu in, 1390cc
Power (SAE net): 170 bhp @ 6000 rpm
Transmissions: 6-speed manual, 6-speed manual with automated shifting and clutch
Wheelbase: 101.5 in
Length/width/height: 166.0/69.3/57.7 in
Curb weight: 3150 lb
Manufacturer’s performance rating:
Zero to 62 mph: 7.9 sec
Fuel economy:
European urban cycle: 29 mpg
extra-urban cycle: 46 mpg
combined: 38 mpg
Source: caranddriver
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