BMW Brings Back The 4-Cylinder With The Z4 sDrive28i

[William Maley]

BMW Brings Back The 4-Cylinder With The Z4 sDrive28i

New 2.0-liter turbocharged four-cylinder offers performance of a six

Woodcliff Lake, NJ – Embargo: April 18, 2011 1:00PM EDT… Following the announcement in February of the return of a 4-cylinder engine to the US BMW line-up, BMW today announced that the new 2.0-liter TwinPower Turbo 4-Cylinder will first power the Z4 sDrive28i that will arrive in BMW Centers this fall. Like the company’s latest TwinPower Turbo 3.0-liter turbo inline-6, the new 2.0-liter engine will combine highpressure direct-injection and BMW’s VALVETRONIC intake control (hence the name: TwinPower) with a forced induction system consisting of a single twin-scroll turbocharger. With 240 horsepower and 260 lb-ft of torque, it offers more power and torque than BMW’s normally aspirated 3.0-liter inline-6 that it replaces in the Z4 sDrive30i.

The maximum output of 240 horsepower is achieved at 5,000 rpm, 1,500 rpm lower than in the normally-aspirated 3.0-liter inline six. The peak torque of 260 lb-ft, comes on stream at just 1,250 rpm. Not only is that 30% more torque than the aforementioned inline-6, it also peaks 1,500 rpm earlier. The vigorous power comes on early and climbs steadily all the way to redline.

The 4-cylinder engine with its all-aluminum crankcase is lighter and more compact than a 6-cylinder engine of equivalent power. The turbocharger is a twin-scroll system. The exhaust streams leaving the two pairs of cylinders are kept completely separate as they flow through the exhaust manifold and the turbocharger, taking a spiral path to the turbine wheel. This configuration results in very low exhaust back pressure at low engine rpm, and allows the energy of the exhaust gas pulses to be optimally managed and translated into powerful rotation of the turbine blades, without a delay in throttle response.

The patented BMW VALVETRONIC system with seamlessly variable intake valve lift control dispenses with the throttle valve system typical of conventional engines. Instead, combustion air mass is controlled inside the engine, resulting in much faster response.

Pumping losses are kept to a minimum, making the engine more efficient. The High Precision Injection direct-injection system also helps to improve efficiency. Centrally positioned between the valves, solenoid injectors with a maximum injection pressure of 200 bar (2,900 psi) precisely control the supply of fuel. The fuel is injected very close to the spark plug, resulting in clean and homogeneous combustion.

The cooling effect of the injected fuel also allows for a higher compression ratio than might otherwise be possible. This results in further efficiency improvements. In the Z4 sDrive28i, we expect a fuel efficiency gain of approximately 20% over the naturally aspirated engine it replaces when combined with the 8 speed automatic transmission.

Detailed performance and efficiency specifications will follow at a later date, but this is clearly a new chapter in the story of BMW EfficientDynamics.

[Satty]

I love the idea of a 4cyl roadster, but the Z4 is huge.

[Robert Hall]

I love the idea of a 4cyl roadster, but the Z4 is huge.

'huge'? It may not be as small as the Miata or the old Z3, but it's still a pretty tiny car..these are the specs of the current model, I would expect the 4cyl one to be lighter and better balanced..

Wheelbase 2,496 mm (98.3 in)

Length 4,239 mm (166.9 in)

Width 1,790 mm (70.5 in)

Height 1,291 mm (50.8 in)

Curb weight 1,470 kg (3,241 lb) (sDrive30i manual)

1,500 kg (3,307 lb) (sDrive30i auto)

1,565 kg (3,450 lb) (sDrive35i manual)

1,585 kg (3,494 lb) (sDrive35i auto

[Satty]

The Miata is the perfect size, the Z4 just seems like more of a cruiser than an actual sporty car.

[Drew Dowdell]

The lightest one weighs as much as a Sonata, the heaviest one is V6 Malibu territory.

[Satty]

Also 10-12 inches longer than a Miata, depending on which generation you're talking about.

[siegen]

What I want to know is why BMW's naturally-aspirated 3.0 only generates 230 hp (and for that matter, why mine only generates 215~ or whatever).

In 2003, the Honda Accord had a 240 hp 3.0 V6. In 1989, the NSX had a 270 hp 3.0 V6. Surely, the epitome of sports cars could develop more output than that.

Edited April 19, 2011 by siegen

[Drew Dowdell]

What I want to know is why BMW's naturally-aspirated 3.0 only generates 230 hp (and for that matter, why mine only generates 215~ or whatever).

In 2003, the Honda Accord had a 240 hp 3.0 V6. In 1989, the NSX had a 270 hp 3.0 V6. Surely, the epitome of sports cars could develop more output than that.

Because they are tuned for torque and as a result are able to get good fuel economy while providing a fun drive.

[balthazar]

>>"...240 horsepower...260 lb-ft"<<

Getting closer to the '07 turbo Ecotec...

[siegen]

What I want to know is why BMW's naturally-aspirated 3.0 only generates 230 hp (and for that matter, why mine only generates 215~ or whatever).

In 2003, the Honda Accord had a 240 hp 3.0 V6. In 1989, the NSX had a 270 hp 3.0 V6. Surely, the epitome of sports cars could develop more output than that.

Because they are tuned for torque and as a result are able to get good fuel economy while providing a fun drive.

Having a torque curve that drops off early in the rev range does not equate to better FE. Variable camshafts and other mechanisms can adjust how an engine breathes, allowing it to achieve high efficiency in both low and high rpms.

In a Camry a low-rpm powerband is acceptable, since it isn't designed to be in the high rpm range and it is cheaper to forgo those breathing technologies, but for a BMW it is unacceptable!

[David]

Interesting that the driving machine of the world is cheapening up their cars. Wonder if they took a page out of Americas how to go bankrupt play book for building cheap cars.

[regfootball]

i thought BMW's calling card was the velvety inherent smoothness of their inline 6's........

what the hell, we'll just make cheap as sht fours like everyone else who buys our overpriced stuff!

[Z-06]

What I want to know is why BMW's naturally-aspirated 3.0 only generates 230 hp (and for that matter, why mine only generates 215~ or whatever).

In 2003, the Honda Accord had a 240 hp 3.0 V6. In 1989, the NSX had a 270 hp 3.0 V6. Surely, the epitome of sports cars could develop more output than that.

Because they are tuned for torque and as a result are able to get good fuel economy while providing a fun drive.

Having a torque curve that drops off early in the rev range does not equate to better FE. Variable camshafts and other mechanisms can adjust how an engine breathes, allowing it to achieve high efficiency in both low and high rpms.

In a Camry a low-rpm powerband is acceptable, since it isn't designed to be in the high rpm range and it is cheaper to forgo those breathing technologies, but for a BMW it is unacceptable!

That is half of the story. The E90 BMW 330i sedan had 260 hp prior to getting the 335i twin turbo N54. The engine was detuned to put into the 328 moniker cars. BMW went on cost saving spree using the 3 liter engine for lower siblings rather than having a smaller 6 cylinder.