• Apr 18, 2011
2011 BMW Z4 – Click above for high-res image gallery

Forced-induction, four-cylinder engines and small cars go together likes punch and pie. BMW understands this, and the automaker has officially announced that the Z4 is the first U.S. model to get its new turbocharged mill. This marks the first time in decades that BMW is bringing a four-banger to U.S. shores. Fans of the 2002, rejoice.

The BMW Z4 sDrive28i Roadster will serve up its engine bay for the new turbocharged 2.0-liter inline-four. Output is rated at 240-horsepower at 5,000 rpm and 260 pound-feet of torque, which arrives at just 1,250 rpm. Using a combination of direct-injection, BMW's Valvetronic intake management and a twin-scroll turbo allows the engine to produce V6 power with I4 efficiency. BMW expects to see a 20 percent improvement in fuel efficiency compared to the outgoing motor. The eight-speed automatic transmission will also certainly help the Z4 in the fuel economy fight.

No word yet on pricing or a date when we can see the turbocharged Z4 sitting in dealer showrooms. Click past the jump to read the full press release.

[Source: BMW]
Show full PR text
BMW 4-Cylinder Engines Return to US in 2011 in the Z4 sDrive28i

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

Woodcliff Lake, NJ – 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 high-pressure 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.

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    • 1 Second Ago
      Scott Rogers
      • 3 Years Ago
      Umm decades? I had a 318ti with a 4 in 1996. Also the full 3 series had a 318 model till at least 99. The first Z4's had 4's as well. Looking forward to the return of the 4's especially with the turbo.
        • 3 Years Ago
        @Scott Rogers
        I think you're thinking of the first Z3s having 4-cyl engines. I don't think any of the Z4s had them. Either way, it's clearly not been decades since the US saw a 4-cyl BMW.
          Scott Rogers
          • 3 Years Ago
          Yep you are right, I was thinking Z3 and typed Z4. Guess I can't fault the author too much since I made a mistake too.
      • 3 Years Ago
      this looks like a very nice addition to the engine lineup. I understand a lot of people will miss the older inline 6, but times are changing. This new turbo 4 will allow easier, broader engine modification potential to the platform that just wasnt there with the old engine. im wondering what the weight savings will be with the new motor as well.
        • 3 Years Ago
        I wouldn't assume there will be weight savings. The N52 inline 6 engine is very light for its size and it doesn't require all the additional cooling plumbing that a turbocharged engine will. I'm betting it'll be a near wash. As far as mods go, how many Z4 owners are looking to mod their cars? The Z4, with decent options, is a $50-55K cruiser. The new engine might be efficient, but this is the wrong car to introduce it to America. It should be made available in a base 3 Series first, not a $50-55K convertible.
        • 3 Years Ago
        I wouldn't assume there will be any weight savings. The N52 inline 6 is a very light engine for its size (lots of aluminum and magnesium) and it doesn't require any additional turbocharger cooling equipment. I'm betting the weight will be about the same. NVH, however, will undoubtedly suffer. There is no 4 banger available today that can match the silky smooth N52 inline 6. I can see BMW offering this engine as a new base model in the 1 or 3 Series, but I think it's a mistake to stuff it in a $50-55K (with options) luxury convertible. This is not a good way to start easing BMW customers into the 4 cylinder transition.
      • 3 Years Ago
      Decades? More like decade... The 318is was discontinued in 1998, as was the 4 cylinder Z3.
        • 3 Years Ago
        Ah! You beat me to the punch. Was just about to say the same. Except it was 1999, and it was called the 318ti. http://en.wikipedia.org/wiki/BMW_Compact#Sales
      • 3 Years Ago
      Didn't the Z3 roadster originally come with at small 4-pot pushing out ~140 ponies?
      • 3 Years Ago
      I believe the original Z3 was a 4 cyl back in 1996.
      • 3 Years Ago
      It's about time. While they're at it, how about a new version of the 2002 Tii that doesn't weigh as much as a house - which is close to what a current 1-series weighs.
      • 3 Years Ago
      The 90s-era 318ti was a 4-cylinder. Check your engine facts, guys. Better yet, I'll check them for you: http://www.motortrend.com/roadtests/112_9502_1995_bmw_318ti/specifications.html
        • 3 Years Ago
        The 90's was 2 decades ago so 'decades' ago is technically accurate. The z3 was sold into the 2000s but was introduced well back in the 90's
          • 3 Years Ago
          1999, which was that last year the 318ti was sold in the US was in fact 12 years ago, so I do believe "decades" would be inaccurate.
      • 3 Years Ago
      no mention of weight savings? WHY NOT! the straight six is no heavy weight (compared to the competition) at 3300lbs, shouldn't this provide additional weight savings? Sounds pretty sweet to me!
        • 3 Years Ago
        BMW has mentioned in other press material that this new engine weighs less than a comparable six cylinder. However, I suspect that once you add in the intercooler and other supporting hardware, the savings is not very much. Therefore, I am not too surprised they have decided not to tout this in the press release. It will indeed be interesting to see how the weight compares to the outgoing 30i model though.
      • 3 Years Ago
      V6 power, you say. *snicker*
      • 3 Years Ago
      BMW's recent naming scheme is driving me insane. sDrive28i... What does sDrive even mean other than "not xDrive"? And why, in the name of all that is logical, can't they use the actual engine displacement like the used to?? A 2.0 liter engine meant a 2.0 badge!
      • 3 Years Ago
      Seriously V6 power? Who are you people?
      • 3 Years Ago
      Decades? Hardly - More like 12 years. If memory serves, the last 4-cylinder 3-Series available in the US was the E36 318i back in 1998 or 1999... ...and the Z3 was available w/ a 4-cylinder thru the 1998 model year.
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