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BMW Z4 Roadster
First turbo four model will arrive this fall

Earlier this year, we reported that BMW's normally aspirated inline-6 engines will be ushered out and replaced by a new family of turbocharged four-cylinder engines. BMW today confirmed that four-cylinder power would return to U.S.-bound BMWs after a 10+ year absence. 

The first model to get BMW's new 2.0-liter TwinPower Turbo four-cylinder engine will be the Z4 sDrive28i Roadster (say that five times fast). The engine develops 240 hp and 260 lb-ft of torque (30 percent more torque at 1,500 fewer RPMs than the naturally aspirated 3.0-liter inline-6).

BMW says that the new turbo four will be 20 percent more fuel efficient than the inline-6 when paired with the 8-speed automatic transmission. We're sure that there are fuel efficiency gains to be made with the 6-speed manual transmission as well, but it's likely nowhere near 20 percent (or else BMW would have mentioned it in the press release).

The Z4 sDrive28i Roadster will arrive in showrooms this fall, and the turbo four will likely filter down to other BMW models soon after.





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Awesome Powerplant
By Stuka on 4/18/2011 4:04:37 PM , Rating: 3
quote:
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.

I love the current Audi/VW 2.0T, with it's low torque peak and great power buildup, but this motor looks to be an order of magnitude better. Kudos to BMW for continuing their superb engine heritage. I hope you can still cruise off-boost though, as that to me is the key reason for turbo power over normal aspiration.




RE: Awesome Powerplant
By Stuka on 4/18/2011 4:08:01 PM , Rating: 2
quote:
I hope you can still cruise off-boost though, as that to me is the key reason for turbo power over normal aspiration.

That is to say, that fuel mileage off-boost is favorable compared to cruising with an N/A engine with similar power output.


RE: Awesome Powerplant
By tdktank59 on 4/18/2011 4:16:29 PM , Rating: 2
all you have to do is keep your foot out of it and boost will not be produced, the turbo is always spinning as long as the car is on, just at some point it spools faster and starts generating boost. that point changes tho based on the engine and other characteristics.

For example my SR20DET w/ GTiR T28 turbo spools at ~3100rpm
I can get a turbo that drops that down to ~2800 or get a bigger one that pops it up to 4500 so it all depends on the application and setup.

Just because im sitting at 4000rpm doesn't mean im producing boost, I need to put my foot down quite a bit to start generating boost, and I can keep it out of boost if I want to but it feels like im driving like a granny.

Im going to guess that for the roadster they will pick the right turbo to generate good gas millage while at the same time produce power in the upper part of the rpm band. It is a average joe car after all :p


RE: Awesome Powerplant
By Flunk on 4/18/2011 4:48:33 PM , Rating: 4
Average joes can't afford BMWs, this is a richman's car.


RE: Awesome Powerplant
By tdktank59 on 4/18/2011 6:14:51 PM , Rating: 2
True

What i ment to say was its not being sold as a race car, rather just a sporty roadster.


RE: Awesome Powerplant
By Spuke on 4/18/2011 8:15:59 PM , Rating: 3
quote:
Average joes can't afford BMWs, this is a richman's car.
It's not necessarily a rich man's car. I'm not anywhere near rich but can afford one of these. Besides, a lot of average Joe's lease them and with BMW's free maintenance, they're not expensive to own. Now after the warranty is up....

About the new turbo 4, the current sDrive30i gets 18/28 on both transmissions. Should translate to ~22/34 for the auto.


RE: Awesome Powerplant
By dubldwn on 4/18/2011 5:19:18 PM , Rating: 2
quote:
this motor looks to be an order of magnitude better.

What makes you say that? Audi's 2.0T does 211HP @ 4300 and 258lb-ft @ 1500. I haven't seen the graph for this new engine, though. Maybe it has much better torque curve at higher revs?


RE: Awesome Powerplant
By 91TTZ on 4/18/2011 5:41:39 PM , Rating: 2
It sounds like it's just a higher revving engine than the one you mentioned, which is really a low revving engine.


RE: Awesome Powerplant
By shiftypy on 4/19/2011 3:57:25 AM , Rating: 2
I hope you can still cruise off-boost though, as that to me is the key reason for turbo power over normal aspiration.

GTDI gasoline direct injection turbocharged...

Screams for stratified charge lean-burn cruise for me.
Only one small step needed in NOx trap and we are good to go


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