Analysis: How the 2.0L Turbo Four May Compare To the 3.0L NA Six

Interesting | January 19th, 2011 by 13
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It was just a matter of time before BMW took the thinking that went into the N54/N55 direct injected turbocharged six cylinders and applied it …

It was just a matter of time before BMW took the thinking that went into the N54/N55 direct injected turbocharged six cylinders and applied it to the naturally aspirated N52 six. And the result is a direct injected two liter turbocharged four cylinder that will roll out in the North American market in the X1 and, before long, probably all other vehicles that use that currently the N52B30 six.

Odd thing is, if you look at the rated HP/Tq numbers for the N52 they vary by installation. The 128i/328i show max HP as 230 and torque at 200 lb ft (at 2750 RPM). The new ‘X3 xDrive 28i’ (can they make the naming
any more ridiculous?) is 240 max HP and 221 lb ft (at 2750-4000 RPM). The 528i is 240 max HP and 230 lb ft (at 2600 – 3000 rpm). So, it would appear that the engineers are optimizing torque for the platform the
engine is used in.

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BMW N52 6-cyl shown here

What we know about the turbo direct injection motors is that they start with bags of torque off idle (~ 1300 RPM) and the torque curve stays flat to at least 4000+ RPM. Stump pulling amounts of torque. The new four compares quite favorably with an NA six for power output.

For instance the Mercedes Benz C300 Sport uses a 3 liter V6 that produces 228 HP and 221 lb ft of torque from 2700 to 5000 RPM. That’s decent power. Lose a liter gain a turbo and you get slightly better HP and significantly better torque right off the line (1250 RPM) with the new BMW engine.

So it’ll be a decent substitute for the N52 from a power production standpoint. Because it’s shorter, it may also contribute to even better handling dynamics. And since it’s a turbo, there will be after market mods galore for it and within five months of it appearing in the US market some tuner will be bragging about hitting 325 HP with the thing.

Any downside? Yeah, just a bit – the N52 seems to be the swan song of the naturally aspirated inline six (even Volvo may walk away from their NA inline six if rumors are correct). And in the grand scheme of things,
while the new engine will be more powerful and more frugal, it’ll still bring a wisp of sadness when the N52 is no more . . .

13 responses to “Analysis: How the 2.0L Turbo Four May Compare To the 3.0L NA Six”

  1. Bryce says:

    As much as I’ve loved the NA engines I’ve had in BMWs over the years, I agree with BMW that it’s time to start introducing more turbocharged engines to the lineup. The fuel efficiency to power ratio of turbocharged engines make them ideal for the modern consumer.

  2. Murph says:

    Makes me want to buy something with the N52 in it – just for the sake of keeping those engines alive.

  3. Misha says:

    I love how the new 2.0L 4 cyl turbo sounds on paper. However, as an ower of 2 E90s with the N52 engine I can say it was an absolute beauty of an engine. It was silky smooth, had decent mpg, and sounded amazing paired with BMW Performance Intake and Exhaust. I really miss it. It was a little short on torque down low, but the smooth power delivery all the way to red line made up for it. I wish BMW kept the Euro version of the N52B30 (268 hp @ 6700 rpm and 240 lb·ft @ 2750 rpm ) found in the 330i in production and brought it over to the states for the 328i. Then bumped the N54 and N55 to about 320 hp. Wishful thinking on my part. Great article, Hugo. Thanks

  4. Laszlo says:

    it sound good on paper. totally different on real driving condition.

    Plus BMW had a wonderful 3.0l engine that they used for 1 or 2 years only. It made 270HP and came around 2002-2005 era. first it made 255 and then in some cases (maybe the Z3) it made 270HP.

    So the reality of making close to 300HP from a naturally aspirated engine is there.
    The Turbo engine always opens up a can of worms/problems.

    Look at the N54/55 engine high pressure pump failures. The turbo failures. The added cost/packing of inter-cooler, pipes, turbo, complex manifolds with excessive heat, etc. And on top of that the turbo lag is always present. In any turbo engines. It can be reduced liek BMW did with the twin turbo but never goes away. A NA engine will always be better to drive and will be smoother then the turbocharged. I’d rather have a supercharged engine but that seems to be fading away. MB tried it in the early 2000’s and had several of them incl AMG versions. Audi did SC a 3.0l engine instead of turbo and it works and works very good indeed. What I would love to see is a combination of super/turbo charged engines. In europe VW already experimenting with it. 1.4l 170HP engine. That has a potential to become a 1.6l 200HP engine.

  5. e30i says:

    I just hope It makes a nice throaty deep exhaust note. The exhaust note on an e46 330i is probably one of the sweetest engine noises ever

  6. Alex says:

    The reason I buy BMW’s is the inline 6 and RWD..In future I guess I can start considering other makes again!

  7. dilidolo says:

    I have 335, but I’d take NA over turbo any day.

  8. Clinton says:

    I have a 335icp and a 535xiT right now. I have driven every BMW with the twin turbo or twin scroll turbo since it came out in 07. In every vairation, including stick shift, 6 speed auto, 8 speed auto, 300hp, 320hp, or 325hp. (yes, I have some connection with BMWNA)

    The only time when you can tell there is turbo lag is if you are in the wrong gear or abrupt off the line from a stand still.

    Keep the revs up, ie spirited driving or track driving, was never an issue.

    Former owner of a 964 3.6T with a large single turbo here. Talk about turbo lag.
    These direct injection, variable everything turbos are pretty impressive. And I am all for the engines getting smaller and lighter. Cause the rest of the car ain’t.

    • Misha says:

      I recently picked up a new 135i with the single turbo twin scroll N55 engine. This is my first BMW with a turbo engine. Turbo lag is virtually indiscernible. I previously owned two 3-series sedans with the N52 engine. These new turbo engines from BMW are impressive. I’m sure the new 2.0L 4cly will be no exception.

  9. Ben says:

    Much earlier, I read the rumored engines for the next 3 series will be:

    328 (I6, 240 horses), 330 (I6, 270 horses), 335 (I6 turbo, 300 horses).

    Any thoughts of BMW continuing with at least one I6 with no turbo charges?

    Seriously, I won’t buy a car with a 4 cylinder turbo.

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