Exclusive: The NEW ///M Motor in Depth

May 1 • //M, //X5 M, //X6 M, EfficientDynamics, Official News, Technology21 Comments

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While most enthusiasts have cried out in anger with the recent news that the ///M division has gone the forced induction road; the news may not be all that bad. The BMW ///M motors of the past have always been fairly low in displacement, peaky in horsepower and torque, but loving to rev to sky high red lines. The newest rendition from the ///M camp is a bit different from those engines; it was intentionally designed to be different and change the playing field. It is capable of producing more torque and more horsepower with less displacement and greater efficiency than the motors of the past.

The recently announced X5 & X6 ///M models have been chosen to usher in this new era of high performance BMW engines. With virtually the same block as the revolutionary N63 4.4l reverse flow V8 as in the 750i and X6 xDrive50i, this ///M motor features significant revisions in nearly every other aspect.The internal components have been upgraded along with the newly engineered cylinder heads (diesel standards for strength) to deal with the high compression ratio and increased forced induction. The dual twin scroll turbos put out an astonishing 21 lbs of max boost. Two high-capacity water-to-air intercoolers help cool the incoming combustion air before it is shot with precise amounts of fuel by another ///M first: Direct Injection. BMW has not offered Direct Injection on any naturally aspirated (non-turbo) motor in the US due to the sulfur content of US fuel and they do not plan on offering it on them in the future (as we have been told). So all of you on the fence about buying an ///M3 and fearing direct injection will be offered, can rest a little easier.

Turbo charging has come a long way in the past few years as many a BMW 335 (N54 I6 twin turbo) owner will tell you, but another significant improvement will debut on this motor. The Cylinder-bank Comprehensive Manifold (CCM) is a BMW patented exhaust manifold that separates this motor (and future variants) from the competition. The CCM solves the problem of an irregular schedule of exhaust gas pulses on the turbines. An irregular schedule of pulses causes lag and back pressure in typical turbo charging applications.

The CCM creates an exhaust gas pulse at every 90 degrees of crank rotation on one of the turbo scrolls, keeping the supply of exhaust gas regular and consistent. How this achieved is visible in our exclusive diagrams of the inner working of the CCM and twin scroll turbos from BMW ///M.

Complimentary cylinders are paired through the manifold ‘s pipes, which have been tuned for diameter and length, 1 + 6, 2 + 8, 3 + 5,and 4 + 7.

These pipes (each highlighted by a certain color in the diagrams) combine to feed one of 4 exhaust gas intakes on the 2 twin scroll turbos.

With the twin scroll setup there are two separate paths to each turbo, with each targeting its own set of vanes. The use of twin scroll chargers allows for the maximum capture of exhaust gas flow currently possible, thus increasing the turbos overall efficiency while keeping it spooled up. The concept of the CCM would be extremely cumbersome and inefficient without the development of the reverse flow V8, the development of one allowed for the other.

This complex network of pipes and turbos is entirely contained within the “V ” of the engine, allowing for an engine with relatively small dimensions. Some of you are probably thinking that all of that exhaust piping and turbos within such a close proximity to engine block can not be good on a thermal level;BMW has designed the engine with that in mind and there are auxiliary cooling systems in place if the need should arise for them.It is not a general concern.

What all of this plumbing and forced induction produces is 555 hp at 6,000 rpm and 500 lb-ft of torque from 1500 to 5,650 rpm with reportedly no perceivable lag. The onboard engine control unit software has been programmed/tuned for this application in the SAVs and the specific driving needs of them, as is evidenced by the huge flat spot in the torque curve. It can be adjusted/tuned as is necessary in future applications and variations. What that means to us enthusiasts is that this engine is highly flexible and we may not yet be seeing its true capabilities. The true redline (not software induced) of this motor setup has yet to be disclosed by ///M at this time. With this motor as the basis of other future high performance ///M offerings we are fairly sure that there is some excess capacity to increase the performance on other models…

We have been told that many of the features of this motor will trickle down across the model line. We can expect to see the use of twin scroll turbos and future applications of a form of CCM in other models sooner than one would think. The current 1.6l John Cooper Works MINI (and MCS) engine is the only other BMW Group gasoline product currently using twin scroll turbos; a shift from variable vane is coming.With all of this turbo jargon we will be creating a guide to the terms and compare and contrast them as soon as we can!

While this engine is not a typical high-rev ///M offering, the shift to turbo charging was needed to increase efficiency and performance.On paper, it looks like a success and we will give you our final verdict once we can log some miles with it!

As always we would love to hear your opinion; feel free to comment on this motor and BMW heading down the road of high performance forced induction as a whole!

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  • krash

    wow, awesome article, thx for the info!

  • http://www.bridger.us/ Gabe

    I’ll admit I’m one of those people that has a strong distaste for this new era of forced induction //M powerplants. However this article goes a long way in presenting a valid case for them.

    That said I can’t help but think the gorgeous white E60 M5 I heard this morning roar past me with it’s complex and high revving V10 will be something to be treasured in the years ahead.

  • mellowmcs

    one small correction on the article. the standard mini cooper S also uses twin scroll turbocharger.

  • JonPD

    Great article.

    I shed a single tear the day M went to forced induction. While I understand why they choose this path I am not a fan of turbochargers (despite their advantages). The best sound ever by BMW was the high revving powerplants that have come out of the M Division for many years something that I feel quickly marching away.

    I know M will continue to make desirable cars in the future but have to say I think the best audio performance in its history will be in its past.

  • http://bimmerfile.com Michael

    Gabe-

    I love the sound of the larger NA ///M motors. In fact that beautiful sound is part of the reason I have an ///M3. The sound is “love” to my ears, it is intoxicating. It wails like an F1 car with less refinement- the perception of sound is one of the most individual characteristics we as humans have and is one of the most difficult to describe- the V8 in the ///M3 is just in its own class.

    What will be interesting is to hear what these turbos sound like, did the miracle workers in Munich tune it to sound NA or was that too hard of a task, or is it so throaty and deep that the love affair we have with the current motors will be gone and in turn create more of a desire for the current NA motors in the future. Part of my original reasoning getting the ///M3 was because I knew the end was coming for NA motors.

  • JonPD

    You choose very well indeed Michael, that monster V8 makes me smile every time I see one go rumbling by, still waiting on hearing a stock M some day on the track where that beast can be unleashed.

  • http:ww.mvmclub.org Tim

    Regardless of your like or dislike for the lack of NA ///M Motors these days. You have to admit that they certainly do some mind bending with these amazing designs… the sheer brilliance of the engineering is staggering to me. Or the sheer standard operating procedure for the Germans for that matter… Who else would bring this kind of perfection to us?

  • http://bimmerfile.com Michael

    Tim- I could not agree more! The engineering in these things is mind blowing and in turn may alleviate many concerns of turbo charging. Having had a good deal of turbo experience I look forward to seeing what ///M really has done. Granted I will miss the sound of a NA V8!

  • Barry

    Wow, what a great write-up! I loved the pictures and detailed diagram as well.

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  • chaz

    21 ft/lbs of max boost??? Pounds per square inch maybe?

    (Was a typo-fixed!)

    I understand the drive to move to turbos, but I like cars that have the power (and sound) build like the NA cars do. I also have felt that if you drive turbos hard, as you would an ///M car, you are generating large amounts of heat and just shortening the life (as my $5,000 bill to replace a twin turbo setup showed me).

    Can’t wait until the ///M division comes out with an M turbo diesel SUV! (ouch, did I say that)?

  • T Bone

    Michael,

    Excellent write-up, thank you. I am one of multi-generational ///M car owners that is less than pleased with the need to go to forced induction but with the emissions rules, I understand the necessary trade off for more power.

    Clearly BMW set a new bar with turbo engines with the N54 (I have a 335xi in addition to my M6) but the lag is definitely perceptible.

    If the new M5 / M6 is based on this V8, I am hoping it could rev to 8000 rpm with peak torque in to 6000-8000 rpm range with about 650 hp (this is where the motor works during max acceleration). Hopefully, the drivetrain will also features KERS.

    One other concern I have is the weight of the drivetrain that a big torque motor would necessitate. You may recall the various BMW marketing materials that claim there is a great weight savings with the lower torque, high rpm concept.

    Keep up the great writing.

    T Bone

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  • Bimmernet

    I too have owned more than one generation of M-Engine and I know it’s likely going to get me roundly booed but my favorite M motor was the 3.2 in my ’98 M3. It’s meaty torque and flexible power available at any engine speed off idle is I believe closer to the new Turbo motors than the high RPM E60/92 motors.

    While I love the current crop (I am the acknowledged “M-Specialist” at the BMW Center where I sell) I am very interested in getting a chance to drive the new M Turbos. If they are an extension of the ones in the new 2009 750Li then it will be a bloody great drive.

    With the government mandated emission and fuel economy standards we’re lucky to be looking forward to anything as powerful and responsive as those M Turbos being planned for introduction in the not too distant future.

    Bimmernet

  • http://bimmerfile.com Gary O

    Excellent article, excellent graphics. As an owner of two M3 (e36 and e46) I welcome the advent of turbo motors to the M line. Part of my interest is the fact that I live at over 5000 ft and the power loss is significant in NA engines. Yes, we are talking losses of over 20% on most days! So anything that helps recover some of that lost power is well recieved by me and the M enthusists that live in Colorado. This all too real, where newer 335 and 135 models are walking the older e46 M3′s at the track. A sad but very true fact. Yes, I love the “rasp” and I’ll always love my s54 engine (the most powerful NA six ever produced). But that will all be soon forgotten once I have a chance to sample one of these new engines at altitude. My hats are off to the BMW M division. Keep up the excellent work!

  • Scott

    As an owner of an 07 335i Manual Transmission I must say the N54 Engine is absolutely fabulous. A two time international Engine winner, with nearly no turbo lag what’s so ever. I added the Juice Box 3 to my car a few months ago that adds ~80 hp and ~80 additional ft lb torque all for under $500. I also have an 05 Subaru WRX STi that I have had since new. Again for a few dollars these turbo engines can be additionally tuned to unreal levels.

    I looked long and hard at the new M3 when it first came out. Right off the bat I was totally disappointed by the lack of Direct Fuel Injection. At the end of the day less than 20 mpg on the freeway compared to the real world 30 mpg of my 335i, yet performance wise my 335i will just make a stock M3 cry in a straight line race. The M3 leaves very little left for performance gains, and should you try expect to pay several thousands for very little gained.

    While spinning a V8 to 8300 RPM’s is pretty cool its just not very practical. The 7000 RPM red line in my 335i still sounds great, and the heritage sound of my BMW straight 6 is totally BMW. Why not have 500 ft lb tire shredding performance from 1500 RPM up rather than 297 from ~4000 on. The new M3 engine builds power very smoothly but never really feels all that strong, where my 335i feels like it will through you in the back seat from almost any gear from 1500 RPM to red line.

    I can’t wait for the new M3 Turbo. I will be saving my money starting today

  • Surya

    I have the newest ///M3 in my garage right now. I love it to bits. Its not straight line performance that I care about. I have an MV Agusta F4 Senna 1000R for that if I ever needed to feel just outright acceleration and blast past nearly everything except for a Veyron. What I love about the ///M is the hunkered down look, the awesome leather/carbon interior, the quiet menace the car exudes and lets not mention the noise that thing makes when you step on the gas! Not to mention the way it handles in M mode. Its like driving Muhammad Ali! The car destroys corners with aplomb! I agree that you cannot exact more power out of it without resorting to spend thousands of dollars but I dont care. The high revving V8 is only one small part of the equation. The ///M3 is the sum of its overall package always! I for one will lament the loss of the NA engines. Will the next versions of the ///M models be epic? Hell yes this is BMW we are talking about! Will I keep this ///M3 forever? Hell yes!

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  • identiti_crisis

    Back in the sixties it was common to see the exhaust manifold nestled in the vee like that in F1 etc., precisely so that cylinders from opposite banks could be paired if necessary for optimal scavenging. It’s quite a sight to behold, particularly on the Ferrari V12s of the time.

    Given this setup tended to cause the exhaust valves to overheat, the intake was moved back into the vee instead. The cross-plane V8 engines had to make do with a x- / y- / balance-pipe to approach the benefits of proper 180-degree (or “bundle of snakes”) headers, as fitted to the GT40 and other cross-plane V8s of the time, which have their own problems with heat.

    In this example, each turbo receives a pulse every 180 degrees overall (like each collector in 180 degree headers), and each scroll receives a pulse every 360 degrees, not 90 degrees as stated in the article. 720 / 8 = 90; so each successive cylinder is 90 degrees away. If each scroll got a pulse separated by 90 degrees, it would have to wait 630 degrees for the next one – precisely what is being avoided by using this pairing method! This 180° spacing is identical to a single twin-scroll turbo setup on the Subaru rally cars, where their road-car equivalents have themselves had uneven pulses historically. I wouldn’t be at all surprised if BMW took their inspiration from motorsport. I can’t quite get over the sound of this engine, though.

  • http://pulse.yahoo.com/_CMU6FPGJG2CN6ZJXQ63N6VV6BM BavarianMotorsportClub.org

    Interesting

  • http://pulse.yahoo.com/_CMU6FPGJG2CN6ZJXQ63N6VV6BM BavarianMotorsportClub.org

    Interesting

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