• BMW twin turbo V8 analysis - Power potential, tuning, performance, and architecture of the N63 and S63 motors

      The future of BMW tuning is going to be based around turbo motors. The decision was made, so time to get comfortable with it. Two motors that will be at the heart of BMW tuning for some time to come will be the N63 4.4 liter V8 and the S63 which is the M version based on it. These motors will be powering the vast majority of M cars as well as the higher end BMW's for some time to come. With the F10 M5 set to hit interest in tuning this powerplant will only grow.


      What are they?

      The BMW N63 and S63 are both twin turbo and direct injected V8's. They are different from traditional turbo V8's in the sense that the intake and exhaust systems are reversed. By designing the intake and exhaust this way BMW is able to put the turbos in the V, or valley, of the motor on top instead of the traditional location which would have turbos at the bottom off the exhaust manifold. The advantage is that the exhaust gas leaves the head traveling a very short distance to reach the turbo. BMW engineers have often prided themselves on the response of their motors and with this type of design even when going to turbo motors they are able to provide very little lag and strong response from low RPM. Not to mention, top mount turbos are just flat out cool.

      How are they different?

      The S63 is based on the N63 but there are some very significant differences between the two motors. The main difference being that the S63 uses a pulse tuned, cross engine exhaust manifold. That sounds cool, but what does it mean? It means that each turbo gets its exhaust flow from 4 exhaust pulses but also from opposite cylinder banks. This exhaust gas is fed into twin-scroll turbos which means there are two passages for the exhaust gases in the turbos. The N63 on the other hand uses single scroll turbos which means one passage for the exhaust gases. It is this pulse tuned exhaust manifold as well as the twin-scroll turbos that is major difference in the architecture of the S63 vs. the N63.




      BMW released the graphics above to illustrate what is taking place. By using this manifold with the twin scroll setup BMW is able to keep constant exhaust pulses flowing to the turbos at every 180 degree rotation. The N63 on the hand will have uneven exhaust pulses as it is fed by only one bank of cylinders instead of a cross-engine setup. This is a significant difference that shows BMW innovation in turbo development.

      Any other differences?

      Yes. The exhaust camshafts on the S63 are different, designed for higher lift. The S63 has a different cooling system using a belt-driven mechanical pump. An additional oil cooler is used in it that is mounted below the radiator as well as a larger engine oil cooler. The water to air intercoolers on the S63 are larger than those on the N63. The transmission fluid cooler used is also larger. The turbo bearings receive a separate cooling circuit on the S63. The intake setup is slightly different as well but this is more to meet pedestrian crash regulations than a design difference for performance.

      The redline on the two motors is slightly different with the N63 set at 6500 whereas the S63 revs to 6800 rpm. In the upcoming F10 M5, it is likely the cam profiles in the S63 will be slightly different from the X5 and X6 M as the photos of the tachometer have shown a redline in the low 7000 range. The final major difference is that the compression ratios between the two are not the same also leading to speculation that the the S63 pistons may be stronger. The N63 compression is at 10.0:1 while the S63 is at 9.3:1. Why the compression difference? The S63 runs more boost with 17.4 psi peak vs. the N63 hitting 11.6 psi of maximum boost pressure. Other than these differences, the motors are the same with identical bore/stroke, valve sizes, and engine blocks.




      Can I just add the S63 turbos, manifold, and other parts to my N63?

      Maybe. Wish I had a better answer but that is where we are currently at with these platforms. Sure, you can order the parts as they are available from dealers but it is not quite so simple as just bolting them on. Yes, physically, you will have no issues matching them up. The problem would be the tuning. I can tell you there currently are tuners trying to do exactly this. Have they been successful? Well, the jury is still out on that as the hurdle seems to be the tuning. What is more likely is that upgrades that are currently in the works will apply to both the S63 and the N63. Since these upgrades will be more efficient than the factory parts anyway it will make the most sense to simply skip trying to mimic an S63 and go big. One of the reasons these motors will be so much fun to tune and will get so much attention is that with having the same basic architecture most if not all of the hardware will apply. The wildcard as always is the tuning but we expect that to be figured out especially with how much competition there will be in this sector.

      What is the power difference between the two?

      Well, in stock form the N63 is rated at 400 horsepower and the S63 is rated at 555 horsepower. The reality of it is that the motors are fairly close to one another in stock form, at least closer than the crank ratings from BMW would have you believe. The N63's higher compression likely plays a role in that allowing more horsepower per psi. Below you will see a dyno of a stock X6 M vs. a stock X6 50i. The cars actually belong to the same owner and the fuel is 91 octane and as luck would have it are from the same gas station. You will notice the peak horsepower difference is only 60 all wheel hp and the torque difference is just under 30 pound feet. The torque curves from 2750 to about 5000 rpm mirror each other pretty closely.

      What happens at 5000 rpm though is the N63 falls off a cliff. The S63 does not look pretty either but the turbos show greater sustainability up top not only due to their size but also due to being fed with more exhaust pulses. Look at the large area under the curve from about 5000 to 6500 rpm for the S63. The N63 really stands to benefit up top from some larger turbos and that higher lift exhaust cam. To be perfectly honest, compared to the table top flat torque curves across the range of BMW naturally aspirated jewels like the S65 or S85, these curves look embarassing for a company like BMW that set such a high standard previously. Are turbos letting them be lazy? Clearly, these are all about the down low torque and not the top end although the S63 is able to shift its peak power to the right considerably compared to the N63. We have heard some preliminary details on the S63 in the M5 and it should have a powerband slightly more conducive to the top end we have grown accustomed to in M5's previously although it will not be anything like an S85.


      What is the power potential?

      The majority of tuning that will take place for these motors will be bolt on's and basic tuning. This means exhaust and ecu modifications for the most part. The N63 has more room to gain from stock vs. the S63 since it is not in as high of a state of tune also running less boost. Dinan is a notoriously conservative (for street applications) but solid tuner and their gains illustrate this point well. For the N63 Dinan gains about 100 horsepower and 100 pound-feet of torque from the base. On the S63 the gain is only 56 horsepower and 74 pound-feet of torque. This makes sense as boost can not be raised as much with the S63.

      Here is an X6 M graph of a before and after tune by OE Tuning. You will see the gains primarily come under the curve down low and the peak HP is not affected all that much. That does not mean the car will not be much faster, area gained is huge but up top at peak there is not as much room to gain as there is with the N63.


      What about upgraded turbos?

      Yes, oh yes, these will come. Some claim to already have them but we remain skeptical. A tuner named ALSA for example claimed to have upgraded turbos capable of over 700 horsepower for the X6 M. We asked for a dyno graph to substantiate this but never received it. More than one tuner claims such a package but there have not been any real world details to substantiate the claims.

      So nobody has done upgraded turbos?

      No, Alpina has. The Alpina B7 uses larger turbos on the N63 so clearly it can be done. The thing is, Alpina doing upgraded turbos on an N63 is almost like BMW doing it themselves. The relationship between the two is so close that Alpina can get whatever software support it needs to make the hardware work. This type of work trickles down to other tuners over time but that is the thing, it takes time. So do we believe anyone has a working turbo upgrade package out there yet? Other than Alpina, no, but they will come.

      How much power will these motors hit?

      I wrote an article in January of last year where I said 700 horsepower will be common place. It will be, as 700 horsepower will not be a number that opens too many eyes on this motor after a while when tuners start hitting it routinely. Even early last year tuners such as Noelle were claiming 650 horsepower out of the N63, let alone the S63. ALSA already is claiming over 700. On the stock internals and fuel system, this is going to be about the limit for the S63. The N63 internals may be hindered slightly by the compression but with big enough turbos even it should approach the 700 mark on the stock internals. There have been no complaints about the fuel system not having enough headroom for this level.


      These motors are going to hit big numbers fairly quickly as that is the advantage of having a forced induction motor from the factory. With the S63 being in four M vehicles (X5M, X6M, M5, and M6) at no other time has an M motor been in so many different models at once. Not to mention the number of N63's out there which will benefit from development of the S63. With the proclivity of M owners to seek higher and higher performance and the ease at which forced induction motors are tuned, the tuner competition is going to be intense. Wise tuners would already be working on their offering as hitting quickly to gain control will be vital.

      The N63 will be capable of hitting anything the S63 can. With the stock hardware the N63 will not be able to go as far, similar to the difference between a 996 K16 turbo and an X50 K24 996 turbo, but with built internals and larger turbos they both will be able to hit the same eventual peak. One does not have to buy an M motor any longer to be able to have the same type of headroom as an M motor. There is something about that which is bittersweet but it opens BMW tuning to a greater range of people while keeping BMW's own costs down. Not to mention the fuel efficiency gains but we could also argue 555 horsepower 5300 pound SUV's and efficiency are oxymorons.

      Any downsides?

      Well, not from BMW's perspective. They can take a motor and give it bigger turbos while changing the tuning and call it an M motor. Lowers costs, improves fuel economy, the marketing and accounting departments are happy. For some cars they don't even have to bother with doing anything other than minor software changes (1M coupe). We feel these motors no longer show off the M engineers skill in the same way. They allow them to be lazier as they no longer need to strive for squeezing out every last NA horse. It also allows them to muscle out parts of the tuning market by offering their own software upgrades providing a secondary cash grab. This might force out some of the weaker tuning houses as you all know how BMW owners are weenies when it comes to preserving their warranty. More power and a warranty? For the more restrained/timid crowd it will be an easy choice.

      There still is great innovation as the top mount turbos in the V show but the motors are not quite as impressive of an engineering feat or as unique as the naturally aspirated M motors were. These also have a completely different character with a curve that is very unlike what we have grown to expect out of M. Then again, these motors need a ton of torque to move heavy 5300 pound SUV's quickly. Tuning will be different than what we are used to such as trying to add aftermarket forced induction but it looks like there will be more of it and faster. So, there are only downsides depending on your perspective. Many welcome increased torque and easier tuning along with MPG gains, I just wish BMW still gave the customer the choice.
      This article was originally published in forum thread: BMW twin turbo V8 analysis - Power potential, tuning, performance, and architecture of the N63 and S63 motors started by Sticky View original post
      Comments 94 Comments
      1. oddjob2021's Avatar
        oddjob2021 -
        yes it was mentioned but twin scroll doesnt mean spin opposite, it usually just means that it takes the exhaust pulses in a divided flange. the s63 turbos do spin opposite for whatever reason, i just hope bmw didnt make it that way to limit aftermarket options.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by oddjob2021 Click here to enlarge
        yes it was mentioned but twin scroll doesnt mean spin opposite, it usually just means that it takes the exhaust pulses in a divided flange. the s63 turbos do spin opposite for whatever reason, i just hope bmw didnt make it that way to limit aftermarket options.
        I see, so what is the reason though?

        The N63 may be able to accommodate the turbos as long as it uses the S63 twin-scroll manifold.
      1. oddjob2021's Avatar
        oddjob2021 -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        I see, so what is the reason though?

        The N63 may be able to accommodate the turbos as long as it uses the S63 twin-scroll manifold.
        the reason? im not sure really. imho its BMW trying to prevent aftermarket tuning and performance options. they want to limit warranty work that is unwarranted Click here to enlarge in the case of the modder who goes back to stock for dealer help.

        the n63 will never be able to take the s63 turbos unfortunately, no engine can, unless it has the dme from it too. what i meant by the turbos spin backwards is the blades of both wheels are machined so that the wheel and shaft spin opposite (in the turbo world). which ever way the blades are facing is the way the air pushes and moves them. in the case of the s63 they engineered it to push the opposite way...

        i dont mind that you dont edit the OP, its just going to be bad when some unlucky person doesnt read this whole thread and tries to swap his n63 turbos with the s63 or whatever, its going to be more of a headache than just tuning i assure you.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by oddjob2021 Click here to enlarge
        the n63 will never be able to take the s63 turbos unfortunately, no engine can, unless it has the dme from it too. what i meant by the turbos spin backwards is the blades of both wheels are machined so that the wheel and shaft spin opposite (in the turbo world). which ever way the blades are facing is the way the air pushes and moves them. in the case of the s63 they engineered it to push the opposite way...
        It is highly unlikely the S63 turbos will work as you stated but they can just be skipped then. Also, if someone does figure out the DME then they can be used.

        Click here to enlarge Originally Posted by oddjob2021 Click here to enlarge
        i dont mind that you dont edit the OP, its just going to be bad when some unlucky person doesnt read this whole thread and tries to swap his n63 turbos with the s63 or whatever, its going to be more of a headache than just tuning i assure you.
        Well I hope they read the post and clearly see nobody is saying the S63 turbos can be used on the N63. We stated maybe that will be possible eventually but as of right now it isn't.
      1. oddjob2021's Avatar
        oddjob2021 -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        It is highly unlikely the S63 turbos will work as you stated but they can just be skipped then. Also, if someone does figure out the DME then they can be used.
        im just curious why you say it is highly unlikely. do the research yourself, call BMWNA or e-Mail, whatever method you choose. the blades are opposite i can bet money on that. but you're right, if somehow the dme can be transferred it may work, but when's the last time you heard of a dme swap on a modern production car?
      1. Jimefam's Avatar
        Jimefam -
        Don't worry about it sticky his reliable source is Asr who has upgraded N63 turbos in the works. I talked to them awhile back as I grew up on 152nd st and 137th ave right by where they're at and they thought I'd be stumped by the reverse flow also but I'd already heard that so we discussed alternatives and agreed that if you were willing to redo alot of the IC piping it could be made to work but more trouble than it's worth.
      1. Jimefam's Avatar
        Jimefam -
        Click here to enlarge Originally Posted by oddjob2021 Click here to enlarge
        im just curious why you say it is highly unlikely. do the research yourself, call BMWNA or e-Mail, whatever method you choose. the blades are opposite i can bet money on that. but you're right, if somehow the dme can be transferred it may work, but when's the last time you heard of a dme swap on a modern production car?
        Look up UGR and MOTEC if you've got the cash and are determined to make it happen anything is easy it's just not necessary for this application.
      1. oddjob2021's Avatar
        oddjob2021 -
        jimefan, you're right, everything you posted is true, are you still local, or in miami? i'd like to meet up if you're interested, would like a member on here to experience my car who is not a friend of mine already.

        just curious why you didnt chime in sooner to help my cause of correcting misinformation Click here to enlarge
      1. Jimefam's Avatar
        Jimefam -
        Nah I live in Atlanta now but my businesses warehouse is on 163rd and 137th so I go often. I didn't correct it because it's not misinformation, it CAN work and if I was impatient I would just buy the manifold and turbos from an S63 and I could have it working in a month for probably 6k BUT the S63 turbos ain't all that to begin with and if I'm gonna spend the $$ I'm gonna go big. If someone wants to see it though send me the 6k and by the end of august I'll have the turbos working I bet lol
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by oddjob2021 Click here to enlarge
        im just curious why you say it is highly unlikely. do the research yourself, call BMWNA or e-Mail, whatever method you choose. the blades are opposite i can bet money on that. but you're right, if somehow the dme can be transferred it may work, but when's the last time you heard of a dme swap on a modern production car?
        It's highly unlikely that anyone adapts the S63 DME or figures out the N63 DME enough to do it anytime soon but the door is open for someone to try.
      1. oddjob2021's Avatar
        oddjob2021 -
        sticky you replied to me saying 'it is highly unlikely that they work they way i said they do'. i am and was right, they do spin backward, this is because of the way the blades were angled in the engineering. the dme is one thing, and sure that may be unlikely to adapt, as i initially said anyway. and jimefan is right, the s63 turbos aren't that amazing anyway, spinning normally or not, so for someone to go through the trouble of putting s63 turbos on a n63, if ever, will be wasting money, that money could have been spent trying to find precision or garrett turbos that work and going that route. im not looking for credit or anything about letting this information out or anything if thats what you think, i want to help the community is all, and in this case, explaining that the s63 turbos are way different, down to the direction of rotation! and wont swap to any platform without a heavy wallet.

        edit: im also saying that in order to upgrade the turbos on the s63, you need a turbo company to engineer the blades the same way, which is big money if not mass production, if you are using the stock dme.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by oddjob2021 Click here to enlarge
        sticky you replied to me saying 'it is highly unlikely that they work they way i said they do'. i am and was right, they do spin backward
        Uh, no, you misunderstood. What I wrote was:

        It is highly unlikely the S63 turbos will work as you stated but they can just be skipped then
        I said it is highly unlikely the S63 turbos will work on the N63 agreeing with what you stated, nothing about the way they spin.
      1. oddjob2021's Avatar
        oddjob2021 -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        I said it is highly unlikely the S63 turbos will work on the N63 agreeing with what you stated, nothing about the way they spin.
        okay then, well in any case, dont you think its a good idea to edit the OP? or would you like more information before making changes, since there is a significant difference between the n63 and s63 turbos, and one paragraph title says: Can I just add the S63 turbos, manifold, and other parts to my N63? and the initial answer is Maybe.

        edit: and to add, since the s63 turbos spin backward, it is a much harder platform to upgrade on if changing turbos or more simply, CHRA's. the n63 as of now is the platform to upgrade when using the stock dme. what i want to know is if the s63tu turbos are the same. jimefan do you have that info?
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by oddjob2021 Click here to enlarge
        okay then, well in any case, dont you think its a good idea to edit the OP? or would you like more information before making changes, since there is a significant difference between the n63 and s63 turbos, and one paragraph title says: Can I just add the S63 turbos, manifold, and other parts to my N63? and the initial answer is Maybe.
        I don't really understand why the OP needs to be updated. I stated maybe the S63 turbos will work. That is where we stand, nobody knows but people are currently trying to do it. The answer is Maybe.

        What would need to be changed?
      1. oddjob2021's Avatar
        oddjob2021 -
        it should say No, sticky, it should state that the s63 turbos will not directly swap with the n63, no matter how you cut it, unless you transplant every single item that corresponds with it, including the dme, which we all agree that is unlikely. there is no maybe to it afaik. maybe is the answer you give when you dont have all the pertinent information, in this case, there are facts, one of them being the blade angles are opposite.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by oddjob2021 Click here to enlarge
        it should say No, sticky, it should state that the s63 turbos will not directly swap with the n63, no matter how you cut it, unless you transplant every single item that corresponds with it, including the dme, which we all agree that is unlikely. there is no maybe to it afaik.
        Well I know people who actually are trying to do this. You kind of sound like the people who said an M3 could not be supercharged because of 12.0:1 compression.

        Do we really know 100% for sure the N63 can't use S63 hardware? I'm not 100% certain.
      1. oddjob2021's Avatar
        oddjob2021 -
        okay fair enough, i didnt know about those companies. i suppose time will tell, success or failure right? its possible some of the hardware and components will swap, but afaik the turbos themselves just will not swap mani included or not. but leave it as it is, thats fine, its your forum, your thread, your rules, i just dont want to hear about the poor fool who spent a boat load trying to make the turbo swap work.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by oddjob2021 Click here to enlarge
        okay fair enough, i didnt know about those companies. i suppose time will tell, success or failure right? its possible some of the hardware and components will swap, but afaik the turbos themselves just will not swap mani included or not. but leave it as it is, thats fine, i just dont want to hear about the poor fool who spent a boat load trying to make the turbo swap work.
        Yes, exactly, I think it is a time will tell issue. Simply too early to tell.

        If someone foolishly decides to do that without the proper research, well, I think chances are it would have happened with or without post editing.
      1. Jimefam's Avatar
        Jimefam -
        Oddjob why do you say that the dme would need to be changed? The only difference between the turbos would be plumbing the piping. It's not a dme issue it would just be a pain to reconfigure the inlet and outlets. The solution most places are gonna come up with is upgrading the wheels on the turbos or swapping housings. That will be enough to satisfy 98% of the market but some will want more than can be squeezed out of two gt22's. I'd love to put in two gtx28's and hopefully longterm I'll get some manifolds that will allow it. Sticky the answer to that question IMO should read:

        "yes it can be made to work but the real question is is it worth it?" IMO the determing factor for that question will be the max cfm for the S63's and the cost and cfm's for whatever upgrades the aftermarket comes out with.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Jimefam Click here to enlarge
        Sticky the answer to that question IMO should read:

        "yes it can be made to work but the real question is is it worth it?" IMO the determing factor for that question will be the max cfm for the S63's and the cost and cfm's for whatever upgrades the aftermarket comes out with.
        And you can write that in your article Click here to enlarge

        I'll stick with Maybe.