• BMW 2.0 liter four cylinder N20 turbo motor already having issues? Head cracks under stress above 331 pound-feet of torque?

      Some interesting information was posted in the N20 section of the BimmerBoost BMW forums regarding the durability of the N20 motor. Now, the motor is becoming very popular and is winning multiple awards and rightfully so as it is currently the best factory 2.0 liter turbo four cylinder in production. The keyword there being factory as apparently it is not going to be a stout aftermarket tuning platform at least not yet. Take the information you are about to read as unconfirmed but from an interesting source.

      There are companies that stress test engines for OEM's. One of these companies has been testing the N20 apparently. The advice given is not to go beyond Stage 2 on the N20 which means a slightly more aggressive tune on the factory turbocharger. Why? The N20 head apparently cracks at around 331 pound-feet of torque. That is not exactly a whole lot of torque in the turbo tuning game especially considering the motor puts out an underrated 258 pound-feet from the factory.

      Apparently the engine is just running very hot and multiple heat cycles are creating problems. BMW behind the scenes is supposedly trying to correct the issue. For whatever reason BMW seems to have a reputation for problems with new motors. S54 bearings, S65 bearings, and the next BMW new motor issue looks to be the N20 head cracking.

      The story is that one of the lead designers and engineers for the N20 was flown out to the USA to inspect the findings for himself. It is doubtful BMW would do that unless there was something of substance to this. This same company also apparently tested other BMW motors including turbo motors such as the N54 and N55 when they were new and they did not run into these head issues.

      So what is going to happen? Well, right now it is not recommended for N20 owners to push their motors too far which they can't anyway as there are not aftermarket turbo options out just yet. BMW will likely resolve the problem with a new head which will mean for those with the N20 there will either be a recall or there will be a BMW part number option to get the new head. We will have to wait and see what happens but N20 owners should be aware of the potential issue especially if intending to tune as BMW is unlikely to say anything until they have to.

      This article was originally published in forum thread: N20 Owners started by VargasTurboTech View original post
      Comments 167 Comments
      1. cstavaru's Avatar
        cstavaru -
        This is a shame. But maybe it's by design Click here to enlarge
      1. VargasTurboTech's Avatar
        VargasTurboTech -
        Core just came in. Don't have it apart yet but with a quick inspection it is basically a mini version of the N55 turbo, reverse rotation, twin scroll, electronic diverter valve. It does have some changes, plastic wastegate actuator housing for one. I can also tell you the compressor wheel is TINY. It looks like a reverse rotation stock N54 wheel. The turbine wheel looks pretty good actually. This thing might be a good candidate for a stage 1 style upgrade. When I get it apart I will let you guys know more. Sticky as far as where I got it. I never reveal my sources...Click here to enlarge
      1. VargasTurboTech's Avatar
        VargasTurboTech -
        Click here to enlarge Originally Posted by Charrigan Click here to enlarge
        He had a meeting with a few of the lead engine designers about the N20 last week. BMW must have felt there was a big enough issue to fly them to the states to see what the failures looked like.

        They also did testing on the n54 and n55 when they first came out. They actually never blew a n54/55. He said they were testing at 600-650hp.


        As far as the n20 they broke multiple engines the same way. When they do this testing they do run the engines pretty hard. He said he would feel safe running a stg2 n20 for 100k miles but beyond the 450nm range he said its only a matter of time till the head cracks. As most of you know the 320i and 328i use the same crank, head, rods, and a few others. He said the pistons are different but he said the crank is "suspect" beyond 450nm. He feels the high coolant temps and the heat cycles they put these test engines through caused the cracked heads.


        I was not implying all n20's will blow at beyond stage 2 but the n20 is no n54. He said he would not be surprised at a head change very soon.

        Another fun fact he brought up is that the next updates to all engines will have thermostats that open at 240 degrees and operate at 250.
        Not to call BS here. But 650 hp on the N54? Really, what turbos were they running? RB's were not available then, even if they were, they are not more then 475-500 on pump, we know they were not spraying meth. So you are saying with a set of stock turbos and pump gas or even race gas they were putting out 650 hp. That's not possible. So I am taking all these "facts" as nothing more then a rumor, as I said stuff like this was said about the N54 when it first came out as well.
      1. m54b25's Avatar
        m54b25 -
        Click here to enlarge Originally Posted by Charrigan Click here to enlarge
        I would be extremely cautious on going beyond stage 2 on the N20 engine. My good friend does FEA and actual engine limit testing for multiple companies. BMW is one of their customers. They are currently working with bmw to try and correct issues with the N20 head cracking at ~450nm. The believe its due to multiple heat cycles and the engine it self running so hot.

        He also said the crank will become an issue not far beyond the breaking point of the head.
        Well, I have a few questions before flaming BMW:

        a) Number 1 question. Going beyond Stage2 from who???
        b) Which BMW N20 engines variations (w/corresponding rpm)..which one did they use for testing?:
        -135kW at 5000rpm maximum power & 270Nm at 1250–4800rpm
        -180kW at 5000rpm maximum power & 350Nm at 1250–4800rpm
        c) The engine was designed for a maximum combustion-chamber peak pressure
        of 130 bar. How much peak pressure did your source tested the engine at??
        d) The department Manager Inline engines Projects, department Manager design
        Inline engine & director development petrol engines at BMW Ag in Munich; went thru required test cycles and under real-life condition to approve this engines for at least 3-4 years ahead of engine production. How come it nows get FEA test again?
        e) Obviously, an increase from 350Nm to 450nm...~73.75ftlb crank grain from a tuning box it will mean problems, since it has no control over many Lambda strategy functions.

        Hope you can shed some more light on this since a gravity die-cast
        AlSi7MgCu0.5 alloy heat-treated cylinder head seems pretty strong in design.
      1. E90Company's Avatar
        E90Company -
        Click here to enlarge Originally Posted by VargasTurboTech Click here to enlarge
        Not to call BS here. But 650 hp on the N54? Really, what turbos were they running? RB's were not available then, even if they were, they are not more then 475-500 on pump, we know they were not spraying meth. So you are saying with a set of stock turbos and pump gas or even race gas they were putting out 650 hp. That's not possible. So I am taking all these "facts" as nothing more then a rumor, as I said stuff like this was said about the N54 when it first came out as well.
        Maybe nitrous.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by m54b25 Click here to enlarge
        Well, I have a few questions before flaming BMW:

        a) Number 1 question. Going beyond Stage2 from who???
        b) Which BMW N20 engines variations (w/corresponding rpm)..which one did they use for testing?:
        -135kW at 5000rpm maximum power & 270Nm at 12504800rpm
        -180kW at 5000rpm maximum power & 350Nm at 12504800rpm
        c) The engine was designed for a maximum combustion-chamber peak pressure
        of 130 bar. How much peak pressure did your source tested the engine at??
        d) The department Manager Inline engines Projects, department Manager design
        Inline engine & director development petrol engines at BMW Ag in Munich; went thru required test cycles and under real-life condition to approve this engines for at least 3-4 years ahead of engine production. How come it nows get FEA test again?
        e) Obviously, an increase from 350Nm to 450nm...~73.75ftlb crank grain from a tuning box it will mean problems, since it has no control over many Lambda strategy functions.

        Hope you can shed some more light on this since a gravity die-cast
        AlSi7MgCu0.5 alloy heat-treated cylinder head seems pretty strong in design.

        Stage 2 definitely varies by tuner but ultimately the warning seems to be past 331 pound-feet.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by E90Company Click here to enlarge
        Maybe nitrous.
        If testing it on a bench that's a bit different.
      1. DIMSUM's Avatar
        DIMSUM -
        Thank god, I didn't bother getting a Fxx.
      1. VargasTurboTech's Avatar
        VargasTurboTech -
        There seems to be interested. The problem right now is cores. The cars are so new there are not many floating around. What I am going to do is buy the parts needed for the stage 1 and we will have to do a send in and upgrade program with a guarantee of 1 day turnaround. I will be posting pricing in the next week or so.
      1. George Smooth's Avatar
        George Smooth -
        Click here to enlarge Originally Posted by VargasTurboTech Click here to enlarge
        Not to call BS here. But 650 hp on the N54? Really, what turbos were they running? RB's were not available then, even if they were, they are not more then 475-500 on pump, we know they were not spraying meth. So you are saying with a set of stock turbos and pump gas or even race gas they were putting out 650 hp. That's not possible. So I am taking all these "facts" as nothing more then a rumor, as I said stuff like this was said about the N54 when it first came out as well.
        More often than not the R&D guys use one off turbos for different testing. The first N54 test mule was a single turbo.
        The same happens software wise. There are many internal files with various power levels. Sometimes these leak and it's the beginning step for most tuners in the evolution of the tunes. You can see with the F10 M5 that most guys are using a "press file" with similar gains as it's what is being bounced around. Soon a stronger file will come out as it leaks across tuning houses. SAme is going to happen with F Series N20 with a 230whp 320i file being the first to hit the steers.
      1. VargasTurboTech's Avatar
        VargasTurboTech -
        Click here to enlarge Originally Posted by George Smooth Click here to enlarge
        More often than not the R&D guys use one off turbos for different testing. The first N54 test mule was a single turbo.
        The same happens software wise. There are many internal files with various power levels. Sometimes these leak and it's the beginning step for most tuners in the evolution of the tunes. You can see with the F10 M5 that most guys are using a "press file" with similar gains as it's what is being bounced around. Soon a stronger file will come out as it leaks across tuning houses. SAme is going to happen with F Series N20 with a 230whp 320i file being the first to hit the steers.
        Ok thats all well and good, so if this guy is such good friends with said testers, then what turbo / turbos were they running? And there already people making more then those numbers he claims are fail point and have been doing so for a while and the engine has been fine. As I said, still calling bs on this. BMW is not going to produce a motor that fails at those levels, that is my opinion, and is just that opinion. But until he can tell us some more details, what he is saying doesn't really add up.
      1. George Smooth's Avatar
        George Smooth -
        Click here to enlarge Originally Posted by VargasTurboTech Click here to enlarge
        Ok thats all well and good, so if this guy is such good friends with said testers, then what turbo / turbos were they running? And there already people making more then those numbers he claims are fail point and have been doing so for a while and the engine has been fine. As I said, still calling bs on this. BMW is not going to produce a motor that fails at those levels, that is my opinion, and is just that opinion. But until he can tell us some more details, what he is saying doesn't really add up.
        I also call bull$#@!. This shouldn't have even made front page.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by George Smooth Click here to enlarge
        I also call bull$#@!. This shouldn't have even made front page.
        I disagree. It's very interesting.
      1. bobS's Avatar
        bobS -
        I think some good points are being made....how can they run a n54 to 600+ hp on stock turbos? Hmmm. If they did swap out turbos to run up the hp, why would they even do this? They would have to make a lot of changes just to make it work.... I call bull$#@! also

        Maybe they estimate the n54 being able to make 600+ but it's only a estimation
      1. dzenno@PTF's Avatar
        dzenno@PTF -
        I call bs on this to be honest. I had one of the pretty well known euro tuners (who makes downpipes) claim that without a flex section in the downpipes the heads would 100% crack on the N54 Click here to enlarge how many are running downpipes with flex sections in them again?
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by dzenno@PTF Click here to enlarge
        I call bs on this to be honest. I had one of the pretty well known euro tuners (who makes downpipes) claim that without a flex section in the downpipes the heads would 100% crack on the N54 Click here to enlarge how many are running downpipes with flex sections in them again?
        What does the N54 have to do with the N20 though?
      1. dzenno@PTF's Avatar
        dzenno@PTF -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        What does the N54 have to do with the N20 though?
        Forgot to highlight, this is just an opinion based on what we've lived through before...take it FWIW
      1. bobS's Avatar
        bobS -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        What does the N54 have to do with the N20 though?
        Bc the op's source said that about the n54. How reliable is the source when we all know how much hardware changes are required to make that power on a n54?
      1. Terry@BMS's Avatar
        Terry@BMS -
        Click here to enlarge Originally Posted by Charrigan Click here to enlarge
        I would be extremely cautious on going beyond stage 2 on the N20 engine. My good friend does FEA and actual engine limit testing for multiple companies. BMW is one of their customers. They are currently working with bmw to try and correct issues with the N20 head cracking at ~450nm. The believe its due to multiple heat cycles and the engine it self running so hot.

        He also said the crank will become an issue not far beyond the breaking point of the head.
        We're running ours at 300whp / 350wtq (dynojet) and so far it's running well. Will throw a larger turbo on it as soon as its available so we can see if there is any truth to that! Click here to enlarge
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by bobS Click here to enlarge
        Bc the op's source said that about the n54. How reliable is the source when we all know how much hardware changes are required to make that power on a n54?
        The op's source said the N54 was fine to 600 hp or so I thought? It was a euro tuner that said the N54 head would crack right?