• 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 163 Comments
      1. benzy89's Avatar
        benzy89 -
        Just wait for the coupe & more N20 tunes/bolt-ons.... There will def be a market for it soon
      1. bigdnno98's Avatar
        bigdnno98 -
        @Terry@BMS can you tune a turbo upgrade for the N20 yet? I have a feeling this motor is going to be special and a VTT turbo upgrade tuned by BMS sounds pretty badass.
      1. inlineS54B32's Avatar
        inlineS54B32 -
        I just had my M in for service, and really liked the N20 powered X1 - and I usually dismiss everything SUV. I think this engine is awesome in that it gets ridiculously awesome mileage in the city, and is not gutless down low. The SA said that a tune gets you N55 stock power levels, but you get to keep the MPG for free. If I were to buy an economical daily driver right now, I would start first with everything powered N20.

        The only thing I didn't like was the noise - and that was only when it was below 2k RPMs, the windows were down - and walls were next to me on both sides. I didn't get to hear it much from the outside, but I don't think it was terrible sounding - just nothing impressive is all. I would almost guarantee that this motor gets higher MPG than what BMW claims it does. I averaged a tad under 25 in the city in a heavy SUV when I was somewhat trying. That's good in my book - on the highway, 30+ no problem including the spirited 0-100 blast from the tool booth.
      1. Charrigan's Avatar
        Charrigan -
        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.
      1. bigdnno98's Avatar
        bigdnno98 -
        Click here to enlarge Originally Posted by Charrigan Click here to enlarge
        This quote is hidden because you are ignoring this member. Show Quote
        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.
        thats really unfortunate. I had high hopes for that motor modded. Interested to see what it's limits and the CLA45 AMG motors limits are.
      1. VargasTurboTech's Avatar
        VargasTurboTech -
        Click here to enlarge Originally Posted by Charrigan Click here to enlarge
        This quote is hidden because you are ignoring this member. Show Quote
        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.
        This kinda sounds like the stuff they were saying about the N54 a year after it was out... Hmmmmm
      1. dzenno@PTF's Avatar
        dzenno@PTF -
        Totally dig the N20. Love that little motor. I also think it'll be very special.
      1. dzenno@PTF's Avatar
        dzenno@PTF -
        Click here to enlarge Originally Posted by Charrigan Click here to enlarge
        This quote is hidden because you are ignoring this member. Show Quote
        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.
        Thanks for the words of warning but motors do at times have strange issues. Early issues such as this one could just be freak accidents and not necessarily attributed to quality.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by VargasTurboTech Click here to enlarge
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        We ordered an N20 core last week and should have it soon.
        How/where did you get this already?
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Charrigan Click here to enlarge
        This quote is hidden because you are ignoring this member. Show Quote
        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.
        Can you give us more info than this? @Charrigan
      1. bobS's Avatar
        bobS -
        1st post....hmmmm , yes more info would be nice
      1. Charrigan's Avatar
        Charrigan -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        This quote is hidden because you are ignoring this member. Show Quote
        Can you give us more info than this? @Charrigan

        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.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Charrigan Click here to enlarge
        This quote is hidden because you are ignoring this member. Show Quote
        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.
        Can you give me anything I can actually reference as a source?

        What about differences between the 320i and 328i? Same crank, same head, same rods, what is different? Pistons? Turbo is the same?

        What will the thermostat change do? Cooling comes on sooner than it does currently?

        This is all golf so far, good stuff.
      1. Charrigan's Avatar
        Charrigan -
        Can you give me anything I can actually reference as a source?
        I would prefer to not reveal his name or the company he works for. I wouldn't want him to get into trouble for telling me anything. They are the leaders in FEA testing and engine testing.

        What about differences between the 320i and 328i? Same crank, same head, same rods, what is different? Pistons? Turbo is the same?
        the 320i and 328i are essentially the exact same engine. Crank, rods, cams, head, turbo, exhaust manifold etc. the only differences he is aware of is the pistons and the dme tuning.


        What will the thermostat change do?
        the thermostat change will happen on all bmw engines as far as he knows. This will make them run hotter than every bmw offering currently. He does not understand why since a lot of these issues are caused from high coolant temps. Not to mention hotter oil temps.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Charrigan Click here to enlarge
        This quote is hidden because you are ignoring this member. Show Quote
        I would prefer to not reveal his name or the company he works for. I wouldn't want him to get into trouble for telling me anything. They are the leaders in FEA testing and engine testing.
        I understand but then how do I write an article on the N20 tuning potential?

        Click here to enlarge Originally Posted by Charrigan Click here to enlarge
        This quote is hidden because you are ignoring this member. Show Quote
        the 320i and 328i are essentially the exact same engine. Crank, rods, cams, head, turbo, exhaust manifold etc. the only differences he is aware of is the pistons and the dme tuning.
        Interesting. Why would they change the pistons but not anything else? Guessing weaker pistons to prevent tuning so you spend more money to get the better pistons? If they are better?

        Click here to enlarge Originally Posted by Charrigan Click here to enlarge
        This quote is hidden because you are ignoring this member. Show Quote
        the thermostat change will happen on all bmw engines as far as he knows. This will make them run hotter than every bmw offering currently. He does not understand why since a lot of these issues are caused from high coolant temps. Not to mention hotter oil temps.
        This makes no sense. They should do the exact opposite.
      1. bobS's Avatar
        bobS -
        The heat may play a crucial role in fuel economy and emissions....while sacrificing some performance. Just a guess...
      1. klipseracer's Avatar
        klipseracer -
        Tons of stress and no n54 failures. What turbos did they use to achieve that power?
      1. Sticky's Avatar
        Sticky -
        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.

        Click here to enlarge
      1. Puerto Rican 335d's Avatar
        Puerto Rican 335d -
        Sticky I cant understand where the thermostat would be hotter if ANYTHING it should open sooner, i added a 180 degree thermostat for my 02 MCS since it had 200 whp and NEVER did it crack the engine or ever heard of anything like it. If I may I suggest the Thermo should open at 180 to aliviate heat in the engine, dont u agree on this, yes they are two different engines 1.6 Pentagon engine and this N20 a two liter BMW engine but I strongly believe that for the head NOT to crack you should keep the engine coolant at a lower level to enhance performance for the car. ANYONE correct me on this I am not a techie or engine guru but had my share of cars.
      1. ajm8127's Avatar
        ajm8127 -
        Click here to enlarge Originally Posted by Charrigan Click here to enlarge
        This quote is hidden because you are ignoring this member. Show Quote
        What will the thermostat change do?
        the thermostat change will happen on all bmw engines as far as he knows. This will make them run hotter than every bmw offering currently. He does not understand why since a lot of these issues are caused from high coolant temps. Not to mention hotter oil temps.
        I'm sure it is for efficiency. Those looking to extract maximum performance should consider a low temp t-stat.