Has BMW Downgraded the 135i & 335i?

BMW 135i with N54/DCT

The short answer is; we don ‘t know. But let ‘s take a look at what we know. Last weekend we exclusively broke the news that the 135i was not only getting the DCT 7 speed dual clutch transmission but also the N55 inline six turbo. More specifically BMW is replacing the N54 dual turbo with the N55 single turbo twin-scroll. It ‘s great news for fans of the 1 Series and DCT technology but what about that engine change?

As you may have heard from our interview with Martin Birkmann, the switch to the N55 is all about efficiency. And on paper it makes sense with identical numbers in regards power and torque. But what about the N54 ‘s power being under-reported? We had heard for years from automotive magazines and websites that dynoed the engine that the N54 was actually putting out well over 320 hp (and sometimes much more). While no one yet has dynoed an N55 we ‘d guess that we will not see those kind of numbers from the single turbo twin-scroll set-up. What does all this mean? While on paper the N55 is a match for the N54, in the real world we can ‘t help but wonder if the 2011 135i and the 335i didn ‘t just lose a little power versus the 2010 models.

BMW 135i with N55/DCT

Anything lost (even unofficially) BMW will be giving back in the form of the forthcoming BMW Performance engine kit for the N55. Engineers are currently fine-tuning the kit and expect to have it available sometime in the latter half of the year. However beyond that option, BMWfirmly believes that the N55 will be “tuner proof “. They expect that tuning the N55 will be infinitely harder to do as compared with the N54. So while the N55 has the efficiency, for the enthusiast it clearly has some downsides. If you take away the N54 ‘s oil cooler issues it ‘s been a fantastic engine for BMW and the enthusiast market. It has fantastic power and torque while delivering respectable fuel figures.

Will the N54 equipped 135i and 335i be the more coveted cars in the years ahead? No doubt some will think so. However if true, we ‘d guess that would only be the case for the enthusiast market. The N55 will surely continue to serve multiple BMW models well while being noticeably more efficient. It ‘s just a shame that we may have lost some of that unadvertised oomph that the N54 was known for.

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  • Mpowered

    i think this is more about making sure that the M1/1series M powerplant will be significantly distinguished from the 135i engine. i do think this will increase value of N54s…

  • Mark Smith a.k.a IT WRKS

    We all have to look at the effect of our government and the new laws for fuel efficiency that are in place. Unfortunately we are our own worst enemy when it comes to fuel consumption and these are the fruits of our own planting. BMW wouldn’t put inferior hardware on the road though so I think the majority of people buying this car will not notice the difference. Also someone should be able to pick up a car equipped with an N54 as there are plenty of sedans, coupes, and convertibles out there.

  • I am one to think that as time progresses on the N54 will be remembered as an engine of great accomplishment and the one that reintroduced the world to BMW turbos BUT these new motors will be more efficient and more than likely produce the same output in different future forms.

    With the Valvetronic and use of Borg Warner twin scrolls the sky may be the limit for BMW with this motor- the aftermarket is a different story.

    Gabe’s view that the new motor may be a performance downgrade is spot on as we have yet to see dyno numbers on the N55, and we all know that the N54 was underrated significantly. Who knows though, we may be surprised to see the numbers are the same on the dyno but until we or someone else get a car tested we are left to wonder if the new N55 is just like it is advertised 300/300.

  • MatB

    I bought a 135i this past weekend and am absolutely in love with it. That said, I was mildly annoyed when a host of ‘improvements’ were announced this week. I did however wonder the same thing as this post. Has anyone seen dyno figures on the new Z4 with the twin scroll engine? Either way, I don’t think the changes are enough to merit much jealousy from current 135 owners.

  • MatB the Z4 does not have the twin scroll engine (N55). There are 0 cars in the US currently with it.

    They will be here after March.

  • I have had my 135i for two years this coming May. I am in love with my car and have been from day one. Really, if I were to change anything about it that would be fuel economy. In the city though – on the highway I’m quite pleased and impressed with the fuel economy. City economy is not so wonderful, however that is related in part to my driving habits. Unless you’re tracking the car, I cannot imagine noticing any measurable difference that would make someone envious of a prior model year, etc.

  • why tuner proof? If they are worried about hacking the code and blowing up engines, why not just build a bit-map compare function into the dealership testing hardware to detect changes? Dinan and all the other tuners have enhanced BMWs market presence with improved performance for those that want and can afford it. This seems to me to be brain dead.


  • Dr Obnxs- the reason for tuner proof is because there are piggy backs available on the market that overboost the motor and can cause long term reliability issues- which would impact used car values and CPO warranty claims. Not that this is a huge problem but how would you feel if you bought a used car that had been overboosted and subsequently the life of the engine was decreased- oh and there was no way to tell.

    There are some ways with the current MSD in the N54 but the N55 will be a more sure fire way to ID these issues.

    I do not share your opinion that the tuners have enhanced BMWs market presence, they (tuners) are in fact there because of BMWs market presence. People do not buy BMWs because there are aftermarket tuners- sorry. And the latest generation of tuners are nothing more than computer hackers on many levels, there is no R&D, no longevity testing and no care put towards a sustainable product. Dinan, Turner and the like are a different story.

    Most people are buying a cheap (not that much money at all) piggy back and tricking the ECU into running higher boost pressures, so it is not really improved performance for those that can afford it- it is more like anyone with $300 can now hack the car to performa beyond it’s recommended limits which is great for light to light drag racing.

    I am an enthusiast and have tuned and will in the future but to me it is much more than what most people are doing. We are talking about $40k+ cars that people lease and then put $300 into and beat then turn back in…. this will impact the reliability of BMWs used cars but the question is what the penetration is. BMW and other brands will continue to invest in anti-tuning technology because there is a lot more at stake for them than the investment in preventing it.

    I think that the move to the N55 and its proposed lack of tunability may be a good move for the sake of the brand, and BMW will of course give us enthusiasts their version of tunes as will the likes of Dinan and Turner but for those of us that are willing to pay to play….

  • Chris Brake

    With the many N54 suicides that have already occurred I got to thinking that this is BMW just canning a complex engine that just isn’t as dependable as it should be for prime time.

  • Jared

    I could care less about tuning, but I would be surprised if the tuners are unable to hack in. Look at a company like DirecTV. They went through four versions of their access cards and spent 10’s of millions on security consulting before they designed a hackproof access card. I would doubt BMW has put that level of time and money into the software security on the new engine, but we will see.

  • kit

    ^ Argh, sorry, internet pet peeve… It’s COULDN’T care less, not could.

    Ok, anyway, on to the real comment: I just hope that BMW has figured out how to make a reliable high pressure fuel pump for the n55, because they have had a really high failure rate in the n54.

  • Eliot R.

    All of this is just speculation at this point. It will be interesting to see what happens when cars start hitting the test track and dynos. However, I think there will be pros and cons to either. The N54 might make slightly more power out of the box, but the 10% improvement in fuel efficiency isn’t something to ignore completely. I think the reason why some are viewing this as a downgrade as purely because of the assumption that two turbos is better than one. And I don’t think that is necessarily the case here with the twin-scroll single turbo.

    Ultimately, my guess is that the performance will be nearly indiscernible between the two engines, with the N55 being slightly more responsive due to the Valvetronic. But that’s just a guess on my part…

  • RJ

    Echoing the comments by Kit…..the high pressure fuel pump has been a real problem on the N54-equipped cars, from what I read on the enthusiast boards (if they can be believed).

  • GSP

    This is simple economics … they’re creating a market above the 135. In the car business it’s ALWAYS about money!

  • J R Kenyon

    Just purhased the Z4 35s three months ago adn would like to get the same power out as per the new one being launched is this possible with still having good reliability?

  • goat

    An interesting read. Congrats on the 2010 135i matB… it does seem that the current batch of 1-ers driving around will make highly desirable CPO cars! 🙂 Let’s not get carried away until we see performance reviews though… a bit less power in the N55 seems likely but the power delivery could be interesting in itself and if gearing is revised the accelerative performance could be quite similar for “out of the box” cars running stock tunes.

  • Bimmer1

    “Ok, anyway, on to the real comment: I just hope that BMW has figured out how to make a reliable high pressure fuel pump for the n55, because they have had a really high failure rate in the n54.”

    I highly doubt the N55 pump will be any different than the N54, as both motors require the same capability of the N54 pump. It would not make sense to manufacture a different pump when they already had to change the N54 design to accomadate us.

    Many people don’t know this, but many BMW insiders blame the ethonol in american fuels as the primary cause of high pressure pump and piezo injector failures. The parts are not to blame…well not completely anyways. They don’t use ethonol in Europe like we do here because they are smart enough to know that it’s a money making ploy by the US government to take advantage of the suckers that are american consumers. The GOV knows we will buy whatever they force us to, because we really don’t have another viable option. It’s hard to find a pump that doesn’t say “up to 10% ethonol” on it. And don’t get me started on Sunoco. We frequently see ethonol levels around 20% from them. That is way to high for BMW engines to run properly. If you are not using a top tier fuel, as BMW recommends, don’t complain about ignition issues. And now here we are on the brink of passing increasing ethonol standards to 15%+ just so the GOV can pay farmers to grow corn instead of real food to eat. But that’s a totally different issue altogether. I bet you’d never guess that our GOV would be responsible for your BMW breaking down! Guess again!

  • Bimmer1

    “Just purhased the Z4 35s three months ago adn would like to get the same power out as per the new one being launched is this possible with still having good reliability?”

    Yes, it’s called Dinan Stage II software. Go get it!

  • Bimmer 1- I believe they are on Rev. 3 of the HPFP, so they have made changes, as with most things improvements continue to be made if necessary. I will check on Moday but I am fairly certain there are 3 part numbers for the pump since SOP.


  • goat

    Well said Bimmer1 – ethanol is a shameful scam and it is being perpretated on us up here too by the Canadian gov (along with rule by absence as in the current 2 month proroguing of our parliament!). The fuel economy penalty alone should be enough to raise outcry but when nearly every fuel supplier contains 10%+ E it is tough to find alternatives. The tyranny is nearly complete, is another way of putting it. (And while consumers pay more out of pocket and enviro and social impacts both locally and globally increase the subsidies keep flowing to the ethanol lobby.)