BMW N54 Upgraded Twin Turbo Guide

While the BMW N54 can push incredible power and torque through the small stock twin turbos, many enthusiasts look to take their N54 to the next level. Upgraded turbos are the forefront of discussion when it comes to unleashing the N54’s full potential. Despite its reputation as a strong factory motor, upgrading to a big single turbo or larger TD04 twin turbos comes with considerable risk. With so many options on the market it is tough to determine where to even start but worry not. In this guide we will explore upgraded twin turbo options and the benefits, risks, and costs of each.

BMW N54 Single Turbo Guide

A Little About the BMW N54

Before diving into the discussion about upgraded twin turbos we want to diverge briefly to discuss the N54 engine. It’s a relatively high compression engine featuring an open-deck block; on paper, neither of these facts lead one to believe the N54 can handle big boost. Though, in the real world, the N54 has shattered expectations and proven its ability as an outstanding high-performance motor. This leads some, us included, to believe the N54 will handle whatever we throw its way. We can’t fault anyone for believing this; it really is one hell of an engine.

However, prior to upgrading your N54 twin turbos, let’s come back to reality throughout this post. There are hundreds, maybe thousands, of N54’s pushing 600+whp and torque through unopened motors. Additionally, there are countless examples of blown motors at those power levels and surely many more that have not been documented. The N54, like any other engine, is far from indestructible. At these power levels it may only take one pre-detonation to grenade the engine. Please seriously consider this before upgrading your N54 turbos - can you afford, and are you willing, to drop a new motor into the car if you blow your N54?

Upgraded Twin Turbos vs Single Turbo

We will expand on this once we release our single turbo guide and roll everything into one holistic article. However, for now, we want focus on one important difference: low-end torque.

Low-End Torque

Twin turbos are typically going to roll in torque at significantly lower RPM’s than a big single turbo. The below dyno charts are an excellent comparison.

N54 Twin Turbo Dyno

N54 Upgraded Twin Turbo DynoPin

N54 Single Turbo Dyno

N54 Single Turbo DynoPin

You can see the power band of the single turbo is shifted right; peak torque occurs right around 5200 rpms while power peaks near redline. The single turbo N54 also makes less torque but manages 125 horsepower more than the twin turbo setup. On the contrary, the twin turbo setup rolls in a whopping 636 wheel-torque below 4500rpms while peak power occurs prior to 5000rpms.

Good or Bad for Twin Turbos?

Well, that depends on your goals and budget. The single turbo N54 above is going to be a faster car, however, the twin turbo setup will provide (in our opinion) a more fun daily driver. You’re not going to really need to string out the motor to redline to have a blast. However, low-end torque is extremely tough on engines. At lower engine speeds, the pistons are travelling slower which exposes the engine to high cylinder pressures for longer periods of time. Additionally, torque is tougher on engines as compared to power; upgraded twin turbos typically make more torque than single turbos as evidenced above.

This can all be adjusted with proper tuning but cutting boost and torque on the lower-end may also defeat the purpose of a twin turbo N54. In general, twin turbos are tougher on the N54. If you want to run an aggressive twin turbo setup you may be best off building the motor.

Upgraded Twin Turbo Setups

Alright, now that we got most of the background information out of the way, it’s time to dive into the fun part. We will break down the various setups for the following goals:

  • “Modest” 500whp N54 Twin Turbo Setup
  • 600whp Twin Turbo Setup
  • “Full Send” 700+whp Setup

Keep in mind – even if your initial goal is a modest 500whp you may consider opting for twin turbos capable of handling significantly more power. Not only will running the turbos below their upper limits help with reliability and longevity, but it also provides the option to extract more power from your N54 down the road without needing new turbos again. Of course, one downside to consider is that switching to larger, more capable TD04 turbos will increase turbo lag slightly.

TD03 vs TD04 Turbos

When looking for aftermarket turbochargers you will frequently see or come across TD03 and TD04 for the N54. This refers to the size of the center section, with TD04 being larger (TD03 stock on the N54). TD04 turbos are more efficient, run cooler, and typically flow more air leading to more power. Upgraded TD03 turbos typically use larger than TD03 sized internals.

9b vs 12b (Compressor Blades)

This simply refers to the number of blades on the turbine wheel. As you likely guessed by now, 9b refers to 9 blades while 12b is 12 blades. All else constant, a 9 blade wheel will flow more air at lower PSI, but the 12 blade wheel will flow more at higher PSI.

15T, 17T, and 19T

These numbers refer to the size of the compressor wheel; higher numbers indicate a larger compressor wheel. A larger wheel will have higher flow.

**Final Note: N54 OEM turbos feature TD03 center section, 10T compressor wheel, and TD03L 11 blade turbine wheel

“Modest” 500whp N54 Twin Turbo Setup

I am referring to this as “modest” simply because the stock turbos on the N54 can push roughly 500whp. However, there are still many benefits to running upgraded turbos over stock even at these power levels. A few of these benefits include:

  • Better top-end power
  • Flow more air at lower PSI
  • Turbo longevity
  • Less heat

In general, larger or more efficient turbos will produce better power on the top-end; even if your goal is to keep peak power the same as your maxed stock turbos, upgraded turbos will produce more power at 6000+rpms. Additionally, larger twin turbos may flow more air at lower PSI; stock turbos run about 23psi to produce 500whp while a larger TD04 turbo would make the same 500whp at less than 23psi. Running a turbo below its maximum limit will help with turbo reliability and longevity. Lastly, upgraded turbos will help reduce IAT’s and keep overall temperatures down.

500WHP N54 Twin Turbo Options

If you decided somewhere in the ballpark of 500whp is the goal for your N54 the following options may be your best bet. For those who may want more power in the future, consider upgrading to the more aggressive turbo setups listed in the 600-700+whp sections.

1. RB Twos (475-525whp)

TD03, Billet 15T Compressor Wheel, High Flow Custom Enlarged 9-blade Turbine Wheel

Starting at $1,999

These are a great balance of performance and cost. RB recommends keeping these turbos in the ballpark of 475-525whp, however they have proven capable of being pushed above those power levels. Though going above the recommendation may result in premature wear and shorter life-span.

2. Pure Stage 1 (450-500whp)

TD03, Unknown Compressor and Turbine Wheels

Starting at $1,950

There does not seem to be much information regarding the unknown compressor and turbine wheels. What is known is that these turbochargers are capable of peaking around 500whp, so you would likely be best keeping these turbos slightly under the 500whp goal. Like the RB Twos above, the Pure Stage 1 turbos are a solid choice for those looking to make reliable power on a budget, but they are slightly less capable than the RB Twos.

3. Vargas Turbo Tech (VTT) Stage 1 (450-500whp)

TD03, Choice of Billet or Non-Billet 14T Compressor Wheel, OEM Turbine Wheel

Starting at $1,499 ($1,649 w/ Billet Wheel)

Yet another solid option for those on a budget looking for upgraded turbos. The VTT stage 1 turbos are capable of roughly 525whp but are likely best kept in the 480-500whp range.

4. RB Next Gens (500-550whp)

TD04, Billet 15T Compressor Wheel, High Flow TD04L 11-Blade Turbine Wheel

Starting at $2,399

A little pricier than the previous options, the RB Next Gens are somewhat of an “entry-level” TD04 turbo; these turbos will flow much more efficiently than the smaller center section TD03’s. Good for 500-550whp but capable of being pushed a bit further. Though 550whp may not seem like a huge upgrade from the RB Twos 525whp these are a considerable upgrade. They will hold power later in the RPM range creating a broader power band. Proven to run sub 11 second quarter miles @ 130+ mph these turbos are no joke. Excellent, reliable option for those looking to daily drive in the low-mid 500whp range with the ability to be turned up to 550+whp for occasional glory runs.

Final Thoughts on “Modest” 500whp Turbos

There are many N54 twin turbo options on the market that will meet these modest power goals so please keep in mind this is far from an exhaustive list. We make NO money recommending any of these turbo setups; this is an honest list of recommended turbos based on extensive research.

Most importantly, these 500whp setups are likely best for N54 owners looking to make practical, daily-drivable power. Though proper supporting mods are important, a 500whp N54 will be less demanding than more powerful setups. As we progress to more powerful setups, it should be noted – the turbos themselves may not be significantly more expensive but the supporting mods add up quickly. More on this later.

600WHP N54 Twin Turbo Setups

600+whp N54 setups are beginning to near the limit where you may consider building your engine. Though the low 600’s is commonly accepted to be a safe limit (with proper tuning and supporting mods) for the N54 this is still a considerable amount of power where the likelihood of a blown engine increases. You’ll also be best running full E85 due to its improved detonation resistance.

Basic Supporting Mods

  • Port fuel injection
  • Stage 2+ LPFP
  • Upgraded axles
  • Limited Slip Differential
  • Dual oil coolers
  • 7”+ FMIC
  • Upgraded inlets/outlets

Due to the more demanding fuel of these setups you are likely going to need a stage 2+ LPFP along with the addition of port injection. The stock direct injection with a stage 2+ LPFP will likely max out around 550whp, depending on the amount of E85. You will also struggle putting down this kind of power in your N54 without a limited slip differential, and there is an increasing possibility of snapping an axle with each launch. Although larger turbos run more efficiently and cooler, 550-600+whp is going to generate some serious heat. Consider dual oil coolers and a larger FMIC to keep temps in control. Lastly, stock N54 inlets will really limit the potential of these turbos and cause additional stress.

This is not an exhaustive list of supporting mods, and you may be able to get by without everything listed above. To reiterate though, at these power levels you want to ensure you are doing things right. These following upgraded twin turbos may not seem terribly expensive up-front, but the full setup with proper supporting mods may easily run into $10,000+ territory.

600+WHP N54 Twin Turbo Options

1. RB Next Gen Plus (550-600whp)

TD04, Billet 17T Compressor Wheel, High Flow TD04L 9-blade Turbine Wheel

Starting at $2,599

RB’s Next Gen Plus turbos are capable of efficiently running in the 550-600whp range with the ability to be pushed upwards of 625-650whp for some additional fun. These turbos will provide an excellent balance between quick spool, low-end torque, and big top-end power. Known to trap the quarter mile in the mid 130mph range these turbos back-up their power claims with real world results.

2. Vargas Turbo Tech (VTT) Stage 2+ (575-625whp)

TD04, Custom Billet Compressor Wheel, TD04L 9-blade Turbine Wheel

Starting at $2,199

Capable of being pushed towards 675whp, these turbos are likely best kept in the low 600whp range for daily driving. Featuring a 2” turbo inlet, these turbos require 2” aftermarket silicone inlets. Like the RB Next Gen Plus turbos, the VTT Stage 2+ will retain a great balance between quick spooling and high top-end power.

3. MMP Stage 3 Gen 2 (600-650whp)

TD04, 43mm Billet Compressor Wheel, 43mm Turbine Wheel

Starting at $2,500

Though MMP states their State 3 Gen 2 turbos are capable of 700whp max at 30psi, we advise keeping these turbos in the low-mid 600whp range. Given the larger design of these turbos they trade off a little spool and torque in favor of more top end power.

4. Pure Turbos PURE600 (550-600whp)

Custom Turbine and Billet Compressor Wheel

Starting at $2,200

The PURE600 turbos are an excellent option for those looking to stick right around or under 600whp. Though they can push 600whp they are likely best kept around 550whp for daily driving. Retaining great spool and low-end torque these turbos also make peak power near redline.

5. RB Super RB Stealths (575-625whp)

TD04, Billet 19T Compressor Wheel, High Flow TD04L 9-blade Turbine Wheel

Starting at $2,649

As compared to the RB Next Gen Plus, the Super RB Stealth’s see an upgraded 19T compressor wheel supporting an efficient 575-625whp. They can also be pushed a bit further, although anything above 625whp is starting to get out of the efficient range for the housings. Additionally, these turbos will take a slight hit when it comes to spool. There do not appear to be many sets out there on the N54 but one of the few out there has managed 10.7 quarter mile times at 130+mph.

Final Thoughts on 600whp Turbos

The above turbos are not an exhaustive list but are all excellent options for any N54’s looking to make consistent power figures in the high 500s to low 600s. Though some of the turbos are capable of being pushed further, it is always a good idea to keep the turbos below their upper limits in most situations. For occasional fun or “glory runs”, many of the above options can be pushed to their limits to make well over 600whp on the N54 engine.

The supporting mods required for an N54 to reliably and consistently make 600+whp are considerable. Again, you may even want to consider building your motor if you’re planning to make that much power for the long-term. Or, at least be prepared that the eventual fate of your N54 may be death. As we move into the next category things really start to heat up quickly. We’re now looking to push the N54 to, and likely past, it’s upper limits.

“Full Send” 700+WHP N54 Twin Turbo Setups

As the title states, these setups are quite literally full send and not at all intended for the faint of heart. Building a use-able twin turbo 700+whp N54 will likely run into the range of $25,000-40,000, if not more. This list of supporting mods is far from exhaustive but just to name a few: port injection, LSD, upgraded axles, dual oil coolers, transmission coolers, fully built motor, massive intercoolers, and extensive tuning.

Just to Reiterate

This is some serious sh**; not the kind of setup you want to jump into without extensive knowledge, experience, and/or a very deep wallet. If you push 700+whp through an unopened motor it’s not a question of IF it lets go, but rather WHEN it lets go. Similarly, if you launch your N54 from a dig at 700+whp it’s not a question of if you snap an axle, but when you do. Additionally, depending on your specific goals, you may be pushing these turbos close to their limits thereby increasing the chances of blown turbos.

OK, as we stated earlier, this stuff can possibly be avoided with proper tuning and rolling in boost/torque later in the RPM range. However, at that point you’re likely best opting for a single turbo. Even then, a 700+whp single turbo setup is pushing the upper limits of the N54 capabilities. Let’s dive into the options that will reach these power goals.

700+WHP N54 Twin Turbo Options

1. MMP1000 (700-800+whp)

TD04, 46mm Turbine & Compressor Wheels

Starting at $3,500 (currently on sale for $2,800)

With claims of being the most powerful N54 twin turbo offering on the market, these turbos were designed to handle 1000hp (about 850whp). We have not located any data or dyno charts showing these turbos truly pushed towards their upper limits. However, given these are larger turbos and an upgrade over MMP’s stage 3 gen 2 turbos (which have eclipsed 700whp), it is safe to say these turbos will meet your 700+whp goals.

2. Vargas Turbo Tech (VTT) “GC 2.0” (700-850whp)

TD04, Fully Custom Designed Turbo Internals

Starting at $3,299

Given the lack of 700+whp twin turbo N54’s in existence, these may be (at least from our research) the most proven high horsepower twin turbos on the market. Terry at Burger Motorsports, the manufacturers of the popular JB4 tunes, pushed these turbos to 761whp and 660wtq. He also managed a 5.41 second 60-130 time – nothing short of incredible (and may still be the N54 record to date). There is another example that managed a breathtaking 847whp and 726wtq with over 600-wheel torque at a mere 3000rpms. This car trapped an n54 world record 170.49mph in the half mile.

3. RB Super RB EVO 19T (650-700whp)

TD04, Billet 19T Compressor Wheel, and TD04HL 9-blade Turbine Wheel

Starting at $2,749

Super RB EVO 19T turbos do not have a lot of information out there, but still deserve a mention for the highest horsepower N54 twin turbo setups. There is an example of the smaller 17T setup making 575whp at only 21psi. What is more incredible is the 668 wheel torque the smaller 17T turbos made on that same dyno pull at 21psi, with claimed misfire issues.

The RB Super Stealths referenced in the 600+whp section look similar on paper. However, the Super RB EVO’s feature larger custom cast TD04 compressor housings. It is unknown whether these Super RB EVO’s will eclipse 700whp, however, they should make incredible torque in the mid-range as evidenced by the above referenced dyno.

4. Pure Stage 2 Hi-Flow Turbos (650-700whp)

TD04, Specs Unknown

Starting at $3,595

Although Pure’s Stage 2 Hi-Flow twin turbos are just about maxed at 700whp they deserve an honorable mention for their proven results. There are many N54’s running these turbos with countless dynos showing 600-700whp, and a few 700+whp examples.

Final Thoughts on 700+whp N54 Twin Turbo

There are not many examples of 700+whp twin turbo N54 engines, so anyone opting for this setup is entering relatively unknown territory. What is known, these twin turbo setups will still produce amazing low-end torque and put massive amounts of stress on the N54. Not for the faint of heart, these setups will require built motors and extensive supporting mods likely driving all in costs north of $25,000.

Keep in mind – even with a built motor, the most capable turbos, and proper supporting mods there is still a chance of blowing the motor and/or turbos. You may be able to afford the up-front costs of these 700+whp setups, but it is important to understand additional costs may still be incurred. If you’re committed to a 700+whp setup, we are very jealous and hope to one day join you.

BMW N54 Twin Turbo Setups – Turbo Manufacturers

We try to avoid any drama between turbo manufacturers, and there is quite a history of some bickering back and forth on the various forums. The four turbo companies referenced throughout this post – RB, Vargas, MMP, and Pure – are some of the most common turbos on the N54 market. You will find complaints and horror stories about each on the internet, and we hold nothing against any of these turbo manufacturers, nor are we paid by any of them.

Pushing Turbos Past Their Limits

It is important to note – many of the horror stories arise from people pushing their N54 and turbos to the absolute limit. When pushing an engine, turbos, or anything for that matter, past its limit there always remains the possibility of unforeseen issues. Keep this in mind when researching what may be the best option for you.

Summary of N54 Twin Turbos

As discussed throughout this post, the N54 nor any aftermarket turbochargers are indestructible. We know this is cliché but is it so true and as the saying goes: you gotta pay to play. Understand your goals and know what you are looking to get out of your N54. If you know you are looking to make a consistent 600whp don’t opt for upgraded turbos that are absolutely maxed out at those power levels. Additionally, ensure you are budgeting the appropriate supporting mods for your goals. While a modest 500whp setup can get by with minimal supporting mods, a 700+whp setup will require demanding supporting mods that can add up to tens of thousands.

There is a plethora of offerings available for the N54 engine, so be sure to research diligently and take your time. Purchasing upgraded turbos likely isn’t a decision you will make overnight. With all of that being said, a set of upgraded N54 twin turbochargers have the ability to boost your car to the next level. Most importantly, have some fun.

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16 thoughts shared

  1. I have always wanted to ask someone in the know, what will probably be a stupid question, but it’s worth asking anyway, so I’ll take one for the team. Why not mix and match turbos. If smaller turbos give better torque in lower rpm’s, and bigger turbo’s give more torque and power on higher rpm’s, why not have one smaller turbo and one larger one in a twin turbo setup??? Would this not give the best of both worlds?
    On a more serious note, you didn’t mention Hexon RR600’s. So I’m wondering what your opinion of them are, and how much HP they normally make with all the other FBO upgrades? I bought my 335i with most of the big upgrades already on the car. It runs very well, but I’m in the middle of a problem with my Stage 2 LPFP falling on it’s face when pushed hard. But I’m curious to know more about these turbos upgraded internals, and haven’t found much online. Thanks for a great article.

    1. There are a few things that go into this and it’s known as a sequential turbocharging. It probably wouldn’t work too well on the N54 and here’s why:

      The turbos are powered by two banks. Bank 1 is cylinders 1-3 and bank 2 is cylinders 4-6. It’s not a problem to spool small turbos with 3 cylinders. So let’s say the bank 1 turbo is a stock N54 turbo. It’s going to build boost pretty quickly at low RPM’s but it won’t be a lot (roughly half of what it would be with two stock turbos). Now, you’ve got a big turbo on bank 2. It would only be powered by 3 cylinders and that’s going to be really really hard to spool it up. Overall, I think you’d get a terrible powerband. That’s all beside the fact you’re subjecting the engine to un-even amounts of heat, stress, back-pressures, etc.

      I think to do it properly you’d need a single exhaust manifold with some sort of valve to direct air-flow to either the smaller or larger turbo. There would need to be tons of time, research, and money invested into something like that. If it could even be done with the space we have in the engine bay.

      Best Regards,
      BMW Tuning

  2. hey zack,
    I have E92 335i DCT,
    all FBO and 7.5 intercooler.
    in my country there is no such a thing called e85 and the selling of meth is prohibited for normal people,
    my goal is to make 600whp
    which is the best way to get there
    RB GF 19t
    MMP1k
    Pure stage 2 HF
    DAW s4
    speedtech 6266
    speedtech 6466

    my goal is 600whp on 91 oct ( 95 ron ) or at least the closest i cant get economically.
    (for example if a single turbo can get me around 30whp more for an extra 1k is not worth it for me.)

    if i cant get 600whp what i can normally get on 91 oct with all of the above.

    or should i just switch platform to s55 or b58. to get that 600whp

    1. Hi Moto,

      Yikes. It’s always a tough decision without access to E85 or methanol injection. It’s going to be really really hard to make 600whp on 91 octane. With 91 octane I think a 6466 single would be your best bet but that might even struggle to hit 600whp on 91 octane. You’re also adding a lot of risk of blowing the motor on straight 91 octane so I think you’re probably better suited to 525-550whp.

      It’s unfortunate but the N54 loves octane and it struggles without it. If you prefer the TT options you could probably hit somewhere around 525-540whp. I just got RB Twos Plus on my car and love the RBs so my personal preference would be the GF 19Ts. I believe someone made like 580whp on GF 19Ts at 25psi on 93 octane. Pure Stage 2 HF is a great option, too.

      Ultimately, a 6466 is going to be the best option for power. A 6266 would probably struggle to clip much over 550whp, but I wouldn’t feel comfortable pushing the N54 much beyond 550whp on 91 octane anyways. Hope this helps. If you can find any means of getting access to E85 or meth injection you’ll have no problem hitting 600whp with the options you listed.

      Best Regards,
      Zach

  3. Thanks Zak. I’ve read there is a great tuner guru at Wedge. That’s the route I’ll take. Just want a fun fast daily drive. I’ll keep you posted. Take care, be safe.

  4. Hi Zach,
    Awesome article spelling out almost everything about the N54 turbo puzzle.
    Although there seems to be a lot of scattered information about BOM/tuning.
    There is no real step by step priority guide in coordination of importance.
    Main main goal was to fix it up gradually and drive it.
    BUT – but the smoke was so bad it could decimate the neighborhood squirrel population.
    For example, I purchased a ‘cheap’ 2009 E93 and have completed the engine PM:
    – new oil filter housing gasket
    – new belt by previous owner
    – valve cover gasket by previous owner
    – intake valve chemical cleaning
    – upgraded PVC
    – upgraded all vacuum lines
    – new pvc plastic pipe
    – new front plastic pipe
    – new spark plugs
    – new coils
    – new fuel injector seals (index 5 – probably should upgrade to index 12 – costly)
    – new battery
    – used MHD app and INPA to systematically troubleshoot and get rid of the errors
    – drop down test – good
    – compression test – good
    Currently
    – oil pan gasket has been replaced by previous owner
    – replacing turbos with TD04/17t with silicon 2″ inlets
    – replacing water pump/thermo and all coolant hoses while sub-frame off
    – replacing motor mounts
    After everything is sorted and buttoned up and the car starts and runs (hopefully), now what?
    From all the articles, tuning will be needed, but who, what, where?
    As you assume a boatload of cash has sailed out to sea.
    I just now want to drive the dang car and stop the bleeding before summer is over!
    Kind regards,
    Pat

    1. Hi Pat,

      What are your goals with the upgraded turbos? There are multiple ways to go about tuning. We recommend custom tunes for upgraded turbos if you’re looking to dial things in to your particular setup and engine. However, there are some excellent off-the-shelf (OTS) options as well. MHD OTS tunes are designed for stock turbos. If you want an OTS solution you’d be looking at a JB4 along with an MHD or BB back-end flash map. You could also stack the JB4 with a custom back-end flash map.

      The cheapest route for you is likely opting for a custom tune since you already have the MHD software. Twisted Tuning, Motiv, and Wedge/BQ are a few custom tuning options, and there are a handful of others around.

      Best Regards,
      Zach

  5. Firstly, I’d like to say the articles on this site are very informative and the delivery of said information is efficient and easy to digest. I’m relatively new to the performance modification world and I’ve tried to read up on the subject which lead me to your write up on N54 Turbo Options. The article has been greatly beneficial as has the information provided by the readers in the comment section. I wanted to ask your advice on how to best achieve my goal if I may. I currently own a 2008 535i with 160k miles with stock turbos. I’m assuming i’m at or near the end of the turbos’ lifespan and will need to replace them at some point in the near future. I thought it’d be a good opportunity to upgrade. Aside from ensuring the maintenance pieces i.e gaskets, seals, plugs & coils, etc. are up to par, I wanted to ask what your thoughts are on what the best configuration would be if my goal was to have a comfortable 500whp on tap with standard run of the mill pump gas or even if it’s possible. What I mean by “comfortable” is that the added stress on the supporting components from the increase in power isn’t at a level where they are constantly on the brink of destruction i.e transmission etc. Based on what I’ve gathered (please point me in the right direction if I’m off target) I would probably need the typical bolt ons such as catless downpipes, charge pipe & BOV, intake, and FMIC to go along with RB Twos or RB Next Gen turbos and a tune. Would you believe it necessary to get inlets & outlets as well? And in regards to the FMIC, would a 5″ stepped be sufficient or would a 7.5″ be more suitable for my goal? My apologies for the long winded question. Any insight would be greatly appreciated.

    1. Hi Elias,

      We appreciate the kind words. The standard bolt-ons you mention are a great starting point. I’d say a 5″ stepped intercooler would suffice if you were looking to make the power on meth and/or E85. However, on pump gas you’re going to need more turbo and more boost. As such, you’re likely best suited to a larger 7.5″ IC. We highly highly recommend opting for inlets & outlets with upgraded turbos. I believe inlets will actually be required, and outlets may be required depending on specifically which turbo option you decide on. An LPFP shouldn’t be required unless your fueling system is tired. However, it’s something to consider too.

      RB has since updated their turbo options a little bit (we’ve been meaning to update the post). RB Twos are good for about 525whp though they can be pushed a bit further. However, those numbers are assuming an E85 mix and/or meth. On pump gas – depending on whether you’re ACN91, 91, or 93 octane – the RB Twos will likely be best suited to ~425-475whp. I think you’d probably be looking at RB Twos Plus which are good for about 525-575whp on E85. These turbos have actually been pushed north of 600whp. With proper tuning on 93+ pump gas they should make 500whp.

      Finally, if you really want the “safest” option to make 500whp on pump gas you’re looking at moving into true TD-04 turbos. These will be the RB Game Finishers and they will make 500+whp on pump gas all day. However, these size turbos are starting to get into the area where some think they’re too laggy. That’s also part of the reason they’re “safer”, though. TD-04 turbos will shift the power right, result in lower manifold back pressure, and make more power with less boost when compared to the previously mentioned turbos.

      Ultimately, I would recommend either the RB Twos Plus or Game Finishers. It’s just a matter of your personal preference. The RB Twos Plus will get the job done (or at least get you in the ballpark of your goal) and retain closer to OEM-like spool. Game Finishers will make 500whp all day with tons of breathing room if you want to turn things up in the future, and they’re also a bit easier on the engine and transmission. However, that comes at the cost of less low-end torque. Another option is running E50+ fuel or meth injection and opting for RB Twos or RB Twos Plus, which will both make 500+whp with proper fueling.

      You’re welcome to give me a call at 832-443-1506 (Zach) anytime if you would like to discuss further. Rob Beck (RB turbos) is also a great guy and he would also be able to talk through your goals and discuss what the best turbo options are for your goals and planned mods/fueling.

      Best Regards,
      Zach

      1. I really appreciate the highly detailed feedback. You’ve provided me with a more informed position as I consider which way to go. Thank you.

  6. hey … i keep landing on your blog and im happy i found it b/c u seem to know what ur talking about and write your articles very well. i usually hate reading blogs b/c it’s a waste of time, but yours is not.

    Anyway i was reading your twins vs single n54 post and you mentioned how ‘engines don’t like torque’ … the other person i heard say this was Jake Spence.

    I am always trying to expand my knowledge and i was hoping you could explain this concept a little more? i don’t really comprehend how and engine doesn’t like torque?

    my current goal (i’m bone stock n54) is to really just bring this car to life but in a ‘factory’ type way. so currently thinking def, intercooler, downpipes, intakes … but i was also kind of really thinking of a ST kit because i don’t like internal wastegates.

    no matter what it will be a DD for now and from reading it seems like going over 500whp you have to start doing bigger mods. i think i’d be happy with 350-450whp tbh .. however one of the uncertainties to me is this ‘instant torque” situation … that could potentially push me into ST turbo territory if it’s a huge concern.

    1. Hi Paul,

      We appreciate the kind words, and are glad you’ve found some of our content helpful. More than happy to expand on the torque comments. Before diving into that…your goals of 350-450whp are modest. The N54 is a pretty strong, resilient engine. On stock twins at 400-450whp you’re likely not making much over 450wtq. The instantaneous low-end torque really only becomes concerning as you push beyond ~550wtq.

      So there are two primary pieces to this. 1) Torque itself and 2) low-end torque. I’ll break this down below.

      1) Torque is the actual twisting force (the piston being forced downward by the combustion stroke, and in turn rotating the crankshaft). All else constant, in order to create a greater force you need a more “powerful” combustion stroke. Therefore, torque is a more important measure than horsepower when you consider how much stress you’re subjecting the engine to.
      HP = Torque x RPM / 5252
      Let’s say you have two cars each making 600wtq peak. Let’s further assume on smaller twin turbos your peak power occurs at 5,500 RPM’s while torque is at 600 (torque then quickly drops off).
      600 torque x 5,500 RPM’s / 5252 = 628whp
      Now, take the large single turbo that makes 600wtq at 7,000 RPM’s (you need a big turbo to flow enough air on the top-end)
      600 torque x 7,000 RPM’s = 799.7whp

      Both engines are subjected to roughly the same stress with a peak torque of 600wtq. However, the engine that carries that torque further in the rev range is going to make bigger power.

      2) I think we touched on this briefly in the post. At lower engine speeds the pistons are moving slower. This creates a larger window during the compression stroke to which the engine is subjected to the high boosted pressures. Likewise, it’s a larger window for a potential pre-detonation event to occur. If pre-detonation occurs you have a piston that’s coming up no matter what, but you now have a combustion with extreme forces trying to push the piston downwards. That’s a recipe for bent rods as you have opposite forces.

      I know this wasn’t the best explanation as there’s a lot that goes into it. It could definitely be a long post by itself. We love writing about this kind of stuff, so it’s something we will definitely consider writing about more in-depth. We’re always happy to chat further on the phone or via e-mail if you ever have any questions or just want to chat. Zj@bmwtuning.co or 832-443-1506 (Zach).

      Best Regards,
      Zach

  7. This guide would benefit by discussing placement of the torque curve (more), and additionally what benefits torque gains and where. Personally, I’m looking to keep the torque curve more or less where it is, more hp at higher rpm is secondary.

    1. Hello,

      We appreciate the feedback. This post does need some updating anyways, as RB has since changed their product line a bit. All else equal, larger and larger turbos are going to push the torque and power further right. It’s tough to get perfect comparisons for all of the turbo options since mods, tunes, dynos, etc are going to be different. Additionally, the RPM’s at which the dyno pull begins are important and that often varies, too.

      TD-03 options are really the only way to keep a very similar torque curve to OEM turbos. RB ones would probably be the best option to retain spool and low-end torque. While they can make over 500whp they’re really best suited to the 450-475whp range. They’re going to make that power much more reliably than OEM turbos and also provide benefits on the top-end. It’s just tough to make THAT much more power and torque than OEM turbos without sacrificing at least a little bit of spool. If you want more than 500whp you’re going to have to sacrifice some spool. Some vendors and manufacturers will have you believe their turbos can make 600whp with OEM-like spool and it’s simply not true.

      https://www.bimmerboost.com/content.php?2866-stock-vs-RB-vs-single-dyno-comparison

      The above link shows a good comparison. The first dyno is OEM turbos maxed out compared to RB’s. This was back in 2012 so the offerings were a bit different but those RB’s would be similar to the RB ones. You can see spool is very similar, but the RBs pick up bigger numbers on the top-end. It looks like the RB’s also started at slightly lower RPM’s and were running much richer AFR’s on the low end. The richer AFR’s actually work against the RB’s since running leaner generally helps with turbo spool.

      RB Twos are also going to have good spool and a very similar curve to OEM while making a reliable 500-525whp. I believe people have pushed these turbos over 550whp (I know the RB Twos Plus have been pushed past 600whp), though it’s definitely not recommended. The RB ones, RB twos, and RB twos plus are all TD-03 turbos so they’re going to be closest to OEM. However, within that group, RB ones will be closest, RB Twos will sacrifice a bit more spool, and Twos Plus will sacrifice even more spool. They’re still going to be closer to OEM spool than TD-04 or single turbos.

      It really boils down to a simple trade-off. If you want to stay as close to OEM spool as possible then you’re going to have to opt for smaller upgraded turbos that simply won’t make huge power numbers. If you want to make a reliable 550-600+whp then you’re going to have to sacrifice at least some spool.

      Best Regards,
      BMWTuning

  8. Hello
    This might seem like a dumb question but can you give me a few options for aftermarket axles and a LSD for a 600whp 335i? I have looked online have seen many options but cant decide on one.
    Amazing post and great detail.
    Thanks