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We'll break this B58 FAQ guide into the following sections:
- General B58 Info
- B58 Standard Maintenance
- Common B58 Problems & Reliability
- B58 Tuning & Mods
*We will likely continue adding to this post over time. Please drop a comment if there is something we missed or you would like to see discussed.
BMW B58 General Information FAQ's
Below is some general FAQ's including specs, design, and more about the BMW B58 engine.
What is the BMW B58?
BMW's B58 engine is a 3.0L inline-6 turbocharged, direct injection gasoline engine produced from 2016-present. As with the N55, the B58 engine uses a single twin-scroll turbocharger. Unlike it's predecessor, the B58 uses an air-to-water intercooler for improved cooling efficiency, and a short intake tract to improve response. So far, the B58 won four Ward's 10 Best Engine awards.
What BMW's use the B58 Engine?
The BMW B58 engine is found in the following models:
- 2016-2019 M140i
- 2016-present M240i
- 2016-present 340i
- 2019-present M340i
- 2016-present 440i
- 2020-present M440i
- 2020-present M440i
- 2017-present 540i
- 2017-present 640i
- 2016-2019 740i / 740Li
- 2020-present 740i
- 2020-present 840i
- 2017-present X3 M40i
- 2017-present X4 M40i
- 2018-present X5 40i
- 2020-present X6 40i
- 2018-present X7 40i
- 2018-present Z4 M40i
How Much Horsepower (HP) Does the B58 Have?
The B58 horsepower ranges from 320-382hp straight from the factory. 340i and 440i models received the 320hp variant with 332 lb/ft of torque. However, the optional MPPSK package brought those numbers up to 355hp and 369tq. In 2018, the B58 received a technical update known as the B58TU1. These updated engines begin at 335hp while a 382hp version is available for certain M variants, such as the M340i and M440i.
Does the B58 Have Forged Internals?
Yes, the B58 crank and rods are forged. The B58 crankshaft is made of forged steel. BMW's B58 engine also uses drop-forged cracked connecting rods. Don't panic about the cracked part. It's actually a solid process for designing rods. The connecting rods are actually made in one piece. Then the rod eye is cracked in two which ensures a precise fit. The pistons are cast, but remain strong.
How Many Miles Will the B58 Last?
How long an engine will last is always a tough topic. There's no right answer, but in general the B58 should last as long as you're willing to continue repairs and standard maintenance. The internals and design are plenty strong to surpass 200,000 miles.
What is the B58 Compression Ratio?
11.0:1. This is an increase over the 10.2:1 compression shared between the N54 and N55. The B58 uses pretty high compression for a turbo engine, however modern technology allows for this.
How Many Valves Does the B58 Have?
The B58 has 24 valves. It is an inline-6 double overhead cam (DOHC) engine. This means each cylinder uses 2 exhaust and 2 intake valves for a total of 24 valves.
How Fast is the BMW B58?
Most are limited to 155mph from the factory. Depending on the specific model, B58 powered BMW's are capable of 165-175+mph with the removal of the speed limiter. Speeds upwards of 180-190mph are possible with tunes and bolt-ons. However, it's going to take a lot of road to reach those speeds.
How Many Turbos Does the B58 Have?
The B58 uses a single twin-scroll turbo. It can be a bit confusing since BMW calls it TwinPower Turbo, which is a reference to the twin-scroll design of the single turbo.
BMW B58 Standard Maintenance FAQ's
*We will focus specifically on the engine for the purpose of this post. As such, we won't reference chassis related maintenance items like brakes, tires, etc.
What Are the Common B58 Standard Maintenance Items?
A few common B58 standard maintenance items include:
- Fluids (oil & coolant)
- Spark plugs & ignition coils
- Walnut blasting (intake valve cleaning)
We'll touch more on these standard maintenance items in the rest of this section. Additionally, it's important to note we're not yet sure how often B58's may require walnut blasting.
How Much Oil Does the B58 Hold? What is the B58 Oil Capacity?
The B58 holds 6.9 quarts (~6.5L) of engine oil. This is the exact same as the N54 and N55 engines.
What Oil Weights Are Approved on the B58?
The recommended oil weight from BMW is 0W-20. They also recommend using an LL-14 FE+ approved fuel. However, LL14FE oils are designed with fuel economy in mind. LL01 approved oils will also work well on the B58. Ultimately, 0W-20, 0W-30, 5W-20, and 5W-30 will all work well. Some B58 owners even opt to run 0W-40 or 5W-40.
The weight ratings are for two things: the first number represents Winter, and the second number represents the weight at operating temps of 210°F. We recommend running a 0W-30 weight oil on the B58. However, those in hot climates may be better suited to 5W-30.
What is the Best Oil for the B58?
We recommend Liqui Moly oil products for the B58. That's what we've run on all of our BMW's with great success. It's a quality oil for a good price. However, there are many other excellent brands of engine oil for the B58.
How Often to Change B58 Oil? Recommended B58 Oil Change Interval
B58 oil changes should be done every 5,000-8,000 miles, or once a year - whichever comes first. Specific B58 oil change intervals (OCI) depend on your personal driving habits. Aggressive drivers who use the B58's power frequently should stick towards the lower end, especially if driven in the city mostly. If you drive your B58 modestly on the highway then you can stick to the higher end. Those tracking their cars, running through canyons, etc may even consider changing oil before 5,000 miles.
Ultimately, BMW recommends oil changes every 10,000 miles. You're not going to blow the motor up if you make it to that mark. However, we think it's a bit too long between oil changes. Use your own judgement, but we always use 5,000 to 6,000 mile OCI's.
What is the Best Coolant/Water Mix on the B58?
We recommend a 50/50 mix of water and coolant for the B58. Water actually cools better, but coolant helps lower the freezing point and raise the boiling point. Coolant also helps prevent corrosion. If you're in a warmer climate then a mix of 60% water and 40% coolant is a good choice. Some B58's may even run up to 70-80% water for track duty. Again, water is actually more effective at cooling. However, be cautious of using too much water in colder climates.
Is B58 Coolant Really Lifetime?
BMW considers coolant to be a lifetime fluid. We don't really love that idea. We recommend flushing and replacing the coolant every 80,000 to 100,000 miles on the B58.
How Often to Change B58 Spark Plugs?
As with many turbo BMW engines the B58 loves to burn through spark plugs. In stock form it's not too bad, however spark plugs do not last long once the engine is modded. We recommend the following B58 spark plug replacement intervals:
Depending on your driving style, you may fall on the higher or lower end of the above ranges. Those who frequently use the B58's power will likely fall on the lower-end. Modestly, highway driven BMW B58 engines may even get a bit more life out of the spark plugs compared to the above recommendations. Spark plugs are a standard maintenance wear and tear item. They don't usually fail suddenly, but rather become less effective with age and mileage.
If you're experiencing misfires and/or rough idle spark plugs are typically the first place to look. Don't overlook this basic maintenance item on the B58.
What B58 Spark Plugs are Best?
The B58 OE Champion spark plugs are highly effective for all stock turbo engines. Normally, we recommend colder spark plugs on highly modded BMW engines. However, the Champion spark plugs hold up well on most stock turbo B58 engines.
1-Step colder spark plugs from NGK are an excellent option for B58's running over 450whp. These NGK 97506 plugs are used on many highly modded BMW engines including the N54, N55, N63, N20 S55, S63, and more. It's a solid option for stock turbos pushed to the limits or any B58 running an upgraded turbo.
Why Run Colder Spark Plugs on a Modded B58?
Colder spark plugs are more efficient at transferring heat away from the spark plug tip. Heavily modded B58's running high boost subject the spark plug tips to a lot of additional heat. This may cause misfires or engine knocks. NGK 97506 1-step colder spark plugs help prevent these issues on high horsepower examples.
How Often to Change B58 Ignition Coils?
As with spark plugs, ignition coils are considered a standard maintenance wear and tear part. Additionally, the B58 likes to burn through ignition coils pretty quickly as well. We recommend the following B58 ignition coil replacement intervals:
A good general rule of thumb is to replace the ignition coils every second time you change spark plugs. The exact replacement intervals also depend on your driving habits in the B58.
What is B58 Walnut Blasting?
Ahhh...walnut blasting. As avid N54 enthusiasts this is one of our favorite topics. Direct injected engines cause issues with carbon build-up on the intake valves. Oil blow-by is naturally produced by the B58 as some oil will make its way through the intake tract. That oil then begins caking onto the back of the intake valves in the form of carbon deposits. This of course restricts airflow into the engine. It's simply due to the nature of direct injected engines. Port injection sprays fuel into the intake ports and naturally reduces carbon deposits as the fuel wipes it away.
Now, there is good news. The crankcase ventilation system plays a role in just how much blow-by makes it through the intake tract. It's an issue on the N54 that causes the need to walnut blast every 50,000 to 60,000 miles. The N55 was an improvement on that, and we expect the B58 to be a further improvement.
Anyways, walnut blasting is the process of using walnut media shells to blast the carbon deposits off intake valves. All direct injected engines will likely need this at some point. Time will tell how often it's necessary on the B58.
Is Walnut Blasting Needed for the B58?
Probably. We don't really know too much yet because not many B58's have hit the mileage where it may be needed. As we discussed briefly above, the N55 was an improvement over the N54. The N55 only requires walnut blasting every 80,000'ish miles. Even then, it's not truly needed. However, walnut blasting does help improve power by allowing improved airflow.
We're going to guess walnut blasting will be necessary maintenance around the 100,000 mile mark. You can likely stretch that further. However, time will tell just how bad the valves look around the 100,000+ mile mark.
How Expensive is B58 Standard Maintenance?
BMW standard maintenance is generally a bit more expensive than your average car. That's beside the fact most B58 powered BMW's are mid-range cars relative to their line-up. Turbo engines are also a bit more demanding on standard maintenance. Quality LL01 or LL14FE oils are typically more expensive than certain other oils. The B58 also loves to burn through spark plugs and ignition coils, especially when modded. Point is, standard maintenance isn't cheap. It's also not terribly expensive, especially for the DIY crowd. Expect the following B58 standard maintenance costs:
- Oil & Filter Changes: $60-100
- Spark Plugs: $119-135
- Ignition Coils: $249-$319
- Walnut Blasting: $400-600
Add in some extra expenses if you plan to have any of the work done at a shop. Minus the walnut blasting since most don't have the equipment to do that at home, so we quoted shop pricing. All in all, it's not too bad. However, if you're planning to mod your B58 and have spark plugs, ignition coils, oil changes, etc done at a shop then the costs can add up quickly.
BMW B58 Common Engine Problem FAQ's
Is the B58 Reliable?
Yes. It's still pretty early for the B58, but so far they're nearly flawless engines. The N54 is well known for being a pretty unreliable car. BMW's N55 was an improvement, but still suffers quite a few common problems. However - to date - the B58 is shaping up to be a highly reliable engine.
Yes, Toyota slightly tweaked the B58's design for use in the Supra. However, we believe Toyota opting to use the B58 says a lot.
What Are the Most Common B58 Engine Problems?
We wrote an article here about the most common problems on the B58. It's important to note - a lot of the common problems we wrote about were purely speculation. No engine is perfect and no engine is exempt from potential problems. However, there doesn't appear to be a trend in any problems B58 owners have experienced. Miscellaneous issues are scattered here and there. Nothing seems to indicate any major design flaws with the B58.
How Expensive is the BMW B58 to Own?
It's tough to say. We broke down the rough engine maintenance costs above. Outside of that, engine problems are still rather unknown and uncommon. Again, the B58 seems to be highly reliable in its early days. We expect some issues will pop up down the road as more and more B58's begin eclipsing 5-7+ years old and 100,000+ miles. Look for things like cooling system problems and gasket oil leaks. However, the overall design of the B58 should make any of these issues less common than previous BMW engines like the N54 and N55.
Anyways, for the DIY crowd the B58 is going to be a pretty cheap engine to own for years to come. Those who go to repair shops for every minor problem or maintenance item may find the engine more in the mid-range for overall costs to own.
Why is My B58 Idling Rough?
Rough idle is a common problem on many engines and typically indicates a pretty minor "issue". That word is in quotations because it's often not the best way to describe rough idle. Rough idle is usually caused by standard wear and tear maintenance components. If your B58 is idling rough then consider the following:
- Spark plugs
- Ignition coils
- VANOS solenoids
- Dirty intake valves (walnut blast needed)
With the current age of the B58 you'll likely find the rough idle is caused by old, worn spark plugs or ignition coils. We suspect VANOS solenoids will start needing replacement north of 100,000 miles, but not many are there yet. The same can be said for walnut blasting.
BMW B58 Tuning & Modding FAQ's
What is the Best B58 Tune?
There is no perfect answer to this. Tons of tuning options exist for the B58. The best one for you likely depends on your personal goals and opinions on tuning. However, we recommend starting with one of the following B58 tunes:
- bm3 (bootmod3)
These are three of the most common off-the-shelf (OTS) tuning options for the B58. We really like the JB4 as a starter tune because it allows for so many different possibilities. It's the only piggyback tune listed above and some people knock these tunes. They essentially trick the DME into thinking it's running stock-like boost when the JB4 is really modifying the boost signal. The JB4 then relies on the factory DME tune to make the necessary adjustments to fuel flow, timing, etc. As such, the JB4 is limited by the parameters built into the stock DME. However, the JB4 can be stacked with a flash tune, known as a back-end flash. We'll discuss this more in the next question below.
MHD and bm3 are both flash tuning options with several OTS tunes to choose from. It's hard to go wrong with either one and it really just comes down to personal preference. Anyways, we ultimately recommend the JB4 and we'll dive into that more.
Is the JB4 a Good Tune for the B58?
Again, we absolutely love the JB4. Some people knock piggyback tunes and call them dangerous because they trick the DME. That is far from the truth. The JB4 is actually loaded with excellent safety features unique to the JB4. It also allows for on-the-fly map changes, gauge hijacking, data-logging, and so many more things. Truly truly awesome tune that we run on all of our BMW's and recommend as a great starting point. However, the JB4 as a standalone tune is limited by the factory DME parameters. Enter the JB4 + back-end flash option.
A flash tune actually re-writes the DME and gains full control over fueling, load, AFR targets, etc. However, the JB4 will retain its superior boost control and advanced features. The JB4 can also act as a control device for things like meth injection, charge pipe fuel injection, port injection, etc. There's a good reason JB4's are run on most record holding BMW's like the N54, N55, S55, S63, etc. We truly believe a JB4 + BEF is the ultimate tuning solution.
How Much Horsepower Can a Stock Turbo B58 Make?
~480-500whp. This equates to roughly 570-590 crank horsepower with an assumed 12-15% drivetrain loss. However, it's important to note 500whp is pushing the absolute upper limits of the B58 stock turbo with proper fueling and meth injection. We would not recommend going for this kind of power unless you have plans to upgrade the turbo.
Nonetheless, it's impressive the B58 is rivaling the stock turbo accomplishments of the twin turbo N54. It's also doing so with greater overall reliability.
How Much Torque Can a Stock Turbo B58 Make?
~500-525wtq. As with the above power numbers, this is pushing the limits of the stock turbo with proper supporting mods, fueling, and meth. It's a lot of torque for a factory single turbo bolted to a 3.0L inline 6. Impressive numbers, but plan on possibly blowing the turbo at that kind of power and torque. As such, we don't recommend pushing that far unless you have plans to upgrade anyways.
What Does FBO B58 Mean? What does FBO Stand For?
FBO B58 means full bolt-on B58. Typically, FBO on the B58 refers to a tune, intake, and downpipe. Normally, we would include an intercooler in the definition of FBO. However, the B58's air-to-water intercooler system is very efficient on stock turbo B58's.
What is the Max Boost on B58 Stock Turbo?
We wrote a short post about the max boost here. Expect about 20-21psi to be a safe limit for the stock turbo. However, some B58 stock turbos have been pushed beyond 23psi. Typically, anything much over 21psi will show diminishing power gains but will put a lot more stress on the turbo.
What is the Best B58 Catless Downpipe?
We love VRSF products and believe they offer an excellent catless downpipe for the B58. Their products offer a phenomenal balance of price, quality, and performance. Look no further.
How Loud Are B58 Catless Downpipes?
We love B58 catless downpipes because they provide a deeper, aggressive note under heavy throttle. You'll also notice a bit more sound on cold starts. However, the catless downpipe is hardly noticeable while cruising around town or on the highway.
It's a good balance, in our opinion. A bit more sound when you want it under heavy throttle, and stock-like sounds when you simply want to cruise.
How Much Horsepower Does a B58 Catless Downpipe Add?
Expect gains in the ballpark of 15-30whp with a catless downpipe. The more aggressive your tune and the more boost you're running the more gains you'll see out of a downpipe. Check out our B58 downpipe guide for more info.
What is the Best B58 Performance Intake?
Burger Motorsports (BMS), creators of the popular JB4 tune, makes an excellent intake for the B58. We recommend opting for an open intake like the BMS option. Don't worry - the "hot air intake" myth has been debunked many times. Since the BMW B58 uses an intercooler the temperature of the air entering the intake does not matter much.
What Are the Limits on Stock Internal B58 Engines?
Good question, and there is no perfect answer. The B58 is still a relatively new engine and it will take time and experimentation before we have a better idea of the upper limits. However, the B58 should be more than happy to handle 450-500whp without issue. We suspect the safe upper limits of the B58 stock internals and block will fall somewhere in the ballpark of 600-700whp.
Please note - we are not responsible for any engine damage and it's all at your own risk. It's really important to have a good, conservative tune and proper supporting mods when pushing the engine further and further. Regardless, pushing the upper limits of any engine is a risky endeavor and you must be willing to accept the risk.
It's a vague answer, but there's really no perfect answer. Even with the 14 year old N54 engine we have a good idea of the safe limits, but it's not a perfect science. Some let go at 500whp while others hold up for years at 700whp. The same will apply to the BMW B58.
**Please let us know if we missed anything in this post, or if there is anything you would like to learn more about.