BMW N20 FAQ
Meet Zach
Zach is a BMW enthusiast with a passion for performance. With over 10 years of experience modifying and performing DIY work on BMWs, he’s developed a deep understanding of virtually every BMW engine. He’s also the proud owner of a 600whp N54 with upgraded twin turbos and an E30 325i drift car and has a particular affinity for the S58 engine. Zach is highly knowledgeable about all things BMW, but his expertise in tuning and performance mods sets him apart. His experience as an enthusiast, combined with his technical knowledge, makes him an essential resource for anyone looking to improve the performance of their BMW.
In this article we’ll simply dive into a bunch of various questions and answers about the BMW N20 engine.
If you are interested in learning more about the BMW N20 engine, take a look at our N20 Engine Page which covers everything from specs to popular performance mods to common problems.
Let us know in the comments if there is anything we miss or that you’d like to see more info regarding. Use the following keys to search for a specific topic:
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We will break this N20 FAQ guide into the following topics:
- N20 General Info
- N20 Standard Maintenance
- Common N20 Engine Problems & Reliability
- N20 Tuning & Mods
BMW N20 General FAQs
What is the BMW N20 Engine?
The N20 is a 2.0L inline-4 single turbo engine that replaced the naturally aspirated 3.0L N52/N53. It also features dual VANOS, valvetronic, and direct injection. These are all pretty standard specs for most modern BMW engines. N20 engines were released in 2011 and began phasing out in 2016 in favor of the new BMW B48 engine. As a final note – the N20 is closely related to the larger N55 3.0L single turbo engine.
What BMW’s use the N20?
The N20 engine is in the following BMW models:
- 2013-2016 Z4 sDrive 18i / 20i / 28i
- 2013-2017 X3 sDrive 18i
- 2011-2015 X1 xDrive 20i
- 2011-2017 X3 xDrive 20i
- 2014-2016 220i / 228i
- 2012-2015 320i
- 2014-2016 420i / 428i
- 2011-2016 520i
- 2011-2016 328i
- 2012-2016 528i
- 2016-2018 X5 xDrive 40e
How Much Horsepower (HP) Does the N20 Have?
Stock N20 engines offer anywhere from 154 to 241 horsepower. The 18i models receive 154 horsepower while 20i models have 181 horsepower. BMW 28 models offer the most power with 241 hp. Torque ranges from 177 lb-ft to 258 lb-ft depending on the model.
All variants of the N20 engine are
Does the N20 Have Forged Internals?
BMW N20 engines do use a forged crankshaft. However, the rest of the internals are cast. Rods and rod bearings are the main weak points when increasing boost and power. We’ll dive into this more in the tuning & mods section.
How Many Miles Will the N20 Last?
Longevity is a tough topic for any engine and that applies to the N20, too. Theoretically the N20 will last as long as you’re willing to keep spending money on it. The BMW N20 engine internals should hold up to 200,000+ miles in many cases. Though, they aren’t the strongest engines internally so tuning and mods may reduce this number.
One major consideration is the amount of money required for maintenance and the age/value of the car. We’ll circle back to all of this in the common problems and reliability discussion. However, as the N20 ages then maintenance/repair costs may begin exceeding the value of the car.
What is the BMW N20’s Compression Ratio?
Most N20 engines use a 10:1 compression ratio. However, some of the less powerful variants found in 18i and 20i models actually use an 11:1 compression ratio.
What is the N20 Bore x Stroke?
The bore and stroke of the N20 engine is 84mm x 90.1mm (3.31″ x 3.55″). This makes the N20 an undersquare engine design. It’s a design that generally favors torque, especially low-end torque, rather than peak power.
How Fast is the N20?
A majority of N20 engines are electronically limited to a top speed of 130mph. When removed top speed can vary quite a bit by model. Something like an X3 likely won’t achieve the same top speeds as a 228i. Weight doesn’t play a big role, but rather the aerodynamics of a smaller car will help with top speed.
Anyways, removing the speed limiter will result in top speeds around 150-160mph on most BMW N20 models. Speeds upwards of or exceeding 170mph may be possible with tunes and other mods.
How Many Turbos Does the N20 Use?
BMW uses the term “TwinPower Turbo” for engines like the N20. It doesn’t mean the engine is actually twin turbo. The N20 utilizes a single twin-scroll turbo. You can learn more about the term TwinPower Turbo here.
N20 Standard Maintenance FAQ
*As an important note – we’re focusing on the BMW N20 engine for the purposes of this article. As such, we are not covering chassis or other non-engine maintenance items like brakes, brake fluid, tires, etc.
What Are N20 Standard Maintenance Items?
Some standard maintenance items for the N20 2.0L inline-4 engine include:
- Fluids (oil + coolant)
- Walnut blasting
- Spark plugs & ignition coils
Again, we’re looking at the engine here so other maintenance should be taken into consideration. Anyways, there really aren’t too many standard maintenance items for the BMW N20. We’ll break down the above info into further FAQ’s.
How Much Oil Does the N20 Hold? What is N20 Oil Capacity?
N20 engine oil capacity is 5 liters (5.3 quarts).
What Oil Weights Are Approved in the N20?
BMW N20 engines originally used 5W-30 oil from the factory. That was eventually changed to 0W20 to improve fuel economy. Anyways, oil weights ranging from 0W20 to 5W40 are all solid oils for the N20.
Newer LL-14 and LL-17 oils target fuel economy improvements. However, for engine protection, we prefer the older LL01 oils. All of these options are acceptable for the N20, and some simply comes down to personal preference.
What is the Best Oil for the BMW N20?
This is somewhat a subjective question. You can find all kinds of varying info on which oils truly offer the best protection. Most will likely deliver similar results as long as you’re sticking with well-known brands, LL approved oils, and proper weights.
We’ve always run Liqui Moly oils with great success. It’s not the highest quality oil, but Liqui Moly still delivers good quality for a fair price. Those tracking or pushing the limits of the N20 may consider pricier, high-end racing oils.
How Often to Change N20 Oil? N20 Oil Change Interval (OCI)
We recommend changing the engine oil on the BMW N20 every 5,000 to 8,000 miles. It’s also a good idea to change the oil every 12 months even if the mileage has not been exceeded. Specific oil change intervals also slightly depend on personal driving style and habits. Those who are mostly driving highway miles can likely get away with longer N20 OCI’s.
If you’re mostly driving in the city, often use the N20’s power, or idle the engine for longer periods then stick with the shorter end. Some may even change the oil before 5,000 miles. It’s not a bad idea if you’re pushing the N20 hard or taking it to the track.
What Is the Best N20 Coolant/Water Mix?
Generally, a 50/50 water and coolant mix is the best option for the N20 engine. The water actually offers better cooling benefits than the engine coolant itself. However, the coolant has many benefits of its own. Notably the fact it lowers the freezing point and increases the boiling point of the mix. It also helps prevent corrosion.
In warmer climates a higher water mix like 60% water and 40% coolant works well. It’s not uncommon to see some run 70-80% water for short periods when tracking the car. Definitely stick with a 50/50 mix if you’re in a climate subject to near or below freezing temps.
Is N20 Coolant Really a Lifetime Fluid?
BMW considers coolant to be a lifetime fluid. We don’t completely agree with this designation, and believe it’s a good idea to flush and replace the coolant every ~80,000 miles. For those who can DIY it’s a pretty easy and inexpensive job, so you might even consider changing the coolant sooner.
How Often to Change N20 Spark Plugs?
Most turbo BMW engines have a knack of burning through spark plugs. Spark plug life is already fairly low, and tuning/modding the BMW N20 can kill spark plugs even faster. We recommend the following N20 spark plug replacement intervals:
- Stock: 40,000 to 60,000 miles
- Modded: 15,000 to 25,000 miles
Exact spark plug life can depend on many factors, though. Your driving habits play a big role. If you’re using power and boost often then spark plugs will wear down quicker. Once tuning and adding bolt-ons to the N20 engine the spark plugs will likely only last about 15,000 to 25,000 miles.
What N20 Spark Plugs Are Best?
We’re big fans of the OEM N20 spark plugs. The engine actually uses NGK 97506 spark plugs from the factory. We recommend these exact spark plugs for almost any tuned BMW. They’re great on the N54, N55, N63, S55, etc.
How Often to Change N20 Ignition Coils?
Ignition coils also have a fairly short life in the N20 inline-4 turbo engine. We recommend the following intervals:
As with spark plugs, ignition coil wear depends on driving habits. Pushing the N20 harder will put more stress on the ignition system and result in faster wear.
What is N20 Walnut Blasting?
Walnut blasting is the process of cleaning the intake valves. Engines produce some oil blow-by that makes its way into the intact tract. Port injection helps prevent any oil deposits from forming. However, on direct injection engines – like the N20 – there is no fuel flowing over the intake ports and valves. Over time, carbon deposits form on the intake valves and begin restricting air-flow.
Anyways, walnut blasting involves a shop-vac and walnut media shells. This removes carbon deposits and help restore power, performance, and smoothness.
Do You Need to Walnut Blast the N20 Intake Valves?
It’s not absolutely required to walnut blast the BMW N20 intake valves. However, it’s good maintenance to knock out every 60,000 to 100,000 miles. Carbon build-up can cause a ton of drivability issues. Things like power loss, misfires, and rough idle are possible due to excess carbon build-up on N20 valves.
How Expensive is BMW N20 Maintenance?
Of course, maintenance on BMW engines can be a little more demanding and expensive than an average car. Turbo engines are also a bit more demanding on maintenance. The N20 likes to burn through spark plugs and ignition coils fairly quickly. Quality oils can be a bit more expensive than for an average car. In other words, the N20 isn’t going to be the cheapest engine around to own. Though, it’s generally pretty inexpensive compared to many other BMW engines.
- Oil & Filter: $50-100 every 5,000 to 8,000 miles
- Coolant: $30-200 every 80,000 miles
- Spark plugs: $60-90 every 15,000 to 60,000 miles
- Ignition coils: ~$160 every 25,000 to 90,000 miles
- Walnut blasting: ~$400-600 every 60,000 to 100,000 miles
Costs generally come in on the higher end if you’re having the work done at an independent repair shop. Those who insist on going to a BMW dealer will notice costs can be quite a bit higher. Overall, maintenance isn’t too demanding on the BMW N20 engine. It’s very reasonable for those capable and interested in DIY’ing some of it.
BMW N20 Reliability & Problems FAQ
Is the N20 Engine Reliable?
Yes and no. The N20 likely falls somewhere in the middle of the pack reliability wise. There are much less reliable BMW engines like the N54 and N63 which were made around the same era. N20 engines also likely have a reliability advantage over the N55 due to its smaller size.
However, we like the newer B48 engines if you’re looking for something more reliable. Anyways, the N20 offers solid reliability for a BMW but it is a BMW. Don’t expect the N20 to be a completely hassle free engine.
What Are the Most Common N20 Issues?
Timing chains are the main flaw with BMW N20 engines produced prior to 2015. BMW offered a 7 year, 70,000 mile warranty on the timing chain and components. However, it’s an expensive repair if you end up paying out of pocket. The new timing chain design has proven to be more reliable.
Otherwise, the N20 is prone to some standard BMW issues like the cooling system and gasket oil leaks. As these cars continue aging chances are you’ll run into a few oil leaks or cooling system problems.
How Expensive is the BMW N20 to Own?
N20’s are likely more expensive to own when compared to the average street car. Standard maintenance is reasonable, but mix in a few engines issues along the way and costs can add up. Simple oil leaks can cost $600+ to fix even when it’s a cheap $20 gasket thanks to labor.
The DIY crowd will definitely appreciate the savings by working on the N20 on their own. Those going to a repair shop for everything might become overwhelmed after a few repair bills. In essence, the N20 can be fairly inexpensive to own if you’re comfortable doing some work on your own but costs add up at shops.
Why is My N20 Idling Rough?
Rough idle and misfires can be a common issue on the N20 and many other modern turbo BMW engines. Fortunately, it’s usually small stuff that causes a rough idle. If your N20 is idling rough or misfiring consider the following parts:
- Spark plugs + ignition coils
- VANOS solenoid
- Carbon build-up
Plugs and coils are definitely among the most common causes of the N20 developing a rough idle. The VANOS system is another common area of trouble. Excess carbon build-up may also cause these symptoms. If you know the intake valves haven’t been walnut blasted for a long time it might be something to consider.
N20 Tuning & Mods FAQ’s
What is the Best BMW N20 Tune?
There isn’t a perfect answer to this question since it often comes down to personal preference. Tons of tuning options exist for the BMW N20 engine. Most importantly stick with a quality, trusted tune. Anyways, our favorite tuning options for the N20 are:
These are among the most common “off-the-shelf” tunes for the N20. They’re a great starting point and offer multiple maps/tunes depending on other mods. We really like the JB4 for its simplicity, but some prefer flash tunes like the bootmod3 (bm3) option. Again, tons of options exist and some of it simply comes down to personal preference.
How Much Power Can a Stock Turbo N20 Make?
Stock turbo BMW N20 engines can make just north of 325whp and about 350wtq. Not bad numbers for a few basic bolt-on mods.
How Much Boost Can the Stock Turbo Handle?
We wrote an in-depth post about this topic here. Long story short, we recommend keeping the boost around 20-22psi for turbo and engine longevity. The stock turbo can make upwards of 25-26psi, though.
What Does N20 FBO Mean?
FBO stands for full bolt-on. Generally the mods included in a FBO N20 are a tune, downpipe, FMIC, and intake. Turbos and many other parts are considered bolt-on mods, too. Some people have different definitions of FBO on the N20. Anyways, the previously mentioned mods are typically referred to as FBO.
What are the Best Mods For the BMW N20?
A few of the best basic bolt-on mods for the N20 include:
- Tune
- Downpipe
- FMIC
- Intake
This is a little repetitive with some of the above. We consider these mods FBO for stock turbo engines. Running these mods can help push the N20 around the 300whp ballpark. The N20 can be pushed further with additional mods, but anything much over 300-325whp and 350wtq is starting to push the limits of the engine.
What is the Best N20 Downpipe?
Our favorite bolt-on mods for just about any turbo BMW are from VRSF. We believe they offer an excellent balance of price, quality, and performance. It’s hard to go wrong with an N20 downpipe from VRSF.
What is the Best N20 FMIC?
As with the downpipe we highly recommend the VRSF FMIC options. They offer both a 5″ performance FMIC and 6.5″ competition FMIC. Most can likely get away with the 5″ option. However, if you intend to push the car hard – especially at the track or canyons – then the 6.5″ is probably a safe bet.
What are the Limits on N20 Stock Internals?
We also wrote an in-depth post on this topic. The N20 hasn’t earned the best reputation for strength. It’s generally sturdy up to about 325-350whp and similar torque. Anything much over that is starting to push the limits.
i have a 220i (n20) that has run rod bearings,after replacing the rod bearings i found that the oil heavilly gas contaminated after changing the oil and just running the engine for a short period of time, 15mins, The car has been tuned (not sure which level or option) i seem to be hearing knocking sounds again.
NB: oil pressure good, (new oil pump also fitted)