BMW N20 Tuning Guide – 350hp for $1,500

BMW’s N20 engine featured in the 228i, 328i, 428i, 528i, as well as other 28i variants, did not built up the greatest aftermarket and tuning reputation, as the engine has been touted as fragile. Although the N20 is not the strongest motor there is still plenty of power to be unleashed with a tune and basic bolt-ons. In stock form, the N20 was quoted right around 240hp and 258tq, however, independent testing in the real world shows the engine is stouter than BMW suggests. Dyno results place the actual numbers in the ballpark of 275hp and 290tq. A tune and a few basic mods, all for under $1,500, can boost the N20’s power and torque into the 350 range.

Before Tuning Your N20: Spark Plugs and Ignition Coils

Adding power to any engine typically brings forth issues that go un-noticed when the car is in stock form. Two of the most common problems that pop up when tuning your BMW engine are spark plugs and ignition coils. The newfound power requires a stronger spark to ignite the increased air/fuel mixture, and old, worn, or faulty spark plugs and coils cannot generate enough of a spark to fully burn the air and fuel.

Jake and I talk about spark plugs and ignition coils a lot as we both experienced the same thing on our N54 engines. We were so excited to install our tunes and a few bolt-ons, only to go out for the first drive with an engine that was running poorly. There was nothing worse than having to wait a week to get new spark plugs and ignition coils.

Typically spark plugs should be replaced on stock N20’s every 40,000 – 50,000 miles, and ignition coils every 50,000 – 60,000 miles. However, a tune and bolt-ons cut the life of these parts in half, roughly. If you know you have not replaced the N20 spark plugs or coils within the recommended time it may be a good idea to do so before tuning the engine. The OEM products can be found below:

N20 OEM Spark Plugs
N20 OEM Ignition Coils

Other Things to Consider Prior to Tuning

Spark plugs and ignition coils are not the only issues that may come to light after modifying your BMW N20. A few other things to look out for may include, but are not limited to:

  • Test and check for boost leaks
  • Compression Test
  • Suspension, brakes, and tires
  • Fuel system
  • Engine Fluids

Boost leaks may not be significant enough to create any issues on stock boost levels, however, with the increased boost a small leak may become more significant. A compression test will ensure your engine internals are running properly, and there are no serious internal issues that may pop up after tuning. With the increased power you will likely put more strain on your brakes, suspension, and tires so it is important these parts are ready to handle the task. Additionally, increased power will require increased fuel flow, and will subject the engine to additional heat.

Five BMW N20 Mods For 350 Horsepower

Without further ado, let’s jump in and discuss the five mods for your BMW N20 that will increase your horsepower and torque into the 330-350 range. A tune is the first and most obvious modification, followed by a few bolt-ons. These include an upgraded intake, front mount intercooler, and a catless downpipe. Typically, engines with these 4 mods are referred to as FBO, or Full Bolt-On. Some consider a full exhaust system an important part of being FBO, however, a catless downpipe is the most important exhaust component that will lead to the most significant increase. A full exhaust may net a few extra horsepower, which is insignificant compared to the cost. The fifth “mod” we recommend for the BMW N20 is a small mixture of E85 fuel.

Mod List for a 350HP BMW N20

1. Tune – JB4 Piggyback Tune

BMW N20 JB4 Flash TunerPin

Jake and I, along with many others in the turbo BMW community, run a JB4 on our BMW’s. The JB4 is a piggyback tune, which is a simple plug-and-play harness that installs directly on the ECU. This tune adds roughly 60hp to an otherwise stock BMW N20, and may add up to 100hp on a FBO N20 with a small E85 mixture. The JB4 tune sells for $479 brand new, and used tunes can be found for closer to $300. This mod is the best bang for the buck, and if you were going to only put one modification on your BMW N20 then we highly recommend a tune, and specifically the JB4. Another excellent feature is the ability to couple a back-end flash tune with the JB4. A back-end flash will net additional power due to having better control over fueling, timing, etc., while allowing the JB4 to function with its advanced boost control and safety features.

Price: $479 new, ~$300-350 used

Horsepower Gains: 60-100hp, depending on supporting mods

2. Catless Downpipe – VRSF 4.5” Downpipe

VRSF N20 DownpipePin

One of my personal favorite mods on my N54, a catless downpipe will not disappoint on the N20 either. The best exhaust on a turbocharged car is no exhaust after the turbo; for most of us, this likely is not practical for daily driving on public roads. The pressure drop from pre-turbo to post-turbo plays a significant role in allowing the turbocharger to spool and build boost. Removing the catalytic converter from the downpipe will increase horsepower and torque by 10-20. Additionally, a catless downpipe will allow the turbo to spool quicker, which means torque hits instantly and is a great feeling on the butt-dyno. Lastly, a catless downpipe produces a more aggressive exhaust note without sounding intrusive or droning during normal cruising. Lay into the throttle and it really brings the sound to life, however if you set cruise control on the highway the exhaust still sounds completely stock.

Price: $250

Horsepower Gains: 10-20, and faster turbo spool

3. Frount Mount Intercooler (FMIC) – VRSF 5” or 6.5”

N20 Upgraded IntercoolerPin

While peak power gains are not quite as impressive as the tune or catless downpipe this mod ensures consistent performance throughout the rev range by keeping IAT’s (intake air temps) down. Cooler IAT’s mean the N20 will produce more horsepower later in the rev range and prevent the turbos from heat soaking. On a hot summer day, you can feel the effects of heat soak on a stock intercooler; after a few wide-open throttle pulls you can really begin to notice the decrease in performance. Additionally, and most importantly, cooler intake temps will reduce the risk of the N20 pre-detonating or knocking. This is extremely helpful in ensuring the longevity of your BMW N20 engine as engine knocks may be harmful to engine internals.

Price: $380 for 5”, or $480 for 6.5”

Horsepower Gains: 5-15

**Most importantly, consistent performance and reduce chance of engine knocks

For European customers we recommend Masata Intercoolers. Importing an intercooler over seas is very expensive and finding VRSF products locally is very difficult.

4. Upgraded Air Intake

This mod found its way a bit further down the list as the performance benefits are up in the air. An air intake will only increase horsepower if the factory intake is not able to flow enough air. It appears the BMW N20 factory intake can flow enough air for modified cars, and as such an upgraded intake has minimal performance gains. That being said, FBO N20’s on E85 mixtures may see a few horsepower and torque from this mod. Regardless, we still highly recommend this mod as the sound is absolutely intoxicating, in our opinion. Under boost you can really hear the turbos come to life as the air intake begins to pull in as much air as possible.

Price: $200+

Horsepower Gains: 0-5

**Intoxicating sound, in our opinion. Power gains are likely minimal until you run into a wall where the factory intake simply cannot flow enough air.

5. E85 Fuel Mixtures

The last “modification” to take your BMW N20 to the next level and boost horsepower and torque into the 350s, or more. We may be mentioning E85 last, however, this mod has some serious potential. E85 has too many benefits to list in a sentence so let’s make a quick list:

  • Increase Horsepower & Torque
  • Burns significantly cooler than gasoline
  • Reduces chance of knocks/pre-detonation
  • Cheaper than gas (though at the cost of some fuel efficiency)

Not only does E85 naturally burn cooler than gasoline, it further benefits from burning at a lower stoichiometric ratio than gasoline. This means more fuel is required per each part of air in the cylinder. More fuel injected into a cooler engine (as compared to regular 91/93 octane) significantly reduces the chance of engine knocks. Horsepower and torque may see drastic increases due to cooler temps and less risk of engine knocks, which allows the engine to run more aggressive timing. The JB4 and stock fueling system on the BMW N20 are compatible for a roughly 40% mixture of E85 fuel. Higher mixtures may be used with a flash tune or JB4 coupled with the back-end flash as this will allow the ECU to flow the additional fuel required. Horsepower gains depend greatly on the specific amount of E85 used.

Price: Depends on area – comparable to lowest grade fuels such as 85/87 octane

Horsepower Gains: 10-50+

**Reduces risk of engine knocks; helps engine run cooler internally

How to Ensure Your N20 Remains Reliable After Tuning

Some people have concerns regarding reliability and longevity of their engines with modifications compared to stock form. Of course, those concerns are well warranted as increasing horsepower does increase engine heat as well as the many other stresses put on an engine. An engine knock can suddenly become devastating at higher power levels, so it is important to ensure your N20 is running well after mods. As the N20 is not the strongest of recent turbocharged BMW engines, here are a few recommendations:

  • Limit boost to 22psi
  • Watch AFR’s – ensure engine is not leaning out
  • Fluids such as oil and coolant are changed within recommended time frames
    • Or sooner if driven aggressively
  • Let oil temps warm up to 160F before pushing the engine

22psi seems to be the generally accepted boost for the N20’s factory internals. If you want to push the car any further, it may be time to consider forged internals and the necessary supporting and engine cooling mods. Pay attention to your air-fuel ratios; the N20 has been known to run a bit on the leaner side, which may be a recipe for blown motors. A properly set up, conservative tune and occasional monitoring will help mitigate this risk. Ensure your N20 has proper oil and coolant flow to maximize engine cooling and reduce the risk of oil starvation.

Remember, N20 powered BMW’s were not designed to be all-out track cars and pushing the car too hard around long, fast corners and heavy braking may lead to oil starvation situations. Increased boost will cause the turbocharger to run hotter, and the turbo heats up a lot faster than the oil does. Cold oil splashing on a hot turbo and hot turbo seals is not recommended for the longevity of the turbo. The JB4 does limit the engine to stock boost levels until the oil reaches proper operating temperatures.

Overall Thoughts on N20 Tuning

Although the BMW N20 is not known for its strength and durability, the engine is capable of producing and handling power levels significantly above stock. No offense to the N20, but it is not quite the same engine as the N54, N55, B58, or S55 engines. You cannot simply dump a bunch of power into the N20 and expect it to handle the power as well as the larger 6-cylinder engines mentioned above. The BMW N20 requires a slightly more conservative and cautious approach to tuning and modifying.

Ensure you are running proper supporting mods such as an upgraded intercooler, and E85, if available, as these mods will assist in reducing pre-detonation risks. Play it safe, and the BMW N20 is a great engine that really comes to life with a tune and bolt-ons. For under $1,500 your BMW N20 may be capable of producing upwards of 350hp. Impressive numbers for a small 2.0L 4-cylinder engine, just remember to play it safe and do not risk your engine to stretch for a few extra horsepower.

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19 thoughts shared

    1. Yes you can, it is actually smoother and safer as you may know. My 428i has FBO with bm3 on e30 tune and it drives great. I have yet to get it dynoed.

  1. Did the mods…listed here.
    Pretty amazing.
    Car lifts at 100km/h & pushes way harder then the previous tune done by a shop.
    Sounds fantastic too & reduced knock is noticeable.
    Lovely post, thank you.
    Adding performance breaks, suspension & muffler delete soon.
    🙂

    1. Hi P,

      Glad to hear you’ve had a good experience with the mods discussed in this article. A few basic bolt-ons really help push the N20 to the next level. After the brakes and suspension it sounds like you’re going to have an incredible all around car. As fun as all the engine mods are some handling/brake upgrades can be equally as fun, if not more so.

      Best Regards,
      Zach

  2. I posted this in a later thread, but thought it relevant to put here as well, since it affected power suggestion #5 (E85 fuel).

    There’s an important distinction to be made here in the N20 engines: the pneumatic wastegate (pre 2014) versus the electronic wastegate (2014+) versions.

    In short, according to Burger Motorsports (https://www.n54tech.com/forums/showthread.php?t=15536) the old pneumatic wastegate versions were more tuner friendly, allowing for freedom to control boost. Furthermore, “E85 mixtures are not suggested for the electronic wastegate x28i model as the high pressure pump may have a hard time keeping up with fuel volume demand.”

    At some point later, Burger Motorsports cracked the code with the electronic waste gate and now provide a product that will handle EWGs better….but “For the N20 motor the wastegate harness is relatively easy to reach but there is little benefit to be had. The JB4 can control up to map 2 levels well and the N20 motor is not reliable at higher boost levels. For these reasons we’ve not done much N20 EWG development.”

    Its true that a true BMW power aficionado would likely not be targeting the N20 for their vehicle purchase (so it’s no big loss to not have EWG support for N20 engines), but it is a bit disappointing for those of us who want to max FBO the EWG 320i or 328i we just so happen to own. (It’s also even more disappointing for me, personally, because I currently live in Brazil and E100 is available at literally every gas station in the country.)

  3. Hello my name is Jonathan I have 2014 n20 I have cts turbo intake and muffler delete and I want to put a tune next how much hp will I be pushing when I put a tune? Or should I wait for a tune and add more things before a tune Bc I want my car to be reliable I’m thinking putting the bootmod3 tune or take to tune place and have them tune it I don’t really know that much about tuning and especially n20 motor if I can gets some tips and some recommendations that would be great thanks

  4. First of all, that was incredible & secondly.
    I want to print all this out and take it to my mechanic
    for a FULL overhaul and just pay the dam 10K or whatever
    and sit in my Bimmer one day and say.
    I don’t need that 750 HP Corvette anymore cause I will
    definitely get a suspended license more often than not the
    way I drive BUT to experience a decent pull on a bimmer.
    Well, that’s just great cause the 300hp I hit with the N20 now
    was done without the intercooler or mix and POOF…she is
    knocking none stop and needs that fixed..
    I was quoted to redo the lifters,etc…and it makes sense but
    I need to take this print out to them and get this stuff done.
    At least some of it..to avoid the knock again.

  5. My N20 has lost compression on cylinder 4, running 308bhp with 40k miles on it (no bolt on upgrades, just a map)
    I’m getting the engine rebuilt, with new pistons, rods and everything else.
    I want to make the engine bullet proof.
    Any advise on stronger pistons, rods, if I should go bigger bore etc.
    Thanks

  6. Comment author image

    Steven Costabile

    says:

    Ive got a 2016 328i F30 N26, what are the upper limits of this motor? the shops are saying 270-290whp max and that they’ve heard of cars in that range having their engines blow up so someone with experience with this model engine please let me know. thanks.
    FYI I want to add
    Intake
    catless DP
    Axle back exhaust
    FMIC w/ all charge pipes and TIC
    autowerkes flash tune for 91 & 93 octane (never e85)

    I need to make sure this wont blow my engine and cost me $3k for a new on. thanks.

    1. Hi Steven,

      We wrote a post about the N20 upper limits here. The N20 and N26 are essentially the same engines less a few emissions components so there upper limits should be about the same. However, there is no perfect science to stating an engines upper limits. If only it were as simple as saying, “You’re 99% safe at 300whp, but there’s a 50% chance of blowing the N20/N26 at 320whp.”

      That said, in general 300-325whp should be a relatively safe limit for the N20. Although, you say never E85 so you’d probably be safer staying around 290-300whp tops. E85 is excellent fuel and greatly reduces the chance of pre-detonation. Fueling is one of the most important aspects to upper limits and that limit is lower without E85. Good tuning & monitoring are among other important aspects. Oil starvation is possible around corners, especially long, high G corners.

      We would recommend limiting boost to about 22psi peak. E85 and/or WMI will also help make more power with less chance of pre-detonation occuring. That may be something to consider down the road if you’re dying for more power. Anyways, there is always risk in modding cars and that’s something you must be willing to accept. All else equal, the further you push things the greater that risk becomes. There are always exceptions. Plenty of N54’s have let go at 500-600whp while others hold up for years and years at 650+whp. Typically the ones that hold up best are larger TD-04 frame twins or single turbo conversions since they shift the power band right and trade off some low-end and mid-range torque in favor of more top-end power. It’s really torque that determines an engines upper limits, but that’s a whole different conversation. Hope this helps clear things up some.

      Best Regards,
      Zach

  7. Hey fellas I bought the vrsf downpipe, intercooler, upgraded chargepipe and intake….after installing these parts what should my next step be before driving the car?

  8. Yeah, just thinking about, if I put a bigger turbo, dropping 1 or 2 psi of boost, I’m able to move the torque at higher rpms, relaxing the internal stress. N20 tends to be very torquy because of smaller turbo, resulting in early torque/hp action. More lag but less internal stress. Maybe this way I could make it to 320whp without building the bottom end.

    1. Hi George,

      Great question. An N20 upgraded turbo post is on our to do list at some point in the near future. A few things to consider here. For one, the N20 definitely isn’t known for being incredibly strong. It would be safe to upgrade internals especially if you’re shooting for 400+whp. There is a lot that goes into it though. It’s not just about power. You need to have a good tune that errors on the side of caution. Pre-ignition on the N20 at those power levels could easily result in a blown motor. Another thing is limiting boost on the lower end. Low end torque is brutal on engines; the piston is traveling at slower speeds so you’re subjecting the engine to boosted pressures for an extended period.

      Again, you could play it extremely safe and opt for upgraded internals. We would argue that isn’t worth it though. Costs will add up to 5 digits pretty quickly once you factor in turbo, fueling, tuning, built motor, etc. At that point you could sell the N20 and pick up a 2014+ N55 or B58. Add a tune and a few bolt-ons to those engines and you’re safely making 350-400whp.

      Best Regards,
      BMW Tuning

  9. Question,

    Should I get the FBOs before or after the JB4 tune?

    Wouldn’t it make more sense to add the bolt ons first then tune it?

    1. Hi Jeff,

      We recommend tuning and then adding bolt-on parts for the N20. It would be a different story if you were going a custom tune route. At that point you don’t want to build out a custom tune on a tune-only car and then introduce a bunch of bolt-ons. However, the JB4 has different maps with varying boost targets based on mods, fueling, etc.

      Best Regards,
      BMW Tuning

      1. what’s the difference of adding fbo then a custom tune ? rather then tune and fbo which is safer , and which is a better tune jb4 bm3??