The BMW N54 engine featured in the 135i, 335i, and 535i is one of the most tune-able engines ever. Some people call it the '2JZ' of German engines, but we think the N54 is on a whole new level. The N54 engine has forged internals, meaning it can handle an immense amount of power without requiring any expensive engine modifications. We have seen N54's break 800+whp on the stock internals - good luck achieving that with a 2JZ. BMW rates the engine at 300hp and 300tq to the crankshaft directly out of the factory. It is widely known that BMW undershoots their power estimates, and this is especially true with the stock N54 putting down roughly 280hp and 290tq to the wheels!
The great thing about the N54 engine and its forged internals, is that it's very easy to generate crazy amounts of power very for very little amounts of $$$. This guide will take you step-by-step on the mods necessary to build a 500hp 135i, 335i or 535i. And we are going to do it for less than $1,500!
First, Let's Talk Spark Plugs...
Horsepower is created from combustion. So to make more horsepower you need more combustion. This means that the car needs to pump more gas into the combustion chambers to create more horsepower (your mpg will go down, yes). If you have bad spark plugs, the plugs won't be able to ignite all of the gas in the engine. As a result, gas is left in the engine and then can pre-detonate, or cause misfires due to the high temperature levels in the engine. New spark plugs won't give you more horsepower, but it will prevent misfires and unleash lost horsepower caused by bad or foiled plugs!
Before shooting for significant horsepower gains, you should change your spark plugs! But which spark plugs should you be using?
Which N54 Spark Plugs Should You Use?
The OEM spark plugs are great, but only if you are running stock boost levels. More boost causes for more fuel, which creates more combustion, which creates higher engine temperatures! These higher engine temperatures are what cause pre-detonation and misfires. We combat this by using "colder" spark plugs. Spark plugs have heat ranges which control the temperature that they ignite at. Using a colder spark plug will reduce engine temperatures and prevent misfires and pre-detonation caused by burning more gasoline.
Here are our spark plug recommendations, follow this and you shouldn't be running into any misfire or performance issues:
- OEM N54 Spark Plugs: use these for all stock N54's or modified N54's that are running stock boost! These should be replaced every 40,000 miles for stock N54's.
- 1-Step Colder N54 Spark Plugs: all tuned cars (up to 420whp) should be using these. If you have a Jb4, Cobb, etc. you should be using these plugs that are 1 heat range colder. These should be replaced every 15,000-20,000 miles.
- 2-Step Colder N54 Spark Plugs: for all N54's running upgraded turbos or meth/forced injection. These should be replaced every 15,000-20,000 miles.
And don't forget ignition coils! Ignition coils should be replaced every time you replace your spark plugs. Ignition coils power the spark plugs - bad coils can cause the same problems as bad spark plugs so it is important to replace these as well.
- OEM N54 Ignition Coils: replace these every time you replace your plugs. We recommend Bosch since they are $110 cheaper and the Eldor coils don't provide any significant benefits over Bosch.
Click any of the links above and use the code "N54TUNERS" for 5% off any order of spark plugs or ignition coils!
Looking for more than 500hp? Check out our upgraded turbo guides
For those that 500hp isn't enough for...we've written two blogs posts on upgraded turbos, both for upgraded twin turbo setups and single turbo setups. Check out these guides if you are already FBO and looking for the next step!
Best N54 Bolt-On Upgrades
The best bolt-on power mods for the BMW N54 135i 335i and 535i include:
- Dual Cone Intakes
- LPFP (for higher E85 mixes)
- Inlets & Outlets
These upgrades (with proper tuning) will take the N54 to its limit on stock turbos, which is right around the 475-500whp ballpark. Turbo longevity may become a concern at 20+psi, however some hold up for a while. We've blown a few stock turbos on the N54 engine around 20psi, so understand the risks in pushing the limits. We recommend keeping things a bit more modest unless you intend to upgrade the turbos anyways. We'll discuss the above N54 bolt-ons in greater depth throughout the rest of the post. We will also dive into a few supporting bolt-on mods to help make the power.
Mod List for a 500HP BMW N54
Dual cone intakes are an essential bolt-on upgrade for your N54 if you are looking to further tune and modify your car. DCI's will allow your twin-turbos to take in more air, creating more pressure and combustion, resulting in more horsepower. This was the first mod Zach and I put on our cars, and it is, in my opinion, one of the most necessary supporting mods for breaking 500hp. I say it is a "supporting mod" because the extra airflow is crucial in maximizing additional horsepower gains from other mods, such as the JB4 tuner.
Aside from additional horsepower, you also get an awesome and aggressive engine sound that is intoxicating. People also claim DCI's will improve fuel efficiency, but you can throw that out the window at 500hp. If you care about fuel efficiency, you probably don't want 500 horsepower.
If you are unsure of which dual cone intake is the best for you, you can read our tuning guide on intakes which lists all of the available options, their prices, and horsepower gains. For the purpose of this guide, we are trying to achieve 500hp with spending the least amount of $$ possible, so I recommend either VRSF or BMS dual cone intakes. For UK and International customers, Masata offers a great dual cone intake upgrade too.
Horsepower Gains: 20hp to the wheels!
Second on the list is a set of catless downpipes. The catalytic converters on the OEM downpipes are very restrictive, and limit the amount of airflow leaving the engine. This becomes an issue when we put a tuner on our car and increase our boost pressure (psi). With catless downpipes, you will be able to run more air through the turbo system which results in higher boost pressures, and better spool times.
These are second on my list after the dual cone intakes, because once you are bringing more air into the engine and turbos, you will need to allow more air to flow out. Downpipes and an intake are the best mods to do before you add a tuner to your car. These mods will allow the tuner to maximize horsepower gains through increased boost. As with above we are looking for a cost-effective set of downpipes, so we recommend the VRSF downpipes. From a quality standpoint, they are highly praised throughout the N54 community, and they come at a price of only $350 brand new. Definitely one of the best bolt-on mods for the N54 engine.
As a disclaimer, removing the catalytic converters on your N54 will result in the car failing emissions tests. Technically it is "illegal", but the majority of N54 owners will run catless, you simply need to find a shop to do your inspection that is more so on the lax side of things. If you are concerned with this, and don't want to run an illegal setup, you can get "high-flow" downpipes that still have the catalytic converters, but are less restrictive than OEM. The high flow downpipes don't create as much power as catless, but they are still a huge improvement over OEM.
Horsepower Gains: 25hp to the wheels!
Alright, when it comes to tuners for the N54, no product holds more world records than the JB4. The JB4 has the record for the highest horsepower N54, and also has more cars running in the 11 seconds on the quarter miles than any other tuner. The JB4 is a piggyback tune so it's a bit different from traditional flash tuning. Some people love it and others hate the idea of piggyback tunes. Nonetheless, the JB4 makes tuning simple and it's packed with loads of awesome features.
I'm not going to get into the details of this tuner, because it is exhaustive, but click the link below to read our guide on tuners that compares all of the options on the market. If you are someone that likes to buy things new, a JB4 is going to run you near $500. If you don't mind a used item (in the case of tuners, I personally don't think it matters) then you can grab one for around $350 from someone on the forums.
Price: $500 new, ~$350 used
Horsepower: 60-100hp, depending on supporting mods and maps
Buy Here: BMS JB4 $479
4. Front Mount Intercooler (FMIC) - VRSF 7.5" Competition Intercooler
Bolt-on mod #4 on our road to 500hp, is a front mount intercooler. An intercooler cools the air that comes from the turbos, before entering the engine. The OEM system is designed to support low boost levels and lower levels of airflow. With a DCI and downpipes you are going to need an intercooler that can support the amount of air you are bringing into the car. The JB4 tune, or any of the others, will have you running higher boost pressure. Running high psi of boost on the OEM intercooler is dangerous because it overwhelms the system, creating heatsoak from high air temperatures which results in a loss of power. VRSF is once again, the best cost-efficient manufacturer. I recommend the 7.5" Competition Intercooler, which will support you up past 600hp, for a price of just $400. If you are shooting for 650hp+ I recommend using their 7.5" Race Intercooler (pictured above).
Horsepower: 15-20hp to the wheels
Link: VRSF 7" Stepped FMIC
5. MHD Flash for E85 Ethanol - 40% E85
The MHD Flasher in an Android application that allows you to use a phone or tablet to tune and monitor the ECU in your N54. This app allows you to directly flash your ECU and run various different tune setups, etc. It plugs directly in to your car and is a great tool for monitoring and data logging various engine figures.
The MHD flasher couples well with the JB4, and provides additional
Horsepower: Depends on the flash you run, check the posts below for additional info
Link to all MHD info: http://www.e90post.com/forums/showthread.php?t=1096242
MHD Guide by BMS: http://www.n54tech.com/forums/showthread.php?t=29236
JB4 Backend Install: https://play.google.com/store/apps/details?id=com.mhd.flasher.n54&hl=en
These 5 mods will get you to 500hp at the crank, but what about at the wheels? 500hp at the crank is likely to be around 430-440whp. For those who want a serious 500WHP, keep reading!
Optional/Recommended Bolt-On Mods
1. Upgraded Chargepipe
When you reach the point of 500hp or upwards, you are really going to need a performance chargepipe. This isn't a power mod, meaning you shouldn't expect any performance benefits from it. The chargepipe supports boost pressure, and once we starting increasing our boost pressure with our tuner and other mods, the OEM chargepipe is likely to fail. The OEM chargepipe is made from plastic, so it is very unstable, and can't handle high amounts of boost. While this isn't a necessary upgrade, it eventually will become one once you burst your OEM chargepipe from high boost pressure. The OEM system will commonly leak boost pressure, resulting in less boost and therefore less power. Replacing it ensures you will be holding the maximum boost power possible, and it will prevent the chargepipe from cracking or bursting while you are driving. Some people like to upgrade it before they start increasing boost pressures, others just replace it when they blow their stock pipe. The choice is up to you, but expect to have to eventually upgrade your chargepipe. Prices range from $200 and upwards depending on the blow off valve.
VRSF is our recommendation for US folks. We recommend the Masata N54 Chargepipe for European and international readers.
2. Low-Pressure Fuel Pump (LPFP) - Stage 2 (500hp) or Stage 3 (550+hp)
Above, we suggested running around 40% E85 with the MHD backend flash tuner. At 40% ethanol fuel, you are adding serious horsepower, but likely running your low-pressure fuel pump at a full 100%. If you want to run higher than 40% ethanol, which we suggest if you are looking to push past 450whp, you will need to upgrade your low-pressure fuel pump. With a stage 2 or 3 LPFP bolt-on upgrade, you can safely run 100% E85. The stock LPFP can generally handle around 430whp on E85 and near 460whp on E50. At higher percentages of ethanol fuel, your stock pump will hit capacity and not be able to pump fuel fast enough. We recommend a Stage 2 pump ($450) for people who are shooting for the 500hp range. If you are looking to break 550whp, you're going to need a Stage 3 LPFP ($850). We recommend Fuel-It's LPFP upgrades. The dudes there are great and their pumps are the most praised in the community.
500hp is loads of fun, but it isn't so fun when you don't get to use it! After I installed my JB4 I couldn't put my foot to the floor until I was in 3rd gear...buzzkill. My Pilot Super Sports were down to about 15% left in the rear and I had no traction, even running mild levels of boost. You can read about it on my build thread, and about my fantastic experience ordering new Michelin Pilot Super Sports from Tire Rack. The performance benefit of new (high performance) tires is enough in itself for you to grab a new set for the summer. But lets also keep in mind the safety benefit of new tires as well. The last thing we want is your N54 in a tree and you in the hospital.
500WHP with this One Additional Mod
1. Upgraded Turbo Inlets & Outlets - 50+whp & 60+ft-lbs tq
Intake inlets are the piping that goes from the intake filters to the turbochargers themselves. From the picture above you can see the dual cone intakes, the inlets are the aluminum piping that follows the filters down to the turbos. The stock inlets on the N54 engine get as small as 1" and also flatten out at various points. The small size of the inlets decreases the amount of air fed to the turbos, which results in less turbo boost. A set of upgraded inlets, such as the VRSF inlets, features larger piping all the way through, increasing air flow and boost pressure. Inlets are a great upgrade for the stock turbos, as they generate more than 50whp and 60wtq, and also increase the natural boost pressure by more than 3psi. Inlets are a necessary upgrade for people whom are upgrading their turbos, as the stock inlets are too small for upgraded turbos.
The catch, is that turbo inlets are a pain in the a** to install. The inlets only cost around $250, but the installation can be tedious. We recommend this mod if you are a very handy DIY expert and can handle something of this magnitude yourself. If not, we recommend this if you have $1,000 to spend freely. Otherwise, wait to upgrade these when you upgrade to larger turbo's if you ever plan to do so as it won't add much of an addition install cost.
Buy Here: N54 VRSF Stock Location Silicone Inlets
What bolt-on mods do you have on your N54? Which are you considering?
Drop a comment and let us know!