If you want strong performance, go for a car with a turbocharged engine, such as the BMW N55 engine. But some people are not satisfied with the power that this stock engine can deliver. They even want to push its already powerful 365-hp engines. In this article, I’ll discuss the BMW N55 Turbo upgrade.
You need money to boost your stock BMW N55 engine significantly. For instance, the cost is around $3,300 for a turbo kit, depending on the type of turbo you want. You should also set aside an additional $1,200 for the port injection plus about $850 for the stage 3 low-pressure fuel pump (LPFP).
To perform the correct boost upgrade for your BMW N55 engine, you should consider the maximum amount of power that the stock engine can handle. The N55 stock engine can deliver 365 horsepower maximum. With the right turbo boosting, you can jack this up to about 550 hp. and around550 lb.-ft. of torque.
Read on to learn more about the BMW N55 turbo upgrade and the relevant details you need to know if you want to pursue this project.
BMW N55 Turbo Upgrade
BMW N55 Turbo Engine Can Crank a Maximum of 365 HP at 6,500 RPM
In its stock form, the BMW N55 turbo engine is already a powerful engine fit to be installed in a performance car. Its engine can crank a maximum of 365 hp at 6,500 rpm and 343 lb.-ft. of torque at 1400 – 5560 rpm.
Cost of Upgrading the BMW N55 Turbo Engine
To boost this power, you will need money. You will need a turbo kit that can cost around $3,300 plus, depending on the type of turbo kit you buy.
And then you should also prepare an additional $1,200 for the port injection upgrade. In addition, you should also set aside around $850 for the stage 3 LPFP.
An Upgrade Can Boost the Engine’s Power to Around 550 HP
But before boosting the turbo of your BMW N55 engine, you should first consider the maximum amount of power that it can handle. In its stock form, this engine can handle up to 400 horsepower.
If you perform the right boosting, you can stretch this maximum to around 550 hp and 550 lb.-ft. of torque.
N55 Engines Can Handle a Maximum Boost of Around 25 to 26 PSI
The maximum boost that the N55 engine can handle is around 25 to 26 pounds per square inch (psi). You can achieve this if you use a dependable twin-scroll turbo. But if you want to stretch the life of this engine, the recommendation is not to boost the engine more than 20 to 21 psi.
If you boost the engine at more than 20 psi, the turbo will operate outside of its range of efficiency, and the increase in performance will be minimal.
Stock Form BMW N55 Engine Reliability
While there are many misconceptions about the reliability of BMW vehicles, the BMW N55 engine is pretty reliable in its stock form.
Of course, it has its common problems, just like all the other engines manufactured by other car makers. The issues usually come from the oil filter housing gasket, water pump, VANOS solenoids, valve cover, and gasket.
If you want to upgrade the N55 engine of your BMW vehicle, there are several options that you can choose from. Upgrading this engine can be done in three different stages.
So, you need to ask yourself: at this point, what stage should I get to? In a nutshell, these are the BMW N55 turbo upgrades you can do and the potential horsepower boosting you can get from each stage:
N55 turbo upgrade stage 1 – about 400 to 425 whp boost
N55 turbo upgrade stage 2 – about 450 to 550 whp boost
N55 turbo upgrade stage 3 – about 600 to 650 whp boost
Note: whp stands for wheel horsepower. It is different from the standard horsepower. The whp is the power of the engine measured at the wheels. It is a critical value because it shows how much power is transferred from the engine to the wheels. The whp is usually lower than the standard horsepower.
Must-Haves Before Upgrading Your BMW N55 Engine
Upgrading your stock turbo engine will surely boost its performance. However, there are preparatory works that you should do before you undertake this project.
If you want more power for your engine, it must be supported by components that will enable it to handle that boost in power and deliver without causing any problem.
So, you will need the right components if you want your engine to deliver more performance. To upgrade the stock turbo of your BMW N55 engine, here are the other parts that you will need:
New N55 ignition coils
1-step colder spark plugs – this is needed to run the engine more than its stock design
Upgraded intercooler
Upgraded intake
Upgraded charge pipe – the stock pipe is not designed for boosting, so you should change it.
Tune – the engine must be properly tuned with the turbo upgrade.
Catless downpipes
If you want your N55 engine to deliver more horsepower, you should also consider changing and adding components such as fuel pumps, port injection, meth kits, and so forth.
What Happens During an N55 Stage 1 Turbo Upgrade?
Stock Capabilities Modification
Stage 1 of the N55 turbo engine upgrade slightly modifies its stock capabilities. In this stage, the turbo is the same size and is still contained in the same housing unit. However, the turbine/compressor wheel inside the turbo is bigger.
With this bigger wheel, the engine can maintain the power boost until around 6,500 rpm. This is greater than the stock turbo, which experiences a considerable drop in power at about 5,500 rpm.
Best If You Have Blown the Existing Turbo
This stage 1 upgrade is best if you have already blown your existing turbo and need a new one. And since the turbo itself is the same size with only a bigger wheel inside it, the dealer won’t be able to see that you have modified it. So, your warranty will not be voided by this slight upgrade.
Improvements
The improvements that you can expect in the stage 1 N55 turbo upgrade are the following:
Increase in horsepower – from 400 to 425 whp, reliable and consistent delivery
Required additional mods – none; the turbo kit includes everything you will need
If you want more than 425 whp on your N55 engine, you must perform a Stage 2 N55 turbo upgrade. This is usually the stage where serious engine tuners start. Naturally so, because it involves more modifications than what Stage 1 requires.
A stage 2 turbo upgrade will need the following:
Machined/bored out center section that will accommodate bigger wheels
Upgraded turbine wheels and compressor
Like the Stage 1 upgrade, Stage 2 is a direct bolt-on to the stock setup. So they will not be easily detected by the dealer. However, the other mods that you will add will expose your upgrade.
For a Stage 2 upgrade, you are looking to increase the engine’s power from 450 to 550 whp However, be aware that as you push the range to the upper limit, engine reliability suffers. Proper tuning of the engine can mitigate this.
Standard Option or Pure Stage 2 N55 Turbo Upgrade
Stage 2 is for you if you want more than 425 whp on your N55 engine. But that will cost you more money. There are three options for Stage 2 upgrade. What I will give you now is the standard option used by tuners.
They call it Pure Stage 2 N55 Turbo Upgrade. This turbo upgrade is the most commonly used for N55’s E-Series and F-Series. With this setup, your N55 engine can deliver a maximum of 525 whp.
Like the Stage 1 upgrade, this option will use the original housings. So it will look like it is still stuck. However, the center of the housing is machined to accommodate bigger wheels.
Materials and Cost
What you can expect to spend to get this power upgrade are the following:
Turbo kit – approximately $2,500
Installation – around $220
Inlets and outlets – about $250 (this is not required, but since you are upgrading, it would be foolish not to upgrade these parts as well).
Total Cost – around $2,970 (barebones)
This upgrade will be more complete if you will add the following components:
Fuel pump – about $405
Direct port or meth injection – approximately $1,200 (if you use the charge pipe method, the estimated amount will be less than $900).
Total added cost – around $1,605 (or $1,305)
Adding the bare-bone cost to the added price ($2,970 + $1,605), your total estimated cost will be around $4,575.
Cost of Other Stage 2 Options
As for the cost of the other two Stage 2 options, one of them costs about $4,120. The highest whp you can get from this second option is 525 whp. They call this option Vargas (VIT) Stage 2 Turbo Upgrade.
The third Stage 2 option is called Steam Turbochargers Stage 2.5 N55 Upgrade. This upgrade will give you a maximum whp of 550. The cost of the turbo kit is approximately $2,500.
Like the first two options, you will also have to buy additional components to complete the upgrade. You have to add the costs of these other components to the cost of the kit to get the total cost of this upgrade.
Again, how much boost can N55 handle? The BMW N55 turbo engine can handle a maximum 25-26 psi upgrade. But, for reliability and longevity, experts recommend a boost of about 20-21 psi. Beyond this range, you’ll get a minimal upgrade in performance.
What Happens During an N55 Stage 3 Turbo Upgrade?
Stage 3 Allows You to Break the 550 whp Barrier
If you want to break the 550 whp barrier, the Stage 3 N55 turbo upgrade is the way to go. You can push over 500 whp on your BMW N55 engine daily. This upgrade does not use the stock turbo of the N55 engine.
Uses a Bigger Turbo and a Custom Manifold
A kit for a Stage 3 upgrade uses a bigger turbo and a custom manifold. The bigger the size of the turbo, the more horsepower you can get from the N55 engine. But all these will enable you to get more than 550 whp from the stock engine.
However, be aware that running your N55 engine on 500 to 550 whp daily will put tremendous pressure on the engine and stress on the turbo parts, which can translate to reduced reliability.\
BigBoost N55 Stage 3 Turbo Upgrade
One option for a Stage 3 turbo upgrade that you can consider is the BigBoost N55 Stage 3 Turbo Upgrade. This option offers four different stages within the stage 3 turbo kit. The different stages refer to the size of the turbo.
Here are their details:
Turbo size: 3.1: 5459: 470 whp
Turbo Size: 3.2: 5959: 520 whp
Turbo size:3.3: 6159 turbo: 620 whp
Turbo Size: 3.4: 6564 turbo: 800 whp
Materials and Cost
As for the amount you will spend for a typical stage 3 turbo upgrade, here is a breakdown of the cost.
Turbo kit – $3,300
Port injection – $1,200
Stage 3 LPFP – $850
Custom tuning – $500
A set of Carillo forged pistons – $1,100 (optional and recommended for 650 whp)
Carillo forged rods – $1,500 (optional and recommended for 650 whp)
This brings us to a total estimated cost of $8,450.
N55 Engine Turbo Upgrade Limitations
The BMW N55 engine delivers a certain amount of power consistently and accurately. Any modifications performed on its parts will undoubtedly affect its operation, reliability, and longevity.
In other words, there is a limit to what can be upgraded in the N55 engine. You need to know these limits because any upgrade or mod you perform on it will affect its crankshaft, piston, rods, and so forth.
The BMW N55 turbo engine can handle approximately 550 whp and 550 wtq (wheel torque) in its stock form. It is wise to remember that there is a considerable risk in increasing its power by turbo upgrades, especially the Stage 2 and 3 upgrades.
The general rule of thumb should always be followed: The more power you extract from the BMW N55 turbo engine, the greater the risk.
Frequently Asked Questions
Here are some of the answers to the most frequently asked questions about this topic that may help you remember the things discussed in this article:
What Is a BMW N55 Turbo Upgrade?
An N55 turbo upgrade is a procedure for upgrading the stock engine performance. For example, the stock N55 engine can deliver 365 horsepower. If a turbo upgrade is performed in the stock engine, it will be able to deliver up to 400 plus whp or even more.
What Is the Limit of the N55 Turbo Engine?
The limit of the N55 stock engine is around 500 whp and 550 wtq. A turbo upgrade kit can bump this up to 650 whp.
However, increasing the N55’s power delivery increases the stress and strain on the engine internals and other engine components. That will considerably affect its reliability and consistency of power delivery.
Is the BMW N55 Turbocharged Engine Reliable?
Yes, the turbocharged BMW N55 engine is reliable in its stock form. As long as you keep it in stock form and give it its proper care and maintenance, this engine will last long.
Some have reported their N55 engines having already reached 150,000 miles. Others said their N55 has already clocked 250,000 miles.
In Closing: BMW N55 Turbo Upgrade
It will cost you money to perform an upgrade to your stock BMW N55. Firstly, you will need a turbo kit which costs around $3,300 depending on the type of turbo kit that you want.
Secondly, you should also prepare an additional $1,200 to upgrade the port injection. Thirdly, you should also set aside around $800 for the third stage LPFP.
Before performing the turbo upgrade, you should first consider how much power the stock engine of your BMW N55 can handle. The stock engine of this car can deliver a maximum of 400 whp. With the right turbo boosting, you can jack this up to about 550 whp with around 550 wtq.
