BMW N73 Tuning

"All you need to know about performance parts and tuning the BMW N73 engine!"

The N73 engine, with its B60 and B68 variants, stands as a compelling chapter in BMW's illustrious history of powerplant engineering.

Introduced in the early 2000s, the N73 is part of BMW's N Series of engines, embodying the brand's commitment to delivering a seamless blend of power, sophistication, and innovation.

In this exploration of modifying and upgrading the N73 engine, we embark on a journey that delves into its historical evolution, power specifications, notable revisions, and the distinctive features that define its engineering prowess.

As a V12 engine, the N73 represents the zenith of BMW's commitment to performance luxury. Its initial power specifications boasted a formidable output, with the B60 variant delivering around 438 horsepower and the later B68 variant elevating the stakes even further.

The N73 found its home in flagship BMW models like the 7 Series, showcasing a harmonious marriage of luxury and performance.

The evolution of the N73 engine has seen meticulous revisions aimed at refining its capabilities.

The N73B68 variant, in particular, introduced enhancements that not only elevated power output but also embraced technological advancements to meet evolving standards in efficiency and emissions control.

Features such as Double VANOS (Variable Camshaft Timing) and High Precision Injection underscore the N73's commitment to optimizing combustion dynamics for both power and efficiency.

As engineering enthusiasts navigate the landscape of modifying and upgrading the N73 engine, they are met with a canvas rich in possibilities. From performance-enhancing modifications to precision tuning solutions, the N73 beckons to be explored and optimized.

This article aims to guide fellow engineering minds through the labyrinth of potential upgrades, unraveling the intricate dance between mechanical components and cutting-edge algorithms that define the N73's journey from the drawing board to the pinnacle of luxury performance.

The BMW N73 are fantastic to work on and with the ultimate sports enhancements like ECU maps, turbo kits and camshafts you will substantially enhance your driving pleasure.

The N73 is a NASP V12 and hold the record as the first V12 engine to use gasoline direct port injection DOHC and double Vanos!

Let us review and look at N73 tuning and report on the greatest modifications for your car.

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History, Power & Specs of the Engine

• N73B60
  327 kW (439 hp)@6,000 rpm 600 nm (443 lbft)@3,950 rpm

• N73B68
  338 kW (453 hp)@5,350 rpm 720 nm (531 lbft)@3,500 rpm

Tuning the BMW N73 and best N73 performance parts.

Best N73 mods

Just because particular tuning parts are are common on N73 it doesn't mean you should fit it, instead we will outline what we hold up as the most optimal tuning parts that will give your N73 the best power gain for you money.

Significant gains on the N73 can be made from VANOS adjustments. Altering the cam timing profile alters the intake and exhaust durations on the engine and can dramatically change the torque and power output.

The Dual VANOS (Variable Camshaft Timing) system in the N73 engine is a sophisticated technology designed to optimize the timing of the engine's camshafts. Simply put, it adjusts when the engine opens and closes its intake and exhaust valves.

Here's a simple breakdown:

Variable Timing:

The term "variable" means that the timing is not fixed; it can change based on driving conditions. In the case of the N73, there are two VANOS systems, one for each camshaft.

By adjusting the timing of the camshafts, the engine can optimize its performance at different engine speeds.

This is crucial because the engine operates differently at low speeds (like when you're idling or driving slowly) compared to high speeds (when you're accelerating or cruising on the highway).

Power and Efficiency:

When you need more power, like during acceleration, the Dual VANOS system can advance the timing to allow more air and fuel into the cylinders, optimizing combustion for increased power.

Conversely, at lower speeds or during cruising, it can retard the timing to improve fuel efficiency and reduce emissions.
The ability to adjust the timing on both the intake and exhaust camshafts allows for smoother transitions between different driving conditions.

This contributes to a more responsive and efficient engine.
In essence, Dual VANOS in the N73 engine should be viewed as having a dynamic, adaptable engine management system that optimizes the performance and efficiency of the engine across a range of driving conditions. It's a key technology that helps strike a balance between power and fuel economy in a way that benefits the overall driving experience.

On a daily driver should ideally to optimize your engines power to your cars usage.

Some N73 engines respond better to different cam durations so view each engine as unique.

The map and fuel pump and injectors also have an effect on the power gains you'll achieve.

A longer valve duration can alter the power band and on most engines the exhaust and intake durations do not need to match, although most cams and tuners use matched pairs there are some advantages to extending the intake or exhaust durations.

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Best mods for your N73

1. Engine Tunes - engine tuning/remapping provides the most advantage in terms of cost savings,  aftermarket ECUs, and piggyback ECUs are all alternatives.
2. Flywheel lightening - a lower weight flywheel will improve the engines free revving nature. But not always suitable for all N73 engines.
3. Intake and Exhaust - Note that on their own these mods will NOT ADD POWER in most cases, but they can help enhance power after other mods by removing the restriction.
4. Head work - The goals of porting and flowing the head are to get air flowing into the engine while removing flow restrictions and turbulence.

N73 Tuning Stages

Typical stage 1 mods often include: drilled & smoothed airbox, Panel air filters, Remaps/piggy back ECU, Sports exhaust header/manifold, Intake manifolds.

Typical stage 2 mods often include: Fuel pump upgrades, Ported and polished head, Sports catalyst & performance exhaust, high flow fuel injectors, induction kit.

Typical stage 3 mods often include: Adding or Upgrading forced induction (turbo/supercharger), Crank and Piston upgrades to alter compression, Twin charging conversions, Internal engine upgrades (head flowing porting/bigger valves), Engine balancing & blueprinting, Competition cam.

Mapping should help to fully realize the full potential of all the modifications you've fitted to your N73.

(In some cases, as the factory ECU is locked flashing is not an option, so an aftermarket ECU is the route to take, and many of these will outperform factory ECU's but make sure it has knock protection and that you get it setup properly.)

Tuning the Digital Motor Electronics (DME) system in the N73 engine involves making adjustments to the engine control parameters to optimize performance, power delivery, and efficiency. Here are the general steps involved in tuning the N73 DME which a specialist tuner will carry out:

Adjust Fuel Mapping:

Modify the fuel maps to optimize the air-fuel mixture for improved combustion. This can enhance power output and fuel efficiency. Tuners may adjust fuel injection timing, duration, and quantity.
Ignition Timing Optimization:

Fine-tune the ignition timing maps to optimize the timing of spark plug firing. This can affect power delivery and overall engine performance. Advanced timing can enhance power, but it must be balanced to avoid detonation.

Variable Camshaft Timing (VANOS) Tuning:

Since the N73 engine features Dual VANOS, tuning the variable camshaft timing is crucial. Adjusting the VANOS parameters can optimize power delivery at different engine speeds.

Throttle Response and Torque Management:

Tuners may adjust throttle response to make the engine feel more responsive. Additionally, torque management systems may be fine-tuned to optimize torque delivery during acceleration.
Transmission Tuning (if applicable):

If the N73 is coupled with an automatic transmission, tuning may extend to the transmission control module (TCM). This involves adjusting shift points, shift times, and other transmission-related parameters.

Dyno Testing and Road Tuning:

After making adjustments, it's crucial to perform dyno testing or road tuning to validate the changes. This involves real-world testing to ensure that the modifications result in the desired performance improvements.

Implement safety measures, including monitoring engine parameters to prevent excessive stress on components and avoid potential damage. This includes setting up safeguards for factors like air-fuel ratios and engine temperatures.

It will usually give you around 15% on NA (naturally aspirated) engines, but the outcome may differs on the modifications you've applied and the condition of your engine.

It is the whole point to any engine tuning job to shove more fuel and air into each cylinder

Intake transmit the air during the suck phase from the intake filter and allow it to be pulled into the engine and mixed with fuel.

Shape and flow characteristics of the Air Intake manifolds can make a substantial effect on to fuel atomisation and engine efficiency on the N73.

I usually find air intake manifolds are ripe for performance upgrades, although a few car makers provide fairly well optimized air intake manifolds.

Larger N73 valves, getting port work and head flowing will also raise power, and significantly will allow you to get a greater power increase on other tuning mods.

N73 Turbo upgrades

NA (naturally aspirated) engines need quite a lot of work when you add a turbo, so we have a separate guide to help you take into account the pros and cons of going this route on your N73

The more air you can get into an engine, the more fuel it can burn and uprating the induction with a turbocharger upgrade makes excellent power gains.

There are practical limits for every engine, with some being incredibly solid and some only just able to handle stock power

It is important to find these limitations and install better quality components to handle the power.

We've seen people spending a loads of money on turbo upgrades on the N73 only to suffer the humiliation of seeing the N73 go up in smoke on it's first outing after it's been finished.

Large capacity turbochargers commonly suffer no power at low rpm, and low capacity turbochargers spool up more quickly but won't have the peak rpm engines power gains.

Thanks to progress the range of turbo chargers is always evolving and we now see variable vane turbo chargers, allowing the vane profile is altered according to speed to lower lag and increase top end bhp and torque.

Twin scroll turbo chargers divert the exhaust gases into a couple of channels and feed these at differently angled vanes in the turbo. They also boost the scavenging effect of the engine.

It is common that there's a limit in the air flow sensor MAF/MAP on these engines when a lot more air is being drawn into the engine.

Going up you'll find 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor was restricting performance at a much lower level.

Adding a supercharger or additional turbo will make large bhp gains, although more difficult to configure. We have this article covering twinchargers if you want to read more.

N73 Fuelling

When you increase the power you will need to look at to the fuelling.

More power needs more fuel. It is important to over specify your injector capacity.

As a rule of thumb add another 20% when specifying an injector, this takes into account injector deterioration and gives some spare capacity should the engine need more fuel.

We think this one is common sense, but you'll need to match your fuel injector to the type of fuel your car uses as well.

Exhaust Mods for the N73

You only need to boost your exhaust if your current exhaust is actually creating a restriction.

On most factory exhausts you'll find the flow rate is fine even on modest power gains, but when you start pushing up the power levels you will need to get a better flowing exhaust.

Don't go with the widest exhaust you can buy you'll reduce the exhaust flow rate - the best for power gains are usually between 1.5 to 2.5 inches. It is the shape and material more than the bore size.

Typically exhaust restrictions come around the filters installed, so adding a freer flowing high performance aftermarket one will improve air flow, and rather than doing an illegal decat, will keep the car road legal.

Weak spots Issues & problem areas on the N73

The N73 engines are generally reliable and solid units, as long as you follow the manufacturers service schedules, and use a good quality oil to ensure longevity. Few problems should happen as long as they are regularly serviced and maintained.

Carbon build up in the head, particularly around the valves which will sap power or create flat spots, this is a larger issue on direct injection engines but should be looked out for on all engines. We have tips on removing carbon build up.

Some of our members have had issues with flat spots or glitches after applying mods and upgrades or tuning, this is not usually related to this engines design, so instead see our article on diagnosing flat spots and problems after tuning which should help you get the bottom of this issue.

The Vanos components should be checked, carefully maintained and replaced at high milages.

Regular oil changes are vital on the N73, especially when tuned and will help extend the life and reliability of the engine.

If you would like to know more, or just get some friendly advice on Tuning your N73 engine please join us in our friendly forum where you can discuss tuning options in more detail with our tuning articles to get a full grasp of the benefits and drawbacks of each modification.

Please help us improve these tips by sending us your feedback in the comments box below.

We love to hear what our visitors have got up to and which tuning mods work best for you on your car. Which helps us keep our guides and tips up to date helping others with their modified car projects. Your feedback and comments are used to keep this page up to date, and help improve the accuracy of these N73 tuning guides which get regular updates and revisions.

This article is flagged for an update, so please pass on specific tips below that I can include. All articles, and content was written by me, Waynne Smith TorqueCars founder. Some outlines are just too general so I appreciate your feedback and suggestions. This entry was filed under BMW. You can leave a response below or join our forum to discuss this article and car modification in detail with our members.

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