BMW N74 Tuning

"All you need to know about performance tuning the BMW N74 engine!"

We shall outline options for your N74 tuning and provide tips on the premier upgrades. BMW N74 make awesome project engines and with a few sensible uprated tuning mods like a remap, turbo kits and camshafts you will certainly enhance your driving pleasure.

This twin-turbo V12 petrol engine replaced the N73 and BMW dropped valvetronic and overall tweaked a very solid reliable engine evolving it into the N74.

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History, Power & Specs of the Engine

Thanks to the engine design, the torque band starts way down at 1500rpm, and although this peaks at 5500rpm thanks to the nature of a V12 engine which should never be considered rev happy and should be tuned with that in mind.

That said the redline is still up at 7000rpm for most engines in this range, giving the tuner plenty of overhead to work in.

• N74B60 536 hp  553 lbft
• N74B66 563 hp -593hp 575 lbft - 620lbft
• N74B66TU 602 hp 590 lbft
• N74B68 563 hp 664 lbft

Tuning the BMW N74 and best N74 performance parts.

Best N74 mods

When talking about the best modifications for your N74 engine, we are going to focus on the ones that give the biggest return for your cash.

Significant gains on the N74 can be made from cam upgrades. Altering the cam profile alters the intake and exhaust durations on the engine and can dramatically change the bhp and power output.

Fast road cams usually increase the power through the rpm band, you may lose a little low end power but higher rpm power will be lifted.

Motorsport cams, increase the higher rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

A Motorsport and race cam makes it harder when on the daily commute, because the lumpy idle will make the car prone to stall and smooth driving at low rpm becomes impossible. If you are developing a track car this doesn't matter as you are in the high end of your RPM range anyway and that is where you want the power to be.

You should ideally match your bhp range to your usage of the car so for a car used daily stick with a fast road N74 cam

Each engine responds better to different camshaft durations so view each engine as unique.

The engine timing and fuel pump and injectors also will make differences on the power gains you'll achieve.

Longer valve durations 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 N74

1. Fast road cams are one of the most significant mechanical changes, but should always be fitted by someone competent and you might struggle to find one but you might have a local firm to regrind a stock camshaft .
2. Turbo upgrades - A New Turbo is the most efficient approach to improve intake air supply, allowing you to combust more fuel and make more power. Typically one of the most challenging modifications you'll see massive gains.
3. ECU Tunes - N74 engine tuning/remapping provides the most advantage for the money, replacement ECUs, and piggyback ECUs are all alternatives.
4. Intake and high flowing exhausts - NB: on their own these mods will NOT ADD TORQUE in most applications, but they can help lift power after other mods by lessening the restriction.
5. Lightened Flywheels - a reduced weight flywheel will significantly improve the engines rev changes. But not always beneficial for all N74 engines.
6. Flowing and porting the Head - Head work will get air flowing into the engine while removing turbulence or restrictions.

N74 Tuning Stages

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

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

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

ECU mapping will help fully realize the full potential of all the upgrades you've done to your N74.

(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.)

It will usually give you around 30% more power on turbocharged vehicles and you can expect to see around 15% on NA (naturally aspirated) engines, but your mileage usually differs on the upgrades you've applied and the condition of your engine.

It is the whole point to any tuning project to pull more fuel and air into each cylinder

Intake carry the air from the air filter and allow it to be drawn into the engine and mixed with fuel.

Design and flow rate of the Intake manifold can make a large effect on to fuel atomisation and engine efficiency on the N74.

Many mass produced engine air intake manifolds are crying out for an upgrade, although some OEM provide well optimised air intake manifolds.

Larger N74 valves, carrying out N74 port enlargement and head flowing will also raise performance, & more importantly will allow you to get a better performance increase on other upgrades.

Turbo upgrades on the N47

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 N74. Lowering compression ratio and making sure engine is balanced and fitted with stronger components are your primary aim.

The more air you can get into an engine, the more fuel it can burn and uprating the induction with a turbocharger upgrade makes significant power gains. The Aim of an N74 is to deliver a wide torque band over a relatively short RPM range, the engine was not designed for high RPM's so your choice of turbo needs to reflect this or you'll end up with lots of lag and a very short power band.

There are common areas of failure for every engine, with some being incredibly solid and some only just able to handle stock power so I suggest you discover these limitations and fit higher quality components to utilize the power.

We see many people spending a lots of money on turbo upgrades on the N74 only to see the N74 throw a rod on it's first outing after it's been completed.

Larger upgraded turbo chargers often experience low end lag, and small turbo chargers spool up more quickly but won't have the high rpm torque gains.

We are pleased that the world of turbochargers is always increasing and we are seeing variable vane turbochargers, permitting the vane angle is altered according to speed to lower lag and increase top end performance.

Twin scroll turbochargers divert the exhaust gases into two channels and flow these at differently angled vanes in the turbo charger. They also boost the scavenging effect of the engine.

It is not unusual that there's a limitation in the air flow sensor (AFM/MAF/MAP) on the N74 when loads more air is being sucked into the engine.

You'll see that 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor sapped bhp at a much lower level.

Adding a supercharger or additional turbo will make large performance gains, although more complex to configure. We have this feature on twinchargers if you want to read more.

Fuelling Upgrades on the N74

When you raise the torque you will need to pay attention to the fuelling.

More torque needs more fuel this is a simple fact of tuning, more air + more fuel = bigger bang!

It is important to over specify your injectors flow rate.

The accepted safe increase is to add 20% to the flow rate when fitting an injector, this takes into account injector deterioration and gives a little 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 Upgrades for the N74

Only look to boost your exhaust if the existing exhaust is creating a flow problem.

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

Sports exhausts generally help improve air flow through the engine but avoid an exhaust that is too wide or you might just stuff your flow rate and make things worse. So generally speaking, keep to a size of 1.5 to around 2.5 inches to maximise flow rates, and this should take into account the amount of air your engine is moving.

Common exhaust restrictions are in the catalysts installed, so adding a freer flowing sports alternative is the answer. This keeps the car road legal and will flow much better due to it's higher internal surface area and design, so has the added benefit of keeping your car road legal. The alternative decat should be considered an off road only mod, as removing a catalyst is illegal in most territories and regions for road registered cars..

Weak spots, Issues & problem areas on the N74

The N74 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 high pressure fuel pumps have been known to cause some issues primarily due to the magna fuel diaphragms splitting, but most of these have now been replaced with the conti tech ones.

Regular oil changes are vital on the N74, 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 N74 engine please join us in our friendly forum where you can discuss tuning options in more detail with our N74 owners. It would also be worth reading our unbiased tuning articles to get a full grasp of the benefits and drawbacks of each modification.

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We love to hear what our visitors have got up to and which upgrades 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 N74 tuning guides which get regular updates and revisions.

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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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