Tuning the BMW N52

"All you need to know about performance tuning the BMW N52 engine!"

Carref prides itself on providing the latest tips and guides to your modification project.

The N52 replaces the M54 and had a lighter engine block, an electric water pump and variable flow oil pump. Valvetronic was also added. The camshaft is also of a hollow design, to save weight.

The engine is controlled through a Siemens MSV70 ECU.

We detail the best approach to N52 tuning and show the optimum mods that work. BMW N52 provide a fun base for your project and with carefully picked sports mods like a remap, turbo upgrades and camshafts you will enhance your driving enjoyment.

We rely on our visitors to pass on tips and tell us about their projects and what worked on their car, and this article is the culmination of the feedback we have received. First let us look at the history and specs of this engine and then consider which tuning modifications work best on it.

History of the N52 Engine

There were 2 versions, the N52B25, and N52B30. The differences between these engines are the N52B25 has a smaller bore and stroke, so pistons, crank etc are different, but they share the same block and head.

The N52 was a straight 6 NASP engine  and won a Wards best engine award in 2007 and 2006. It also had double VANOS

N52B25

• 174 bhp @5,800 rpm 170 lbft @3,500-5,000 rpm 2005-2008
• 201 bhp @6,400 rpm 184 lbft @2,750 rpm 2007-2011
• 215 bhp @6,500 rpm 184 lbft @2,750-4,250 rpm 2005-2011

N52B30

• 215 bhp at 6,100 rpm 199 lb⋅ft at 2,500-4,250 rpm 2006-2010
• 215 bhp at 6,100 rpm 207 lb⋅ft at 2,500-3,500 rpm 2010-2011
• 228 bhp at 6,500 rpm 229 lb⋅ft at 2,750 rpm 2008-2011
• 241 bhp at 6,500 rpm 229 lb⋅ft at 2,750 rpm 2008-2011
• 255 bhp at 6,600 rpm 221 lb⋅ft at 2,500-4,000 rpm 2010-2011
• 255 bhp at 6,600 rpm  229 lb⋅ft at 2,600 rpm  2009-2015
• 261 bhp at 6,600 rpm 232 lb⋅ft at 2,750-4,250 rpm 2005-2009
• 268 bhp at 6,650 rpm 232 lb⋅ft at 2,750 rpm 2006-2010

What are the most effective N52 (N52B25,N52B30) tuning mods

The greatest mods on an engine are in our opinion the ones that give the best power gain for you spend.

We won't be swayed by popular N52 mods, they need to be cost effective.

Altering your N52 camshaft will make a dramatic difference to the engine bhp. Choosing a higher performance camshaft profile raises the bhp accordingly.

Fast road cams usually increase the torque over the rev range, you may sacrifice a little low down torque but your higher rpm power will improve.

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

On a daily driver you need to match your bhp range to your usage of the car.

You'll never have found a Race camshaft is a pleasure to live with when on the daily commute.

Some N52 engines (N52B25,N52B30) respond better to more or less aggressive camshaft durations check your engine on a rolling road.

The engine timing and fuelling also will make differences on the bhp gains you'll get.

A longer valve duration can alter the bhp 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.

Tuning the Modification stages for the N52B25 & N52B30

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Modifying to Stage 1:

 Sports exhaust manifold, Remaps/piggy back ECU, Drilled & smoothed airbox, Fast road camshaft, Panel air filters, Intake headers.

Modifying to Stage 2:

 Sports catalyst & performance exhaust, induction kit, fuel pump upgrades, high flow fuel injectors, Ported and polished head, Fast road cam.

Modifying to Stage 3:

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

ECU flashing allows a tuner to to establish the full potential of all the upgrades you've done to your N52.

It will usually give around 10% of a power gain on the NASP engines, but your mileage will vary depending on the upgrades you've done and the condition of your engine.

It is vital to any tuning job to pull more air into each cylinder.

Plenum carries the air during the suck phase from the air cleaner and allow it to be pulled into the engine cylinders.

Shape and flow characteristics of the Plenum can make a substantial effect on to fuel delivery on the N52B25 &N52B30.

We often see intake manifold are crying out for a performance upgrade, although some makers provide fairly well optimized intake manifold.

Increasing the N52 valve size, carrying out port matching and head flowing will also raise power, & more importantly will afford you an improved power increase on other parts.

Which turbo upgrades are best?

NASP 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 N52

But adding forced induction is the only way to make significant power gains on both the N52B25 and N52B30, as the engines are quite well setup from the factory, leaving little room for improvement without resorting to major upgrades and work.

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

When an engine has a turbocharger parts are more reliable and you will discover turbocharged engines will have many forged and stronger components.

However you'll find engines have weakspots or components that are more prone to fail. So discover these restrictions and upgrade to more solid crank and pistons to handle the power.

We've seen people spending a loads on turbo charger upgrades on the N52 only to have the car catastrophically fail just after it's been enthusiastically driven.

Larger upgraded turbochargers commonly suffer no power at low rpm, and small turbochargers spool up quickly but don't have the high rpm bhp gains.

In the last 10 years the world of turbo chargers is always evolving and we now see variable vane turbo chargers, where 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 two channels and feed these at differently angled vanes in the turbo charger. They also help the scavenging effect of the engine.

It is not unusual that there is a limit in the air flow sensor MAF/MAP on these engines when loads more air is being drawn into the engine.

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

Adding a supercharger or additional turbo will make large bhp gains, although more difficult to get working. We have a twincharger bhp adding guide if you want to read more.

Fuelling

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

More bhp and torque needs more fuel. We would recommend you to be generous with your flow rate on the injectors.

The accepted safe increase is to add 20% when buying an injector, this accounts for injector deterioration and affords some spare capacity should the engine require 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.

Choosing the right performance exhaust

One of the most common mistakes and problems we see in tuning projects is usually down to the exhaust, or rather a poorly chosen exhaust for your engine.

You only need to to improve your exhaust if your current exhaust is actually causing a restriction in flow.

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

Note that with the largest exhaust you can buy this will slow the exhaust rate - the best exhausts for power gains are usually between 1.5 to 2.5 inches. It is the shape and material more than the bore size.

Usual exhaust restrictions come around the emissions filters installed, so adding a better flowing sports alternative will help avoid this restriction.

Weak spots Issues & problem areas on the N52

The engines are generally reliable and solid as long as they are regularly serviced and maintained.

There are issues with lifter/tappet noise due to a lack of oil pressure

There was a recall following a fire risk from the crankcase ventilation valve shorting, this was back in 2017 so most will have had the recall work done now.

Regular oil changes are vital on the N52, especially when tuned and will help extend the life and reliability of the engine.

For more information on Tuning your engine please join us in our friendly forum where you can discuss tuning options in more detail with our owners. It would also be worth reading our unbiased 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 upgrades work best for them on each model of car. Comments are used to improve the accuracy of these articles which are continually updated.

This article was written by Waynne Smith on TorqueCars, and I appreciate your feedback and suggestions. This entry was filed under BMW. You can leave a response below or join TorqueCars forum to discuss this article and car modification in detail with our members.

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