Tuning the BMW N52

"Comprehensive guide to tuning the BMW N52 engine!"

This pages aim is detail the best approach to N52 tuning and show the optimum modifications for your car. BMW N52 make a good tuning project and with the ultimate modified modifications like remapping, turbo upgrades and camshafts you will definitely maximise your driving pleasure.

When talking about the best ultimate for your N52 engine, we are going to concentrate on the mods that give the best power gain for you money. This guide has been updated on our main site so please check out our new N52 Tuning article.

N52 and camshafts

The stock cams are hollow and light, so not as durable as some but if you can source a more aggressive profile then you are on the way to making some pretty neat power gains.

Significant gains on the N52 can be made from camshaft upgrades. Altering the camshaft profile alters the intake and exhaust durations on the engine and can dramatically change the power band and power output.

NB: Fast road cams normally raise the bhp over the rpm range, you may lose a little low down bhp but the high end rpm power will be lifted.

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

A Race cam makes it harder when driving around busy urban areas.

You should ideally optimize your power band to your driving style so for a car driven daily stick with a fast road N52 cam

Different N52 engines respond better to less aggressive cam durations check your engine on a rolling road.

The map and fuelling also have a large bearing on the power gains you'll hit.

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.

Stage 1 modifications: Intake headers, Fast road camshaft, Panel air filters, Sports exhaust manifold, Remaps/piggy back ECU, Drilled & smoothed airbox.

Stage 2 modifications: Sports catalyst & performance exhaust, fuel pump upgrades, Ported and polished head, induction kit, Fast road cam, high flow fuel injectors.

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

N52 engine mapping

The N52 power plant respond well to mods and we see that there are quite a few choices of upgrades and tuning parts around.

Remaps allows a tuner to to establish the full potential of all the parts you've fitted to your N52.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but your results will vary depending on the parts you've carried out and the condition of your engine.

Your access to specialist mappers is very much dependent on where you live, but generally speaking you'll see around 20% more power from a remap, and around 10-15% for a tuning box.

Mods for the N52 intake

It is the whole point to any engine upgrade project to pull more fuel and air into your N52 so let's look at the intake.

The intakes used on the 330i utilized a better design and boasted a triple valve DISA to push the air efficiently into the cylinders that most required it. Fitting one of these intakes to a standard N52 will usually make another 20hp or so, and has become a go to mod for the N52.

Design and flow characteristics of the Intake manifold can make a big effect on to fuel engine efficiency on the N52.

Commonly we find the intake are improved through aftermarket parts, although a few makers provide well optimised intake. In the case of the N52 BMW filter designs are not bad, the most you can hope to gain from an aftermarket kit is around 5hp, but the induction noise alone makes this mod worthwhile.

Big valve conversions on the N52, getting 3 or 5 angle valve jobs and porting and head flowing will also improve bhp and torque, and importantly will raise potential for increasing the bhp and torque increase on other parts.

Turbo upgrade kits for the N52

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

TorqueCars recommends the BorgWarner EFR turbo 6258 which should be good for around 400bhp and the 6758 takes you to 450 but has more low end lag (obviously you'll need to sort out fuelling and mapping, and other mods will usually be required to reach the upper end of these figures). (The intake and compressor wheel size forms the BW model number)

Bimmer Performance Center did an interesting 71-63 turbo, that could potentially boost to around 500hp on the N52, and you could always swap in turbos from the N54 or N55 for around 300-400hp.

There is also a kit that comes with a GT3076R which is good for around 70hp more from Laurent motors which we have yet to try out but the specs seem good to us.

If we were adding forced induction then  we would probably go with a centrifugal supercharger which matches the engines power delivery, and we find that they are more straightforward to setup than a turbo when it comes to mapping them.

If a car is turbo charged tuning parts are more reliable and you'll see that turbocharged engines will have uprated components.

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

See where you'll find these restrictions and install better quality crank and pistons to handle the power.

It's not unheard of drivers spending a a stack of money on turbo upgrades on the N52 only to experience the engine explode soon after it's used on the roads.

Top mount turbos are generally easier to install rather than going with a low rear exhaust mounted turbo where space is limited to the smaller turbo units. You will need a custom manifold, and although the N54 and N55 heads look similar there are notable differences, namely the water inlet and the location of the aircon compressor which affect the design.

Sacrifice your aircon and you make life a little easier, but why do that when there are lots of suitable modified manifolds out there you can use.

Bigger turbos commonly experience no power at low rpm, and smaller turbos spool up really quickly but do not have the top end power band gains.

Bimmer Performance Center did an interesting 71-63 turbo, that could potentially boost to around 500hp on the N52, and you could always swap in turbos from the N54 or N55 for around 300-400hp.

For a street car we would recommend looking at the BorgWarner EFR turbo BW 6258 should be good for around 400bhp and the BW 6758 takes you to around 450bhp but has more low end lag.

It is common that there is a limitation in the air flow sensor AFM/MAF on the N52 when a lot 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 performance at a much lower level.

Adding a supercharger or additional turbo will make large bhp and torque gains, although more difficult to install. We have this in depth look at twinchargers if you want to read more.

Fuelling upgrades and mods

You will need to ensure that the engine is not starved of fuel so should uprate the fuelling when you start exceeding 20% of a torque increase.It makes sense to over specify your flow rate on the injectors.

The accepted safe increase is to add another 20% when specifying an injector, this allows for injector deterioration and allows a little 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.

Exhaust upgrades and mods

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

On most factory exhausts you'll see the exhaust flow rate is still fine 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 can help equal out the flow of air through the engine.

But if the exhaust pipe is too big, ie: over 2.5 inches bore, you will lose a lot of the exhaust flow rate and end up lacking power and torque.

Typically exhaust restrictions can be traced to the filters installed, so adding a faster flowing race alternative will help avoid this restriction.

Weak spots, Issues & common problem areas on the N52

The engines, if regularly serviced and maintained, are generally very reliable and have few issues.

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, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

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

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.

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We really like hearing from our readers, and hearing about which upgrades were the most effective for them, it helps us improve our recommendations and articles to reflect current trends in modifications and ensures that our guides and tips are kept up to date.

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