BMW M47 Tuning

"All you need to know about performance tuning the BMW M47 engine!"

The BMW M47 are good project engines and with the optimum sports parts like ECU maps, turbo improvements and camshafts you will noticeably maximize your driving enjoyment.

This pages aim is look into M47 tuning and provide tips on the best mods that work.

History of the Engine



Transverse engine with Rover and Steyr based on M47 design.


  • 85 kW (114 hp)  (207 lb⋅ft)2003-2005 E46 318d
  • 110 kW (148 hp) (243 lb⋅ft)2001-2005 E46 320d
    E83 X3 2.0d (up to end of 2006)


Tuning the BMW M47 and best M47 performance parts.

Best M47 parts

Just because particular modifications are popular with M47 owners it doesn't mean its worth having, we shall best modifications that will give your M47 the biggest power gain return for your cash.

The camshaft profile plays a big part in the engines power output so camshaft upgrades make quite a large difference. The intake and exhaust durations will alter depending on the chosen camshaft profile, so large power band gains are on offer for camshaft upgrades.

Fast road cams usually push up the performance through the rpm band, you could drop a little low end power but higher rpm power will be lifted.

For a typical daily driver you need to optimize your bhp range to your cars usage.

The map and fuelling also will say much on the bhp gains you'll make.

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.

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

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

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

The M47 engines are great to work on and we're pleased to see that there is a growing number of modifications and tuning parts around.

Mapping should help to release the full potential of all the modifications you've fitted to your M47.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but the outcome will depend much on the modifications you've applied and the condition of your engine.

Feeding air into the M47 engine is the aim to any engine upgrade task.

Air Intake manifolds take the air from the intake filter and allow it to be pulled into the engine cylinders with fuel for the squish phase.

The bore size, shape and rate of flow of the Plenum can make a large effect on to fuel atomisation on the M47.

We often see intake are in desperate need of aftermarket tuning parts, although some car makers provide decently flowing intake.

Larger M47 valves, doing a bit of port matching and head flowing will also improve performance, this will make space for a better performance increase on other tuning parts.

Turbo upgrades

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 M47

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

If an engine is fitted with a turbocharger tuning mods are giving better power gains and turbocharged engines are made using better components.

However every engines have limits

Research these restrictions and fit stronger pistons, crank and engine components to cope with the power.

It's not unheard of mechanics spending a lot of money on turbocharger upgrades on the M47 only to have the engine throw a rod just after it's finished.

Large upgraded turbo units tend to experience no power at low rpm, and little turbo units spool up quickly but do not have the high rpm power band gains.

In the last 10 years the world of turbochargers is always moving on and we now see variable vane turbochargers, permitting the vane angle is altered according to speed to lower lag and increase top end bhp and torque.

Twin scroll turbochargers divert the exhaust gases into a couple of channels and flow these at differently designed vanes in the turbo. They also help the scavenging effect of the engine.

You'll commonly see there is a limit in the air flow sensor AFM/MAF on these engines when loads 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 sapped bhp and torque at a much lower level.

Adding a supercharger or additional turbo will make large bhp and torque gains, although more complex to configure. We have this guide to twinchargers if you want to read more.


Don't forget to look at the fuel delivery when you are increasing the torque - it makes the car more thirsty. It makes sense to be generous with your injector capacity.

As a rule of thumb add another 20% when specifying an injector, helps cope with injector deterioration and affords 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.


You may need to improve your exhaust if the current exhaust is actually creating a flow problem.

On most factory exhausts you should find that the exhaust flow rate is still 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 can help increase the flow of gases through the engine.

But if the exhaust pipe is too large, ie: it's over 2.5 inches bore, you will lose a great deal of the flow rate and end up losing power and torque.

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

Weak spots Issues & problem areas on the M47

The M47 engines are generally reliable and solid as long as they are regularly serviced and maintained.

Swirl flaps are prone to breaking and can cause serious engine damage. Many owners get these removed as a precaution.

DMF failures are common, especially when the DMF is not replaced at the same time as the clutch.

Regular oil changes are vital on the M47, especially when tuned and will help extend the life and reliability of the engine.

For more information on Tuning your M47 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 mods work best for them on each model of car. Comments are used to improve the accuracy of these M47 articles which are continually updated.

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