Comprehensive guide to tuning the M47 engine from BMW

All you need to know about "Tuning the BMW M47"

"Comprehensive guide to tuning the BMW M47 engine!"

Hello, diesel devotees! Today, let's shine a light on the BMW M47 engine – a powerhouse that has left its mark in the world of efficient and spirited diesel performance.

The M47 is at the heart of some notable BMW models, including the 3 Series and 5 Series. Born from the German engineering precision, this diesel engine is all about delivering a dynamic driving experience with an emphasis on fuel efficiency.

Now, let's delve into the details. The M47 is a four-cylinder diesel engine, showcasing BMW's commitment to marrying power with practicality. With a displacement tailored for optimal efficiency, this engine isn't just about raw power; it's about torquey responsiveness that makes every drive a delight.

Under the hood, the M47 proudly features a Double Overhead Camshaft (DOHC) setup. It's the mark of precision engineering, ensuring accurate control over the valves for an optimal combustion process. While variable valve timing might not be stealing the show here, it's the simplicity and effectiveness that set the stage for potential modifications.

So, why consider upgrading your M47? Whether you're after a bit more torque for that spirited acceleration, improved fuel efficiency, or just want to personalize your diesel driving experience, the M47 is a canvas waiting for your enthusiast touch.

In the articles to come, we're not just exploring the M47; we're on a mission to save you time and money while guiding you through the process of unlocking the true potential of your Bavarian diesel powerhouse. Get ready for a journey of upgrades that'll have your M47 humming with newfound vitality. Let's hit the road, fellow enthusiasts!

The BMW M47 provide a fun base for your project and with carefully picked tuning mods like a remap, turbo upgrades and camshafts you will noticeably increase your driving enjoyment.

Here we look into M47 tuning and highlight the ultimate mods that work.

When talking about the best parts for your M47 engine, we are going to focus on the upgrades that give the best value for money.

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

NB: Fast road cams normally push up the performance through the rev band, you could drop a little low end bhp but your top end will be lifted.

Race cams, push up the top end band but as a result the car will not idle smoothly and low end power nearly always suffers.

On a road car must carefully try to optimize your power band to your cars usage.

I'd never have ever thought a M47 Competition camshaft is a pleasure to live with when on the daily commute.

Some M47 engines respond better to extreme camshaft durations check your engine on a rolling road.

The ECU mapping and injectors and fuel pump also have a large bearing on the bhp gains you'll hit.

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.

Our top 7 top upgrades for your motor, and we will break these into stages and discuss them in detail for you.

  1. Map Tunes - remapping, via either OBD port, or piggyback ECU's and aftermarket ECU's can all make decent gains
  2. Fuelling Pump Injectors - You'll need to match the greater air flow with more fuel to unlock the power
  3. Turbo upgrades - Improving the intake charge with a large turbo and better flowing intercooler will be the biggest power gain you'll see (but one of the most complex especially where conversions are required).
  4. Suspension Upgrades - always improve your cars handling, tuning is not just about engine mods
  5. Brake Upgrades - Even before adding power improve your cars brakes to effectively stop the car
  6. Intake - make sure the intake is not restricted, use filters and intake upgrades to improve this
  7. Exhaust - as with intakes it helps to remove a restriction in the exhaust, cats are the usual bottleneck

This video guide to tuning cars is a great starting point to work from in your project.

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

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

Stage 3 mods: Competition cam, Crank and Piston upgrades to alter compression, Internal engine upgrades (head flowing porting/bigger valves), Adding or Upgrading forced induction (turbo/supercharger), Twin charging conversions, Engine balancing & blueprinting.Plan your options and then buy your mods and set yourself a power target to void expensive mistakes.

Tuning tips and articles Engine tuning Transmission tuning Care care Intake & exhaust mods Improve handling Forums

Mapping allows a tuner to release the full potential of all the parts you've done to your M47.

You will typically expect to see gains of approximately 20-30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but your results may depend much on the parts you've carried out and the condition of your engine.

Forcing more air into each cylinder is the aim to any engine tuning project.

The intake plenum take the air from the filter and allow it to be drawn into the engine cylinders.

Shape and rate of flow of the Headers can make a noticeable difference to to fuel delivery on the M47.

We often see headers are in dire need of an upgrade, although a few OEM provide fairly well optimized headers.

Larger M47 valves, doing a bit of port matching and head flowing will also lift torque, and significantly will raise potential for raising the torque increase on other mods.

Turbo upgrades

To get a turbo working on a NASP engine there is a lot involved, from lowering compression ratio to improved fuel supply and mapping, so we have a separate guide to helpavoid the common pitfalls or end up with an unfinished project because you were not told what you were getting into by doing this on the 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 major power gains.

When your motor has a turbo already fitted modifications are relatively easy and you will discover turbo engines are made using better components.However you will find an engines will need better parts at higher power limits

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

We see many mechanics spending a a stack of money on turbo charger upgrades on the M47 only to suffer the humiliation of seeing the M47 throw a rod just after it's first rolling road session.

Large capacity turbochargers commonly experience low end lag, and small turbochargers spool up really quickly but don't have the high rpm bhp gains.

In the last 10 years the range of turbo units is always improving and we commonly find variable vane turbo units, permitting the vane angle is altered according to speed to lower lag and increase top end torque.

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

It is common that there is a limitation in the air flow sensor AFM/MAF on the M47 when a lot more air is being pulled into the engine.

We see 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor sapped performance at a much lower level.Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large performance gains, although more challenging to configure. We have this article on twincharging if you want to read more.

Fuelling upgrades and mods

Don't overlook the need to ramp up the fuel system when you are increasing the performance - it makes the car more thirsty.

It is important to be generous with your injector capacity.

The accepted safe increase is to add 20% capacity when buying an injector, this allows for injector deterioration and affords a little spare capacity should the engine need more fuel.

Don't forget that different fuel grades will usually require different settings, a high octane fuel will burn more efficiently than lower octane fuel for example. A car will trim fuel supply to keep within the ideal air fuel mix but at the extreme ends you may need to adjust your injector capacity, or the mapping or you'll get flat spots and potential lean or rich fuel issues..

Exhaust upgrades and mods

Only look to replace your exhaust if your current exhaust is actually causing a flow problem.

On most factory exhausts you should find that the 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 usually air flow out of the engine but avoid an exhaust that is too wide or you could will reduce the flow rate. Stick to one and a half to two and half inches as a rule of thumb.

Usual exhaust restrictions can be traced to the filters installed, so adding a better flowing performance alternative will help avoid this restriction.

Weak spots, Issues & common problem areas on the M47

The M47 engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the M47, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

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 M47 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 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 M47 guides and tips are kept up to date.

Additional references

Tuning the BMW M47 and best M47 performance parts.

If you liked this page please share it with your friends, drop a link to it in your favourite forum or use the bookmarking options to save it to your social media profile.

Check out TorqueCars new YouTube channel, and see their awesome new content...


Please use our forums if you wish to ask a tuning question, and please note we do not sell parts or services, we are just an online magazine.

Help us improve, leave a suggestion or tip

Your Constructive comments on this article