BMW M47 Tuning

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

The BMW M47 represents a good project engine, and with the optimum performance upgrades and mods you can really make it sparkle. With parts and modifications like ECU maps, intake and exhaust tweaks, turbo improvements, and camshafts you will noticeably maximize your driving enjoyment.

This page's aim is to look into M47 tuning and provide tips on the best mods that work.

With so many different models and a long production run there is plenty of modified M47's out there, and much of the trial and error approach to tuning has been worked out for you.

History, Power & Specs of the Engine

In 2006 BMW dropped the Garrett turbos and started using Mitsubishi turbos so there are some physical differences in the layout and configuration.

M47D20

M47R

Transverse engine with Rover and Steyr based on M47 design.

M47TUD20

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

M47TU2D20

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 it's 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 engine's 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 car's usage.

The map and fuelling also will say much about 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.

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

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

Typical stage 3 mods often include: 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 you around 30% more power on turbocharged vehicles, but the outcome will depend much on the modifications you've applied and the condition of your engine. We've seen many claiming a power hike from 163 to 230hp from a remap, but we suspect others mods will be required to support this.

We would expect a remapped 163hp M47 to hit around 210hp, but the thing you'll appreciate the most is the big wide torque band surge, it totally transforms the engine.

The most important thing to note with any remap is the torque curve rather than the peak power claims made. Always ask to see a dyno graph, and any mapper who's worth his salt can provide one.

M47 air intakes

Feeding air into the M47 engine is the aim to any engine upgrade task. We have to mention the swirl flaps fitted to the M47, the theory behind these is to spiral the air into the cylinders helping the fuel to mix with the air more thoroughly.

The swirl flaps are only really effective at lower RPMs so it's more of an economy and emissions feature than a performance one.

As the EGR (exhaust gas recirculation) valve does its thing oil residue builds up coating the intake with carbon, narrowing the intakes, and in some cases, we've seen these lose 50% of their capacity to flow air.

When you add the EGR issues to the swirl flaps the problems just keep getting bigger, and instead of helping emissions and low RPM efficiency, it degrades it further.

So many owners are opting to remove the swirl flaps completely, but this may not be legal in some areas.

The merits of doing so is questionable, as this could well lead to further carbon build up issues, so opting to upgrade the swirl flaps to a better made solution makes more sense.

Keep an eye out for symptoms of carbon build up in the intake.

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 air intake systems are in desperate need of aftermarket tuning parts, although some car makers provide decently flowing intake.

Larger M47 performance intake, exhaust valves, and 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 on the M47 engine

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

Beware though, that the spool up and top end power are at either end of the spectrum, so generally you can't have the best of both worlds, there is a compromise.

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.

We would prefer to have a faster spool up and low end torque, than a massive top end, but we totally understand people are different.

We suspect that BMW opted to use a twin turbo setup  instead of a larger turbocharger.

We have found that on the M47 the GTB2260 is a great turbo upgrade, and good for around 295bhp.

Hybrid turbos takes the components from the intake and compressor side and blends them into an OEM casing making a straight swap part (apart from the need to remap) With this in mind, something like the  GT1749V turbo effectively and adding around 7mm to the compressor wheel effectively making an equivalent to the GT1756 and on the M47 a 1756 should flow well to give around 230bhp at the peak.

The Garrett GTB1756L was used in the Alpina D3 and we've seen some projects reaching around 270hp on those, making it another great choice.

Ask around your local breakers yard, if you are familiar with the full range of M47 engines you can often pick up bargain upgrades from those performance variants.

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

In the last 10 years the world of turbochargers is always moving on and we now see variable vane turbochargers, permitting the vane angle to be 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 in power with turbo upgrades, you may well hit errors from the air flow meters, MAP/MAP sensors, make sure it is clean, reset the ECU and if you are still having issues you'll need to uprate these items or you'll end up sapping 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.

Fuelling upgrades on the M47

Don't forget to look at the fuel delivery when you are increasing the torque - it makes the car more thirsty.

If you approach the limits of your fuelling you may end up running lean or throwing error codes, and this can be quite common on older injectors where turbo upgrades have been applied.

It makes sense to be generous with your injector capacity.

In fact, as a general rule of thumb we would recommend that you add another 20% when specifying an injector, as this helps the engine cope with injector deterioration, and affords a little spare capacity should the engine need more fuel, or you desire a little more power.

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 headers and upgrades on the M47

You may need to improve your exhaust if the current exhaust is actually creating a flow problem. Replacing the headers will likely only release another 7hp, so not a massive gain considering the outlay, but for heavily tuned M47's you might gain a little more.

On most factory exhaust setups 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.

The main gain you'll get here is sadly not road legal, because it involved removal of the catalyst and thankfully as far as we know the M47 was never fitted with a DPF.

Sports exhausts can help increase the flow of gases from the engine and will help the turbo spool up if it's designed correctly.

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 catalyst removes the restriction. We note that performance cats perform similarly to decats and have the added benefit of keeping your car street legal, as decats or catalyst removal is illegal in most territories for road going cars.

Weak spots Issues & problem areas on the M47

The M47 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.

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.

If you would like to know more, or just get some friendly advice 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.

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3 Responses to “BMW M47 Tuning”

  1. Silviu Galusca says:

    Hi,nice article thank you!
    All this modification can be made on rover 75 2.0 cdti! M47R
    Becouse the ECU is from rover not BMW

    • TorqueCars says:

      The Rover MEMS cannot be mapped (at least not back when I had a Rover 200 and looked into this), you’ll need to use something like the ICON RACE aftermarket/piggyback ECU which we used back in the day on the Rover.

  2. Ebeniza Shoniwa says:

    I hope this will help many of us on the e46 320d 2004 model m47 engine and Gearbox issues

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