Tuning the BMW M47

"Comprehensive guide to tuning the BMW M47 engine!"

The BMW M47 provide a fun base for your project and with the optimum motorsport parts like remaps, turbo improvements and camshafts you will substantially maximize your driving enjoyment.

We shall review and look at M47 tuning and report on the best modifications for your car.

The top M47 parts on an engine are as we have found the ones that give the biggest return for your cash.

We won't be swayed by popular M47 parts, they need to be cost effective.

Significant gains on the M47 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 tend to raise the torque through the rpm band, you could sacrifice a little low down torque but your high end rpm power will be higher.

Motorsport and race 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.

On a road car should ideally to optimize your power band to your driving style.

I'd be shocked if you have ever thought a M47 Motorsport cam is a pleasure to live with when in heavy traffic.

Each engine responds better to more aggressive camshaft durations so set your engine up on a rolling road.

The ecu map and fuelling also have an effect on the torque gains you'll make.

Extending exhaust or intake durations can alter the torque 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: Panel air filters, Drilled & smoothed airbox, Intake headers, Remaps/piggy back ECU, Sports exhaust manifold, Fast road camshaft.

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

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

The M47 engines are great to work on and we're finding that there are plenty of mods and tuning parts out there.

A remap allows a tuner to release the full potential of all the tuning parts 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 usually rely on the tuning parts you've done and the condition of your engine.

It is vital to any engine upgrade task to force more air and fuel into the M47 engine

Headers transmit the air from the air filter and allow it to be sucked into the engine cylinders.

Design and flow rate of the Intake can make a large difference to to fuel atomisation and engine efficiency on the M47.

I usually find intake headers are in desperate need of aftermarket parts, although a few OEM provide reasonably good intake headers.

Increasing the M47 valve size, carrying out M47 port enlargement and head flowing will also lift performance, & importantly will afford you increasing the performance increase on other 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 Garrett GTB1756L was used in the Alpina D3 and we've seen some projects reaching around 270hp on those. Also the GTB2260 is a great turbo upgrade, and good for around 295bhp.

Hybrid turbos which use your compressor housing but swaps out the compressor wheels would make your  GT1749V a GT1756 with a 7mm larger compressor wheel and on the M47 this should flow well to give around 230bhp.

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

If an engine is turbo charged tuning parts are giving better power gains and most turbo charged engines are made with better components.

There are practical limits for every engine, with some being incredibly solid and some just sufficiently able to handle stock power

We recommend you find these limits and upgrade to higher quality crank and pistons to cope with the power.

There are many drivers spending a loads of money on turbocharger upgrades on the M47 only to have the M47 go up in smoke just after it's been finished.

Bigger upgraded turbo units commonly experience no power at low rpm, and little turbo units spool up really quickly but won't have the peak rpm torque gains.

Thanks to new tech the world of turbo units is always developing and we commonly find variable vane turbo units, allowing the vane profile is altered according to speed to lower lag and increase top end torque.

Twin scroll turbo units divert the exhaust gases into a couple of channels and push these at differently designed vanes in the turbocharger. They also improve the scavenging effect of the engine.

You'll commonly see there's a restriction in the air flow sensor (AFM/MAF/MAP) on the M47 when considerably 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 and torque at a much lower level.

Adding a supercharger or additional turbo will make large power gains, although more difficult to install. We have this feature on twinchargers if you want to read more.

Fuelling upgrades and mods

When you raise the performance you will need to increase to the fuelling.

More performance needs more fuel. We strongly recommend you to be generous with your injectors flow rate.

The accepted safe increase is to add 20% capacity when fitting an injector, helps cope with injector deterioration and allows some 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.

Exhaust upgrades and mods

You should look to boost your exhaust if your exhaust is creating a flow problem.

On most factory exhausts you should find that the 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.

Do not go with the biggest exhaust you can get you'll slow the exhaust rate - the best for power gains are usually between 1.5 to 2.5 inches. It is the shape and material more than the bore size.

Common exhaust restrictions come around the catalyst installed, so adding a higher flowing sports 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.

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, 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 tuning articles to get a full grasp of the benefits and drawbacks of each modification.

History of the Engine

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

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