Modding uprating the BMW N47 engine!

Tuning guide "N47 Modifications"

N47 Modifications Guide

How to modify and upgrade the BMW N47

"Comprehensive guide to performance parts and tuning the BMW N47 engine!"

Our friends at TorqueCars are always getting posts about how to improve the N47 from people inquiring about getting more power from the N47 and wanting to know what are the things tuners are recommending when it comes to N47 power upgrades. So let us look into BMW N47 modifications and outline the best mods that work on this great engine and point out some frequent tuning mistakes along the way.

Car Tuning Tips will examine the options for your N47 tuning and highlight the greatest upgrades. BMW N47 are popular tuning projects and with the right uprated enhancements like ECU maps, turbo improvements and camshafts you will greatly improve your driving enjoyment.

Just because particular tuning parts are popular with N47 owners it doesn't mean its worth having, so we'll concentrate on the ultimate tuning parts that will give your N47 the best power gain for you money.

Without us subscribing to the popular mentality of 'if it's shiny and makes more noise it must be good' you seem to get in many tuning magazines and on car forums'.

N47 induction kits

Improving air intake on the N47

You need air and fuel for an engine to work. If there is little supply of fuel then it will run lean, if there is not enough air it runs rich losing power . We'll pick up on fuelling later in this article but for now we shall look at air supply.

So the goal to any engine tuning job to pull fuel and air into your N47 but this has a knock on effect with the air flow sensor.

It is common that there's a limit in the air flow sensor (AFM/MAF/MAP) on the N47 when a lot more air is being drawn into the engine.

We see 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor sapped bhp and torque at a much lower level.

Headers carry the on the suck phase from the air filter and allow it to be drawn into the engine cylinders.

The shape and flow characteristics of the Intake can make a big change to fuel delivery on the N47.

Most plenum chambers are improved through aftermarket parts, although some OEM provide reasonably good plenum chambers.

Larger N47 valves, carrying out 3 or 5 angle valve jobs and porting and head flowing will also improve torque, and importantly will make space for a greater torque increase on other upgrades.

N47 performance cam tips.

Each engine responds better to more or less aggressive cam durations so view each engine as unique.

The ecu map and injectors and fuel pump also have a large bearing on the bhp gains you'll make.

Altering valve durations 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.

Significant air intake, and exhaust improvements on the N47 can be made from camshaft upgrades. Changing the camshaft profile alters the intake and exhaust durations on the engine and can dramatically change the torque and power output.

NB: Fast road cams normally raise the performance through the rev range, you may lose a little bottom end bhp but the top end will be lifted.

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

A Motorsport cam is not great in heavy traffic.

You should ideally match your power band to your preferences so for a road car stick with a fast road N47 cam

Stage 1, 2 and 3 mods for the N47

Stage 1 N47 parts:

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

Stage 2 N47 parts:

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

Stage 3 N47 parts:

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

The N47 power trains respond well to mods and we note that there are quite a few choices of upgrades and tuning parts out there.

ECU mapping will help unlock the full potential of all the upgrades you've done to your N47.

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

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 the outcome usually vary depending on the upgrades you've fitted and the condition of your engine.

Turbo modifications on the N47

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 found a great 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 N47.

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

If the engine is turbocharged, upgrades are going to net you a larger power gain and turbo charged engines use uprated components.

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

Research these limitations and install better quality components to cope with the power.

There are many mechanics spending a fortune on turbocharger upgrades on the N47 only to suffer the humiliation of seeing the engine block throw a rod just after it's been finished.

Big capacity turbochargers tend to experience no power at low rpm, and small turbochargers spool up really quickly but do not have the peak rpm power band gains.

We are pleased that the range of turbo units is always moving on and we are seeing variable vane turbo units, where 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 direct these at differently profiled vanes in the turbo charger. They also increase the scavenging effect of the engine.

Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large bhp gains, although more challenging to configure. We have this in depth look at twinchargers if you want to read more.

Tips about fuel supply on the N47

You will need to ensure that the engine is not starved of fuel so need to look at the fuelling when you start extending past 20% of a torque hike. Don't forget to over specify your injector capacity.

As a rule of thumb add 15% to the flow rate when buying an injector, this accounts for injector deterioration and gives a bit of 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..

Recommended N47 performance exhaust upgrades

We'd only recommend you look to increase your exhaust system with an upgraded one is if your current exhaust is actually creating a restriction.

On most factory exhausts you should find that the flow rate is still ok even on modest power gains, but on a serious tuning project with a big boost in power you will certainly need to get a better flowing exhaust.

Sports exhausts balance the flow of gases through the engine.

But if the exhaust pipe is too large, ie: over two and a half inches diameter, you will lose a lot of your flow rate and end up lacking power and torque.

Usual exhaust restrictions are traced to the catalysts installed, so adding a freer flowing sports alternative will help avoid this restriction.

Catalyst removal (NB:catalysts reduce harmful engine emissions) is illegal in most countries and regions.

Faults issues and things to look out for on the N47

Like most engines an N47, should have few issues if it gets properly serviced and looked after.

We cannot stress enough the need for oil changes with the correct grade of oil on the N47, failure to do this will exacerbate engine wear, on a tuned N47 this is more important than ever and close attention should be paid to your maintenance schedule.

If you are interested in learning more or getting impartial tuning advice for your N47 why not pop over to the forums at TorqueCars where you can chat about N47 tuning options and read about others projects who may be planning to do similar modifications on their N47.

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