The Lowdown on "N46 Modifications"

How to modify and upgrade the BMW N46

"Comprehensive guide to tuning the BMW N46 engine!"

Our friends at TorqueCars are always getting emails requesting information on how to improve the N46 from people wanting to know what are the things tuners recommend when it comes to N46 mods that work. So let us look into BMW N46 parts and outline the best modifications on this great engine and point out some frequent tuning mistakes along the way.

Here we examine the options for your N46 tuning and point out the ultimate modifications. BMW N46 are popular tuning projects and with a few sensible uprated parts like remaps, turbo improvements and camshafts you will noticeably maximize your driving experience.

Just because particular parts are popular with N46 owners it doesn't mean its worth having, we shall focus on the greatest parts that will give your N46 the biggest power gain return for your cash.

Without us subscribing to the misaprehension 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'.

Improving air intake on the N46

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

So the whole point to any engine upgrade job to force fuel and air into the N46 engine but this has a knock on effect with the air flow sensor.

It is not unusual that there's a limit in the air flow sensor AFM/MAF on the N46 when considerably 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 limited bhp at a much lower level.

Headers transmit the during the engines suck phase from the air filter and allow it to be drawn into the engine and mixed with fuel.

The size of bore and shape and flow characteristics of the air Intake manifold can make a big effect on to fuel delivery on the N46.

We often see intake headers are in desperate need of aftermarket tuning parts, although some manufacturers provide reasonably well designed intake headers.

Fitting big valve kits, getting port matching and head flowing will also raise power, & more importantly will afford you raising the power increase on other tuning mods.

N46 performance cam tips.

Different N46 engines respond better to different camshaft durations so set your engine up on a rolling road.

The engine timing and injectors and fuel pump also have a large bearing on the power gains you'll get.

Extending exhaust or intake durations can alter the power 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 N46 can be made from cam upgrades. Changing the cam profile alters the intake and exhaust durations on the engine and can dramatically change the power band and power output.

NB: Fast road camshafts normally raise the torque throughout the rpm range, you may lose a little low down torque but the top end will be higher.

Race camshafts, 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 won't do well if driving around busy urban areas.

You should ideally optimize your engines power to your driving style so for a road car stick with a shorter duration N46 cam

Stage 1, 2 and 3 mods for the N46

Before we break the best tuning upgrades down into stages of tune, let's list the most effective tuning upgrades for you.

1. Suspension Upgrades - always improve your cars handling
2. Brake Upgrades - Even before adding power improve those brakes
3. Intake - make sure the intake is not restricted, use filters and intake upgrades to improve this
4. Exhaust - as with 3 ensure there is not restriction in the exhaust, cats are the usual bottleneck
5. Tunes - remapping, piggyback ECU's and aftermarket ECU's can all make decent gains
6. Fuelling - when you've increased power you'll need to match this with more fuel
7. Turbo upgrades - Improving the intake with a large turbo and better flowing intercooler will be the biggest power gain you'll see (but one of the most complex).

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

Stage 1 N46 parts:

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

Stage 2 N46 parts:

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

Stage 3 N46 parts:

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

Remapping will help release the full potential of all the parts you've done to your N46.

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 often differs on the parts you've done and the condition of your engine.

Turbo modifications on the N46

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 N46.

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

If an engine is fitted with a turbo parts are giving better power gains and most turbocharged engines are made using harder and stronger components.

There are weak spots for every engine, with some being extremely strong and some only just able to handle stock power

See where you'll find these restrictions and fit forged components to cope with the power.

We see many people spending a lot of money on turbocharger upgrades on the N46 only to experience the whole thing literally blow up just after it's been finished.

Bigger turbo units will usually suffer a bottom end lag, and smaller turbo units spool up more quickly but do not have the peak rpm torque gains.

In recent times the range of turbochargers is always increasing and we commonly find variable vane turbochargers, where the vane profile is altered according to speed to lower lag and increase top end bhp and torque.

Twin scroll turbochargers divert the exhaust flow into 2 channels and flow 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 get working. We have this feature on twinchargers if you want to read more.

Tips about fuel supply on the N46

You will need to ensure that the engine is not starved of fuel so will have to look at the fuelling when you start exceeding 20% of a torque hike. Most tuners we speak with say to over specify your injector capacity.

As a rule of thumb add 20% when fitting an injector, this accounts for injector deterioration and provides you some 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 N46 performance exhaust upgrades

The only time you should look to increase your exhaust system with an upgraded one is if your current exhaust is actually creating a flow problem.

On most factory exhausts you'll see your flow rate is good 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.

Please dont run with the biggest exhaust you can get this will slow up the exhaust flow rate - the best for power gains are usually between one and a half to two and half inches. Your exhaust design, the bend angles and construction are what have more effect on flow rates than your pipe width to a certain extent. So the exhaust design is a big factor.

Usual exhaust restrictions can be traced to the catalyst and filters installed, so adding a faster flowing high performance 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 N46

Like most engines an N46, 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 N46, failure to do this will exacerbate engine wear, on a tuned N46 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 N46 why not pop over to the forums at TorqueCars where you can chat about N46 tuning options and read about others projects who may be planning to do similar modifications on their N46.

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This entry was posted under Makes and Models. Tags: BMW, engine
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