Modifying and improving: "N13 Modifications"

How to modify and upgrade the BMW N13

"Comprehensive guide to tuning the BMW N13 engine!"

TorqueCars often are seeing threads about how to improve the N13 from people inquiring about getting more power from the N13 and wanting to know what are the best N13 power upgrades. So let us look into BMW N13 parts and outline the best mods that work on this great engine and point out some problems along the way.

In this article we examine N13 tuning and report on the optimum upgrades. BMW N13 great bases for a tuning project and with the optimum uprated enhancements like remapping, turbo improvements and camshafts you will greatly maximise your driving enjoyment.

Just because particular parts are popular with N13 owners it doesn't mean its worth having, we will focus on the greatest parts that will give your N13 the biggest power gain return for your cash.

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'.

Improving air intake on the N13

You need air matched to fuel for an engine to work. If there is little supply of fuel then it will run lean, if there is a lack of air it runs rich sapping 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 more air and fuel into the N13 engine but this has a knock on effect with the air flow sensor.

It is common that there is a limit in the air flow sensor MAP/MAF/AFM on the N13 when loads more air is being drawn into the engine.

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

Intake manifolds flow the air from the intake filter and allow it to be drawn into the engine and mixed with fuel.

Design and flow rate of the Intake headers can make a substantial change to fuel engine efficiency on the N13.

Commonly we find the plenum chambers are in desperate need of a performance upgrade, although a few manufacturers provide reasonably good plenum chambers.

Big valve conversions on the N13, getting N13 port enlargement and head flowing will also increase power, and more importantly will permit increasing the power increase on other mods.

N13 performance cam tips.

Different N13 engines respond better to extreme cam durations than others.

The engine timing and fuelling also have a large bearing on the torque gains you'll make.

Longer valve 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.

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 torque gains are on offer for camshaft upgrades.

NB: Fast road cams commonly increase the bhp across the rev band, you may lose a little bottom end power but your top end will improve.

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

In a typical daily driver you need to match your torque band to your driving style.

I'd be gobsmaked if you have found a N13 Race cam is a pleasure to live with when in heavy traffic.

Stage 1, 2 and 3 mods for the N13

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 N13 parts:

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

Stage 2 N13 parts:

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

Stage 3 N13 parts:

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

ECU flashing allows a tuner to release the full potential of all the upgrades you've done to your N13.

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 will differs on the upgrades you've done and the condition of your engine.

Turbo modifications on the N13

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 N13.

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 your motor has a turbocharger parts are going to net you a larger power gain and most turbo engines will have strengthened components.

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

We recommend you find these limits and fit higher quality components to survive the power.

We see many tuners spending a fortune on turbo upgrades on the N13 only to experience the car throw a rod just after it's completed.

Big upgraded turbo chargers often experience no power at low rpm, and smaller turbo chargers spool up really quickly but don't have the peak rpm engines power gains.

In recent times the selection of turbos is always increasing and we commonly find variable vane turbos, allowing the vane profile is altered according to speed to lower lag and increase top end bhp.

Twin scroll turbos divert the exhaust flow into 2 channels and flow these at differently profiled vanes in the turbo charger. They also boost the scavenging effect of the engine.

Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large performance gains, although harder to configure. We have this guide to twinchargers if you want to read more.

Tips about fuel supply on the N13

When you lift the torque you will need to look at to the fuel delivery.

More torque needs more fuel. Care modifiers usually say to be generous with your flow rate on the injectors.

The rule of thumb is to add another 20% when buying an injector, this accounts for injector deterioration and provides 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..

Recommended N13 performance exhaust upgrades

The only time you should look to boost your exhaust system with an upgraded one is if your current exhaust is actually causing a restriction in flow.

On most factory exhausts you'll find 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.

Sports exhausts can help equal out the flow of air 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 the exhaust flow rate and end up sapping power and torque.

The usual suspects causing problems in your exhaust flow rate are traced to the catalyst installed, so adding a freer flowing race 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 N13

Like most engines an N13, 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 N13, failure to do this will exacerbate engine wear, on a tuned N13 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 N13 why not pop over to the forums at TorqueCars where you can chat about N13 tuning options and read about others projects who may be planning to do similar modifications on their N13.

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