Modifying and improving: "N20 Modifications"

How to modify and upgrade the BMW N20

"Comprehensive guide to tuning the BMW N20 engine!"

Our friends at TorqueCars are frequently getting posts asking how to improve the N20 from people wanting to know what are the optimum N20 mods that work. So let us look into BMW N20 upgrades and outline the best modifications on this great engine and point out some common pitfalls along the way.

In this article we provide a guide to N20 tuning and highlight the premier mods that work. BMW N20 are good project engines and with the right tuning mods like remapping, turbo improvements and camshafts you will noticeably increase your driving pleasure.

The top N20 upgrades on an engine are as we have found the ones that give the best power gain for your hard earned cash.

We won't be swayed by popular N20 upgrades, they need to be cost effective.

Improving air intake on the N20

You need fuel and air for an engine to work. If there is a lack of fuel then it will run lean, if there is too little 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 aim to any engine performance tuning project to force more air into the N20 engine but this has a knock on effect with the air flow sensor.

It is not unusual that there is a restriction in the air flow sensor (AFM/MAF/MAP) on the N20 when a lot more air is being pulled into the engine.

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

Headers carry the during the engines suck phase from the filter and allow it to be fed into the engine cylinders.

The shape and flow rate of the Intake can make a noticeable difference to to fuel delivery on the N20.

On popular production engines intake headers are improved through performance upgrades, although a few makers provide reasonably well designed intake headers.

Larger N20 valves, getting port work and head flowing will also boost power, and more importantly will make space for a better power increase on other tuning parts.

N20 performance cam tips.

Some N20 engines respond better to more aggressive cam durations than others.

The ecu map and injectors and fuel pump also will make differences on the bhp gains you'll hit.

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 N20 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 usually raise the performance through the rev range, you may lose a little low end bhp but higher rpm power will be better.

Race camshafts, raise the higher rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

In a daily driver you should ideally to match your bhp range to your driving style.

I'd be surprised if you have ever thought a N20 Competition cam is a pleasure to live with when driving in heavy traffic.

Stage 1, 2 and 3 mods for the N20

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 N20 parts:

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

Stage 2 N20 parts:

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

Stage 3 N20 parts:

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

Remaps helps unlock the full potential of all the parts you've done to your N20.

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 end result usually differs on the parts you've applied and the condition of your engine.

Turbo modifications on the N20

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 N20.

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

If the engine is fitted with a turbocharger parts are more reliable and turbo charged engines are made using stronger components.

However most engines will need better parts at higher power limits

Research these limitations and fit forged components to cope with the power.

It's not unheard of tuners spending a lots of money on turbo charger upgrades on the N20 only to experience the car catastrophically fail when it's been completed.

Big turbo chargers often suffer a bottom end lag, and little turbo chargers spool up quickly but do not have the peak end power band gains.

In the last 10 years the market of turbos is always increasing and we are seeing variable vane turbos, allowing the vane angle is altered according to speed to lower lag and increase top end bhp.

Twin scroll turbos divert the exhaust gases into 2 channels and direct these at differently profiled vanes in the turbocharger. They also improve 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 and torque gains, although more challenging to install. We have this article covering twinchargers if you want to read more.

Tips about fuel supply on the N20

Don't overlook the need to look at the fuel system when you are increasing the performance - it makes the car more thirsty. It is important to be generous with your injector capacity.

The accepted safe increase is to add 20% when buying an injector, this accounts for injector deterioration and affords 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 N20 performance exhaust upgrades

You only need to to improve your exhaust system with an upgraded one is if the current exhaust is creating a restriction in flow.

On most factory exhausts you'll see your flow rate is 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 your exhaust pipe is too big, ie: it's over two and a half inches diameter, you will lose much of your flow rate and end up lacking power and torque.

Usual exhaust restrictions can be located the catalyst and filters installed, so adding a faster flowing race alternative will help avoid this restriction.

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

Faults issues and things to look out for on the N20

Like most engines an N20, 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 N20, failure to do this will exacerbate engine wear, on a tuned N20 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 N20 why not pop over to the forums at TorqueCars where you can chat about N20 tuning options and read about others projects who may be planning to do similar modifications on their N20.

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