BMW N20 Tuning

"All you need to know about tuning the BMW N20 engine!"

The BMW N20 have loads of potential and with the right sports upgrades like remaps, turbo improvements and camshafts you will definitely maximize your driving enjoyment.

Let us outline options for your N20 tuning and outline the premier mods that work.

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History, Power & Specs of the Engine

It replaced the N53 / N52  and thanks to the turbocharger, it made similar power to the straight 6 predecessor. The Double VANOS and twin scroll turbocharger kept the car in the power band for most of the RPM range.

N20B16

• 168 bhp @5,000 rpm 250 Nm 184 lbft @1,500-4,700 rpm

N20B20

• 154 bhp @5,000 rpm 240 Nm 177 lbft @1,250-4,500 rpm
• 181 bhp @5,000 rpm 270 Nm 199 lbft @1,250-4,500 rpm
• 215 bhp @5,500 rpm 310 Nm 229 lbft @1,350-4,800 rpm
• 241 bhp @5,000 rpm  350 Nm 258 lbft @1,250-4,800 rpm

Tuning the BMW N20 and best N20 performance parts.

Best N20 upgrades

The best N20 upgrades on an engine are typically the ones that give the biggest return for your cash.

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

Altering your N20 camshaft will make a dramatic difference to the engine engines power. Choosing a higher performance camshaft profile raises the engines power accordingly.

Fast road cams usually increase the torque over the rev range, you could sacrifice a little low end bhp but higher rpm power will be better.

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

A Motorsport and race cam will just annoy you whilst in heavy traffic.

You should ideally optimize your bhp range to your cars usage so for a car used daily stick with a fast road N20 cam

Some N20 engines respond better to extreme cam durations check your engine on a rolling road.

The ecu map and fuel pump and injectors also have an effect on the bhp gains you'll achieve.

Extending exhaust or intake 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.

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Best mods for your N20

1. Turbo upgrades - Adding a turbocharger is the most dramatic method to improve intake air supply, this means you are able to utilize more fuel and make power gains. Although one of the most challenging modifications but provides the best gains.
2. Internal engine mods - crank, pistons, conrods & compression ratio including balancing and blueprinting
3. Intake and Exhaust Upgrades - NB: on their own these mods will NOT ADD POWER , but they can help release power after other mods by lessening the restrictive flow.
4. Flywheel lightening - a lower weight flywheel will improve the engines rev changes. But not always suitable for all N20 engines.
5. Engine Tunes - A Remapped N20 ECU provides the most advantage for your outlay, aftermarket ECUs, and inline Tuning boxes are all alternatives.
6. Fast road Camshafts are generally the biggest mechanical mod upgrade, but they must be fitted by someone who knows what they are doing and you might struggle to find one but you might find a local firm to regrind a stock camshaft for you.
7. Intercooler upgrades - a bigger intercooler resists heat soak and reducing any restriction in your intake.

N20 Tuning Stages

Typical stage 1 mods often include: Sports exhaust header/manifold, Fast road camshaft, Intake manifolds, drilled & smoothed airbox, Remaps/piggy back ECU, Panel air filters.

Typical stage 2 mods often include: Fast road cam, Ported and polished head, Sports catalyst & performance exhaust, fuel pump upgrades, induction kit, high flow fuel injectors.

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

ECU mapping will help release the full potential of all the upgrades you've fitted to your N20.

(In some cases, as the factory ECU is locked flashing is not an option, so an aftermarket ECU is the route to take, and many of these will outperform factory ECU's but make sure it has knock protection and that you get it setup properly.)

It will usually give you around 30% more power on turbocharged vehicles and you can expect to see around 15% on NA (naturally aspirated) engines, but your mileage will vary depending on the upgrades you've fitted and the condition of your engine.

Getting air into your N20 is the whole point to any performance tuning task.

The intake manifolds take the air during the suck phase from the filter and allow it to be sucked into the engine and mixed with fuel.

The bore size, shape and flow characteristics of the Plenum can make a noticeable improvement to fuel mixing and power on the N20.

I usually find plenum chambers are crying out for aftermarket parts, although a few OEM provide fairly well optimized plenum chambers.

Fitting big valve kits, doing some port work and head flowing will also improve bhp, and importantly will raise potential for an improved bhp increase on other parts.

N20 Turbo upgrades

NA (naturally aspirated) 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 N20

Increased induction with a turbocharger upgrade increases the amount of gasoline an engine can burn, resulting in enormous power improvements.

Forced induction tuning tweaks will increase the power of a vehicle's engine, and turbocharged engines are constructed with sturdier components.

As with every engine, there are areas where it can't take more power than it was designed for.

Finding these limits and installing stronger pistons, cranks, and engine components is essential.

We've seen technicians spend a lot of money upgrading the N20's turbo charger only to have it fail catastrophically shortly after installation.

There is sometimes a bottom-end lag with large turbo units, and although small turbo units may spool up rapidly, they lack the power improvements in the peak rpm range.

To our delight, we've stumbled upon variable vane turbos, in which the vane profile changes with speed in order to reduce latency and boost top-end performance.

Turbos with dual scroll designs divide the exhaust flow into two separate channels and direct each of these at a different angle. They also aid the engine's scavenging capabilities and improve low end spool up which is why these were chosen for the N20.

Air flow sensors AFM/MAF on these engines are often found to have a limitation when the amount of air being supplied into the engine increases significantly.

We saw 4 bar air sensors dealing with significant power increases, when the OEM air sensor only allowed for a considerably lower amount of torque to be applied.

Adding a supercharger or additional turbo will make large performance gains, although more complex to get working. We have this feature on twinchargers if you want to read more.

N20 Fuelling

You will need to ensure that the engine is not starved of fuel so will have to uprate the fuelling when you start going beyond 20% of a bhp and torque increase.It is important to over specify your injectors flow rate.

The rule of thumb is to add 20% capacity when specifying an injector, this allows for injector deterioration and allows some spare capacity should the engine require 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.

All the following flywheel power targets will assume an injector duty cycle of 80% and a base of 58psi of fuel pressure at idle.

4 Cylinder turbocharged engines

• 58 PSI 340cc/min 200hp
• 58 PSI 511cc/min 300hp

4 Cylinder supercharged engines

• 58 PSI 312cc/min 200hp
• 58 PSI 468cc/min 300hp

Exhaust Upgrades on the N20

You should look to improve your exhaust if the current exhaust is creating a flow problem.

On most factory exhausts you'll see your flow rate is fine even on modest power gains, but when you start pushing up the power levels you will need to get a better flowing exhaust.

Sports exhausts can help balance the flow of air through the engine.

But if the exhaust is too large, ie: over 2.5 inches bore, you will lose a great deal of the flow rate and end up sapping power and torque.

Usual exhaust restrictions can be located the filters installed, so adding a better flowing sports alternative is the answer. This keeps the car road legal and will flow much better due to it's higher internal surface area and design, so has the added benefit of keeping your car road legal. The alternative decat should be considered an off road only mod, as removing a catalyst is illegal in most territories and regions for road registered cars..

N20 Intercooler Upgrades

Before the intake air charge can reach the engine, an intercooler acts as a radiator, cooling it to the proper temperature.

Take advantage of the large volumes of cold air that reach the radiator by installing an intercooler in front.

An efficient intercooler design may produce 5% to 10% more power and can tolerate heat soak for a longer length of time, correspondingly!

It's almost certain that aftermarket intercoolers will outperform those found in most current turbocharged cars as they are not produced to meet a budget and are generally very well designed.

For the most part, the main advantage is that they remain cooler and enable greater power levels for longer periods of time.

Remember that you want to get as much air into the engine as possible, so if the intercooler's internal core impedes airflow, you'll actually lose power. ' It is the intercooler's internal flow characteristics and cooling fins that are responsible for its performance.

The fins should have the largest surface area, while the inner core should have a restricted number of tapered bends and no internal welds to generate turbulence.."

However, considering the benefits of having a high-quality intercooler installed and the modest loss of airflow inherent in a well-designed intercooler, this argument falls flat.

As a practical matter, using an intercooler that is excessively large will cause obstructions in the flow of air (this is something which can be discussed in more detail in our forum.)

Weak spots Issues & problem areas on the N20

The N20 engines are generally reliable and solid units, as long as you follow the manufacturers service schedules, and use a good quality oil to ensure longevity. Few problems should happen as long as they are regularly serviced and maintained.

Carbon build up in the head, particularly around the valves which will sap power or create flat spots, this is a larger issue on direct injection engines but should be looked out for on all engines. We have tips on removing carbon build up.

Some of our members have had issues with flat spots or glitches after applying mods and upgrades or tuning, this is not usually related to this engines design, so instead see our article on diagnosing flat spots and problems after tuning which should help you get the bottom of this issue.

Oil sludge builds up and can wreck the turbo and or oil pump. DONT IGNORE any rattles or buzzes or hums from the N20.

We should mention the class action lawsuit alleging timing chain guide failures due to a manufacturing defect.

Regular oil changes are vital on the N20, especially when tuned and will help extend the life and reliability of the engine.

If you would like to know more, or just get some friendly advice on Tuning your N20 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.

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