Tuning the BMW N20

"Comprehensive guide to performance tuning the BMW N20 engine!"

The BMW N20 offer good returns when tuned and with the ultimate tuning mods like ECU maps, turbo kits and camshafts you will certainly maximise your driving fun.

Our aim here is to review N20 tuning and provide tips on the best modifications.

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

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

Significant gains on the N20 can be made from cam upgrades. Altering 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 power throughout the rpm range, you could sacrifice a little low down torque but top end will be higher.

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

In a road car must carefully try to match your bhp range to your driving style.

I'd be shocked if you have found a N20 Competition camshaft is a pleasure to live with when in heavy traffic.

Some N20 engines respond better to different camshaft durations check your engine on a rolling road.

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

A longer valve duration 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.

Stage 1 modifications: Intake headers, Remaps/piggy back ECU, Sports exhaust manifold, Panel air filters, Fast road camshaft, Drilled & smoothed airbox.

Stage 2 modifications: Fast road cam, fuel pump upgrades, high flow fuel injectors, Ported and polished head, Sports catalyst & performance exhaust, induction kit.

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

The N20 power trains are great to work on and we're happy to report there is a lot of modifications and performance parts around.

ECU flashing allows a tuner to unlock the full potential of all the parts you've fitted to your N20.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but your results often differs on the parts you've applied and the condition of your engine.

Pulling more fuel and air into the N20 engine is vital to any engine tuning project.

Air Intake manifolds carry the air during the suck phase from the air filter and allow it to be sucked into the engine cylinders with fuel for the squish phase.

Structure and flow rate of the Intake can make a large effect on to fuel atomisation and engine efficiency on the N20.

Most intake headers are ripe for performance upgrades, although some makers provide fairly well optimized intake headers.

Big valve conversions on the N20, doing a bit of 3 or 5 angle valve jobs and porting and head flowing will also increase performance, and as an added benefit will give you raising the performance increase on other parts.

Turbo upgrades

NASP 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

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

When the engine has a turbocharger upgrades are going to make more power and you will discover turbo charged engines are built using uprated components.

However most engines have weakspots

Discover these limits and upgrade to better pistons and crank to survive the power.

We see many tuners spending a lot of money on turbo charger upgrades on the N20 only to see the N20 catastrophically fail just after it's first rolling road session.

Larger turbo units tend to experience a bottom end lag, and little turbo units spool up more quickly but do not have the high rpm torque gains.

Thanks to progress the choice of turbo chargers is always evolving and we are seeing variable vane turbo chargers, permitting the vane angle is altered according to speed to lower lag and increase top end bhp.

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

It is not unusual that there's a limitation in the air flow sensor AFM/MAF on the N20 when loads more air is being fed into the engine.

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

Adding a supercharger or additional turbo will make large bhp gains, although harder to configure. We have this feature on twinchargers if you want to read more.

On our main .com site we have more updates on all aspects of N20 Tuning

Fuelling upgrades and mods

You will need to ensure that the engine is not starved of fuel so must ramp up the fuelling when you start going beyond 20% of a performance increase.We would recommend you to over specify your flow rate on the injectors.

As a rule of thumb add 20% to the flow rate when fitting an injector, this allows for injector deterioration and gives some spare capacity should the engine need 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.

Exhaust upgrades and mods

Only look to increase your exhaust if the current exhaust is actually causing a flow problem.

On most factory exhausts you should find that your flow rate is still 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 balance the flow of gases through the engine.

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

Typically exhaust restrictions can be traced to the catalyst and filters installed, so adding a higher flowing sports alternative will help avoid this restriction.

Weak spots, Issues & common problem areas on the N20

The N20 engines, if regularly serviced and maintained, are generally very reliable and have few issues.

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, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information 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.

History 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 250Nm184 lbft @1,500-4,700 rpm

N20B20

  • 154 bhp @5,000 rpm 240Nm177 lbft @1,250-4,500 rpm
  • 181 bhp @5,000 rpm 270Nm199 lbft @1,250-4,500 rpm
  • 215 bhp @5,500 rpm 310Nm229 lbft @1,350-4,800 rpm
  • 241 bhp @5,000 rpm  350Nm258 lbft @1,250-4,800 rpm

We need your help improving this article, so please send us your feedback in the comments box below and pass on any tips, points or facts we have wrong or have not covered.

We really like hearing from our readers, and hearing about which mods were the most effective for them, it helps us improve our recommendations and articles to reflect current trends in modifications and ensures that our N20 guides and tips are kept up to date.

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