Modifying and tuning the N20

Tuners tips on "BMW N20 Tuning"

BMW N20 Tuning Guide

"Modifying the BMW N20 engine!"

The BMW N20 are good project engines and with carefully chosen uprated modifications like remaps, turbo improvements and camshafts you will certainly improve your driving experience.

In this article we review N20 tuning and show the optimum modifications for your car.

When talking about the greatest parts for your N20 engine, we are going to concentrate on the parts that give the best power gain for you spend.

The camshaft profile plays a big part in the engines power output so camshaft upgrades make quite a large difference. The intake and exhaust durations will alter depending on the chosen camshaft profile, so large engines power gains are on offer for camshaft upgrades.

NB: Fast road cams usually boost the bhp and torque through the rev range, you may lose a little low end bhp but the top end will improve.

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

A Competition camshaft is not great on the daily commute.

You should ideally match your engines power to your driving style so for a typical daily driver stick with a shorter duration N20 camshaft

Each engine responds better to more aggressive camshaft durations so set your engine up on a rolling road.

The ECU mapping and fuelling also will say much on the torque gains you'll make.

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.

Our top 7 top upgrades for your motor, and we will break these into stages and discuss them in detail for you.

  1. Map Tunes - remapping, via either OBD port, or piggyback ECU's and aftermarket ECU's can all make decent gains
  2. Fuelling Pump Injectors - You'll need to match the greater air flow with more fuel to unlock the power
  3. Turbo upgrades - Improving the intake charge with a large turbo and better flowing intercooler will be the biggest power gain you'll see (but one of the most complex especially where conversions are required).
  4. Suspension Upgrades - always improve your cars handling, tuning is not just about engine mods
  5. Brake Upgrades - Even before adding power improve your cars brakes to effectively stop the car
  6. Intake - make sure the intake is not restricted, use filters and intake upgrades to improve this
  7. Exhaust - as with intakes it helps to remove a restriction in the exhaust, cats are the usual bottleneck

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

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

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

Stage 3 mods: Adding or Upgrading forced induction (turbo/supercharger), Competition cam, Crank and Piston upgrades to alter compression, Twin charging conversions, Internal engine upgrades (head flowing porting/bigger valves), Engine balancing & blueprinting.Review your options and then buy your parts and set yourself a power target to avoid wasting your time and money.

remap helps fully realize the full potential of all the tuning mods 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 outcome usually depend much on the tuning mods you've applied and the condition of your engine.

It is the aim to any engine modification job to shove more air and fuel into each cylinder

Tuning tips and articles Engine tuning Transmission tuning Care care Intake & exhaust mods Improve handling Forums

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

Structure and flow characteristics of the air Intake manifold can make a noticeable effect on to fuel atomisation on the N20.

I usually find intake manifold are in desperate need of aftermarket parts, although some manufacturers provide well optimised intake manifold.

Fitting big valve kits, doing a bit of 3 or 5 angle valve jobs and porting and head flowing will also lift power, and importantly will afford you a greater power increase on other mods.

N20 Turbo upgrades

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 a separate 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 major power gains.

If the engine is turbo charged mods are giving better power gains and turbo charged engines are built with harder and stronger components.However engines have weakspots

See where you'll find these restrictions and upgrade to better quality crank and pistons to cope with the power.

There are many people spending a a stack of money on turbo charger upgrades on the N20 only to see the engine block explode just after it's finished.

Large capacity turbos commonly suffer a bottom end lag, and small turbos spool up more quickly but do not have the top end engines power gains.

Over the last 20 years the range of turbo units is always developing and we now see variable vane turbo units, where the vane profile is altered according to speed to lower lag and increase top end bhp.

Twin scroll turbo units divert the exhaust flow into a couple of channels and feed these at differently designed vanes in the turbo. They also increase the scavenging effect of the engine.

You'll commonly see there is a limit in the air flow sensor MAP/MAF/AFM on the N20 when considerably more air is being pulled into the engine.

We see 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor sapped bhp and torque at a much lower level.Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large power gains, although harder to configure. We have this feature on twinchargers if you want to read more.

N20 Fuelling upgrades and mods

When you raise the power you will need to ramp up to the fuelling.

More power needs more fuel. We strongly recommend you to be generous with your injectors flow rate.

As a rule of thumb add another 20% when specifying an injector, helps cope with injector deterioration and gives 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..

N20 Exhaust upgrades and mods

You only need to to upgrade your exhaust if the current exhaust is actually causing a flow problem.

On most factory exhausts you'll see the flow rate is good even on modest power gains, but when you start pushing up the power levels you will need to get a better flowing exhaust.Do not go with the widest exhaust you can buy you'll 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.

The usual suspects causing problems in your exhaust flow rate come around the catalyst installed, so adding a higher flowing sports alternative will help avoid this restriction.

N20 Issues & common problems

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

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 N20 owners. It would also be worth reading our unbiased tuning articles to get a full grasp of the benefits and drawbacks of each modification.

Please help us improve these tips by sending us your feedback in the comments box below.

We really like hearing from our readers, and hearing about which upgrades 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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