Modding tuning and best performance upgrades on the VAG D20 engine!

Tuning guide "D20 Modifications"

D20 Modifications Guide

How to modify and upgrade the VAG D20

"Comprehensive guide to tuning the VAG D20 engine!"

Sites like TorqueCars are frequently getting emails requesting information on how to improve the D20 from people inquiring about getting more power from the D20 and wanting to know what are the premier D20 power upgrades. So let us look into VAG D20 mods and outline the best modifications on this great engine and point out some frequent tuning mistakes along the way.

We shall detail the best approach to D20 tuning and report on the best modifications. VAG D20 great bases for a tuning project and with carefully chosen modified upgrades like remapping, turbo upgrades and camshafts you will substantially maximise your driving opportunities.

The ultimate D20 mods on an engine are in our opinion the ones that give the best gains for your money.

We won't be swayed by popular D20 mods, they need to be cost effective.

D20 induction kits

Improving air intake on the D20

You need air and fuel for an engine to work. If there is too little fuel then it will run lean, if there is insufficient air it runs rich sapping power . We'll pick up on fuelling later in this article but for now we shall look at air supply.

So Pulling more air and fuel into your D20 is the primary aim to any engine tuning job.

It is common that there is a limitation in the air flow sensor (AFM/MAF/MAP) on the D20 when considerably more air is being drawn into the engine.

You'll see that 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor was restricting power at a much lower level.

Intake headers flow the during the engines suck phase from the intake filter and allow it to be sucked into the engine cylinders.

The shape and flow characteristics of the Headers can make a big change to fuel mixing and power on the D20.

It's not uncommon that air intake manifolds are improved through motorsport parts, although a few makers provide well optimised air intake manifolds.

Adding a D20 larger valve kit, getting D20 port enlargement and head flowing will also lift bhp, and as an added benefit will permit a greater bhp increase on other upgrades.

D20 performance cam tips.

Some D20 engines respond better to different camshaft durations check your engine on a rolling road.

The ECU mapping and fuelling also will make differences on the power gains you'll make.

Extending exhaust or intake durations can alter the power 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 D20 can be made from camshaft upgrades. Changing the camshaft 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 bump the bhp throughout the rpm band, you could sacrifice a little low down power but higher rpm power will be higher.

Race camshafts, bump 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 must carefully try to optimize your power band to your preferences.

I'd be surprised if you have ever thought a D20 Motorsport and race cam is a pleasure to live with when in heavy traffic.

Stage 1, 2 and 3 mods for the D20

Stage 1 D20 parts:

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

Stage 2 D20 parts:

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

Stage 3 D20 parts:

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

Carefully think through your options and then find your upgrades and set yourself a power target to avoid costly mistakes.

ECU mapping allows a tuner to to establish the full potential of all the tuning mods you've done to your D20.

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 may rely on the tuning mods you've fitted and the condition of your engine.

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

Turbo modifications on the D20

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 D20.

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.

When your car is turbo charged mods are going to net you a larger power gain and turbocharged engines will have stronger components.

There are common areas of failure for every engine, with some being incredibly solid and some just sufficiently able to handle stock power

It is important to find these limitations and fit more solid crank and pistons to survive the power.

There are many tuners spending a loads on turbo charger upgrades on the D20 only to suffer the humiliation of seeing the car literally blow up when it's used on the roads.

Bigger turbochargers often experience a bottom end lag, and low capacity turbochargers spool up much more quickly but do not have the peak rpm power band gains.

In recent times the range of turbo chargers is always evolving and we are seeing variable vane turbo chargers, allowing the vane profile is altered according to speed to lower lag and increase top end bhp.

Twin scroll turbo chargers divert the exhaust gases into a couple of channels and direct these at differently profiled vanes in the turbocharger. They also increase the scavenging effect of the engine.

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

Tips about fuel supply on the D20

When you improve the performance you will need to look at to the fuel system.

More performance needs more fuel. We strongly recommend you to over specify your injector capacity.

The accepted safe increase is to add 20% capacity when specifying an injector, this accounts for injector deterioration and allows some spare capacity should the engine require 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 D20 performance exhaust upgrades

Only look to improve your exhaust system with an upgraded one is if the existing exhaust is actually causing a restriction.

On most factory exhausts you should find that the 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.

Note that with the widest exhaust you can get this will 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 are traced to the emissions filters installed, so adding a better 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 D20

Like most engines an D20, 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 D20, failure to do this will exacerbate engine wear, on a tuned D20 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 D20 why not pop over to the forums at TorqueCars where you can chat about D20 tuning options and read about others projects who may be planning to do similar modifications on their D20.

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