Tuning the Vauxhall Z20LEL

"Comprehensive guide to performance parts and tuning the Vauxhall Z20LEL engine!"

We often are seeing threads asking how to improve the Z20LEL from people wanting to know what are the things we are recommending when it comes to Z20LEL modifications. So let us look into Vauxhall Z20LEL upgrades and outline the best modifications on this great engine and point out some potential pitfalls along the way.

The Vauxhall Z20LEL make a good tuning project and with carefully chosen tuning tuning mods like ECU maps, turbo improvements and camshafts you will positively increase your driving pleasure.

TorqueCars will look at Z20LEL tuning and point out the optimum upgrades.

Just because particular mods are are common on Z20LEL it doesn't mean its worth having, we shall ultimate mods that will give your Z20LEL the best power gain for you money.

Altering your Z20LEL camshaft will make a dramatic difference to the engine engines power. Choosing a higher performance camshaft profile raises the engines power accordingly.

NB: Fast road camshafts commonly increase the torque over the rpm range, you may sacrifice a little low down bhp but your higher rpm power will improve.

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

For a typical daily driver should ideally to optimize your torque band to your cars usage.

I'd be surprised if you have ever thought a Z20LEL Competition camshaft is a pleasure to live with when on the daily commute.

Different Z20LEL engines respond better to mild camshaft durations so view each engine as unique.

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

A longer valve duration 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.

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Guide to the best Z20LEL tuning mods & Upgrades

  1. ECU Map Tuning & Remaps

    Some cars may require a piggyback ECU's or aftermarket ECU's to change the OEM map, but remapping is the most vital step of your tuning project to fully maximise your mods. Expect 10-20% on NASP engines and 30-40% on turbocharged units.

  2. Strengthen Your Engine

    Tuned cars will show up weaknesses, typically in the turbochargers, clutch and internal engine components. Whilst most engines can cope with mild tuning mods, TorqueCars recommend that you upgrade the internal components before these weak spots manifest themselves.

  3. Mods that Remove a Restriction

    A restricted intake or exhaust will have an impact on your performance, so use a better flowing air filter/induction kit and better flowing exhaust (sports cats where legal are a good option) whenever your tuning creates a flow restriction. Turbo engines also benefit from intercooler upgrades as these resist heat soak for longer periods of time.

  4. Mods that Improve Fuelling

    Every tuning project will aim to increase the air supply, but fuel supply is just as vital and will need to match the air the engine can utilise,  a fuel pump and injector upgrade are usual mods, but also in many cases the fuel regulator will need improvement.

  5. Mods to Provide better Airflow

    Increasing the air supply is just as essential as improving fuelling, we suggest you look at head mods (flowing and porting, 5 angle valve jobs), fit bigger valves, fast road cams and forced induction upgrades (adding a better flowing turbo) to improve air intake.

Z20LEL Tuning Stages

Stage 1 Z20LEL modifications: Fast road camshaft, Intake headers, Sports exhaust manifold, Drilled & smoothed airbox, Panel air filters, Remaps/piggy back ECU.

Stage 2 Z20LEL modifications: Ported and polished head, induction kit, Fast road cam, high flow fuel injectors, Sports catalyst & performance exhaust, fuel pump upgrades.

Stage 3 Z20LEL modifications: Crank and Piston upgrades to alter compression, Twin charging conversions, Internal engine upgrades (head flowing porting/bigger valves), Engine balancing & blueprinting, Competition cam, Adding or Upgrading forced induction (turbo/supercharger).

Plan your options and then acquire your parts and set yourself a power target to avoid wasting your time and money.

Mapping allows a tuner to release the full potential of all the mods you've done to your Z20LEL.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but the end result will depend much on the mods you've carried out and the condition of your engine.

It is vital to any engine tuning task to shove more air into the Z20LEL engine

Air Intake manifolds transmit the air from the intake filter and allow it to be drawn into the engine cylinders with fuel for the squish phase.

Design and flow rate of the Air Intake manifolds can make a big change to fuel atomisation and engine efficiency on the Z20LEL.

Commonly we find the intake are begging for performance upgrades, although some manufacturers provide reasonably well designed intake.

Increasing the Z20LEL valve size, carrying out port work and head flowing will also increase torque, the fantastic side effect is it will make space for a greater torque increase on other mods.

Turbo upgrades for the Z20LEL

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 Z20LEL

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

When your motor is turbocharged, upgrades are going to net you a larger power gain and we find turbocharged engines already contain stronger components.

However you'll find engines have weakspots

We recommend you find these limitations and upgrade to more solid crank and pistons to handle the power.

It's not unheard of drivers spending a lots of money on turbo charger upgrades on the Z20LEL only to see the whole thing go up in smoke on it's first outing after it's used in anger.

Large upgraded turbo units commonly suffer a bottom end lag, and little turbo units spool up more quickly but do not have the peak end power band gains.

In the last 10 years the market of turbochargers is always increasing and we now see variable vane turbochargers, permitting the vane profile is altered according to speed to lower lag and increase top end power.

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

It is not unusual that there is a limit in the air flow sensor AFM/MAP on the Z20LEL when a lot more air is being sucked into the engine.

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

Adding a supercharger or additional turbo will make large bhp gains, although more complex to setup. We have this article on twincharging if you want to read more.

Uprating Z20LEL fuel injectors

You will need to ensure that the engine is not starved of fuel so will have to increase the fuelling when you start exceeding 20% of a bhp increase.Don't forget to over specify your injectors flow rate.

The accepted safe increase is to add 20% capacity when fitting an injector, helps cope with injector deterioration and affords a little 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.

Best Z20LEL performance exhausts

You only need to to increase your exhaust if your current exhaust is creating a flow problem.

On most factory exhausts you'll see the exhaust flow rate is still ok 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 generally help improve air flow out of the engine but avoid an exhaust that is too large or you could will reduce the flow rate. Stick to 1.5 to 2.5 inches as a rule of thumb.

Typically exhaust restrictions can be traced to the catalysts installed, so adding a faster flowing performance alternative will help avoid this restriction.

Problems and issues to look out for on the Z20LEL

The Z20LEL engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the Z20LEL, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your Z20LEL engine please join us in our friendly forum where you can discuss tuning options in more detail with our Z20LEL owners. It would also be worth reading our unbiased tuning articles to get a full grasp of the benefits and drawbacks of each modification.

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We really like hearing from our readers, and hearing about which tuning parts were the most effective for them, it helps us improve our recommendations and articles to reflect current trends in modifications and ensures that our Z20LEL guides and tips are kept up to date.

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