Tuning the Vauxhall Z20LET

"Comprehensive guide to performance tuning the Vauxhall Z20LET engine!"

We are regularly getting emails requesting info on the ultimate Z20LET modifications. So let us look into Vauxhall Z20LET modifications and outline the best upgrades on this great engine and point out some potential pitfalls along the way.

The Vauxhall Z20LET make a good tuning project and with the ultimate performance upgrades like remapping, turbo upgrades and camshafts you will certainly maximise your driving opportunities.

TorqueCars will look at Z20LET tuning and provide tips on the optimum mods that work.

When talking about the best parts for your Z20LET engine, we are going to focus on the upgrades 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 torque gains are on offer for camshaft upgrades.

NB: Fast road camshafts commonly push up the bhp and torque throughout the rev band, you may sacrifice a little low down torque but your high end rpm power will be lifted.

Motorsport camshafts, push up the high end rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

In a typical daily driver you need to optimize your engines power to your driving style.

I'd be gobsmaked if you have found a Z20LET Race camshaft is a pleasure to live with when driving around busy urban areas.

Some Z20LET engines respond better to extreme cam durations so view each engine as unique.

The map and fuelling also will say much on the power gains you'll achieve.

Altering valve 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.

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Guide to the Best Z20LET Tuning Mods & Upgrades

  1. Mods that Remove a Restriction

    A restricted intake or exhaust will have an impact on your car's performance, so use an induction kit/filter upgrade and better flowing exhaust whenever your tuning creates a flow restriction.

  2. Mods that Improve Handling

    Braking, Suspension and general alignment of the suspension components is vital for any tuning project even before you start increasing power.

  3. Fit Stronger Parts

    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.

  4. ECU Tunes & Remapping

    While some cars can be easily remapped, others may require piggyback ECU's or aftermarket ECU's but this is the most vital step of your tuning project as it fully releases the power from all of your mods and upgrades. Expect 10-20% on NASP engines and 30-40% on turbocharged units.

  5. More Power Needs More Fuel & Air

    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. Fuel to Air ratio is vital so upgrade the fuel pump & injectors. Also you can look to perform head mods (flowing and porting), bigger valves, fast road cams and forced induction upgrades to improve fuel.

Z20LET Tuning Stages

Stage 1 Z20LET modifications: Fast road camshaft, Intake headers, Sports exhaust manifold, Remaps/piggy back ECU, Drilled & smoothed airbox, Panel air filters.

Stage 2 Z20LET modifications: induction kit, Fast road cam, high flow fuel injectors, Sports catalyst & performance exhaust, Ported and polished head, fuel pump upgrades.

Stage 3 Z20LET modifications: Adding or Upgrading forced induction (turbo/supercharger), Twin charging conversions, Competition cam, Internal engine upgrades (head flowing porting/bigger valves), Crank and Piston upgrades to alter compression, Engine balancing & blueprinting.

The Z20LET engine blocks respond well to mods and we note that there are plenty of mods and tuning parts about.

ECU mapping should help to to establish the full potential of all the upgrades you've done to your Z20LET.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but figures achieved usually depend much on the upgrades you've fitted and the condition of your engine.

It is vital to any performance tuning project to pull air and fuel into the Z20LET engine

Intake headers take the air from the filter and allow it to be pulled into the engine cylinders with fuel for the squish phase.

The bore size, shape and flow rate of the Intake can make a noticeable improvement to fuel mixing and power on the Z20LET.

It's not uncommon that air intake manifolds are improved through aftermarket tuning parts, although a few manufacturers provide decently flowing air intake manifolds.

Larger Z20LET valves, doing some port work and head flowing will also boost torque, the fantastic side effect is it will permit raising the torque increase on other mods.

Turbo upgrades for the Z20LET

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 Z20LET

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

If your motor has a turbocharger mods are going to net you a larger power gain and you'll see that turbocharged engines are made with stronger components.

There are tuning limits for every engine, with some being extremely strong and some just sufficiently able to handle stock power

See where you'll find these limitations and fit more solid crank and pistons to cope with the power.

There are many tuners spending a lot of money on turbocharger upgrades on the Z20LET only to experience the Z20LET explode just after it's been finished.

Big capacity turbo units tend to experience a bottom end lag, and little turbo units spool up quickly but do not have the peak rpm bhp gains.

In recent times the range of turbo chargers is always increasing and we now see variable vane turbo chargers, where the vane angle is altered according to speed to lower lag and increase top end performance.

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

It is not unusual that there's a limitation in the air flow sensor MAP/MAF/AFM on the Z20LET 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 bhp and torque at a much lower level.

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

Uprating Z20LET fuel injectors

Don't overlook the need to raise the fuel system when you are increasing the bhp - it makes the car more thirsty. It is important to over specify your injectors flow rate.

The accepted safe increase is to add another 20% when specifying an injector, this allows for injector deterioration and affords you 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.

Best Z20LET performance exhausts

Only look to increase your exhaust if your exhaust is actually creating a restriction.

On most factory exhausts you'll see the exhaust flow rate is still 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 largest exhaust you can buy this will reduce the exhaust flow rate - the best for power gains are usually between 1.5 to 2.5 inches. It is the shape and material more than the bore size.

Common exhaust restrictions come around the catalyst and filters installed, so adding a freer flowing performance alternative will help avoid this restriction.

Problems and issues to look out for on the Z20LET

The Z20LET engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the Z20LET, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your Z20LET engine please join us in our friendly forum where you can discuss tuning options in more detail with our Z20LET owners. It would also be worth reading our unbiased tuning articles to get a full grasp of the benefits and drawbacks of each modification.

We need your help to complete and improve this page, so do give us your feedback in the comments box below.

We really like hearing from our readers, and hearing about which 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 Z20LET guides and tips are kept up to date.

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