Modding upgrading and tuning the Vauxhall Z20LER engine!

Car tuning tips:Z20LER Modifications"

How to modify and upgrade the Vauxhall Z20LER

"Comprehensive guide to tuning and performance parts on the Vauxhall Z20LER engine!"

Forums like the one at TorqueCars are frequently seeing threads about how to improve the Z20LER from people inquiring about getting more power from the Z20LER and wanting to know what are the best tips for Z20LER upgrades. So let us look into Vauxhall Z20LER mods and outline the best mods that work on this great engine and point out some problems along the way.

Let us detail the best approach to Z20LER tuning and report on the optimum modifications for your car. Vauxhall Z20LER make awesome project engines and with the ultimate performance mods like remaps, turbo upgrades and camshafts you will really maximise your driving opportunities.

The optimum Z20LER parts on an engine are in our opinion the ones that give the biggest return for your money.

We won't be swayed by popular Z20LER parts, they need to be cost effective.

Z20LER induction kits

Improving air intake on the Z20LER

You need air and fuel for an engine to work. If there is not enough fuel then it will run lean, if there is insufficient air it runs rich resulting in lost power and potentially damaging the engine. We'll pick up on fuelling later in this article but for now we shall look at air supply.

So Shoving more fuel and air into each cylinder is vital to any tuning job.

You'll commonly see there's a limitation in the air flow sensor MAP/MAF/AFM on the Z20LER when loads more air is being sucked into the engine.

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

Intake take the air from the filter and allow it to be pulled into the engine and mixed with fuel.

Shape and flow characteristics of the air Intake manifold can make a substantial effect on to fuel engine efficiency on the Z20LER.

I usually find plenum chambers are in desperate need of a performance upgrade, although a few manufacturers provide well optimised plenum chambers.

Big valve conversions on the Z20LER, doing some port matching and head flowing will also lift performance, and importantly will permit a better performance increase on other tuning mods.

Z20LER performance cam tips.

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

The ECU mapping and injectors and fuel pump also will say much on the power gains you'll hit.

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.

Altering your Z20LER cam will make a dramatic difference to the engine power band. Choosing a higher performance cam profile raises the power band accordingly.

NB: Fast road camshafts tend to raise the bhp throughout the rev range, you could sacrifice a little low down bhp but top end will improve.

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

On a car used daily you need to match your power band to your cars usage.

You will never have found a Z20LER Race cam is a pleasure to live with when driving around busy urban areas.

Stage 1, 2 and 3 mods for the Z20LER

Before we break the best tuning upgrades down into stages of tune, let's list the most effective tuning upgrades for you.

  1. Suspension Upgrades - always improve your cars handling
  2. Brake Upgrades - Even before adding power improve those brakes
  3. Intake - make sure the intake is not restricted, use filters and intake upgrades to improve this
  4. Exhaust - as with 3 ensure there is not restriction in the exhaust, cats are the usual bottleneck
  5. Tunes - remapping, piggyback ECU's and aftermarket ECU's can all make decent gains
  6. Fuelling - when you've increased power you'll need to match this with more fuel
  7. Turbo upgrades - Improving the intake with a large turbo and better flowing intercooler will be the biggest power gain you'll see (but one of the most complex).

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

Stage 1 Z20LER parts:

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

Stage 2 Z20LER parts:

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

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

Stage 3 Z20LER parts:

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

The Z20LER engine blocks are fantastic to work on and we note that there is a lot of mods and performance parts about.

Remapping allows a tuner to release the full potential of all the upgrades you've done to your Z20LER.

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 mileage often differs on the upgrades you've applied and the condition of your engine.

Turbo modifications on the Z20LER

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 Z20LER.

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 an engine is turbo charged parts are going to net you a larger power gain and turbo charged engines will have strengthened components.

However you will find an engines will need better parts at higher power limits

We recommend you find these limits and upgrade to stronger pistons, crank and engine components to utilize the power.

We see many mechanics spending a lots of money on turbo charger upgrades on the Z20LER only to have the motor literally blow up soon after it's first rolling road session.

Big capacity turbochargers tend to experience no power at low rpm, and low capacity turbochargers spool up quickly but won't have the top end bhp gains.

In recent times the choice of turbo chargers is always moving on and we commonly find variable vane turbo chargers, where the vane profile is altered according to speed to lower lag and increase top end power.

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

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

Tips about fuel supply on the Z20LER

When you lift the torque you will need to uprate to the fuel system.

More torque needs more fuel. Experienced tuners recommend to over specify your injectors flow rate.

The rule of thumb is to add 15% capacity when buying an injector, helps cope with injector deterioration and allows a bit of 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..

Recommended Z20LER performance exhaust upgrades

You only need to to improve your exhaust system with an upgraded one is if your exhaust is actually creating a flow problem.

On most factory exhausts you'll see the flow rate is still fine 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.

Sports exhausts can usually air flow from the engine but avoid an exhaust that is too wide or you could will reduce the flow rate. Stick to one and a half to two and half inches as a rule of thumb.

The usual suspects causing problems in your exhaust flow rate can be traced to the catalysts installed, so adding a freer flowing sports alternative will help avoid this restriction.

Cat bypassing (NB:catalysts reduce harmful engine emissions) is illegal in most countries and regions.

Faults issues and things to look out for on the Z20LER

Like most engines an Z20LER, 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 Z20LER, failure to do this will exacerbate engine wear, on a tuned Z20LER 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 Z20LER why not pop over to the forums at TorqueCars where you can chat about Z20LER tuning options and read about others projects who may be planning to do similar modifications on their Z20LER.

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

We want to know your experiences with mods on your Z20LER, it helps us improve our tips and keeps us current so please use the comments box to drop a tip.

If you liked this page please share it with your friends, drop a link to it in your favourite forum or use the bookmarking options to save it to your social media profile.

Check out TorqueCars new YouTube channel, and see their awesome new content...


Please use our forums if you wish to ask a tuning question, and please note we do not sell parts or services, we are just an online magazine.

Help us improve, leave a suggestion or tip

Your Constructive comments on this article