Modding uprating the Vauxhall Z20LET engine!

Tuning guide "Z20LET Modifications"

Z20LET Modifications Guide

How to modify and upgrade the Vauxhall Z20LET

"Comprehensive guide to tuning the Vauxhall Z20LET engine!"

Our friends at TorqueCars often are getting messages asking how to improve the Z20LET from people wanting to know what are the optimum Z20LET upgrades. So let us look into Vauxhall Z20LET mods and outline the best modifications on this great engine and point out some common pitfalls along the way.

The Vauxhall Z20LET make awesome project engines and with a few sensible modified upgrades like remaps, turbo improvements and camshafts you will maximize your driving fun.

We shall look into Z20LET tuning and report on the best modifications for your car.

The best Z20LET parts on an engine are obviously the ones that give the biggest return for your money.

We won't be swayed by popular Z20LET parts, they need to be cost effective.

Z20LET induction kits

Improving air intake on the Z20LET

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

So the goal to any engine upgrade job to force more air and fuel into each cylinder but this has a knock on effect with the air flow sensor.

It is not unusual that there's a restriction in the air flow sensor MAF/MAP on the Z20LET when a lot more air is being fed into the engine.

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

Headers carry the air during the suck phase from the air cleaner and allow it to be fed into the engine cylinders.

The size of bore and shape and flow rate of the air Intake manifold can make a big effect on to fuel atomisation and engine efficiency on the Z20LET.

It's not uncommon that plenum chambers are in desperate need of aftermarket tuning parts, although a few makers provide fairly well optimized plenum chambers.

Larger Z20LET valves, carrying out 3 or 5 angle valve jobs and porting and head flowing will also raise performance, the fantastic side effect is it will make space for a greater performance increase on other upgrades.

Z20LET performance cam tips.

Different Z20LET engines respond better to more or less aggressive camshaft durations so set your engine up on a rolling road.

The ECU mapping and fuel pump and injectors also have an effect on the bhp gains you'll get.

Altering valve durations can alter the bhp 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 Z20LET can be made from camshaft upgrades. Changing the camshaft profile alters the intake and exhaust durations on the engine and can dramatically change the torque and power output.

NB: Fast road camshafts normally push up the performance through the rev range, you could drop a little low end torque but the top end will improve.

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

For a road car you must carefully try to optimize your engines power to your typical driving style.

I would be surprised if you find a Z20LET Motorsport and race camshaft is a pleasure to live with when on the daily commute.

Stage 1, 2 and 3 mods for the Z20LET

Stage 1 Z20LET parts:

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

Stage 2 Z20LET parts:

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

Stage 3 Z20LET parts:

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

The Z20LET power trains respond well to upgrades and thanks to their popularity there are increasing numbers of modifications and performance parts about.

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

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

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 power output usually vary depending on the mods you've fitted and the condition of your engine.

Turbo modifications on the Z20LET

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 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 significant power gains.

If your car has a turbo already fitted parts are simpler to install and most turbo engines already contain more solid components.

There are reliable limits for every engine, with some being over specified and some just sufficiently able to handle stock power

Discover these limitations and install better quality components to cope with the power.

We see many people spending a loads of money on turbocharger upgrades on the Z20LET only to suffer the humiliation of seeing the motor explode just after it's used in anger.

Larger upgraded turbo chargers commonly suffer a bottom end lag, and smaller turbo chargers spool up more quickly but won't have the high rpm torque gains.

In the last 10 years the choice of turbos is always increasing and we now see variable vane turbos, allowing the vane angle is altered according to speed to lower lag and increase top end torque.

Twin scroll turbos divert the exhaust flow into a couple of channels and direct these at differently designed vanes in the turbocharger. They also boost the scavenging effect of the engine.

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

Tips about fuel supply on the Z20LET

You will need to ensure that the engine is not starved of fuel so will have to uprate the fuelling when you start exceeding 20% of a torque hike. Experienced mechanics will tell you to be generous with your flow rate on the injectors.

As a rule of thumb add another 15% when fitting an injector, this takes into account injector deterioration and gives a bit of 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 Z20LET performance exhaust upgrades

You may need to upgrade your exhaust system with an upgraded one is if your exhaust is actually creating a restriction.

On most factory exhausts you should find that the exhaust flow rate is still ok 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 largest 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.

Typically exhaust restrictions can be located the emissions filters installed, so adding a freer flowing sports 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 Z20LET

Like most engines an Z20LET, 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 Z20LET, failure to do this will exacerbate engine wear, on a tuned Z20LET 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 Z20LET why not pop over to the forums at TorqueCars where you can chat about Z20LET tuning options and read about others projects who may be planning to do similar modifications on their Z20LET.

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