Tuning the Vauxhall C14NZ

"Comprehensive guide to tuning the Vauxhall C14NZ engine!"

We are regularly seeing threads requesting information on the ultimate C14NZ power upgrades. So let us look into Vauxhall C14NZ modifications and outline the best modifications on this great engine and point out some potential pitfalls along the way.

The Vauxhall C14NZ are good project engines and with carefully chosen tuning modifications like remapping, turbo kits and camshafts you will noticeably enhance your driving pleasure.

In this article we examine C14NZ tuning and outline the greatest upgrades.

When talking about the ultimate parts for your C14NZ engine, we are going to concentrate on the tuning parts that give the best power gain for you money.

Altering your C14NZ 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 cams normally boost the torque across the rev range, you could sacrifice a little low down power but the top end will be better.

Race cams, boost the top end band but as a result the car will not idle smoothly and low end power nearly always suffers.

A Motorsport camshaft makes it harder when driving in heavy traffic.

You should ideally match your engines power to your usage of the car so for a daily driver stick with a fast road C14NZ camshaft

Each engine responds better to extreme camshaft durations so set your engine up on a rolling road.

The map and injectors and fuel pump also will make differences on the torque gains you'll achieve.

Longer valve durations can alter the torque 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.

C14NZ Tuning Stages

Stage 1 C14NZ modifications: Sports exhaust manifold, Drilled & smoothed airbox, Panel air filters, Remaps/piggy back ECU, Fast road camshaft, Intake headers.

Stage 2 C14NZ modifications: high flow fuel injectors, induction kit, Ported and polished head, Fast road cam, Sports catalyst & performance exhaust, fuel pump upgrades.

Stage 3 C14NZ modifications: Adding or Upgrading forced induction (turbo/supercharger), Crank and Piston upgrades to alter compression, Twin charging conversions, Engine balancing & blueprinting, Competition cam, Internal engine upgrades (head flowing porting/bigger valves).

Plan your options and then source your mods and set yourself a power target to save yourself from expensive mistakes.

ECU mapping helps release the full potential of all the tuning mods you've done to your C14NZ.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but your results usually rely on the tuning mods you've fitted and the condition of your engine.

Getting air and fuel into each cylinder is the main goal to any engine performance tuning job.

Intake carry the air during the suck phase from the intake filter and allow it to be pulled into the engine cylinders with fuel for the squish phase.

Shape and flow characteristics of the Intake headers can make a substantial change to fuel engine efficiency on the C14NZ.

It's not uncommon that intake headers are needing a performance upgrade, although a few car makers provide decently flowing intake headers.

Adding a C14NZ larger valve kit, doing a bit of port matching and head flowing will also improve power, the fantastic side effect is it will allow you to get a greater power increase on other upgrades.

Turbo upgrades for the C14NZ

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 C14NZ

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

If the engine is turbocharged, tuning parts are simpler to install and you'll see that turbo engines already contain harder and stronger components.

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

Discover these limitations and upgrade to more solid crank and pistons to cope with the power.

We've seen people spending a lot of money on turbo charger upgrades on the C14NZ only to have the car catastrophically fail soon after it's been finished.

Bigger turbo chargers often suffer low end lag, and little turbo chargers spool up really quickly but won't have the top end engines power gains.

We are pleased that the world of turbochargers is always evolving and we commonly find variable vane turbochargers, permitting the vane angle is altered according to speed to lower lag and increase top end power.

Twin scroll turbochargers divert the exhaust flow into 2 channels and direct these at differently designed vanes in the turbo charger. They also help the scavenging effect of the engine.

It is common that there is a limit in the air flow sensor (AFM/MAF/MAP) on the C14NZ when considerably more air is being pulled into the engine.

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

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

Uprating C14NZ fuel injectors

When you raise the bhp and torque you will need to uprate to the fuelling.

More bhp and torque needs more fuel. We strongly recommend you to be generous with your injector capacity.

The accepted safe increase is to add 20% when buying an injector, this allows for injector deterioration and provides you some 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 C14NZ performance exhausts

Only look to increase your exhaust if the existing exhaust is creating a restriction in flow.

On most factory exhausts you'll see the exhaust flow rate is fine 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 will certainly help air flow through the engine but avoid an exhaust that is too large or you may end up will reduce the flow rate. Stick to 1.5 to 2.5 inches for best results.

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

Problems and issues to look out for on the C14NZ

The C14NZ engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the C14NZ, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your C14NZ engine please join us in our friendly forum where you can discuss tuning options in more detail with our C14NZ 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 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 C14NZ guides and tips are kept up to date.

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