Modding uprating the Vauxhall C14NZ engine!

Modifying and improving: "C14NZ Modifications"

How to modify and upgrade the Vauxhall C14NZ

"Comprehensive guide to tuning and performance parts on the Vauxhall C14NZ engine!"

Sites like TorqueCars often are getting emails asking about how to improve the C14NZ from people wanting to know what are the best tips on C14NZ power upgrades. So let us look into Vauxhall C14NZ parts and outline the best mods that work on this great engine and point out some frequent tuning mistakes along the way.

The Vauxhall C14NZ provide a fun base for your project and with the optimum performance mods like ECU maps, turbo improvements and camshafts you will substantially enhance your driving fun.

Car Tuning Tips will review C14NZ tuning and point out the ultimate modifications for your car.

The optimum C14NZ upgrades on an engine are typically the ones that give the biggest return for your money.

We won't be swayed by popular C14NZ upgrades, they need to be cost effective.

C14NZ induction kits

Improving air intake on the C14NZ

You need fuel and air for an engine to work. If there is too little fuel then it will run lean, if there is too little air it runs rich resulting in lost power . We'll pick up on fuelling later in this article but for now we shall look at air supply.

So Forcing air into each cylinder is the main goal to any engine upgrade project.

It is not unusual that there is a restriction in the air flow sensor AFM/MAF on the C14NZ when considerably more air is being fed into the engine.

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

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

The bore size, shape and flow characteristics of the Plenum can make a noticeable effect on to fuel delivery on the C14NZ.

It's not uncommon that headers are begging for an upgrade, although some makers provide decently flowing headers.

Larger C14NZ valves, doing a bit of C14NZ port enlargement and head flowing will also lift performance, this will allow you to get increasing the performance increase on other tuning mods.

C14NZ performance cam tips.

Some C14NZ engines respond better to more aggressive camshaft durations than others.

The ecu map and fuel pump and injectors also will say much on the torque gains you'll achieve.

Altering 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.

Significant air intake, and exhaust improvements on the C14NZ can be made from cam upgrades. Changing the cam profile alters the intake and exhaust durations on the engine and can dramatically change the bhp and power output.

NB: Fast road camshafts commonly bump the bhp across the rev range, you could drop a little low down power but your top end will be higher.

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

In a road car you should ideally to match your bhp range to your driving style.

I'd be amazed if you have found a C14NZ Competition camshaft is a pleasure to live with when in heavy traffic.

Stage 1, 2 and 3 mods for the C14NZ

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 C14NZ parts:

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

Stage 2 C14NZ parts:

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

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

Stage 3 C14NZ parts:

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

The C14NZ power trains respond well to upgrades and we're happy to report there are quite a few choices of modifications and performance parts about.

ECU flashing will help to establish the full potential of all the parts you've done to your C14NZ.

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 the end result often differs on the parts you've carried out and the condition of your engine.

Turbo modifications on the C14NZ

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 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 significant power gains.

When a car is fitted with a turbo tuning parts are going to net you a larger power gain and you'll see that turbo charged engines will have better components.

However most engines will have power limits

It is important to find these limits and fit more solid crank and pistons to cope with the power.

We see many guys spending a fortune on turbocharger upgrades on the C14NZ only to suffer the humiliation of seeing the engine block literally blow up on it's first outing after it's been finished.

Big capacity turbochargers commonly suffer low end lag, and little turbochargers spool up really quickly but do not have the peak end engines power gains.

Thanks to new tech the selection of turbo chargers is always developing and we are seeing variable vane turbo chargers, allowing the vane angle is altered according to speed to lower lag and increase top end bhp.

Twin scroll turbo chargers divert the exhaust gases into a couple of channels and feed these at differently angled 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 install. We have this in depth look at twinchargers if you want to read more.

Tips about fuel supply on the C14NZ

You will need to ensure that the engine is not starved of fuel so should ramp up the fuelling when you start extending past 20% of a bhp hike. We would recommend you to be generous with your injector capacity.

As a rule of thumb add 20% to the flow rate when fitting an injector, this takes into account injector deterioration and allows 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 C14NZ performance exhaust upgrades

We'd only recommend you look to uprate your exhaust system with an upgraded one is if your exhaust is actually creating a restriction.

On most factory exhausts you'll find your flow rate is 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.

Sports exhausts can help balance the flow of gases through the engine.

But if the exhaust pipe is too big, ie: it's over two and a half inches diameter, you will lose a great deal of the exhaust flow rate and end up losing power and torque.

Usual exhaust restrictions come around the catalyst and filters installed, so adding a better flowing race 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 C14NZ

Like most engines an C14NZ, 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 C14NZ, failure to do this will exacerbate engine wear, on a tuned C14NZ 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 C14NZ why not pop over to the forums at TorqueCars where you can chat about C14NZ tuning options and read about others projects who may be planning to do similar modifications on their C14NZ.

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