Tuning the Fiat Firefly N4

"Comprehensive guide to tuning the Fiat Firefly N4 engine!"

We are always seeing threads about the things we recommend when it comes to Firefly N4 power upgrades. So let us look into Fiat Firefly N4 tuning mods and outline the best mods that work on this great engine and point out some common pitfalls along the way.

The Fiat Firefly N4 are good project engines and with the best modified parts like remaps, turbo kits and camshafts you will maximise your driving enjoyment.

Our aim here is to provide a guide to Firefly N4 tuning and summarise the optimum modifications.

The top Firefly N4 parts on an engine are sensibly the ones that give the biggest return for your cash.

We won't be swayed by popular Firefly N4 parts, they need to be cost effective.

The camshaft profile plays a big part in the engines power output so camshaft upgrades make quite a large difference. The intake & exhaust durations will alter depending on the chosen camshaft profile, so large bhp gains are on offer for camshaft upgrades.

NB: Fast road camshafts usually boost the power throughout the rpm band, you could sacrifice a little low end torque but your higher rpm power will be better.

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

On a car driven daily must carefully try to match your torque band to your typical driving style.

I would be surprised if you have found a Firefly N4 Race camshaft is a pleasure to live with when on the daily commute.

Different Firefly N4 engines respond better to more aggressive camshaft durations so view each engine as unique.

The ecu map and fuelling also will make differences 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.

Firefly N4 Tuning Stages

Stage 1 Firefly N4 modifications: Remaps/piggy back ECU, Intake headers, Fast road camshaft, Panel air filters, Drilled & smoothed airbox, Sports exhaust manifold.

Stage 2 Firefly N4 modifications: high flow fuel injectors, induction kit, fuel pump upgrades, Fast road cam, Sports catalyst & performance exhaust, Ported and polished head.

Stage 3 Firefly N4 modifications: Competition cam, Crank and Piston upgrades to alter compression, Adding or Upgrading forced induction (turbo/supercharger), Internal engine upgrades (head flowing porting/bigger valves), Engine balancing & blueprinting, Twin charging conversions.

Carefully think through your options and then buy your modifications and set yourself a power target to avoid costly mistakes.

ECU mapping will help unlock the full potential of all the tuning parts you've done to your Firefly N4.

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 may vary depending on the tuning parts you've carried out and the condition of your engine.

Pulling more fuel and air into your Firefly N4 is the whole point to any engine upgrade project.

Headers transmit the air during the suck phase from the air filter and allow it to be sucked into the engine cylinders.

The size of bore and shape and flow characteristics of the Intake manifold can make a large improvement to fuel atomisation on the Firefly N4.

Many mass produced engine intake manifold are in desperate need of performance upgrades, although some makers provide decently flowing intake manifold.

Increasing the Firefly N4 valve size, doing a bit of 3 or 5 angle valve jobs and porting and head flowing will also boost performance, and as an added benefit will permit a greater performance increase on other modifications.

Turbo upgrades for the Firefly N4

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 Firefly N4

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.

When a car has a turbocharger tuning parts are going to make more power and you will discover turbo engines use strengthened components.

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

We recommend you find these restrictions and fit better quality crank and pistons to handle the power.

We see many people spending a a stack of money on turbocharger upgrades on the Firefly N4 only to suffer the humiliation of seeing the engine block go up in smoke soon after it's been finished.

Bigger capacity turbo chargers will usually experience low end lag, and smaller turbo chargers spool up much more quickly but won't have the high rpm power band gains.

Thanks to progress the market of turbo units is always evolving and we are seeing variable vane turbo units, where the vane profile is altered according to speed to lower lag and increase top end bhp and torque.

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

It is not unusual that there's a limit in the air flow sensor (AFM/MAF/MAP) on the Firefly N4 when a lot more air is being drawn into the engine.

Going up you'll find 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor was restricting performance at a much lower level.

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

Uprating Firefly N4 fuel injectors

You will need to ensure that the engine is not starved of fuel so will have to uprate the fuelling when you start going beyond 20% of a torque increase.It makes sense to be generous with your injector capacity.

The accepted safe increase is to add 20% when fitting an injector, helps cope with injector deterioration and affords 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 Firefly N4 performance exhausts

You may need to boost your exhaust if your exhaust is creating a restriction in flow.

On most factory exhausts you should find that the flow rate is good 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 generally help improve air flow out of the engine but avoid an exhaust that is too big or you may end up will reduce the flow rate. Stick to 1.5 to 2.5 inches for best results.

Typically exhaust restrictions are in the emissions filters installed, so adding a better flowing sports alternative will help avoid this restriction.

Problems and issues to look out for on the Firefly N4

The Firefly N4 engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the Firefly N4, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your Firefly N4 engine please join us in our friendly forum where you can discuss tuning options in more detail with our Firefly N4 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 tuning 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 Firefly N4 guides and tips are kept up to date.

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