Tuning the Fiat Firefly T4

"Comprehensive guide to performance tuning the Fiat Firefly T4 engine!"

We often are getting messages inquiring about getting more power from the Firefly T4 and wanting to know what are the best Firefly T4 mods that work. So let us look into Fiat Firefly T4 upgrades and outline the best upgrades on this great engine and point out some problems along the way.

The Fiat Firefly T4 provide a fun base for your project and with the ultimate uprated parts like remaps, turbo kits and camshafts you will greatly maximize your driving opportunities.

We shall review and look at Firefly T4 tuning and report on the optimum upgrades.

When talking about the greatest parts for your Firefly T4 engine, we are going to concentrate on the tuning mods that give the best value for money.

Significant gains on the Firefly T4 can be made from camshaft upgrades. Altering the camshaft profile alters the intake and exhaust durations on the engine and can dramatically change the bhp and power output.

NB: Fast road camshafts normally push up the bhp and torque through the rev band, you may lose a little low end torque but your high end rpm power will be better.

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

A Competition camshaft makes it harder when in heavy traffic.

You should ideally optimize your power band to your preferences so for a typical daily driver stick with a fast road Firefly T4 camshaft

Each engine responds better to more or less aggressive camshaft durations so view each engine as unique.

The ecu map and fuelling also will say much on the bhp gains you'll make.

A longer valve duration 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.

Firefly T4 Tuning Stages

Stage 1 Firefly T4 modifications: Panel air filters, Intake headers, Drilled & smoothed airbox, Fast road camshaft, Remaps/piggy back ECU, Sports exhaust manifold.

Stage 2 Firefly T4 modifications: Ported and polished head, fuel pump upgrades, high flow fuel injectors, induction kit, Fast road cam, Sports catalyst & performance exhaust.

Stage 3 Firefly T4 modifications: Twin charging conversions, Internal engine upgrades (head flowing porting/bigger valves), Adding or Upgrading forced induction (turbo/supercharger), Engine balancing & blueprinting, Competition cam, Crank and Piston upgrades to alter compression.

Review your options and then acquire your tuning parts and set yourself a power target to avoid wasting your time and money.

ECU mapping helps fully realize the full potential of all the upgrades you've done to your Firefly T4.

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

Feeding fuel and air into each cylinder is the aim to any engine performance tuning job.

Intake take the air from the filter and allow it to be pulled into the engine cylinders.

Design and rate of flow of the Plenum can make a substantial change to fuel atomisation on the Firefly T4.

Many mass produced engine plenum chambers are crying out for an upgrade, although some car makers provide decently flowing plenum chambers.

Adding a Firefly T4 larger valve kit, getting Firefly T4 port enlargement and head flowing will also improve power, the fantastic side effect is it will give you raising the power increase on other upgrades.

Turbo upgrades for the Firefly T4

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 T4

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 a car has a turbo already fitted tuning mods are giving better power gains and you'll see that turbocharged engines are built with uprated components.

There are tuning limits for every engine, with some being over specified and some only able to handle stock power

It is important to find these restrictions and install better quality crank and pistons to utilize the power.

We see many drivers spending a loads of money on turbo upgrades on the Firefly T4 only to experience the engine go up in smoke soon after it's been finished.

Bigger turbos will usually suffer no power at low rpm, and little turbos spool up much more quickly but don't have the peak rpm torque gains.

Thanks to new tech the choice of turbo chargers is always moving on and we now see variable vane turbo chargers, permitting 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 two channels and feed these at differently angled vanes in the turbo. They also increase the scavenging effect of the engine.

It is common that there's a limitation in the air flow sensor AFM/MAP on the Firefly T4 when a lot more air is being pulled into the engine.

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

Adding a supercharger or additional turbo will make large torque gains, although more challenging to setup. We have this article on twincharging if you want to read more.

Uprating Firefly T4 fuel injectors

Don't forget to raise the fuelling when you are increasing the bhp and torque - it makes the car more thirsty. It makes sense to be generous with your flow rate on the injectors.

As a rule of thumb add 20% capacity when specifying an injector, this accounts for injector deterioration and gives 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 T4 performance exhausts

Only look to replace your exhaust if your exhaust is creating a flow problem.

On most factory exhausts you'll find the flow rate is ok even on modest power gains, but when you start pushing up the power levels you will need to get a better flowing exhaust.

Do not go with the widest exhaust you can find you'll reduce the exhaust flow rate - the best exhausts for power gains are usually between 1.5 to 2.5 inches. It is the shape and material more than the bore size.

Usual exhaust restrictions can be traced to the emissions filters installed, so adding a higher flowing performance alternative will help avoid this restriction.

Problems and issues to look out for on the Firefly T4

The Firefly T4 engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the Firefly T4, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your Firefly T4 engine please join us in our friendly forum where you can discuss tuning options in more detail with our Firefly T4 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 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 T4 guides and tips are kept up to date.

PLEASE HELP: I NEED YOUR DONATIONS TO COVER THE COSTS OF RUNNING THIS SITE AND KEEP IT RUNNING. I do not charge you to access this website and it saves most TorqueCars readers $100's each year - but we are NON PROFIT and not even covering our costs. To keep us running PLEASE Donate here

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.

Please watch this video on our new YouTube channel.


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

Member Benefits

Join our forum today and benefit from over 300,000 posts on tuning styling and friendly car banter.

You will also have full access to the modifed car gallery, project car updates and exclusive member only areas.

(All car owners of all ages and from all countries are welcome).