Mazda Skyactive X Tuning

"All you need to know about performance tuning the Mazda Skyactive X engine!"

One engine that keeps cropping up in emails and questions we get sent, is the Skyactive X, and what enhancements work best on it. so we've created this web page which goes over what we feel are the primary areas you should tune and outline which modifications we feel are the best.

The Skyactive  uses compression ignition rather than a spark, so this is a radical new engine concept. It still has a spark plug to regulate the burn.

The end result is fantastic efficiency or around 20-30% because more power can be extracted from the fuel, and it offers a much cleaner burn. Low end torque is also much higher than a similar petrol engine.

A new engine concept like this presents challenges to the tuner though, so we'll pool the feedback we've had and detail the best approach to Skyactive X tuning and outline the best upgrades.

History of the Skyactive X Engine

Looking at the way diesel engines work, through compression ignition rather than a spark Mazda applied this to the petrol engine, producing a radical new engine concept in the Skyactive X. There is still a spark plug to regulate the burn and additional fuel just before the point of detonation is injected where the spark plug ignites it.

It offers the best of both worlds allowing spark operation at high RPMS and and compression ignition at lower speeds, like a diesel.

The result is great efficiency as more power is extracted from the fuel, and it offers a much cleaner burn. Low end torque is also much higher than a similar petrol engine.

  • ¬†132 kW (177 hp) and 224 Nm 165 lbft

Tuning the Mazda Skyactive X and best Skyactive X performance parts.

Best Skyactive X tuning parts

The greatest Skyactive X parts on an engine are sensibly the ones that give the best value for money.

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

Fast road cams raise the top end power so are more suited to petrol engines, than diesel ones. This will usually provide good peak power increases through performance camshafts on most engines

So altering your Skyactive X camshaft will make a difference to the engine engines power. Choosing a higher performance camshaft profile raises the engines power curve accordingly.

Fast road camshafts tend to boost the performance over the rpm band, you may sacrifice a little bottom end power but top end will improve.

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

On a daily driver it makes a lot of sense to match your power band to your driving style.

I would be surprised if you have ever asserted that a Skyactive X Motorsport and race camshaft is a pleasure to live with when driving around busy urban areas.The low end idle will be very lumpy and irregular, so something you would notice on a track when you drive in the upper third of the rpm band, but on roads this is a serious issue and we've heard from lots of drivers lamenting their decision to add an extreme competition cam profile to their engine.

Different Skyactive X engines respond better to extreme camshaft durations than others.

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

Extending exhaust or intake 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.

Typical stage 1 mods often include:
drilled & smoothed airbox, Panel air filters, Fast road camshaft, Sports exhaust manifold, Remaps/piggy back ECU, Intake headers.

Typical stage 2 mods often include:
Fast road cam, Ported and polished head, fuel pump upgrades, Sports catalyst & performance exhaust, induction kit, high flow fuel injectors.

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

The Skyactive X power plant make great tuning projects and we note that there is a lot of modifications and performance parts about.

Mapping allows a tuner to fully realize the full potential of all the upgrades you've done to your Skyactive X.

(Sometimes flashing the ECU is not an option, so an aftermarket ECU is the route to take, and many of these will outperform factory ECU's but make sure it has knock protection and that you get it setup properly.) 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 often rely on the upgrades you've fitted and the condition of your engine.

Feeding air into the Skyactive X engine is the main goal to any performance tuning job.

Headers take the air during the suck phase from the intake filter and allow it to be sucked into the engine cylinders with fuel for the squish phase.

The bore size, shape and flow rate of the Intake headers can make a substantial change to fuel mixing and power on the Skyactive X.

Many mass produced engine air intake manifolds are improved through aftermarket tuning parts, although some makers provide reasonably good air intake manifolds.

Big valve conversions on the Skyactive X, doing some 3 or 5 angle valve jobs and porting and head flowing will also boost bhp, and importantly will make space for an improved bhp increase on other tuning mods.

Skyactive X Turbo upgrades

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 Skyactive X

It will be much harder to install a turbo on this engine, due to the way it works, and as it is already running a very high compression ratio. Theoretically if you lower the compression ratio, it will be possible to add forced induction and if you have a project along these lines please let us know in the comments because there is a lot of interest in this.

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

You'll commonly see there is a limitation in the air flow sensor MAP/MAF/AFM on the Skyactive X when a lot more air is being sucked into the engine.

We note 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 torque gains, although more difficult to install. We have this feature on twinchargers if you want to read more.


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 bhp increase. Don't forget to be generous with your injectors flow rate.

The rule of thumb is to add 20% capacity when fitting an injector, this allows for injector deterioration and allows a bit of spare capacity should the engine need 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.

Skyactive X Performance Exhausts

You may need to improve your exhaust if your current exhaust is actually creating a flow problem.

On most factory exhausts you'll find the 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.

Please dont run with the widest exhaust you can buy 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.

Typically exhaust restrictions can be traced to the anti polution filters installed (catalysts on the Skyactive X), so adding a faster flowing sports aftermarket catalyst will improve air flow, and rather than doing an illegal decat, will keep the car road legal.

Weak spots, Issues & problem areas on the Skyactive X

The Skyactive X engines are generally reliable and solid units, as long as you follow the manufacturers service schedules, and use a good quality oil to ensure longevity. Few problems should happen as long as they are regularly serviced and maintained.

Regular oil changes are vital on the Skyactive X, especially when tuned and will help extend the life and reliability of the engine.

If you want to know more, or just get some friendly advice on Tuning your Skyactive X engine please join us in our car forums where you can discuss Skyactive X tuning options in more detail with our Skyactive X owners. It would also be worth reading our unbiased Mazda tuning articles to get insights into each modification and how effective they will be.

Please help us improve these tips by sending us your feedback in the comments box below.

We love to hear what our visitors have got up to and which modifications work best for you on your car. Which helps us keep our guides and tips up to date helping others with their modified car projects. Your feedback and comments are used to keep this page up to date, and help improve the accuracy of these Skyactive X articles which are continually updated.

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