Tuning the Subaru EZ30

"Comprehensive guide to tuning the Subaru EZ30 engine!"

We often are getting messages requesting info on the things we recommend when it comes to EZ30 upgrades. So let us look into Subaru EZ30 tuning mods and outline the best modifications on this great engine and point out some common pitfalls along the way.

Now we will examine EZ30 tuning and highlight the best modifications. Subaru EZ30 are fantastic to work on and with carefully picked sports upgrades like remapping, turbo kits and camshafts you will enhance your driving pleasure.

The optimum EZ30 upgrades on an engine are typically the ones that give the best value for money.

We won't be swayed by popular EZ30 upgrades, they need to be cost effective.

Significant gains on the EZ30 can be made from cam upgrades. Altering the cam profile alters the intake and exhaust durations on the engine and can dramatically change the torque and power output.

NB: Fast road camshafts commonly increase the bhp through the rpm band, you may sacrifice a little bottom end power but your higher rpm power will improve.

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

In a typical daily driver should ideally to optimize your torque band to your typical driving style.

I'd be amazed if you find a EZ30 Competition cam is a pleasure to live with when driving in heavy traffic.

Some EZ30 engines respond better to mild camshaft durations check your engine on a rolling road.

The engine timing and fuel pump and injectors also have a large bearing on the bhp gains you'll get.

Longer valve 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.

EZ30 Tuning Stages

Stage 1 EZ30 modifications: Remaps/piggy back ECU, Drilled & smoothed airbox, Sports exhaust manifold, Intake headers, Panel air filters, Fast road camshaft.

Stage 2 EZ30 modifications: Fast road cam, Sports catalyst & performance exhaust, fuel pump upgrades, Ported and polished head, induction kit, high flow fuel injectors.

Stage 3 EZ30 modifications: Internal engine upgrades (head flowing porting/bigger valves), Engine balancing & blueprinting, Twin charging conversions, Crank and Piston upgrades to alter compression, Adding or Upgrading forced induction (turbo/supercharger), Competition cam.

Mapping should help to release the full potential of all the parts you've done to your EZ30.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but power output often rely on the parts you've carried out and the condition of your engine.

Feeding more air into your EZ30 is the whole point to any tuning task.

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

Structure and flow characteristics of the Intake headers can make a substantial improvement to fuel delivery on the EZ30.

Many mass produced engine intake are crying out for motorsport parts, although some manufacturers provide well optimised intake.

Increasing the EZ30 valve size, doing some port matching and head flowing will also lift bhp and torque, the fantastic side effect is it will allow you to get a greater bhp and torque increase on other upgrades.

Turbo upgrades for the EZ30

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 EZ30

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 your car is turbo charged modifications are relatively easy and you will discover turbocharged engines are built using many forged and stronger components.

However most engines have limits

We recommend you find these limits and fit higher quality crank and pistons to handle the power.

There are many drivers spending a lots of money on turbocharger upgrades on the EZ30 only to have the motor literally blow up soon after it's used in anger.

Bigger upgraded turbochargers commonly experience a bottom end lag, and small turbochargers spool up quickly but don't have the peak rpm torque gains.

In the last 10 years the range of turbochargers is always increasing and we are seeing variable vane turbochargers, allowing the vane profile is altered according to speed to lower lag and increase top end power.

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

It is common that there's a restriction in the air flow sensor MAP/MAF/AFM on the EZ30 when a lot more air is being fed 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 bhp at a much lower level.

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

Uprating EZ30 fuel injectors

When you lift the bhp and torque you will need to increase to the fuelling.

More bhp and torque needs more fuel. It is important to be generous with your injector capacity.

As a rule of thumb add 20% capacity when buying an injector, this accounts for injector deterioration and allows a little 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.

Best EZ30 performance exhausts

You should look to boost your exhaust if the existing exhaust is actually creating a restriction in flow.

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 biggest exhaust you can get 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 located the emissions filters installed, so adding a higher flowing race alternative will help avoid this restriction.

Problems and issues to look out for on the EZ30

The EZ30 engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the EZ30, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your EZ30 engine please join us in our friendly forum where you can discuss tuning options in more detail with our EZ30 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 upgrades were the most effective for them, it helps us improve our recommendations and articles to reflect current trends in modifications and ensures that our EZ30 guides and tips are kept up to date.

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This article is flagged for an update, so please pass on specific tips below that I can include. All articles, and content was written by me, Waynne Smith TorqueCars founder. Some outlines are just too general so I appreciate your feedback and suggestions. This entry was filed under Subaru. You can leave a response below or join our forum to discuss this article and car modification in detail with our members.

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