Tuning the Subaru EZ36

"Comprehensive guide to tuning and performance parts on the Subaru EZ36 engine!"

We are always getting messages requesting info on the greatest EZ36 upgrades. So let us look into Subaru EZ36 tuning mods and outline the best modifications on this great engine and point out some potential pitfalls along the way.

Our aim here is to examine the options for your EZ36 tuning and report on the best modifications. Subaru EZ36 offer good returns when tuned and with the ultimate modified enhancements like remaps, turbo kits and camshafts you will dramatically improve your driving opportunities.

Just because particular parts are popular with EZ36 owners it doesn't mean you should fit it, instead we'll ultimate parts that will give your EZ36 the best power gain for you money.

Significant gains on the EZ36 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 cams usually boost the torque over the rpm band, you may lose a little low end bhp but your high end rpm power will be better.

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

A Race camshaft makes it harder when driving around busy urban areas.

You should ideally optimize your bhp range to your driving style so for a daily driver stick with a shorter duration EZ36 camshaft

Some EZ36 engines respond better to more aggressive camshaft durations than others.

The ECU mapping and injectors and fuel pump also will make differences on the power gains you'll hit.

A longer valve duration can alter the power 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.

EZ36 Tuning Stages

Stage 1 EZ36 modifications: Fast road camshaft, Intake headers, Sports exhaust manifold, Drilled & smoothed airbox, Remaps/piggy back ECU, Panel air filters.

Stage 2 EZ36 modifications: fuel pump upgrades, induction kit, Sports catalyst & performance exhaust, Fast road cam, high flow fuel injectors, Ported and polished head.

Stage 3 EZ36 modifications: Internal engine upgrades (head flowing porting/bigger valves), Adding or Upgrading forced induction (turbo/supercharger), Twin charging conversions, Engine balancing & blueprinting, Competition cam, Crank and Piston upgrades to alter compression.

ECU mapping helps unlock the full potential of all the tuning parts you've done to your EZ36.

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

Pushing air and fuel into the EZ36 engine is the whole point to any tuning job.

The intake plenum take the air during the suck phase from the filter and allow it to be pulled into the engine and mixed with fuel.

Design and flow rate of the Plenum can make a noticeable improvement to fuel mixing and power on the EZ36.

I usually find headers are begging for an upgrade, although a few manufacturers provide reasonably well designed headers.

Adding a EZ36 larger valve kit, doing some 3 or 5 angle valve jobs and porting and head flowing will also increase power, & more importantly will permit increasing the power increase on other upgrades.

Turbo upgrades for the EZ36

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 EZ36

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 an engine is turbocharged, tuning mods are going to make more power and turbocharged engines will have strengthened components.

However you'll find engines will have power limits

Research these restrictions and fit higher quality components to cope with the power.

We see many people spending a loads of money on turbo upgrades on the EZ36 only to see the whole thing literally blow up just after it's completed.

Larger capacity turbo units commonly experience no power at low rpm, and little turbo units spool up much more quickly but don't have the high rpm power band gains.

Thankfully the range of turbochargers is always evolving and we commonly find variable vane turbochargers, where the vane angle is altered according to speed to lower lag and increase top end power.

Twin scroll turbochargers divert the exhaust gases into 2 channels and feed these at differently profiled vanes in the turbocharger. They also increase the scavenging effect of the engine.

It is common that there's a limit in the air flow sensor AFM/MAP on the EZ36 when a lot more air is being pulled into the engine.

You'll see that 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor was restricting bhp and torque at a much lower level.

Adding a supercharger or additional turbo will make large bhp and torque gains, although more complex to install. We have this article covering twinchargers if you want to read more.

Uprating EZ36 fuel injectors

When you boost the power you will need to increase to the fuel delivery.

More power needs more fuel. It makes sense to be generous with your injectors flow rate.

The rule of thumb is to add 20% when specifying 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 EZ36 performance exhausts

Only look to increase your exhaust if the existing exhaust is creating a restriction.

On most factory exhausts you'll find your 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.

Sports exhausts increase the flow of air through the engine.

But if your exhaust is too big, ie: it's over 2.5 inches bore, you will lose a great deal of your flow rate and end up losing power and torque.

Common exhaust restrictions come around the catalysts installed, so adding a higher flowing sports alternative will help avoid this restriction.

Problems and issues to look out for on the EZ36

The EZ36 engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the EZ36, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your EZ36 engine please join us in our friendly forum where you can discuss tuning options in more detail with our EZ36 owners. It would also be worth reading our unbiased tuning articles to get a full grasp of the benefits and drawbacks of each modification.

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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 EZ36 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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