Modding tuning and best performance upgrades on the Subaru EZ30 engine!

Modifying and improving: "EZ30 Modifications"

How to modify and upgrade the Subaru EZ30

"Comprehensive guide to performance tuning the Subaru EZ30 engine!"

Forums like the one at TorqueCars often are getting posts asking about how to improve the EZ30 from people wanting to know what are the premier EZ30 mods that work. So let us look into Subaru EZ30 mods and outline the best mods that work on this great engine and point out some problems along the way.

The Subaru EZ30 are awesome to work on and with carefully chosen tuning enhancements like a remap, turbo kits and camshafts you will noticeably increase your driving pleasure.

In this article we review EZ30 tuning and point out the greatest mods that work.

The ultimate EZ30 tuning mods on an engine are usually the ones that give the biggest return for your money.

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

EZ30 induction kits

Improving air intake on the EZ30

You need fuel and air for an engine to work. If there is a lack of fuel then it will run lean, if there is a lack of air it runs rich resulting in lost power which risks damage to the EZ30. We'll pick up on fuelling later in this article but for now we shall look at air supply.

So it's important to any car tuning job to force more air and fuel into the EZ30 engine but this has a knock on effect with the air flow sensor.

It is common that there's a restriction in the air flow sensor AFM/MAF on the EZ30 when loads more air is being sucked into the engine.

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

Engines intake headers carry the air from the intake filter and allow it to be fed into the engine cylinders with fuel for the squish phase.

Design and flow characteristics of the Intake headers can make a big effect on to fuel engine efficiency on the EZ30.

Most plenum chambers are needing aftermarket tuning parts, although a few car makers provide reasonably good plenum chambers.

Increasing the EZ30 valve size, getting port work and head flowing will also increase bhp and torque, and significantly will permit raising the bhp and torque increase on other modifications.

EZ30 performance cam tips.

Some EZ30 engines respond better to more aggressive cam durations check your engine on a rolling road.

The map and injectors and fuel pump also have an effect on the torque gains you'll get.

Longer 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.

Altering your EZ30 camshaft will make a dramatic difference to the engine torque. Choosing a higher performance camshaft profile raises the torque accordingly.

NB: Fast road camshafts tend to push up the bhp throughout the rev range, you may sacrifice a little low end torque but top end will be higher.

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

A Motorsport and race cam won't do well if in heavy traffic.

You should ideally optimize your power band to your preferences so for a typical daily driver stick with a shorter duration EZ30 cam

Stage 1, 2 and 3 mods for the EZ30

Before we break the best tuning upgrades down into stages of tune, let's list the most effective tuning upgrades for you.

  1. Suspension Upgrades - always improve your cars handling
  2. Brake Upgrades - Even before adding power improve those brakes
  3. Intake - make sure the intake is not restricted, use filters and intake upgrades to improve this
  4. Exhaust - as with 3 ensure there is not restriction in the exhaust, cats are the usual bottleneck
  5. Tunes - remapping, piggyback ECU's and aftermarket ECU's can all make decent gains
  6. Fuelling - when you've increased power you'll need to match this with more fuel
  7. Turbo upgrades - Improving the intake with a large turbo and better flowing intercooler will be the biggest power gain you'll see (but one of the most complex).

This video guide to tuning cars is a great starting point to work from in your project.

Stage 1 EZ30 parts:

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

Stage 2 EZ30 parts:

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

Tuning tips and articles Engine tuning Transmission tuning Care care Intake & exhaust mods Improve handling Forums

Stage 3 EZ30 parts:

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

The EZ30 engines make great tuning projects and we're finding that there is an increase of parts and performance parts about.

ECU flashing helps to establish the full potential of all the modifications you've done to your EZ30.

You will typically expect to see gains of approximately 20-30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but figures achieved often vary depending on the modifications you've done and the condition of your engine.

Turbo modifications on the EZ30

To get a turbo working on a NASP engine there is a lot involved, from lowering compression ratio to improved fuel supply and mapping, so we have found a great guide to helpavoid the common pitfalls or end up with an unfinished project because you were not told what you were getting into by doing this on the 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 excellent power gains.

If a car is turbocharged, tuning parts are more reliable and you will discover turbo charged engines will have harder and stronger components.

There are weak spots for every engine, with some being very over engineered and some only able to handle stock power

See where you'll find these limits and fit higher quality crank and pistons to handle the power.

We've seen people spending a lot of money on turbo upgrades on the EZ30 only to suffer the humiliation of seeing the motor literally blow up when it's first rolling road session.

Large capacity turbochargers commonly experience no power at low rpm, and low capacity turbochargers spool up more quickly but do not have the top end engines power gains.

Over the last 20 years the choice of turbochargers is always increasing and we commonly find variable vane turbochargers, allowing the vane profile is altered according to speed to lower lag and increase top end bhp.

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

Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large power gains, although more complex to setup. We have this article covering twinchargers if you want to read more.

Tips about fuel supply on the EZ30

When you increase the bhp you will need to uprate to the fuelling.

More bhp needs more fuel. We would recommend you to over specify your flow rate on the injectors.

As a rule of thumb add another 15% when fitting an injector, this takes into account injector deterioration and gives you some spare capacity should the engine require more fuel.

Don't forget that different fuel grades will usually require different settings, a high octane fuel will burn more efficiently than lower octane fuel for example. A car will trim fuel supply to keep within the ideal air fuel mix but at the extreme ends you may need to adjust your injector capacity, or the mapping or you'll get flat spots and potential lean or rich fuel issues..

Recommended EZ30 performance exhaust upgrades

Only look to uprate your exhaust system with an upgraded one is if your current exhaust is creating a flow problem.

On most factory exhausts you'll see your flow rate is good even on modest power gains, but on a serious tuning project with a big boost in power you will certainly need to get a better flowing exhaust.

Sports exhausts will certainly help air flow from the engine but avoid an exhaust that is too big or you may end up will reduce the flow rate. Stick to one and a half to two and half inches as a rule of thumb.

The usual suspects causing problems in your exhaust flow rate are in the emissions filters installed, so adding a higher flowing performance alternative will help avoid this restriction.

Cat bypassing (NB:catalysts reduce harmful engine emissions) is illegal in most countries and regions.

Faults issues and things to look out for on the EZ30

Like most engines an EZ30, should have few issues if it gets properly serviced and looked after.

We cannot stress enough the need for oil changes with the correct grade of oil on the EZ30, failure to do this will exacerbate engine wear, on a tuned EZ30 this is more important than ever and close attention should be paid to your maintenance schedule.

If you are interested in learning more or getting impartial tuning advice for your EZ30 why not pop over to the forums at TorqueCars where you can chat about EZ30 tuning options and read about others projects who may be planning to do similar modifications on their EZ30.

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