Tuning the Hyundai Epsilon Tuning Tips

"Comprehensive guide to tuning the Hyundai Epsilon engine!"

The Hyundai Epsilon are popular engines and with the best modified upgrades like a remap, turbo upgrades and camshafts you will noticeably maximize your driving enjoyment.

In this article we review and look at Epsilon tuning and outline the ultimate upgrades.

When talking about the best and most optimal modifications for your Epsilon engine, we are going to focus on the ones that give the best power gain for you spend.

The cam profile plays a big part in the engines power output so cam upgrades make quite a large difference. The intake and exhaust durations will alter depending on the chosen cam profile, so large bhp gains are on offer for cam upgrades.

NB: Fast road cams commonly push up the torque through the rev band, you may sacrifice a little low end power but the higher rpm power will improve.

Race cams, push up the higher rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

In a car used daily must carefully try to match your power band to your preferences.

I'd be shocked if you find a Epsilon Motorsport and race cam is a pleasure to live with when on the daily commute.

Each engine responds better to more or less aggressive camshaft durations so set your engine up on a rolling road.

The engine timing and injectors and fuel pump also will say much on the power gains you'll make.

Longer valve durations 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.

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

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

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

The Epsilon power trains respond well to upgrades and thankfully there are increasing numbers of mods and tuning parts about.

Remaps will help release the full potential of all the tuning mods you've fitted to your Epsilon.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but figures achieved may differs on the tuning mods you've done and the condition of your engine.

Getting air into each cylinder is the aim to any engine performance tuning project.

Headers transmit the air from the air cleaner and allow it to be drawn into the engine cylinders.

The shape and rate of flow of the Intake can make a large change to fuel atomisation on the Epsilon.

Many mass produced engine intake manifold are improved through an upgrade, although some OEM provide reasonably good intake manifold.

Larger Epsilon valves, getting Epsilon port enlargement and head flowing will also raise torque, & importantly will give you a better torque increase on other parts.

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 Epsilon

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.

When the engine is fitted with a turbocharger upgrades are relatively easy and turbocharged engines are made using stronger components.

However you will find an engines will need better parts at higher power limits

See where you'll find these limitations and upgrade to more solid crank and pistons to survive the power.

We see many drivers spending a a stack of money on turbocharger upgrades on the Epsilon only to have the motor go up in smoke soon after it's been enthusiastically driven.

Bigger upgraded turbo units tend to suffer a bottom end lag, and small turbo units spool up much more quickly but do not have the top end power band gains.

In the last 10 years the selection of turbos is always improving and we commonly find variable vane turbos, where the vane profile is altered according to speed to lower lag and increase top end performance.

Twin scroll turbos divert the exhaust flow into two channels and direct these at differently profiled vanes in the turbo charger. They also improve the scavenging effect of the engine.

It is common that there is a limit in the air flow sensor AFM/MAP on the Epsilon when loads more air is being fed into the engine.

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

Adding a supercharger or additional turbo will make large performance gains, although harder to setup. We have this feature on twinchargers if you want to read more.

Fuelling upgrades and mods

When you raise the performance you will need to pay attention to to the fuel delivery.

More performance needs more fuel. We strongly recommend you to over specify your injector capacity.

The accepted safe increase is to add 20% when fitting an injector, helps cope with injector deterioration and affords you 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.

Exhaust upgrades and mods

Only look to increase your exhaust if your current exhaust is actually creating a restriction.

On most factory exhausts you'll see your flow rate is still 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 the exhaust pipe is too large, ie: it's over 2.5 inches bore, you will lose a lot of the exhaust flow rate and end up sapping power and torque.

Usual exhaust restrictions are traced to the filters installed, so adding a faster flowing race alternative will help avoid this restriction.

Weak spots, Issues & common problem areas on the Epsilon

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

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

History of the Engine

  • G4HA 0.8L 54 hp at 6000 rpm 51 lbft at 4800 rpm 4 cylinder
  • G4HC  1.0L 61 hp  at 5700 rpm 81 lbft at 3000 rpm 4 cylinder
  • G4HG 1.1L 68 hp at 5500 rpm  72 lbft at 2800 rpm 4 cylinder
  • G3HG 0.8L 55 hp at 5500 rpm 55 lbft at 4000 rpm 3 cylinder

For more information on Tuning your engine please join us in our friendly forum where you can discuss tuning options in more detail with our 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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