Hyundai Sigma Tuning

"All you need to know about tuning the Hyundai Sigma engine!"

A humble V6 which ranged from 2.5 to 3.5L capacity thanks to changes to both bore and stroke.

Most versions had a DOHC but there were SOHC heads used in the Sigma range.

We review Sigma tuning and point out the best modifications. Hyundai Sigma great bases for a tuning project and with carefully chosen tuning upgrades like a remap, turbo upgrades and camshafts you will greatly enhance your driving pleasure.

History, Power & Specs of the Engine

  • 2.5D G6AV DOHC 160 hp at 6000 rpm 150 lbft at 4500 rpm
  • 3.0D G6AT SOHC 158 hp  at 5000 rpm 177 lbft at 3000 rpm
  • 3.0D G6AT DOHC 182 hp  at 6000 rpm 178 lbft at 4500 rpm
  • 3.0D G6CT DOHC 189 hp  at 6000 rpm 192 lbft at 4000 rpm
  • 3.5D  G6AU DOHC 200 hp at 5500 rpm 214 lbft at 4800 rpm
  • 3.5D G6CU DOHC 217 hp  at 5500 rpm 232 lbft at 3500 rpm

Best Sigma mods

Just because a tuning parts is popular with Sigma owners it doesn't mean you should fit it, instead we'll focus tuning parts that will give your Sigma the best power gain for you money.

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

Fast road camshafts commonly push up the performance over the rpm band, you may lose a little low down torque but high end rpm power will be higher.

Motorsport camshafts, push up the high end rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers especially on a 6000rpm v6 like the Sigma.

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

I'd be surprised if you have thought a Motorsport and race camshaft is a pleasure to live with when in heavy traffic because low end power will be very lumpy. Competition cams are designed for maximum power at the top end of the RPM range, a place that most daily commutes will not permit!

Some Sigma engines respond better to less aggressive camshaft durations check your engine on a rolling road.

The ecu map and fuel pump and injectors also will make differences on the torque gains you'll get.

Extending exhaust or intake 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.

Please watch our video which covers the 5 principles of tuning your car. Be sure to keep up with our latest YouTube content and subscribe.

Best Engine Mods for your car

  1. Mapping - remapping provides the most advantage in terms of cost savings,  aftermarket ECUs, and piggyback ECUs are all alternatives.
  2. Fast road cams are one of the most significant mechanical changes, but they must be installed by someone who knows what they're doing and they are not always easy to source but you might find a local firm to regrind a stock camshaft.
  3. Intake and Exhaust - Note that on their own these mods will NOT ADD POWER in most cases, but they can help enhance power after other mods by removing the restriction.
  4. Upgrades to turbochargers and superchargers - forced induction is the most efficient approach to increase air supply, allowing you to burn more fuel and make more power. It is one of the most costly upgrades but provides the best gains.
  5. Head work - The goals of porting and flowing the head are to get air flowing into the engine while removing flow restrictions and turbulence.

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

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

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

The Sigma engine blocks respond well to upgrades and we see that there are plenty of upgrades and tuning parts around.

ECU flashing allows a tuner to establish the full potential of all the parts you've fitted to your Sigma.

(In some cases, as the factory ECU is locked flashing 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 you around 30% more power on turbocharged vehicles and 15% on NA (naturally aspirated) engines, but you mileage will vary depending on the parts you've done and the condition of your engine.

It is the main goal to any engine modification task to feed air into each cylinder

An intake manifold will channel the air from the filter and allow it to be drawn into the engine and mixed with fuel.

The bore size, shape and flow rate of the Intake manifold can make a substantial effect on to fuel mixing and power on the Sigma.

On popular production engines air intake manifolds are ripe for an upgrade, although a few makers provide fairly well optimized air intake manifolds.

Big valve conversions on the Sigma, doing some Sigma port enlargement and head flowing will also lift bhp, and significantly will afford you a greater bhp increase on other tuning mods.

Turbo upgrades

NA (naturally aspirated) 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 Sigma

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

If your motor has a turbocharger modifications are simpler to install and turbocharged engines already contain stronger components.

However you'll find engines have limits

Research these restrictions and fit higher quality crank and pistons to handle the power.

We see many guys spending a a stack of money on turbo charger upgrades on the Sigma only to suffer the indignity of watching the engine explode when it's been enthusiastically driven.

Large upgraded turbos commonly experience a bottom end lag, and smaller turbos spool up much more quickly but don't have the high rpm engines power gains.

Thankfully the range of turbo chargers is always developing and we are seeing variable vane turbo chargers, where the vane angle is altered according to speed to lower lag and increase top end torque.

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

It is common that there's a limitation in the air flow sensor AFM/MAF on these engines when loads more air is being drawn into the engine.

We note 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 bhp gains, although more difficult to get working. We have a twincharger bhp adding guide if you want to read more.

Fuelling

Don't miss you'll need to increase the fuel delivery when you are increasing the torque - it makes the car more thirsty. It is important to over specify your injectors flow rate.

The rule of thumb is to add 20% capacity when specifying an injector, this allows for injector deterioration and provides 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

Only look to boost your exhaust if the current exhaust is creating a restriction.

On most factory exhausts you should find that the exhaust flow rate is still ok 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 pipe is too big, ie: over 2.5 inches bore, you will lose a great deal of your flow rate and end up lacking power and torque.

Usual exhaust restrictions can be traced to the emissions filters installed, so adding a better flowing race alternative such as a sports catalyst pretty much removes this restriction, thanks to it's larger size and surface area, and will effectively raise the performance to levels you would expect without having a catalyst installed, but keeps the car road legal.

Weak spots Issues & problem areas on the Sigma

The Sigma 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.

Carbon build up in the head, particularly around the valves which will sap power or create flat spots, this is a larger issue on direct injection engines but should be looked out for on all engines. We have tips on removing carbon build up.

Some of our members have had issues with flat spots or glitches after applying mods and upgrades or tuning, this is not usually related to this engines design, so instead see our article on diagnosing flat spots and problems after tuning which should help you get the bottom of this issue.

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

If you would like to know more, or just get some friendly advice 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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