Tuning the Hyundai Sigma

"Comprehensive guide to modifying and tuning the tuning and performance parts on the Huyndai Sigma engine!"

TorqueCars will consider Sigma tuning and report on the ultimate modifications for your car. Huyndai Sigma are good project engines and with the right uprated tuning mods like ECU maps, turbo upgrades and camshafts you will certainly improve your driving enjoyment.

The greatest Sigma modifications on an engine are obviously the ones that give the best power gain for you spend.

We won't be swayed by popular Sigma modifications, they need to be cost effective.

History of the Engine

  • 2.5D G6AV DOHC 160 hp @6000 rpm 150 lbft @4500 rpm
  • 3.0D G6@SOHC 158 hp  @5000 rpm 177 lbft @3000 rpm
  • 3.0D G6@DOHC 182 hp  @6000 rpm 178 lbft @4500 rpm
  • 3.0D G6CT DOHC 189 hp  @6000 rpm 192 lbft @4000 rpm
  • 3.5D  G6AU DOHC 200 hp @5500 rpm 214 lbft @4800 rpm
  • 3.5D G6CU DOHC 217 hp  @5500 rpm 232 lbft @3500 rpm

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

NB: Fast road cams commonly boost the torque over the rev band, you could sacrifice a little low end torque but high end rpm power will be better.

Race 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.

On a daily driver should ideally to match your torque band to your preferences.

I'd be surprised if you have ever thought a Sigma Motorsport cam is a pleasure to live with when driving in heavy traffic.

Different Sigma engines respond better to different cam durations check your engine on a rolling road.

The map and fuelling also have an effect on the bhp gains you'll achieve.

A longer valve duration 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.

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

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

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

Carefully think through your options and then buy your mods and set yourself a power target to save yourself from expensive mistakes.

remap will help release the full potential of all the upgrades you've done to your Sigma.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but the end result may depend much on the upgrades you've done and the condition of your engine.

It is vital to any engine modification job to shove more air into each cylinder

Headers carry the air during the suck phase from the intake filter and allow it to be drawn into the engine cylinders with fuel for the squish phase.

Design and flow rate of the Intake manifold can make a big change to fuel engine efficiency on the Sigma.

On popular production engines intake are in desperate need of performance upgrades, although some makers provide fairly well optimized intake.

Fitting big valve kits, doing a bit of Sigma port enlargement and head flowing will also raise bhp and torque, this will afford you raising the bhp and torque increase on other tuning mods.

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 Sigma

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

If the engine has forced induction upgrades are simpler to install and you'll see that turbo engines already contain many forged and stronger components.

However you will find an engines have weakspots

We recommend you find these limits and install higher quality crank and pistons to utilize the power.

We see many people spending a fortune on turbo charger upgrades on the Sigma only to suffer the indignity of watching the Sigma literally blow up soon after it's been enthusiastically driven.

Big upgraded turbos will usually suffer a bottom end lag, and low capacity turbos spool up really quickly but don't have the top end bhp gains.

We are pleased that the range of turbo chargers is always developing and we are seeing variable vane turbo chargers, allowing the vane angle is altered according to speed to lower lag and increase top end bhp.

Twin scroll turbo chargers divert the exhaust flow into two channels and push these at differently profiled vanes in the turbo. They also increase the scavenging effect of the engine.

It is not unusual that there is a limitation in the air flow sensor (AFM/MAF/MAP) on the Sigma when considerably more air is being drawn into the engine.

Going up you'll find 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor limited bhp at a much lower level.

Adding a supercharger or additional turbo will make large torque gains, although more complex to configure. We have this guide to twinchargers if you want to read more.

Fuelling upgrades and mods

You will need to ensure that the engine is not starved of fuel so need to ramp up the fuelling when you start exceeding 20% of a power increase.We strongly recommend you to be generous with your injector capacity.

As a rule of thumb add 20% to the flow rate when buying an injector, this takes into account injector deterioration and provides some 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.

Exhaust upgrades and mods

You only need to to boost your exhaust if your current exhaust is actually creating a restriction in flow.

On most factory exhausts you should find that 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.

Sports exhausts will certainly help air flow through the engine but avoid an exhaust that is too large or you could will reduce the flow rate. Stick to 1.5 to 2.5 inches for best results.

Common exhaust restrictions come around the catalyst installed, so adding a better flowing performance alternative will help avoid this restriction.

Weak spots, Issues & common problem areas on the Sigma

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

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

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.

We need your help improving this article, so please send us your feedback in the comments box below and pass on any tips, points or facts we have wrong or have not covered.

We really like hearing from our readers, and hearing about which tuning 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 guides and tips are kept up to date.

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