Tuning the Hyundai Smartstream

"Comprehensive guide to tuning and performance parts on the Hyundai Smartstream engine!"

The Hyundai Smartstream are fantastic to work on and with a few sensible sports modifications like remapping, turbo upgrades and camshafts you will enhance your driving pleasure.

Let us provide a guide to Smartstream tuning and provide tips on the best modifications for your car.

Just because particular upgrades are popular with Smartstream owners it doesn't mean you should fit it, we will highlight only those upgrades that we reckon are the best and that will give your Smartstream the best power gain for you money.

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 camshafts commonly bump the bhp over the rev range, you may lose a little low down torque but the top end will be better.

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

A Competition camshaft won't do well if on the daily commute.

You should ideally optimize your bhp range to your driving style so for a daily driver stick with a fast road Smartstream camshaft

Different Smartstream engines respond better to different cam durations so view each engine as unique.

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

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

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

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

The Smartstream units respond well to upgrades and we see that there are quite a few choices of mods and performance parts out there.

remap allows a tuner to fully realize the full potential of all the parts you've fitted to your Smartstream.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but your results usually rely on the parts you've applied and the condition of your engine.

Pulling air and fuel into each cylinder is the aim to any engine performance tuning task.

Intake headers transmit the air from the filter and allow it to be drawn into the engine cylinders.

Structure and flow rate of the Intake manifold can make a big difference to to fuel delivery on the Smartstream.

We often see intake are in dire need of aftermarket tuning parts, although some car makers provide fairly well optimized intake.

Increasing the Smartstream valve size, getting port matching and head flowing will also raise performance, and importantly will give you increasing the performance increase on other tuning 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 Smartstream

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.

If an engine has a turbocharger upgrades are giving better power gains and we find turbo charged engines are made using strengthened components.

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

It is important to find these limitations and upgrade to forged components to utilize the power.

We see many people spending a loads on turbo upgrades on the Smartstream only to watch the engine literally blow up when it's used in anger.

Large turbos often suffer no power at low rpm, and small turbos spool up really quickly but don't have the high rpm torque gains.

Thanks to progress the selection of turbos is always developing 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 a couple of channels and direct these at differently angled vanes in the turbocharger. They also improve the scavenging effect of the engine.

It is common that there is a limit in the air flow sensor MAF/MAP on the Smartstream when considerably more air is being pulled into the engine.

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

Adding a supercharger or additional turbo will make large bhp and torque gains, although more challenging to get working. We have this article on twincharging if you want to read more.

Fuelling upgrades and mods

You will need to ensure that the engine is not starved of fuel so will need to increase the fuelling when you start exceeding 20% of a torque increase.Most tuners we speak with say to over specify your flow rate on the injectors.

The rule of thumb is to add 20% to the flow rate when buying an injector, which takes into account injector deterioration and allows a little 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

You may need to increase your exhaust if your current exhaust is actually creating a restriction in flow.

On most factory exhausts you should find that the exhaust 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 equal out the flow of gases through the engine.

But if the exhaust is too big, ie: over 2.5 inches bore, you will lose a lot of the flow rate and end up sapping power and torque.

Usual exhaust restrictions are in the catalyst and filters installed, so adding a freer flowing performance alternative will help avoid this restriction.

Weak spots, Issues & common problem areas on the Smartstream

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

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

History of the Engine

The Smartstream was released in 2018 and comes as a straight 4/6 and V6 configuration and turbocharged versions were also produced, thanks to a lower compression ratio, and updating fuelling and mapping.

  • Smartstream G1.6 121 hp
    Hyundai Venue (2019–present)
  • Smartstream G1.6T 178 hp
    Hyundai Sonata (2019–present)
    Kia Optima/Kia K5 (DL3) (2019–present)
  • Smartstream G2.0 158 hp *(hybrid = 192hp)
    Hyundai Sonata (2019–present)
    Kia Optima/Kia K5 (DL3) (2019–present)
  • Smartstream G2.5 177hp
    Hyundai Azera (2019-present)
    Hyundai Sonata (2019–present)
    Kia Optima/Kia K5 (DL3) (2019–present)
  • Smartstream G2.5T 300hp
    Genesis GV80 (2020–present)
  • Smartstream G3.5T 375hp
    Genesis GV80 (2020–present)
  • Smartstream D3.0 274hp
    Genesis GV80 (2020–present)

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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