The Hyundai Theta is a gasoline-powered four-cylinder engine family. It was the third aluminum engine in production for the Korean automaker Hyundai Motor Company.
Its debut occurred on their fourth generation Sonata sedan, which came out codenamed NF (for North America). HMMA built an entire shop dedicated specifically to building these new models at one of their facilities across Alabama.
What are Hyundai Kia 2.4 Theta MFI/GDI Turbo Engines?
The Hyundai Kia 2.4 Engine is part of the Theta family of engines. The Theta engine features
double overhead camshafts with powder metal cams and pent-roof combustion chambers. The bucket tappet’s inlet manifold is shimless, resulting in a high-rpm response without vibration.
The Hyundai Theta II engine family comprises various gas engines that have 2.4 liters or smaller in size and are referred to as “twins” because they share many similarities with one another when it comes down to powertrain options for both vehicles and brands under the same brand name.
This particular model, the G4KC, has its origins from being shared between KIA Motors Company.
Continuously variable valve timing system enables the intake valves to open as wide or close together at varying speeds depending on demand from outside sources such as speed sensors for fuel efficiency purposes.
This technology also allows operators to use less oil by controlling power fluctuations better than traditional systems because no mechanical linkages are involved, which can wear down quickly under stress when operated frequently like most cars driven every day do.
On top of that, the aluminum alloy engine block is formed using a high-pressure die-cast method and reinforced by ladder frame technology in the lower end of its design.
Other notable features include fracture-split sinter forged connecting rods made from Sintered materials as well stainless steel exhaust manifold components that keep the overall weight down while providing great durability.
Engine Specifications and Design:
- Production Run: 2004 – Present
- Cylinder Head Material: Aluminum
- Cylinder Block Material: Aluminum
- Configuration: Inline-4
- Bore: 88.0 mm
- Stroke: 97.0 mm
- Valvetrain: DOHC with four valves per cylinder
- Displacement: 2.4 L (2359 cc)
- Compression Ratio: 10.5 and 11.3
- Weight: 322 lbs.
- Maximum HP: 201 HP at 5,800 – 6,300 RPM
- Maximum Torque: 184 lb-ft at 4,000 – 4,250 RPM
The engine’s cylinder block is an aluminum open deck design, which was implemented with larger dimensions to increase its displacement. These changes were made possible by installing a new crankshaft and pistons with an 88-mm diameter (instead of 86 mm).
As well as this change in size, there have also been modifications made concerning how many valves per cylinder are fitted; these now number four for everyone connected directly onto each head through double-overhead cams.
The crankshaft drives the intake and exhaust camshafts by using a timing chain. The first generation Theta engines used continuously variable valve timing (CVVT) for the intake, which was later applied on both sides in the Theta II engines.
This CVVT technology allows the change to their cam profile at different operating rates to match specific engine needs while still providing accurate power delivery without any backlash or other issues related to conventional systems.
2.4 GDI (G4KJ)
The Hyundai 2.4 GDI engines are the newest and most advanced technology for Hyundai’s 2-liter engine lineup, providing more fuel-efficient than ever before.
The latest generation of this multi-point injection system uses a high-pressure pump mounted directly on top of each cylinder which is actuated by an additional four-lobe camshaft within its design.
This newer type was first introduced in 2009, with some major updates being made to it since then, including direct injection as well-meaning. They no longer have vaporization injectors but instead, go straight into your cylinders themselves at higher pressures via nozzles.
These new features improve performance while also cutting back emissions that do not require any conversions from car producers.
The engine’s power rating is 200 HP at 6,300 RPM and 184 lb-ft of torque at 4,250 RPM. However, later versions were rated at 185 HP at 6,000 RPM and 178 lb-ft of torque at 4,000 RPM.
Applications of Hyundai 2.4 GDI:
- 2011 – 2019 Hyundai Grandeur/Azera
- 2012 – 2020 Hyundai Santa Fe
- 2009 – 2019 Hyundai Sonata
- 2015 – 2020 Hyundai Tucson
- 2011 – 2019 Kia Cadenza
- 2016 – Present Kia KX7
- 2010 – 2019 Kia Optima
- 2010 – 2021 Kia Sportage
- 2014 – 2020 Kia Sorento
2.4 MPI (G4KE)
The G4KE engine has a 10.3 compression rating and produces 177 HP at 6,000 RPM and 170 lb-ft of torque at 4,000 RPM.
Applications of 2.4 MPI (G4KE):
- 2013 – 2016 Hyundai Azera
- 2008 – 2011 Hyundai Grandeur
- 2010 – 2020 Hyundai Santa Fe
- 2007 – 2019 Hyundai Sonata
- 2010 – 2020 Hyundai Tucson
- 2009 – 2019 Hyundai Cadenza
- 2008 – 2012 Kia Forte
- 2008 – 2019 Kia Optima
- 2008 – 2013 Kia Rondo
- 2011 – 2021 Kia Sportage
- 2009 – 2020 Kia Sorento
2.4 L (G4KC)
The 2.4 G4KC engine has a compression rating of 10.5 and produces 163 HP at 5,800 RPM and 166 lb-ft of torque at 4,250 RPM.
Applications of 2.4 G4KC:
- 2005 – 2008 Hyundai Grandeur
- 2004 – 2007 Hyundai Sonata
- 2005 – 2008 Kia Optima
- 2007 – 2008 Kia Rondo
The Hyundai Theta series started as the result of the World Engine program, which is why these cars have engines that are quite similar to Mitsubishi’s 4B12 engine.
By no means are they only used in Peugeot and Citroen cars; this same 2.4l unit can also be found under the hoods on some models from other companies like Ford.
Engine Modifications, Upgrades, and Tuning
There are four variants or modification that the Hyundai 2.4 engine undergo. Well, the initial release of the 2.4 Theta engine was the G4KC. The G4KC engine has a 162 HP power output, 164 lb-ft of torque. This engine is part of the first-generation Theta engines with a compression rating of 10.5.
After the G4KC, the G4KE emerged. This engine is much powerful compared to the G4KC engine, which has a 175 HP power rating and 168 lb-ft of torque. The G4KE engine is equipped with a Dual CVVT system.
The G4KG engine is similar to the G4KE engine but sold only for the USA and Canada Markets.
Last but not least is the G4KJ engine. The engine boasts its 201 HP power rating, the most potent amongst the mentioned engine. Along with that power, the engine could produce a surmountable amount of torque at 184 lb-ft at 4,200 RPM.
The G4KJ engine is also part of the second-generation Theta engines with direct injection and an 11.3 compression rating.
Problems Surrounding Hyundai 2.4 Theta MFI/GDI Engines
Engine problems are inevitable. They can happen due to age, mileage, and maintenance habits in the long run, but no matter how excellent your engine design is, there will still be issues that arise along with it due to different timelines.
Age affects engines because they have been running for so many years, while maintaining them can cause problems too, such as wear on parts, which leads to breakdowns or even worse accidents if not maintained properly.
1. Engine Noise
The Hyundai 2.4 Theta engine has a lot of noise. Some sources include valvetrain and timing chain, but bad oil can clog the hydraulic tensioner circuit, which makes for more intense operation sounds while driving on public roads or highways with other cars passing by in traffic jams.
2. Piezo Electronic Injectors
The Hyundai 2.4 Theta engine may seem like a small machine, but it’s not without its downsides.
Oil consumption and fuel injection system problems can cause instability in operation over time as this model ages due to size constraints, requiring more expensive repairs or future replacement of parts if you don’t fill up at high-quality stations along your routes often enough.
Replacing these can be quite expensive and require specialized service to avoid problems with a modern fuel system, so simply fill up in proven places for best results.
For those who want to own a car that will never break down on them, the Hyundai 2.4 Theta engine is still worth considering – it’s been around since 2004 has proven time after again as one of Hyundai’s most reliable engines.
All production lines at an automaker may change over the years, but their proprietary technologies often go untouched by competitors because they work so well for customers’ needs.
The Hyundai 2.4 engine was built to last even decades after its production date. Although many car manufacturers have changed up how they design vehicles over time, Hyundai continues to use some models because they still provide excellent drivability and fuel efficiency.