Hyundai Theta engine

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θ engine
Hyundai Motor Company logo.svg      Theta engine
Hyundai Sonata 003.JPG
ManufacturerHyundai Motor Company
Displacement122 cu in (1,998 cc)
144 cu in (2,359 cc)
Cylinder bore86 mm (3.4 in) (2.0L)
88 mm (3.5 in) (2.4L)
Piston stroke86 mm (3.4 in) (2.0L)
97 mm (3.8 in) (2.4L)
Block materialAluminium
Head materialAluminium
Compression ratio10.5:1 (2.0 L)
10.3:1 (2.4 L)
Fuel systemMPI
ManagementEMS-II from Siemens VDO
Fuel typeUnleaded gasoline
Oil systemPressure feed
Cooling systemWatercooled
Power output107 kW (143 hp) at 6000 rpm (2.0 L)
121 kW (162 hp) at 5800 rpm (2.4 L)
Torque output190 N⋅m (140 lb⋅ft) at 4000 rpm (2.0 L)
222 N⋅m (164 lb⋅ft) at 4250 rpm (2.4L)
Dry weight134 kg (295 lb) (2.0L)

The Hyundai Theta is a gasoline four-cylinder automobile engine family. The third all-aluminum engine of Hyundai Motor Company debuted in the fourth-generation Hyundai Sonata sedan (codenamed NF), which was unveiled in August 2004[citation needed] in South Korea. Hyundai Motor Manufacturing Alabama (HMMA) built a Theta II engine shop on the grounds of their Montgomery, Alabama automobile factory.

Global Engine Alliance[edit]

The Global Engine Alliance was a joint venture between Chrysler, Mitsubishi Motors, and the Hyundai Motor Company for developing a line of shared 4-cylinder engines. The initial design of the engine block and cylinder head was handled by Hyundai. However, each manufacturer configured their variants of the initial design differently based on their needs. In 2009, Chrysler bought out Mitsubishi and Hyundai's stake in the joint-venture; however, each company retained rights to build the engines.

Technical details[edit]


The first version of the Theta Engine had two variants, the 2.0L and the 2.4L.

2.0L (G4KA)

The 2.0L version is an inline 4-cylinder engine that carries a bore and stroke of 86 mm and a 10.5:1 compression ratio; the engine makes 143 hp (107 kW; 145 PS) at 6,000 rpm and 140 lb⋅ft (190 N⋅m) of torque at 4,000 rpm. It uses a timing chain instead of belt, and the engine dry weight is 134 kg (295 lb).

2.4L (G4KC)

The 2.4L version is an inline 4-cylinder engine that carries a bore of 88.0 mm, stroke of 97.0 mm and a 11.3:1 compression ratio; the engine makes 162 hp (121 kW; 164 PS) at 5,800 rpm and 164 lb⋅ft (222 N⋅m) of torque at 4,250 rpm.[1]

Theta II[edit]

The second generation Theta engine comes in two sizes, the 2.0L (G4KD) and 2.4L (G4KE)

The engine features hollow stainless-steel dual overhead camshafts (DOHC) with powder-metal cam lobes, pent-roof combustion chambers and shimless bucket tappets in the cylinder head. BorgWarner Morse TEC supplies the complete timing system which uses the company's proprietary silent timing chains. Continuously variable valve timing (CVVT) works on the intake side.

The aluminum alloy engine block, which is formed using a high-pressure die-cast method, has a unique Metaldyne-supplied cassette-type balance shaft module with a two-stage oil pump built-in. In the lower-end, the block is reinforced by a ladder frame. Other notable features include fracture-split sinter-forged connecting rods manufactured by Sinteron and a stainless-steel exhaust manifold.

Theta's EMS (engine management system) software is EMS-II from Siemens VDO and the 32-bit PCM (Powertrain Control Module) calculates the amount of intake air by utilizing a contamination-proof hot-film type MAF (mass air flow) sensor.

The MPI version of the 2.0L Theta engine has a 10.5:1 compression ratio, and it produces 163 hp (122 kW; 165 PS) at 6,200 rpm and 146 lb⋅ft (198 N⋅m) of torque at 4,600 rpm and is available in the Middle East.

The MPI version of the 2.4L Theta engine has a 10.3:1 compression ratio, and it produces 176 hp (131 kW; 178 PS) at 6,000 rpm and 168 lb⋅ft (228 N⋅m) of torque at 4,000 rpm and is available in the Middle East and Europe.

Theta II Turbo[edit]

The Theta engine is turbocharged and was used in the Sonata, Genesis Coupe, i30N and the Genesis G70. The turbo used is a Mitsubishi TD04 model.

The 2.0L MPI turbo in the 2009-2012 Genesis coupe turbo, it produced 210 hp (213 PS) @ 6,000 rpm on 87 octane (AKI) gasoline, and 223 hp (226 PS) on 93 AKI. Torque remains the same at 223 lb⋅ft (302 N⋅m) @ 2000 rpm. In the 2013-2014 model,the engines got upgraded, the new 2.0T now produces 274 hp (204 kW; 278 PS) and 275 lb·ft (373 N·m) torque due to a bigger turbo. The Theta block used is very similar to the Mitsubishi Evolution X 4B11T, as core components like pistons and rods are said to move freely between them,[2] however, the two engines are not identical. The 4B11T is a semi-closed deck block with larger oil and coolant passages, where as the Theta is an open deck block.

The 2.0L GDI turbo in (2011-2014 Sonata) develops 274 hp (278 PS) and 269 lb⋅ft (365 N⋅m) of torque. The fuel economy is rated at 22mpg (10.7L / 100KM) in the city and 34mpg (6.92L / 100KM) on the highway. It comes exclusively with a 6-speed automatic transmission.

The 2.0L GDI turbo in 2019 Hyundai Veloster N and i30 N develops 271 hp (275 PS) and 260 lb⋅ft (353 N⋅m) of torque. The fuel economy is rated at 22 mpg (10.7L / 100KM) in the city and 28 mpg (8.4L / 100KM) on the highway. It comes exclusively with a 6-speed manual transmission.

The 2.0L GDI turbo in the Genesis G70 and Kia Stinger develops 255 hp (259 PS) and 260 lb⋅ft (353 N⋅m) of torque. The fuel economy is rated at 22 mpg (10.7L / 100KM) in the city and 30 mpg (7.84L / 100KM) on the highway. It comes with a 6-speed manual transmission in the entry level "Sport" trim, while all other trims come with a 8-speed automatic transmission.


Theta/Theta-II (2.0L)[edit]

2.0L DOHC engine in a Kia (G4KD)

(G4KA, G4KD)

Theta/Theta-II (2.4L)[edit]

(G4KC, G4KE, G4KG, G4KJ)

Theta-II 2.0 Turbo (2.0T)[edit]

2011 Hyundai Sonata Limited 2.0T, turbo GDI engine

(G4KF, G4KH, G4KL)

Engine recall[edit]

Hyundai and Kia vehicles equipped with Theta II engines were recalled, due to the fact that those engines were, and continue to be, the subject of an investigation by the National Highway Traffic Safety Administration (NHTSA). Safety regulators are investigating if Hyundai and Kia did enough in a timely manner with regards to the recalls of nearly 1.7 million vehicles with Theta engines, which were prone to an abnormal amount of noise and seizing.

In September 2015, Hyundai recalled about 470,000 model year 2011-2012 Sonatas equipped with 2-liter and 2.4-liter Theta II engines. At the time, Hyundai told NHTSA that manufacturing problems left metallic debris around the engine crankshaft, causing problems with oil flow. The pieces of metal interfere with the oil flow through the connecting rod bearings and damage the connecting rods. The automaker blamed the problem on a mechanical "deburring" process used to remove metallic machining debris from the crankshaft.[3]

By April 2017, Hyundai expanded the 2015 recall by including another 572,000 vehicles with Theta II engines, including 2013-2014 Hyundai Sonata and Santa Fe Sport vehicles.[4] Hyundai told safety regulators the same metal debris problem caused the expanded recall. Near that same time, Kia told NHTSA about a recall of more than 618,000 model year 2011-2014 Kia Optima, 2012-2014 Sorento and 2011-2013 Sportage vehicles because the Theta engine bearings wore out too early and caused the engines to seize.[5] Kia said it didn't recall the vehicles in 2015 when Hyundai first recalled its cars because the Theta II engines in the Kia vehicles were built on a different production line and had different problems than Hyundai. In addition to customers complaining about the Theta II engines, a Korean whistleblower who worked for Hyundai as an engineer let NHTSA know what he knew.

Owners started suing after the automaker refused to pay the thousands of dollars to repair or replace the engines, with one lawsuit from 2015 alleging a dealer wanted $4,500 to do the work. Kia was also served papers over a class-action lawsuit in 2016 filed by owners of vehicles equipped with Theta engines. NHTSA says it took action to "investigate both the timeliness and scope of Hyundai's Theta II engine recalls, and Hyundai's compliance with reporting requirements."[6]

In Canada in 2019 Hyundai announced a recall for most vehicles using the affected engines[7], however a class action lawsuit was filed in 2018 as a result of failures of this engine used in Canadian Forte models and lack of manufacturer support against Hyundai Canada.[citation needed]

Based on information from Hyundai Motor company (korea), this recall Not applicable in ASIA PACIFIC market.

Crate engines[edit]

On 2013-11-05, Hyundai announced the creation of a new factory crate engine program at the 2013 SEMA Show in Las Vegas, which initially included a 2.0-liter, turbocharged four-cylinder engine. The crate engine program began in December 2013.[8]

See also[edit]


  1. ^ "Archived copy". Archived from the original on 2014-11-08. Retrieved 2014-02-06.CS1 maint: archived copy as title (link)
  2. ^ Aaron Robinson. "2010 Hyundai Genesis Coupe 2.0T Turbo". Car and Driver (May 2009).
  3. ^ "Part 573 Safety Recall Report 15V-568" (PDF). September 10, 2015. Retrieved March 5, 2020.
  4. ^ "Part 573 Safety Recall Report 17V-226" (PDF). March 31, 2017. Retrieved March 5, 2020.
  5. ^ "Part 573 Safety Recall Report 17V-224" (PDF). March 31, 2017. Retrieved March 5, 2020.
  6. ^ "Hyundai and Kia Theta II Engine Recalls Investigated". Retrieved 2018-07-17.
  7. ^ "Automobile Protection Association | Two major recalls and a warranty extension from Hyundai and Kia Canada". Retrieved 2019-12-11.
  8. ^ Hyundai launches crate engine program with 2.0L four and 3.8L V6

External links[edit]