Hyundai-KIA G4JS 2.4 engine

The 2.4-liter Hyundai G4JS engine was assembled at the plant in South Korea from 1998 to 2007 under license from Mitsubishi, as it was only a modification of the 16-valve version of the 4G64 motor. In our country, this motor of the Sirius II series is known from the Sorento SUV, as well as Santa Fe.

Characteristics of Hyundai G4JS engine

Cars with G4JS engine

Service Regulations

Oil service

• Periodicity: every 10,000 km.
• Oil volume in the system: 4.5 liters.
• Needed for replacement: about 4.0 liters.
• Recommended oil: 5W-30 or 5W-40.

Gas distribution system

1. Type of timing drive: belt drive.
2. Declared timing belt life: 60,000 km.
3. In practice: it is better to change every 50 000 km.
4. Consequences of belt breakage: bends valves.
5. Adjustment of thermal valve clearances: not required (hydrocompensators are used).

Change of consumables

* Platinum electrode spark plugs are replaced every 60,000 km.

G4JS engine construction and repair

In 2000, Hyundai began producing a 2.4-liter variant of the Sirius 2 family, which replaced the first Sirius – G4CS. This motor, like its predecessor, is a copy of the Japanese 4G64, but now a 7-bolt motor. Let’s look at the differences between G4JS and G4CS.

Here is a tall cylinder block (height 235 mm), almost the same as in the CS, inside which there is an updated crankshaft, while the stroke of the piston remained at the same level – 100 mm. The connecting rods are not as strong, but lightweight, and their length is unchanged – 150 mm. Pistons with piston pins are also different, the piston pin has become 22 mm. Pistons are even different from 4G64. The working volume remained the same – 2.4 liters.

On such a low was installed 16-valve twin-shaft DOHC head with hydrocompensators, which did its job and improved the characteristics of the engine. Shafts spin the timing belt, which does not hurt to change every 60 thousand kilometers, because it can break and bend the valves. The drive itself is somewhat different from the Japanese 4G64, as well as materials and quality of manufacturing of all the internal parts of the cylinder-head.

This engine is a part of the Sirius II family, which means that it has two related models: 1.8 liters. G4JN and 2.0-liter G4JP.

In 2005, the engine was discontinued, and its place was taken by the newer G4KC from the Theta series.

Problems and disadvantages of Hyundai G4JS engines

Balancer shaft belt

This engine is sensitive to oil quality and adherence to change intervals. If lubricants are skimped or of poor quality, the balancer shaft bearings may seize and the balancer belt may break. This can lead to serious consequences: the balancer belt gets caught under the timing belt, which usually ends in valve bending and damage to the cylinder head.

Motor Vibrations

On profile forums, complaints about engine vibrations are often mentioned. This can be due to both the wear of the balancer shafts, and the poor condition of the engine supports.

Knocking of hydrocompensators

G4JS hydrocompensators are sensitive to oil quality. If unsuitable lubricant is used or the oil is not changed in time, they can start knocking already at a mileage of about 50,000 km.

Thermostat on Kia Sorento

On the Kia Sorento, the engine is mounted longitudinally and the thermostat is in an awkward location. This can cause the cooling system to malfunction.

Other problems

• Frequent oil leaks.
• Swimming idle speed (contamination of the idle speed regulator – idle speed control valve).
• Electrical faults, especially the DPKV, DPRV and ignition skip sensors.
• On high mileage, piston ring seizure and increased oil consumption.

G4JS engine tuning

Atmo

Do not spend money and time on atmo tuning – the result will be quite mediocre, and the costs are very significant. Nevertheless, if the desire to keep away fails, then put it:

1. tuning shafts from Evolution,
2. a tuning intake manifold.
3. Standard choke from the 4G63T
4. 4-2-1 exhaust
5. straight exhaust
6. tune the control box.

This will raise the power and satisfy the desire to dig into the engine. It is not rational to invest a lot of money and build an evil atmosfernik 200++ forces, it will be much more effective to switch to a turbo.

Turbo

You have a good block, good head (blow-by is better than Evo head), but you don’t have a turbo, so you need to get one. You’ll need an Evo turbo (preferably from an Evo 9) with manifold and intercooler and make an oil feed to the turbo and oil drain. But that’s not all, here are some more tuning parts for 400hp:

• the entire intake is from the Evo
• camshafts from the Evo, keep the sprockets.
• don’t forget to add a larger fuel rail with 630-650 or even 750 cc injectors
• Walbro 255 gasoline pump
• Exhaust on 76mm pipe

Leave the timing drive and assemble all this, after tuning you will get about 400hp. Standard connecting rods will be at the limit, and pistons are better to replace forged to reduce the compression ratio to 8.5. It is desirable to buy good connecting rods and not to worry about it.

For 500 hp you need to change the turbo to FP Green and put similar things:

1. 3“ intercooler and 3” piping
2. enlarged radiator
3. tuned intake manifold
4. Kelford 272 camshafts + cut gears + valve springs + valve plates
5. fuel rail with injectors ~1000cc
6. gasoline pump Walbro 340.

After assembly and tuning it will be possible to remove in the neighborhood of 500 hp.

Next you need to port the head, put large valves, bronze guides and so on. You can put a crankshaft from 4G63T and connecting rods 156 mm (or 162 mm + pistons of lower height), which will allow you to crank the motor to higher revs, while the volume will be reduced to 2.1 liters.

There are options in the opposite direction: 102 mm/106 mm crankshaft + 150 mm connecting rods + lower height pistons, which will give a volume of 2.5 liters.

You can do anything you want with these motors, just like a regular 4G63.

MOTOR RATING: 4+