Kia Motors UK has turned a Stinger GT S pre-production homologation car into a “track day monster” called the Stinger GT420.
The name is a reference to the model’s power, which has been increased from 365 hp (370 PS) in the standard car to 422 hp (428 PS). The peak torque delivered by the 3.3-liter twin-turbo V6 engine has also been raised from 510 Nm (376 lb-ft) to 560 Nm (413 lb-ft).
So how did it come to this? Well, it was Kia UK’s way of saving a pre-production homologation car that otherwise would have had to be crushed. It was the car used for final testing and tuning in the UK, as well as a press car that appeared in many UK car magazines and TV shows such as Top Gear and The Grand Tour.
Impressed by the car’s pedigree and the fact that it had clocked up an impressive (for a homologation vehicle) 10,000 miles (16,093 km), Kia UK decided to turn it into a track car.
With support from the Hyundai Motor Europe Technical Centre in Rüsselsheim, Germany, the team got to work on the Stinger420. The list of engine modifications is very long and includes HKS M45il spark plugs for enhanced combustion, a K&N sports air filter, and a lightweight Milltek Sport quad-exit exhaust system with catalysts deleted.
The automatic transmission was also upgraded with a six-row cooler in place of a four-row item to prevent overheating on the track. Additionally, the gearbox software was recalibrated to provide quicker shifting characteristic in Sport and Sport+ modes.
To successfully turn the road-going Stinger into a track car, the team also removed all unnecessary weight, including the seats and belts, airbags, sound system, interior trim, and rear window regulators. The engine cover, undercovers, parking sensors, boot and bonnet dampers, and rear bumper beam and foam were also taken out.
Furthermore, the rear windows were glued into place and lightweight door cards were installed. Finally, the sunroof was removed and replaced by a steel panel. In total, engineers were able to cut 150 kg (331 lbs) of weight even after the installation of the roll cage, Sparco race seats, belts, fire extinguisher, and underbody stiffening.
To improve track performance, Kia UK also fitted Eibach Pro lowering springs and anti-roll bars, wider OZ Racing Leggera rims shod with Pirelli Trofeo R tires (235/35/R19 at the front and 265/30/R19 at the rear), and uprated Brembo front brakes, among other upgrades.
Rounding off the changes are some visual tweaks that include a Stillen front splitter and rear diffuser, a rear spoiler by Air Design, and an eye-catching wrap.