VL Commodore SS Group A SV
The Holden VL Commodore SS Group A SV was a vehicle developed and built for Holden by TWR and the newly established Holden Special Vehicles company. Released in 1988, it was based on the Holden VL Commodore. 750 examples were built, meeting the minimum requirement of 500 units necessary to allow the model to be homologated for racing under international Group A Touring Car regulations. It replaced the existing Holden VL Commodore SS Group A (which had been developed by Peter Brock's HDT Special Vehicles company) as Holden's Group A race car.
Due to its high use of plastic in the bodykit, it was termed such things as the "Plastic Pig". Other, less derogatory nicknames included the "Walkinshaw" and the most common of all, "Walky" (after TWR's chief Tom Walkinshaw).
With the requirements of Group A regulations, Holden had to have a car capable of being competitive 'straight off the showroom floor'. Thus it needed a bodykit that would produce large amounts of downforce as well as being low drag. TWR developed the famous Walkinshaw bodykit that was stated to reduce drag by more than 25% over the previous Holden Dealer Team (HDT) Group A.
Some people however, say that the bodykit is a direct cause of the so called 'brick wall effect' at about 250–260 km/h.
The engine in the Group A SV, although rated at 5 litres and 180 kW (241 hp), was specially made to withstand racing conditions. The block was specially cast and crankcase was fitted with 4 bolt main bearing caps. The heads were revised with high-flow intake ports and roller rockers.
Special connecting rods, crankshafts, and pistons were fitted as well as a custom exhaust, however the big news was the now fabled Walkinshaw twin throttle body inlet manifold. This was specially developed for the group A, featuring a sequental setup with a smaller and larger throttle body. This was fitted with a restrictor plate on the larger, secondary throttle body, which actually let less air through than the smaller throttle body. Some reports have indicated that as much as 50-60 horsepower can be gained from the removal of the restrictor plates.
The Group A SV was made as a limited run of 500 from March 1988 to November the same year, but HSV decided to make 250 more due to demand. These were slow to sell, some examples only being sold several years after the VL ceased production, and some were modified in appearance by the dealers in an effort to get them out of the show rooms.