Two track racers, one of them a Production Car champion, were killed in racing incidents over the weekend.Multiple South African National champion Curt Alchin died after a tragic accident at the Victory Raceway in Port Elizabeth on Saturday night. He was 44 and was apparently driving a borrowed V8 Stock Car because the water pump on his own racer had packed up.He tried to get a replacement part and approached former racer Terry Moss for help. Moss couldn't supply and told Alchin: "Hey, maybe you are not meant to race - stay home!"The borrowed car, it's throttle apparently stuck, glanced off another car and hit the track wall at high speed. Alchin - a driver well respected and liked among the racing fraternity - is said to have died instantly when hit by the steering-wheel and sustaining severe neck injuries.The vehicle Alchin was driving was owned by a friend, Johnny Weitz, who was driving in the same race. A member of Weitz's team, Andre Kriek, said his boss had to be treated in hospital for shock. NATIONAL COLOURSAlchin's SA National championship titles include 1995 Production Car champion, 1999 Modified Saloons champion, 2002 Standard 1600 Saloons champion, 2005 Modified Saloons Dirt champion and 2006 Modified Saloons 1600 Tar champion. He was awarded National colours in 2004 for his success in international oval-track racing and raced in the Engen VW Cup championship in 2011.On Sunday a motorcycle club competitor died during the Day of Champions event at the Zwartkops Raceway near Pretoria. Wim Pretorius, 37, who started racing in 2009, went off at Turn 5 during the Thunderbikes race. He won the Thunderbike B Class Club championship in 2011 after showing huge improvements.In 2009 he did only eight of 22 races for the year but finished ninth in the total points. In 2010 he did four races from which he took two wins and two seconds.Reports say the rider went straight on at high speed, making no attempt to take the bend. There was speculation that he had a heart attack or other sudden disabling physical event just before he crashed.