A Porsche 934 piloted by three drivers who had never won a major race won the 31st running of the 12 Hours of Sebring (Fla.). Wayne Baker, Jim Mullen and Kees Nierop scored by 1 1/2 minutes over a Porsche Turbo driven by Bob Akin, John O'Steen and Dale Whittington.

The Porsche Turbo of Al Holbert and Hurley Haywood placed third despite fighting headlight problems the last hour of this day-into-night third test on the 1983 circuit for grand touring cars.

The less powerful 934 broke a five-year string of wins by the Turbos, but this was an eighth straight Porsche victory.

Akin was sure a barrel of gasoline with water in it cost him the race. He was leading before his engine quit in the pits, costing him eight laps while a Mazda RX7 took first in the ninth hour.

The Mazda (Pete Halsmer-Rick Knoop) in turn went out with a locked left front wheel, relinquishing the lead to a Cosworth Grid (Milt Minter-Skeeter McKittrick). Then the Grid pitted with a bad rear wheel. Next on the lead was the Holbert-Hurley Turbo, only to need five unscheduled pit stops, while the Baker-Mullen-Nierop car took over with 25 minutes to go and held on despite fuel worries.

The pole-sitting Porsche Turbo of 1982 winner John Paul Jr.; Mike Andretti, son of three-time winner Mario Andretti, and Derek Bell blew an engine early . . .

On the stock car circuit, rookie Ronnie Hopkins led secondary qualifying for today's Atlanta International Raceway 500. Hopkins took 31st spot in the 41-car lineup with a 163.964-mph lap; the first 30 were set Friday, Geoff Bodine's 167.703 taking the pole . . .

On the same course, Mike Waltrip, 19, brother of Winston Cup champion Darrell Waltrip, gained his first professional racing victory. He won the Old South 150 sedan race, good for $1,275, averaging 116.419 mph.