[Rollins]

You have a 944 S? They have a timing chain actually. If the belt went you are looking at probably $1500 in repairs. Maybe more. The whole head has to be removed remachined, and of course the new valves. At 40 mph you could have smashed all of them. My VW's timing belt went on me, when it happened I was at an idle and I didn't hear anything. I was just sitting there and the car died. Luckily for me only one exhaust valve got bent. Anyway, based on what you said I would say it is the timing chain...sorry...
-Tim