The whole thing is really fixed. When they showed up for practice, at LeMans, the Corvettes were 1.5 seconds a lap faster. The FIA slapped a 'performance adjustment' on them, which increased the size of the restrictor--on the Chevy V8's--by 2 mm. But Chevy didn't HAVE any 2 mm smaller restrictors, so had to run 3 mm smaller restrictors. And, as it turns out, the Fords and Ferraris were 'sandbagging' in practice. They were much faster than they showed. In qualifying, the Fords were something like 4.5 seconds a lap FASTER than the Corvettes.......and the FIA made no more changes. Soooooo, I think the Corvettes finished something like 10th in class, when they would have won, if things had stood when practice started. I guess the FIA decided it would be 'more exciting' for Ford to win on the 50th anniversary of their first. Of course, the Fords still have to prove their reliability, which they did. The other interesting thing is that the Chevy V8's are limited to 5.5 liters, from the stock 6.2. Horsepower, consequently, is 'only' about 500, when a stock Corvette Z06 makes 650. But the race engine is naturally aspirated.