For that matter, during the glory years of IMSA, John Bishop spent the majority of his time changing rules to try to get ANYONE else to win a race! It seemed like every two weeks he was changing anither rule to favor John Greenwood's Corvettes, to little avail, anywhere except Daytona.
Then, low and behold, Porsche found that little exhaust driven air pump loophole and came out with the 934/935 and the Corvettes could no longer win at Daytona, either.
If I remember correctly, the final phase was in the GTP class, restricting Porsche to one small turbo and letting everyone else run twin 454's!!!
I think that year, 962's were beaten twice!!
I can remember going to IMSA races in the mid seventies that would have 40 to 45 3 Liter Carerras, with Gregg/Haywood and Holbert and Penske leading the fields. It was the best racing I ever witnessed, week after week, but for some reason it had to be ruined so someone beside Porsche could win. After they destroyed it, every racing body has since tried to come up with a "spec class" to equal that level of driver competition.