If at least 50 cars had been built, sportscars like the GT40 and the Lola T70 were allowed, with a maximum of 5.0  L. John Wyer's revised 4.7-liter (bored to 4.9 liter, and O-rings cut and installed between the block and head to prevent head gasket failure, a common problem found with the 4.7 engine) Mk I won the 24 hours of Le Mans race in 1968 against the fragile smaller prototypes. This result, added to four other round wins for the GT40, gave Ford victory in the 1968 International Championship for Makes. The GT40's intended 3.0  L replacement, the Ford P68, and Mirage cars proved a dismal failure. While facing more experienced prototypes and the new yet still unreliable 4.5  L flat-12-powered Porsche 917s, Wyer's 1969 24 Hours of Le Mans winners Jacky Ickx/Jackie Oliver managed to beat the remaining 3.0-liter Porsche 908 by just a few seconds with the already outdated GT40 Mk I, in the very car that had won in 1968—the legendary GT40P/1075. Apart from brake wear in the Porsche and the decision not to change brake pads so close to the race end, the winning combination was relaxed driving by both GT40 drivers and heroic efforts at the right time by (at that time Le Mans' rookie) Ickx, who won Le Mans five more times in later years.