All engines were 3.0 litre, V10 configuration. Calendar Calendar changes The Portuguese Grand Prix was originally scheduled near the end of the season, to be held at the Estoril circuit on 11 October. The race was cancelled as the government refused to pay for the required safety upgrades. The cancellation left a gap of five weeks to the final race in Japan. Off-season changes At the end of , Renault withdrew as a direct engine supplier from Formula One and thus marked the first season since that Renault-branded engines were absent due to the company's privatisation plan. As a result, the two teams running Renault engines were forced to source alternative suppliers. Williams opted to run engines supplied by Mecachrome, who were working with Renault to develop the most recent iteration of their RS9 engine rebadged with the Mecachrome name. Benetton sourced a similar rebadged Renault engine from Playlife. Neither Williams nor Benetton were competitive to the same level as in previous seasons. Renault themselves would invest in Benetton for , before buying the team outright in . They would not supply engines to other competing teams again until . The Prost and Jordan teams swapped their engine suppliers from 1997: Prost now used Peugeot, whilst Jordan used Mugen-Honda. The 1998 season brought about two significant technical changes to reduce cornering speeds and aid overtaking. The first was the reduction of the cars' track, from to , making them much narrower than in 1997; a previous reduction in track occurred in , when the cars were reduced from to . The second change was the introduction of grooved tyres to replace slicks (the last time Formula One featured grooved dry tyres was in 1970): the front tyres had three grooves, with four on the rear tyres. Grooved tyres would remain in Formula One until the reintroduction of slicks in . For 1998, both McLaren and Benetton switched from Goodyear to Bridgestone tyres, as the Japanese manufacturer expanded to work with six of the eleven teams in their second year competing in the sport. This would result in the two teams who became principal championship protagonists working with different tyre manufacturers. The two top teams from 1997, Williams and Ferrari, opted to retain Goodyear tyres. As Ford-Cosworth/Zetec and Hart switched to V10 engines respectively, all Formula One entrants began using the mandated 3.0-litre V10 naturally-aspirated engines for the first time ever.