The Lotus Renault 98T was designed by Gérard Ducarouge and Martin Ogilvie for the 1986 Formula 1 World Championship and driven by Brazilian Ayrton Senna, in his second year with the team, and Scottish newcomer Johnny Dumfries.
The chassis had slightly different lay-out (a lower monocoque than its predecessor due to a change in regulations requiring a reduction in fuel capacity to 195 liter). And was powered by the new Renault EF15B turbo V6 engine, connected by a six-speed manual gearbox from Hewland.
The EF15B would come in 2 forms: the standard engine and the "D.P." engine with pneumatic valve springs. At the end of the season, Renault introduced the revised EF15C. Although power figures for this period in F1 history are largely speculative, as most engine manufacturers freely admitted that their test setups would not have enough power to measure the 1.5-liter turbo's output at a boost of more than 4 bar. It was said to have produced more than 1000 horsepower during the race, and over 1250 BHP in qualifying trim at its peak with unlimited turbocharging, making it one of the most powerful engines ever used in Formula 1 history.
However, during qualifying, where teams used unlimited boost pressure for maximum power output and for very fast lap times, they were very unreliable and lasted only a few clean laps. Hence, the 98T produced about 900 horsepower in racing trim.
The gearbox was a conventional five-speed gearbox and there was a new six-speed gearbox. The six-speed gearbox was largely a development gearbox and was largely unreliable. While Senna chose to drive only with the five-speed gearbox, Dumfries had to test the six-speed gearbox. Both gearboxes had internal Hewland components in a Lotus-designed housing.
Other notable innovations of the 98T included two-stage height adjustment, water injection via the intercoolers, an early form of an inland vessel and an advanced microcomputer for fuel consumption.
The 98T was also the last Lotus to be powered by a Renault engine as Lotus switched to Honda for the following season. It was also the last car to carry the black and gold John Player Special livery as the next year title sponsor Camel came in to paint the cars completely yellow.
Senna on his way to victory in Detroit.