Audi’s new turbodiesel is an all-round improvement on the R10
The new Audi has a longer wheelbase and its front-to-rear weight balance is much more equal than the tail-heavy R10. At 5.5 litres the R15’s turbocharged V10 is the same displacement as the V12. Like the R10, it’s an all-aluminum, four-valve, DOHC engine with twin Garrett turbochargers. This year’s ACO rules require a 2mm smaller air inlet at 37.9mm and less turbo boost (2.75 rather than 2.94 bar), reducing power from more than 650bhp to around 600. Torque is down from roughly 750lb ft to about 700. The engine uses a pair of new-generation lightweight Dow diesel particle filters.
New rules this year have reduced rear wing width by 40cm and Audi has adopted a topside-mounted ‘quiller’-type wing similar to that on this year’s Acura ARX-02a P1 car. The R15’s aerodynamic package is entirely different to the R10, with much more air channelled through rather than over the bodywork.
The R15 employs a new five-speed gearbox built in partnership with X-trac. It is equipped with new LED low-beam headlights and a lightweight lithium-ion battery, and runs on Michelin radial tyres on 18in OZ wheels front and rear. Fuel from Shell, 81 litres capacity. Weight 900kg.