McLaren has confirmed a GT4 race version of its Artura road car for 2023. The Artura is a hybrid with a 3.0 litre V6 turbo. Its hybrid element is not permitted for GT4 racing, saving 130 kg, while the engine will have to be detuned from its 577 bhp road guise. This racecar will replace the 570S GT4, which uses the long established M838T 3.8 litre V8 twin turbo detuned by regulation to the region of 450 bhp.
The Artura V6 is the first new McLaren engine since the M838T, which also powers the marque’s current GT3 cars. The M838T was designed in 2010 and was co-developed with Ricardo, which manufactures it in a purpose-designed factory. Ricardo now likewise manufactures the V6 turbo on behalf of McLaren Cars.
Unusually this V6 has a 120 degree bank angle. That means that opposing cylinders can share crankpins without the crankpin offset characteristic of a 90 degree V6. Another popular configuration is a 60 degree V6 but the 120 degree bank angle helps substantially to reduce centre of gravity height.
In road car terms a wide angle V6 is impractical for a front-engined vehicle but all McLaren Cars’ productions are mid-engined. The 120 degree bank angle facilitates a ‘hot side inside’ arrangement with the turbochargers located within the vee and inward facing exhaust ports implying short feed pipes that assist response.
A drawback of the 120 degree angle is the primary imbalance created by the two I3 banks that constitute this even-firing V6. To counter it McLaren sets a geared balancing shaft along the centre of the vee. Interestingly the road car has an eight speed gearbox with reverse provided by the hybrid system; with that system removed the race car has a seven speed plus reverse gearbox.