If it's the McLaren F1 road car then it's a 6.1 litre V12, not 1.6 litres.I can't answer your question about the fastest starter. However, at 1.6L the F1's engine displacement is less than the front two cylinders of your RB.
I saw a utube of a 20 million$ McLaren F1 firing up and the starter sounded insane, it spun that engine so fast I was jealous, I want one for my RB. What is the quickest starter out there?