As we recently discovered with Project R7, which concluded last month, an airbox can make a massive difference to the performance of an engine and, therefore, motorbike. On the R7, the gain was 12bhp, which made us want to delve a bit deeper into how that’s possible. Of course, in the case of the R7, the base starting point is particularly low – in so much as the standard airbox is about the size of a cigarette packet, whereas the one we fitted was significantly larger. But surely air is air, and it’s everywhere anyway, so what’s the big deal?
Over on the Isle of Man, at the exact time we were marvelling at the boost in power the R7 had just got from its posh new airbox, a certain Stuart Wood happened to walk past. He’s the head of engineering at Triumph and has forgotten more than I’ll ever know or understand about motorcycle design and physics – and he was also there on a busman’s holiday, so took very little persuading (in the form of a bottle of Batham’s beer) to sit down with me for 20 minutes and explain the dark art of airboxes, starting with some quick sums to illustrate why the R7 struggled so much with its teeny-tiny standard airbox. Ever the company man,
