MotoMatters.com is delighted to feature the work of iconic MotoGP writer Mat Oxley. Oxley is a former racer, TT winner and highly respected author of biographies of world champions Mick Doohan and Valentino Rossi, and currently writes for Motor Sport Magazine, where he is MotoGP correspondent. We are featuring sections from Oxley's blogs, which are posted in full on the Motor Sport Magazine website.
How MotoGP engine-braking control works
High-performance MotoGP engines create a lot of negative torque on the overrun. It is the EBC’s job to control how much gets to the rear wheel
If you’ve been into MotoGP since the early days of 990cc four-strokes you will surely remember watching in delight as a rider braked hard with the rear wheel slewing this way and that, before flopping the bike into a corner.
These were the infant days of engine-braking control (EBC), when the hardware and software weren’t clever enough to reduce negative torque on the overrun, so the engine locked the rear wheel. The riders were left to cope with the consequences as best they could.
Over the next few years engine-braking control software improved dramatically, because generally the fastest way into a corner isn’t sideways, with the rear tyre hopping left and right – even if it looks great. All riders need some engine-braking to help them slow for a corner, but exactly how much depends on individual technique. Jorge Lorenzo likes to enter corners with both wheels perfectly in line, although someone like Marc Marquez prefers the rear wheel skewed just an inch or so out of line to aid turn-in. None of them want too much engine-braking for their riding style.
Engine-braking control works by starving cylinders of fuel and playing with the throttle butterflies to provide just the right amount of negative torque, according to each rider’s needs. In the pre-unified software era the software was very trick, allowing management of individual throttle butterflies, but Dorna’s Magneti Marelli unified software is much more basic.
The toughest era for engine-braking control was a few years ago, when MotoGP regulations reduced fuel capacity to a ridiculously mean 20 litres. Engineers had to save fuel wherever they could to finish the race without having to reduce horsepower, so the obvious place to save fuel was during corner entry.
Read the rest of Mat Oxley's blog on the Motor Sport Magazine website.