DRAWING INSPIRATION FROM LAST YEAR’S WINNING DESIGN
As shown above, Honda is using a log manifold in order to collect burnt gasses, but has switched to multi tube exhausts in Austin. Such design was a distinctive feature on last year’s Mercedes PU106A before the world champions elected to replace it with more conventional exhaust manifolds.
The log-style exhaust is quite short, which helps prevent exhaust gasses from losing too much pressure on exit. This also means that more energy is consequently channelled towards the turbine, and then recovered by the MGU-H. However, engineers have to keep an eye for any potential collisions between the different gas molecules, which in turn might create turbulences. Last but not least, the compactness of the log manifold package shows great reliability while also giving more freedom to aerodynamicists.
Why did Mercedes elect to ditch it for 2015 then? Probably because a longer, more conventional design also has its own advantages, like offering more leeway to regulate exhaust gasses across all RPMs.
Manifolds are made of very thin metal sheets, which leads Honda and rival engine manufacturers to wrap up the exhaust pipes in some sort of insulating blanket in order to limit heat loss and foster gas expansion. On the image above, the log manifold can be seen without its thermal insulation cover.
