The main target for the development of power sport engines is
and will be in future the increase of the power-to-weight ratio.
However, the reduction of carbon dioxide emissions is getting more
and more important as future legislation and increasing customer
demands ask for lower fuel consumption. One possible technology for
CO₂ reduction which is widely used in automotive applications is
downsizing by reducing the engine capacity and increasing the
specific power by charging strategies. Focusing on power sport
applications, like motorcycles, the automotive downsizing
technologies cannot be transferred without major modifications. The
essential difference to automotive applications is the
extraordinary response behavior of today's motorcycles, as well
as the large engine speed spread. Additionally, packaging and cost
reasons exclude the direct transfer of highly complex automotive
technology, like two-stage charging, cam-phasing, etc., to
motorcycle applications.
This publication treats the conceptual design and layout of a
charged 800 cm₃ two-cylinder motorcycle engine with the demand of
excellent driveability, power and response. In detail, the paper
deals with the layout of an exhaust turbocharging system for an
inline two-cylinder engine where the achievement of an appropriate
response behavior is of particular importance. As reference for the
transient behavior a turbocharged automotive engine has been
chosen. The benchmarks for the transient behavior have been a
state-of-the-art naturally aspirated motorcycle on one hand and an
automotive TC engine on the other hand. Based on these targets, a
previously presented simulation strategy for the selection of the
different hardware components has been applied. Stationary and
transient 1DCFD simulations as well as 3D-CFD and coupled
simulations have been performed and various modifications on the
engine and the periphery have been carried out for prototyping.
