RallySport Magazine October 2016

LOOKING AHEAD: 2017 WRC
CITROEN EXPLAINS
2017 ENGINES
The FIA has issued an interesting
interview with Patrice Davesne,
Engine Manager at Citroën Racing,
in which a team talks for the first
time about their work developing their
engines for the new style WRC regulations.
“Concerning the FIA rules, the sole
difference is the inlet turbo restrictor.
It was 33mm and it becomes 36mm,
which means about 20% air flow
increase,” Davesne explains.
“In consequence we need to
change the turbocharger because the
compressor side is not large enough
and we need to develop a new one to
adapt to this new flow.
44 | RALLYSPORT MAGAZINE - OCTOBER 2016
“We have developed a fully new
engine. We decided to change the bore,
it was 82mm since the beginning of
our time in WRC and now we decide
to increase the bore diameter, and we
are now at the limit allowed by the FIA,
which is 84mm.
“Also, due to the increase of the flow
and the diameter of the restrictor,
we need to manage very carefully
the ‘knock’ and we need to develop a
completely new system. It takes a lot
of work on the dyno, it was a very large
job and we have arrived to a good
system that avoids any overcharge of
combustion pressure, and that’s very
important for durability of the engine.
“We also developed some internal
system to reduce friction and of course
to increase global efficiency of the
engine. We are very lucky to have great
experience in WRC events, so for each
problem we have met in the past we
have developed a process and adapted
our dyno to solve these.
“So now when we develop a new
engine we have many, many processes
that we use on the dyno to avoid any
problem we have already met in the
past.
“Also, we are lucky to have a very
good dyno that is able to simulate
conditions; we can run on the dyno a
stage anywhere in the world, except