ACO Regs. – Diesels Stay At The Same Power
But 10% Smaller Fuel Tanks
Smaller Restrictors For LMP2s And GTs
ago, the ACO stated that “concerning the equivalence between
a petrol engine and a diesel engine, the first analyses show an
advantage for the diesel engine….regarding lap time, there
is a difference of about 3.2 seconds in comparison with the highest-performing
petrol-run car. However, when considering this difference, we must
take into account the improvements in performance which are linked
to the chassis, the suspension, the aerodynamics, and of course
to the engine.”
It also stated
then (July 13) that “concerning consumption: the tank capacity
will have to be adjusted in such a way that the cars receive the
same quantity of energy at each refuelling stop. This will mean
a smaller tank for those cars which are equipped with a diesel engine.”
the most significant feature of its 2007 regulation adjustments:
diesel-engined cars will compete with a tank 10% smaller than petrol-engined
rivals – so 81 litres.
logically the ACO is expecting petrol-powered cars, to the latest
chassis regulations, to make up that 3.2 seconds deficit. The only
genuine 2006 LMP1 cars at Le Mans this year were the Courage LC70s,
the Lola B06/10 and the Audis – and neither of the new cars
were as fast as the Pescarolo hybrids.
regulations are framed in such a way as to encourage manufacturers
to take up new challenges,” says ACO president Mr. Jean-Claude
Plassart. “We are delighted with the recent initiative of
two major manufacturers, which have accepted the challenge to race
at Le Mans with a clean diesel engine. AUDI was the first to go
for this technological gamble and so became the first manufacturer
to win the race with diesel power in this year's Le Mans 24 Hours."
Audi and Peugeot
representatives met with the ACO last week.
"When the A.C.O threw down the gauntlet with this diesel challenge
the A.C.O. made it quite clear that it would keep a close eye on
the equivalence between diesel and petrol-engined cars," the
president continues. "Thus, we have been working in close collaboration
with the manufacturers, the petrol companies and major independent
engineers. From these studies and on-going analyses with very sophisticated
simulation models and computer programmes we came to the conclusion
that corrections had to be made but with considerable caution, all
the more so as those in the running for victory were separated by
"First of all, for 2007 we've decided to work on adjusting
the quantity of energy supplied. It's a painstaking job which is
of the utmost importance as we're sure that in the future manufacturers
are going to come along with new technological innovations and above
all with questions linked to different forms of energy."
Aiming to keep suitable lap time differences between the classes,
the ACO as come up with the following for next year (below –
official ACO text). NB. There’s no mention
of performance adjustments during the season – and there is
also an implication that the rule changes apply to the ALMS, as
well as Le Mans and the Le Mans Series. IMSA has made it clear that
it will review performance twice next year, probably at the one-third
and two-thirds points of the season (after four and eight races).
IMSA has adjusted the ACO rules in several respects this year, and
seems likely to do the same again in 2007.
LM P1: Concerning the adjustments to be made to
performances between petrol and diesel-engined cars, the advantages
and disadvantages linked to the use of different types of engines
must be taken into account. After making this clear the A.C.O considers
that for 2007 in the light of the results achieved this year the
size of the air restrictors, the supercharger pressures and the
weight of all the LM P1s should remain identical to those of the
2006 season. The gap between the quantity of energy in a litre of
diesel and a litre petrol being 10% the capacity of the diesel-engined
cars' fuel tanks will be reduced by this amount to 81 litres.
LM P2: The performances of some of the LM P2 cars
are very close to and indeed sometimes even better than the LM P1s
on certain circuits so a reduction is necessary. The air restrictors
will be 5% smaller. In addition, a gap of 1.5% between the best
LM P1 and LM P2 laps times must be respected. If the gap is under
this figure the A.C.O will take steps to re-establish it at the
end of the year.
LM GT1: Given that the performance and top speed
of these cars are constantly increasing approaching those of the
LM P2s, their air restrictors will be reduced by 5%. As the capacity
of the fuel tanks has to be adjusted according to the type of energy
used (petrol or ethanol; see 'fuels' below), the amount of fuel
on board the car must not exceed 90 litres.
GT2: To maintain a reasonable gap to the GT1s the air restrictors
will also be reduced by 5%. As the capacity of the fuel tanks has
to be adjusted according to the type of energy used (petrol or ethanol;
see 'fuels' below), the amount of fuel on board the car must not
exceed 90 litres.
FUEL: In 2007, the ACO will supply only one kind
of petrol and one kind of diesel for the Le Mans 24 Hours and the
Le Mans Series events. To meet the requests of several entrants
who want to use bio fuels, the ACO is currently evaluating the possibility
of supplying a type of diesel and petrol in 2008 that contain a
certain quantity of bio fuel. These fuels will be compatible with
current engines. However, the ACO agrees that the American Le Mans
Series supply a third kind of fuel based on ethanol for its events
in 2007. The capacity of the fuel tanks will be adjusted in such
a way that the quantity of energy will be the same whether it is
petrol or diesel. For safety reasons the capacity of the fuel tank
cannot exceed 110 litres.