Renault Sport F1 deputy managing director, Rob White, sums up engine mapping and the latest developments.
Technical
Feature: Explaining engine torque maps
Renault Sport F1
deputy managing director, Rob White, sums up engine mapping and the latest
developments.
What is a driver torque map?
The driver torque map represents the torque requested by the driver as a
function of engine speed and accelerator pedal position.
What is an engine torque map?
The engine torque map represents the torque delivered by the engine as a
function of engine speed and engine throttle position. In the SECU the
engine torque map is used to position the engine throttles to match the
drivers’ torque demand.
Are there any regulations that govern how you may control engine torque?
Yes; this is covered by Articles 5.5 and 5.6 of the technical regulations.
The main points are:
Except for some specific exceptions, the engine torque must be controlled by
the driver. These exceptions include: downshifts, pit lane speed limiter,
anti-stall function and the end of straight limiter strategy. Note that this
list is not exhaustive.
The driver may only control the torque by means of a single accelerator
pedal.
At zero per cent pedal (off throttle), the torque demand must be less than
or equal to zero; at one hundred per cent pedal (full throttle), the torque
demand must match or exceed the maximum torque output of the engine in its
current state (Article 5.5.3).
There are limits on the shape of the torque demand as a function of pedal
position and engine speed (to prevent engine characteristics that could be
driver aids).
Respecting these restrictions, the torque demand is shaped against throttle
position and engine speed to deliver the desired response for the driver and
car.
Can maps change from race to race?
Yes. Driver pedal maps can change as a function of the circuit
characteristics. For example, drivers might want more precision during
initial pedal application at Monaco. Similarly, some drivers insist on a wet
weather pedal map.
The engine torque maps are also adjusted to take account of the engine’s
power output according to the ambient conditions. The engines will all
produce more torque on a cold day at Silverstone than at Interlagos (low
pressure) or Malaysia (high specific humidity). This ensures that the
drivers feel the same engine response at part load, regardless of weather.
Torque maps may also change as a consequence of changes to exhausts or air
inlet (if teams introduce a new exhaust design or new air box).
This week’s new technical directive from the FIA requires us to submit
reference map from one of the first four races of 2012, from which we can
only vary ± 2%.
What was the issue with maximum torque in Hockenheim?
The FIA questioned the magnitude of difference between the maps from
Silverstone and Hockenheim, where the maximum engine torque in the mid-range
(10000-14000 RPM) was lower.
Why would would you want to generate less torque in the mid revs range?
The trade-offs concern driveability (the response of the engine to the
driver requested torque), acceleration (less torque = less acceleration,
except if grip limited) and fuel consumption. In general, reducing the
torque is achieved by igniting the fuel later in the cycle by means of the
ignition map. This may improve driveability smoothing out the torque curve
which may help the driver manage his tyres. This is not in any way a
forbidden driver aid or an attempt to mimic the behaviour of a forbidden
system (eg closed loop traction control)
Reducing the maximum torque curve increases the amount of exhaust gas
produced at lower torque levels very, very slightly, but does not change the
exhaust gas flow at full throttle. Furthermore the scope to use the engine
to generate exhaust gas is extremely limited by the specific mapping
restrictions introduced for the 2012 season also by the performance
trade-offs mentioned above
After two sessions today, has this made any difference?
Not significantly, but the workload for the trackside engineers has
increased to ensure we maintain the same level of performance from the
engine.
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