A digital dash and data acquisition system for car and motorcycle racing incorporating LED shift lights
A shift light is a warning lamp fitted to vehicles in order to indicate to the driver that maximum
revolutions per minute
Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min−1) is a unit of rotational speed or rotational frequency for rotating machines.
Standards
ISO 80000-3:2019 defines a unit of rotation as the dimension ...
(r/min) has almost been reached. Ideally a shift lamp will illuminate at the engine speed beyond that which delivers the maximum
power
Power most often refers to:
* Power (physics), meaning "rate of doing work"
** Engine power, the power put out by an engine
** Electric power
* Power (social and political), the ability to influence people or events
** Abusive power
Power may a ...
, measured in for example
kilowatt (kW) or
brake horsepower
Horsepower (hp) is a unit of measurement of power, or the rate at which work is done, usually in reference to the output of engines or motors. There are many different standards and types of horsepower. Two common definitions used today are the ...
(BHP), such that the power before and after shifting is the same. Accelerating the engine beyond this point is not conducive to ideal acceleration. In use a shift light allows the driver to judge the exact point that a gear change should be carried out without having to glance down at the
tachometer
A tachometer (revolution-counter, tach, rev-counter, RPM gauge) is an instrument measuring the rotation speed of a shaft or disk, as in a motor or other machine. The device usually displays the revolutions per minute (RPM) on a calibrated analo ...
. This also increases safety for the driver by keeping their focus near the track at all times.
Beginning in the early 1980s, many United States-market vehicles equipped with a
manual transmission
A manual transmission (MT), also known as manual gearbox, standard transmission (in Canada, the United Kingdom, and the United States), or stick shift (in the United States), is a multi-speed motor vehicle transmission system, where gear change ...
began to have shift lights as standard equipment; these would usually signal for an
upshift at an engine speed that provided maximum
fuel efficiency, lower than the ideal engine speed for maximum power. The reason for this was, for a time
EPA
The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it be ...
fuel economy testing rules stipulated that shift lights would be followed on vehicles so equipped- thus, they were calibrated for optimum fuel mileage on the EPA test cycle. Some in the 1980s even had buzzers to alert the driver it was at a certain r/min.
Towards the late 1980s and early 1990s, shift lights saw uses in multiple
motorsport disciplines, such as
Formula One
Formula One (also known as Formula 1 or F1) is the highest class of international racing for open-wheel single-seater formula racing cars sanctioned by the Fédération Internationale de l'Automobile (FIA). The World Drivers' Championship, ...
, to signal for an upshift at an
engine
An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy.
Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power ...
speed which provided optimal power within the torque curve, ensuring optimum
acceleration
In mechanics, acceleration is the rate of change of the velocity of an object with respect to time. Accelerations are vector quantities (in that they have magnitude and direction). The orientation of an object's acceleration is given by t ...
.
References
Automotive accessories
Motorsport terminology
Motorcycle racing
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