EFI Technology Level 2 and...
EFI Technology Level 2 and Level 4 Loggers with a Linear Potentiometer and Rotary Potentiometer.
Data acquisition is employed in almost every type of modern-day racing vehicle. The question is why? What are the advantages, disadvantages, and misconceptions of this technological mess of wires and circuits? In this segment we'll discuss components and hardware (the logger itself, sensors, dash displays, and harnessing).
The Logger Control Unit (LCU) is the heart of the data acquisition systems and, in some instances, it's integral with the dash display unit. The purpose of the LCU is to acquire data and store it through means of complicated circuitry and smoke (the magic stuff that makes electronics work). Image six illustrates a typical layout to give you an idea of how the system works.
Here's the EFI Technology...
Here's the EFI Technology Level 2 and Level 4 Loggers showing off their internals.
As you can see, a central unit has all the sensors connected to it. This LCU provides power (5, 12, and 20-plus volts) and ground, and then monitors the change in the sensors to produce data. A variety of sensors-shock potentiometers, strain gauges, rotary steering pots, pressure sensors, laser ride height, temperatures, IR temperatures, and more-can be utilized. Any sensor with a 0- to 5-volt output can typically be used; we'll look a bit later at the requirements of sensors and how they relate to the LCU.
More complex layouts and installations are available. These types will typically employ remote modules, which are responsible for supplying power and ground sensor amplification, if necessary, and a data stream output back to the central unit. A typical installation of this type is shown in image 4.
EFI Technology Level 4 Logger...
EFI Technology Level 4 Logger with Autosport Connectors
The LCU typically consists of a few main components, a processor, and main board that reads the data (other higher-end units use dual processors to accomplish other tasks). A power supply runs the sensors, dash display, and other related ancillaries. A built-in or external memory system records data, using some type of communications interface (serial, USB, CAN, Ethernet, wireless) downloading data, and sending it to a different configuration. Most high-end data systems also have an interface to receive data from third-party systems, such as tire pressure monitoring, ECUs, GPS, and more. As of late, sending data over a CAN stream allows the system to be expanded to an almost limitless capacity.
EFI Technology Level 4 Logger...
EFI Technology Level 4 Logger Internals: memory boards, comms, and analog cards
Let's now discuss sensors, typical sensors on racings cars, and cars in general that have a 5-volt supply, a signal 0- to 5-volt analog, and a ground. The most common sensor added to a road race car is a linear potentiometer. This is used to measure shock travel and shock velocity, if onboard, or post process math is available. As mentioned before, to make this sensor work it needs three things: 5-volt input, ground, and an analog 0- to 5-volt output to the LCU. As you move the sensor through its range of travel it will produce an output voltage. The LCU will need to be programmed with a calibration to convert this voltage value into an engineering value. A calibration for a rotary suspension pot is shown on image 11.
Other common 0- to 5-volt sensors include rotary potentiometers, which can be used for: gear position, shock travel, steering position, throttle position, and more.
A string potentiometer can also measure a variety of things. Its fragile nature, however, usually makes them inadequate in a race car.
 EFI Technology logger configuration...  EFI Technology logger configuration software with a wheel travel analog calibration shown. |  A complex data system layout...  A complex data system layout including telemetry, TPMS, ECU interface, and remote junction boxes. |  Here's a close-up of Autosport...  Here's a close-up of Autosport connectors and epoxied shrink boots-a completely sealed system for maximum reliability. |