Lubrication supply is a key factor in governing the longevity of a race engine; however, the quality of the lubricant is equally important. For many years, the only component ensuring this was a filter to remove damaging particles from the oil. The only means to test the condition of this oil was to analyse the contents of the filter to try to identify any impending problems, and the analysis was only possible with the car stationary in the pits. Given the complexity and cost of modern race engines, engineers are naturally keen to prevent catastrophic failures so many vehicles racing in the upper echelons of the sport, such as Formula One and at Le Mans, feature onboard sensors capable of monitoring not just the quantity and pressure of oil, but also its condition.
There are a number of sensors on the market that allow engineers to assess oil quality in real time, potentially saving an engine from expiring prematurely. These sensors fall into two brackets - those that monitor the quality of the oil itself, and those that measure the quantity and type of metallic particles in the oil.
Oil quality sensors work by assessing the dielectric constant of the oil - a dielectric is a type of electrical insulator, most commonly used in capacitors - and comparing it to a reference figure from a known sample. This information can then be transmitted over the car's telemetry link, allowing trackside engineers to tell if the oil structure is degrading.
Sensors to measure the quantity and type of metallic particles in the oil work by collecting metallic particles and analysing their composition via a remote diagnostics unit that can discern between the tiny metal particles that are always present in the oil and larger particles that could indicate the imminent demise of the powertrain.
One such sensor on the market is designed to replace a conventional magnetic oil plug or sump plug in either engine or transmission applications. It is a dual-channel device that can detect not only the quantity but the type of metallic debris build-up in the oil. It attracts metallic debris to the face of the sensor (much like a conventional metallic plug) and measures the particle build-up via remote electronics. One output channel provides data on very fine particle build-up, the other on the build-up of larger metallic objects (which could result in the aforementioned demise of the engine).
A second but equally important aspect of any lubrication system is accurate monitoring of oil levels. Oil tanks in racing applications tend to be complex items, having to control oil levels during extreme cornering and acceleration while taking up the minimum space possible. In the bad old days, oil levels were gauged through the medium of a simple sight glass, but in modern racing things are rather more advanced.
The oil tank is a fairly hostile environment for sensors so they need to be suitable for use in high operating temperatures, and are often hard-mounted to the engine, so they need exceptional vibration resistance as well. Most of these sensors are solid state, the lack of any of moving parts reducing the chances of failure, and they tend to be made from carbon fibre or titanium to fit a team's precise packaging requirements.
The oil-level data will be another key parameter monitored from the pit lane, and temperature sensors are often incorporated into the level sensor. If a sudden drop in oil level is noticed, it gives a team the opportunity to take preventative measures and possibly prevent a catastrophic failure.
Written by Lawrence Butcher