A Quick Review of the Use and Benefits of the Tachometer
These days, most vehicles are equipped with a tachometer – a dashboard gauge or readout indicating the revolutions per minute (RPM) of an engine. RPMs are usually referred to numerically in thousands of revolutions per minute. On a tachometer, the readout simply reports engine speed from 0 to 6, 7 or 8, depending on the type of vehicle, engine and transmission. Some engines can have much higher speeds – into the 13s and 14s. Regardless, multiply the gauge number indicated by 1,000 (often “X1000” noted on the readout) to get the RPMs.
Tachometers also display, at the higher end of the readout, an area usually marked by red lines or numbers. These “redline” zones indicate engine speeds where engine damage is most likely to occur. To be clear: Drivers should avoid pushing the engine speed to redline levels.
For the majority of drivers out on the roads today, knowing their engine speed is less important than knowing their vehicle’s ground speed, which of course is reported by the vehicle’s speedometer. Race car drivers, however, need the information provided by tachometers to get the most out of their vehicles as they match throttle control and gears (and therefore engine speed) with race conditions. And for those drivers who either wanted to maximize fuel economy or vehicle performance (or both), manual transmissions and tachometers provided an opportunity to do so.
While manual transmissions are still around (and many drivers still love the overall experience of driving a manual), modern technology and advanced vehicle engineering make today’s automatic transmissions a better choice to maximize fuel economy and power. And interestingly, many modern vehicles with automatic transmissions are equipped with a tachometer, even though most drivers probably don’t pay that much attention to it. Despite the advances in engine control systems and how those carefully manage engine speed, the tachometer is still a useful gauge to the driver, especially if he or she switches to “manual” mode shifting (for sportier driving or off-road driving or even driving in slippery conditions). Engine speed is also an important factor when a vehicle is under an increased payload or towing.
In most scenarios, drivers should keep engine speeds from reaching the redline. And while some engine management systems will automatically prevent this (and therefore help prevent engine damage), a tachometer provides real-time information to a driver so he or she can know exactly how the engine is doing at any given moment.
Bottom line advice: Stay out of the red.