Nov. - Dec. 1998 Lane Racing And Rodding Article By Jim Kaekel, Jr.
Automotive gauges, especially tachometers, have come a long way the past twenty years. Twenty years ago, the tachometer's only function was the monitoring of engine speed (RPM). Contrast that with today's top-of-the-line tachs that not only display engine revolutions, but can activate a shift-lite, record peak rpm attained during a race, and even record the race for later playback in the pits and it's obvious that the tachometer - always an important gauge - now plays an even more important role.
Data acquisition is a big market and major tachometer manufacturers, such as Auto Meter and VDO, are continually developing new technology in order to keep up with the racers' desire for more information. Their efforts in this direction have benefitted greatly from the concurrent evolution of computer technology. The first popular tachometer recording device to come about as a result of the computer technology was the Long Term Memory Logging Device (LTM), released by Auto Meter over ten years ago. The LTM introduced racers to the principal of recording engine RPM over a specific period of time so it could be played back later. The LTM gave race teams a valuable tool for collecting information not only on engine performance, but on slippage in torque converters, clutches, and tires as well. The LTM also gave users the ability to record the highest RPM attained during a race, as well as the RPM during and after gear changes. Race teams were able to use this new and exciting source of information to further "tweak" their cars for maximum performance at a variety of different tracks and surfaces.
VDO entered the recording tachometer market a few years later with the Top Eliminator Series of tachs. The Top Eliminator was the first tach to have the playback features built right in. A keypad, to the direct right of the tach face, controlled its recording and playback functions. In 1997, VDO replaced the Top Eliminator Series with the new Xtreme Series of tachs. The Xtreme added more features which allowed recording to begin as early as the start of the burn-out, a feature of great use to drag racers.
The technology of tachometers continues to become more sophisticated; no doubt as a direct result of the early development of the Auto Meter LTM and VDO Top Eliminator. Auto Meter replaced the LTM with the current Playback line of tachometers in 1995, and the Playback Box, which replaced the discontinued LTM, a year later. The Playback Box (#ATM9150 for drag, #ATM9160 for circle track) converts any Auto Meter tach to playback status. Auto Meter also offers a new Dual Channel Playback Tachometer which records both engine and driveshaft rpm.
The current crop of technologically advanced tachometers can easily record a complete race. Following the race, the recording can be played back and evaluated. Drag racers can determine tire spin, launch RPM, and even evaluate converter flash point and accuracy of shift points on automatic transmission-equipped cars. Circle track teams can view and evaluate engine speed in and out of the turns, and on the straightaways, for help in determining how the car is geared and set-up. Some playback tachs now have peak and valley catchers to measure the RPM attained before and after a gear change.