The slip of paper you get after an exhilarating quarter-mile dragstripride is much more than a license to brag (assuming it's a stellar run).All those numbers on that little piece of paper are important tuningtools that can help identify improvements or problems in your car'sperformance. But if you're like most of us, maybe you take a quickglance at the 60-foot time, e.t., and top-end mph then simply stash theslip away between the seats. If so, then it's time to find out whatyou've been missing.
Of course, having a pack of timeslips doesn't do you much good if youdon't have any detailed information about the conditions, tune-up, ordriving technique used on each of those runs. Make it a point to writedown all the details immediately after a run. Include any changes ormodifications to the vehicle, launch rpm, shift points, tire pressure,and weather and track conditions. Keep all your timeslipstogether--ideally in the logbook that you record these details in.
Knowing how to read a timeslip and keeping detailed notes on each runwill result in a valuable performance portfolio that can help determinewhat changes worked and what didn't, and keep you moving in the rightdirection. Above all, it's free. Let's take a closer look at what allthose numbers mean and how you can use them to your advantage.
Breaking Down the Digits
A timeslip is nothing more than a printout that records in detail how quickly you traversed the 1,320 feet from start to finish. These distances are measured in several individual increments.
Reaction: The time it takes you to get the car to move forward after the tree turns green.
60-foot (I1): The time it takes a vehicle to cover the first 60 feet of the track. The greatest indicator of traction.
330-Interval (I2): Secondary timers record the time it takes a vehicle to cover 330 feet; a good indicator of chassis setup.
1/8 e.t. (I3): Secondary timers record the time it takes to cover 660 feet.
1/8 mph (I3): Secondary timers record a vehicle's miles per hour.
1,000-Interval (I4, when given): Secondary timers record the time it takes a vehicle to cover 1,000 feet.
1/4 e.t.: Secondary timers record the time it takes a vehicle to cover the quarter-mile
1/4 mph: Secondary timers record a vehicle's miles per hour; also known as the speed trap, these timers are located 66 feet before the finish line. Between 1,254 feet and 1,320 feet, the average speed between the two lights produces the mph on your timeslip.
Driver's Round Table
Going fast doesn't happen overnight. To get an insider's perspective, weconvened a panel of seasoned heads-up veterans featuring NMCA Pro StreetChampion and former NHRA Pro Stock racer Pat Musi, NMCA Drag RadialEliminator racer Troy Pirez, and NMCA Real Street racer PatrickTopolinski from The School of Automotive Machinists, to find out howreading timeslips helps them stay at the top of their game.
Car Craft: How important is it to understand the numbers on a timeslip?
Pat Musi: Very important. When read properly, the timeslip can tell youexactly what the car is doing at any given moment of a pass.
Troy Pirez: Numbers are everything. Without them, you'll never knowwhat's going on, which is crucial considering we're trying to get to theend of the track as fast as we can.
Patrick Topolinski: Without the numbers, we would never know if ourtuning changes were working. More importantly, you need to know what thecar runs on a regular basis to effectively use the information.