CRAWDAD Posted September 28, 2010 Report Share Posted September 28, 2010 I was looking for more information on how to analyze my time slips and came across this information contained on http://www.hardtail.com/techtips/analizingtimeslip.html and thought it would be helpful to others to post it up. Enjoy. Analyzing your time slip Are you getting the most benefit out of the drag strip time cards? If your track uses state of the art timing equipment like the "Compulink System", you are provided plenty of data. But how can you use this data? Most race tracks provide you with an elapsed time, trap speed and reaction time. But in 1988, most tracks started using multiple timers that provide 60 foot, 1/16 mile (330 ft.), 1/8 mile (660 ft.) and 1000-foot times also. The newer systems measure the trap speed differently from the old (pre-1988) systems. In the old (NHRA) system, a light beam was placed 60 feet in front of the finish line and 60 feet after the finish line. The computer would calculate your average speed through this 120 foot region. To get a true trap speed, you had to stay on the throttle until you cleared the last light. Today, the trap speed is measured with two light beams only 60 feet apart. A light beam is placed 60 feet in front of the finish line and the finish line is the last beam. Use the 60 foot, 660 foot and 1/4 mile elapsed times for evaluating each run. The 60-foot time is dependent upon traction, gearing, launch rpm and staging depth. It varies little with day-to-day horsepower changes. The 60-foot times can vary by .02 sec. during the evening and up to .15 sec. between a hot track and a cool track (with a leaf spring suspension and 10" tire) or as little as .03 all day on a car with 4-link and 14" tires). The 1-2 shift occurs beyond the 60-foot mark and 2-3 shift occurs before the 660 foot (1/8 mile) point. If you subtract the 60-foot time from the 660-foot time, you will see how well your car is pulling through the gears. I call this the "1st-2nd" figure. The difference between 60-foot & 1/8 mile will be good indication of the proper shift points and whether you are operating in the proper torque range. This value with vary with amount of horsepower production, shifts or weather (headwind, barometer). http://www.hardtail.com/techtips/analizepic.gif The 3rd gear pulls through the remaining 1/8 mile. Take the 1/4 mile elapsed time and subtract the 660 foot time. I call this calculation the "3rd" figure. This is a long pull showing brute horsepower which encounters variables like wind, density altitude (temperature, humidity and barometer) and aerodynamic drag. Changes in jetting, valve lash, ignition timing, etc. show up on this calculation. The difference between the 1/4 mile ET and the 1/8 mile (660-foot) ET will vary greatly with a head or tailwind. Take calculations of this figure during time trials and compare to past races where there was no wind to figure out how much effect (in ET) the wind has on your car. Then if the wind dies down for first run, you'll know how much to lower your dialin, while everyone else breaks out. Breaking these figures down into 60-foot, 1st-2nd, & 3rd encourages more research and development. Let's suppose you've increased the shift points by 200 rpm and you notice the ET dropped .05 sec. You think you're on the right track until you notice the 60-foot time went from 1.69 to 1.64 sec. Unfortunately, the .05 sec. was not the result of a changed shift point. It was due to a sudden "gain" in traction! The shift point had no effect! The 60-foot time is related to the tire's temperature and pressure. Cold tires which have not been run in a while need a lower pressure because the relative increase in pressure during burnout is greater with cold tires. After enough smoke is off rear tires in water box and line lock is released, you have two choices for proceeding: (1) spin out of the water and continue up to the line or (2) Stop the car, roll forward and due two extra burnouts as approaching the line. Tire manufacturers frown on the extra burnouts. They say that the first launch will be the best after the waterbox. The remaining part of the run after 60-foot time will closely follow the Density Altitude (D/A). The D/A makes only a fraction of a difference in the first 60-feet. Keep track of D/A for each run. With a common 60-foot time calculated for each, you should be able to predict your next run. The most difficult time to pick a dial-in is during sundown because everything is changing. Keeping records from week to week will help iron this out. Here are some of the variables. When the sun is going down, traction increases, due to the lack of direct sun rays, which reduces the 60-foot time. Watch for the winds dying down at sundown. Lack of a strong headwind can make a doorslammer go .10 sec. faster! Your reaction to the Christmas tree is different when in bright sun compared to a black background at night The temperatures may fall 10 degrees F creating a lower density altitude and more horsepower The cooler temperatures cause slicks to deflate by up to 1.5 psi. A long delay before first round may allow the carburetor to cool which can change the response time of full throttle. There are many variables involved in racing a car. When you are testing at the dragstrip, be on the lookout for anything causing a reduction of horsepower. You may need to optimize something else first. This is in response to changes made with jetting, timing, valve lash, staging depth, tire pressure, ladder bar adjustments, etc. If you experience several weeks of losing first round, you must review what you have been doing wrong. Not enough concentration on third yellow bulb. Need more attention to opponent's dialin and his expected speed capability. This is so you can figure out what to do, in case you are not in the lead at the end of the track. Concentrate on expected 60-foot time. Compare with traction in similar round last week Look at direct sunshine. A track which does not have direct sunshine will be stickier than one with sunny weather. Concentrate on the density altitude and what times are expected in similar weather for proper dialin. Quote Link to comment Share on other sites More sharing options...
wagner Posted September 28, 2010 Report Share Posted September 28, 2010 Good thread and now a sticky! Quote Link to comment Share on other sites More sharing options...
Main3s Posted September 28, 2010 Report Share Posted September 28, 2010 Wow, a lot more to the time slips then most people think. I've heard of analyzing your 1/8 mile run to your 1/4 mile as well as the whole 60ft and traction deal but I've never broken it down to 1-2 shifts etc... Quote Link to comment Share on other sites More sharing options...
CRAWDAD Posted September 28, 2010 Author Report Share Posted September 28, 2010 When somebody says, "there's nothing to drag racing" Just show them this thread. I have been drag racing 11yrs and have been racing with some really good drag racers, I usually go rounds. It is kind of hard to explain drag racing to somebody that has never been around it. I can tell them but they just look at me with a plan look on there face Quote Link to comment Share on other sites More sharing options...
wagner Posted September 28, 2010 Report Share Posted September 28, 2010 When somebody says, "there's nothing to drag racing" Just show them this thread. I have been drag racing 11yrs and have been racing with some really good drag racers, I usually go rounds. It is kind of hard to explain drag racing to somebody that has never been around it. I can tell them but they just look at me with a plan look on there face I laugh anytime someone makes that sort of statement. If drag racing was easy everybody could be John Force or Bob Glidden. Granted driving a car that is not super fast in the quarter is easy provided you are not a total dumbass. Bracket racing a car at any ET is not an easy task at all. Quote Link to comment Share on other sites More sharing options...
Nickey4271647545519 Posted September 28, 2010 Report Share Posted September 28, 2010 I laugh anytime someone makes that sort of statement. If drag racing was easy everybody could be John Force or Bob Glidden. Granted driving a car that is not super fast in the quarter is easy provided you are not a total dumbass. Bracket racing a car at any ET is not an easy task at all. bracket racing 1/8th mile, become really good in the 1/8th and you'll be golden in the 1/4. Quote Link to comment Share on other sites More sharing options...
Main3s Posted September 28, 2010 Report Share Posted September 28, 2010 bracket racing 1/8th mile, become really good in the 1/8th and you'll be golden in the 1/4. Pacemaker FTW Quote Link to comment Share on other sites More sharing options...
bads2k Posted December 28, 2011 Report Share Posted December 28, 2011 this is a little helpful but not as much as actually having a good datalogging software. the more data you can record to go back through and evaluate the better. We've seen a lot of good info on learing turbo shaft speed and backpressure data so we are adding that into the mix this year. Quote Link to comment Share on other sites More sharing options...
pontiacfreak142 Posted December 28, 2011 Report Share Posted December 28, 2011 Good read, ive been bracket racing for 6 years and never thought of reading that much into a time slip. Guess I've just been lucky with having a consistant car lol Quote Link to comment Share on other sites More sharing options...
hpfiend Posted December 28, 2011 Report Share Posted December 28, 2011 That's an awesome post- thanks! Quote Link to comment Share on other sites More sharing options...
hpfiend Posted December 28, 2011 Report Share Posted December 28, 2011 Bracket racing a car at any ET is not an easy task at all. This I do not agree with but off-topic so please pm me. Quote Link to comment Share on other sites More sharing options...
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