Super Street Category in a VT-VZ Commodore.
This article aims to provide information for those planning to race in bracket racing with a VT-VZ Commodore. It is hoped that it might inspire more people to get involved in the “sport” of drag racing.
Bracket Racing
In straight-out drag racing, close races are rare. Cars usually have clear winners over the 1/4 mile. Sometimes, one driver gets a better start. Even if the cars are evenly matched, they often finish far apart. At 180 kph, cars travel about 50 meters per second. Therefore, a difference of 0.1 seconds means a 5-meter gap. This distance is greater than the length of a car. So, handicapped starts can be introduced to make the races close. This introduces the “sport” of drag racing.
Dial In Accuracy
To create close racers, drivers can “put their money where their mouth is” and nominate for each race based on how fast their car is. The catch is that they may lose if a driver exaggerates and claims a fast time to impress the crowd. This will result in an easy win for an opponent better at estimating their “dial in” time. That is what it is called. In this example, let’s say Car A nominates a time of 12.00 seconds. However, it finishes with a time of 12.50 seconds.
On the other hand, Car B nominates a time of 11.50 seconds and races to a time of 11.51 seconds. Car A’s green light in the race is 12.00-11.50. During the race, Car B began 0.5 seconds behind Car A. Halfway through the race, Car B caught up to Car A and passed it. Car B completed the race in 11.51 seconds. It won by approximately 0.49 seconds. At a speed of 180 kph, this 0.49 seconds translates to approximately 24.5 meters. This distance is roughly equal to 5 car lengths. The loss happened because the driver of Car A did not predict the race time well. If they had estimated that the car would run a time of 12.50, the race finish would have been very close to a tie.
Reaction Times
In drag racing, dial-in accuracy is important. However, another key factor is the driver’s reaction time at the start. This is also compared from driver to driver. This is important for the best bracket racers. Without good reaction times and consistent reaction times, a racer cannot win a race meet. It does not matter how good the car is. Good racers aim for reaction times of around 0.070 seconds. This is possible with practice and good technique. A street-driven car can achieve this when launched off the footbrake. Many people can race to consistent reaction times of 0.170s or slower. This would mean they give away 0.1s in 1/4 Mile Elapsed Time (ET), a car length. Slower drivers often feel more pressure and make mistakes. They push the car harder at the end and guess dial-ins that it might easily exceed. A racer is disqualified if they achieve a quicker elapsed time (ET) than their dial-in. They are also disqualified if they start before the green light, which is called a red light.
In one meeting, the USA Top Fuel Invasion in Dec 2005, I had reaction times of
- Q1 0.072
- Q2 0.234 (distracted by an opponents very early red light)
- Q3 0.073
- Round 1 0.048
- Round 2 0.110
- 1/4 Final 0.021
- Semi 0.050
- Final 0.094
- This was an average in all rounds (other than Q2) of 0.0646s.
Weather Conditions & Track Surface
The other factor affecting bracket racing results is the racer’s awareness of how the changing weather affects the car. In VT-VF Commodores and HSV racing, cars often run in the 11-13 second ET range. Every degree of air temperature at the intake valve can affect power. Specifically, a change of one degree can alter power by about one rear-wheel kilowatt (rwkw). This means that every 7 degrees, the car will change its ET by 0.1s and be 1.1mph, different in its speed at the end (Trap Speed). Also as air pressure changes the car is effected in power, the higher the air pressure the faster the car. Humidity also affects the engine’s power. The wind can change speed, significantly affecting the trap speed and impact on ET. The weather can affect how well a car grips off the line. The track is best when it has been warmed by the sun. It should not be too hot, ideally around 25 degrees Celsius. This temperature helps achieve the best launches in terms of traction. When temperatures are well outside the normal ranges, the racer must know that the car will behave healthily. I have raced an LS1 at 45 degrees. It was, of course, much slower than on a night with excellent weather. That night, there was high air pressure and a temperature of 6 degrees Celsius. A sunny day also helped warm the track. The difference between the two extremes may even approach 1.0s in ET. Dyno manufacturers include weather correction in their power figures. This adjustment accounts for air temperature, pressure, and humidity.
Building A Good Car
A good car needs to be able to launch consistently the same and not be prone to “stuffing up” starts. It must be easy for the driver to launch the same every time. My VE Twin Turbo was not the vehicle that could be launched the same way every time. There was too much to consider when launching the car. A good race car lets the driver focus only on the lights, the launch RPM, and other non-visual tasks. The vehicle must run nicely in every run, regardless of weather conditions. A good car that is enjoyable to race must be easy to set up at the track and take home if problems arise. If you can, it is advisable to trailer your vehicle to the track. This way, if something goes wrong, you can transport it home. You can then park it until you have time to fix it.
Technique Tips For Intending Racers
You will need good habits to be developed to be an effective, consistent racer. This entails identifying good habits and then practising doing them the same every time. Treat every race like it is the final of a major event. This applies to qualifying rounds, test and tune events, or off-street meets. These habits should apply to everything, not just the race itself. This includes the burnout procedure, the car’s warmup, and even the pre-race checks
Burnout Tips
The aim is to get the tyres to the best temperature for the rubber to work and launch the car consistently. Aim to heat the tyres with a high-speed burnout in the dry area, avoiding the water. Keep the burnout as short as possible for the best effect. This needs to be figured out through testing. Attend a test and tune event when the track is well-prepared. Often, at off-street meets, the track may not be fully ready. The track is prepared by spraying it with a special coating that enhances traction. If you walk on a prepared track, the soles of your shoes will stick to it like suction cups. Proper drag tyres, either drag radials or slicks, become very sticky after a burnout. At the correct pressure, which you must find through experimentation, they will provide the best launch. One final tip is to be careful with your limited-slip differential (LSD). Avoid letting the car grab one tire during or after the burnout. To do that, keep the tyre speed high and back off once.
Launch Tips
When racing, put the car on stage first on one white light. So don’t do fancy long burnouts; be the first racer in, and then you can settle yourself better. Edge in mm by mm to get the second white light. This is because your car’s front tyre has just started to block the beam at that point. If you roll forward further, eventually, the tyre will stop blocking the beam. When this happens, you will start the timer or get a red light (if this occurs before the green light on the tree). This distance between the tyre starting to block the beam and not blocking the beam is called runout. It is a chance for a “running start”. By maximizing your distance for a faster time, you can improve your reaction time. Being careful with your launch position on the two white lights helps. This way, you start your launch at the same spot each time. People who are sloppy at positioning their car at “staging” on two white lights do not win race meets.
Another tip is to try using the handbrake at the start if in an auto. It helps to lock the car in position, keep the button pressed the whole time and learn to coordinate the release. If you drive a manual car, watching videos of similar cars launching is helpful. This can help you find strategies that work well for your vehicle and fit your budget for launch parts. Automatics are far easier to launch, more trouble-free, and more consistent than manuals. A good target for a 60-footer is 1.600. If your car can get under that, it’s well setup, and you are doing it right. The best performance for vehicles in the 11-13 second range is 1.500 seconds. At this point, the front left tyre may lift off the ground. The car can achieve 0-100 kph in about 2.8 seconds.
Once two white lights are lit, your car is in stage. The race organiser can press a button when the other driver also stages with two white lights. This will activate three amber lights. These lights will turn on and off consistently for 0.5 seconds each. You will need to test to find out the best time to launch the car for the best reaction. Sometimes, this is when the last amber light comes on. If you blink, you will probably spoil your reaction time by at least 0.1s and give the other racer a likely 1-car length advantage.
Dial In Targets
At one point, we had a street-driven car that could consistently run within 0.030 seconds of its “dial in”. This is less than a third of one-tenth of a second. The variable distance at the end of the strip was under 2 meters. To achieve this level of accuracy, we needed to collect a lot of data and have a well-set-up car.
Data Collection Tip
Collect all your timeslips and record all the weather data you can for every run the car does. Keep notes on everything, such as tire pressures, track surface conditions, and fuel type. Record all this information in a spreadsheet.
Learn to compare runs with Density Altitude Calculators. This will help you see how your car performs in different weather conditions.
Racing Psychology
Every race result has an element of skill that you can develop. It is also a solid percentage of luck. If you take part in bracket racing, luck can play a big role. Often, your wins come from your opponent’s bad luck, like a red light or a mechanical failure. Celebrate your victories and learn from your losses. Sometimes, you can cut a 0.001 reaction, race within 0.050s of your dial-in, and still be beaten. Much of the time, if you can react within 0.100s and race within 0.100s of your dial-in, you will win the race. So make that be your aim.
