Drag Racing Timing System

[SlowerThanYou]

Thanks for sharing. Any pointers are well received.

 

Troy

 

Thanks Troy!

 

You explained everything very well in your initial post; and in the follow up posts. That's really why I don't know what else to add, I guess.

 

Thanks J-M, I took your post the wrong way.

 

I hope to cover all the bases while doing this. If I don't or not explain it right. I hope someone will chime in & set me straight.

 

I don't claim to know it all, but I do have a good amount of racing time under this old belt. I'm just trying to pay back a little racing information I was taught by other's & my own experiences. 

[SlowerThanYou]

Brian, you need to add subjects about Beam jumping and Guard beams along with RT and ET's with staging.

 

I'm not sure I know what beam jumping is, but I think someone can help explain it.

 

I view it differently than jumping the beam. Anyway, that's what the guard beam is for; to start the clock if the stage beam doesn't.

 

While the below link doesn't cover much on the guard beam. I think it covers the below quote notes pretty well.

 

Notes for future subjects:

- When does the timer start in your lane.

- How to change your reaction times & ET with staging.

 

I put the link for this article on the bottom for reference.

 

Racing Technology

Rollout and reaction time —

more important than you might think

 

by Wayne Scraba

 

Rollout is a familiar word in drag racing. Even if you only occasionally race your car in brackets, it's a term that could save you countless red-lights. It also can improve the vehicle's elapsed time and help if you're late. Sound interesting? It is. Best of all, most rollout improvements are free of charge — or at least cheap.

How the system works

Virtually all contemporary dragstrips feature a pre-stage and a stage beam (many also have what is called a "guard beam" that starts the e.t. clock if the stage beam does not). The pre-stage beam is approximately 12 inches ahead of the stage beam; however, this distance can change from track to track or, in rare cases, may change during the course of an event.

To chart your progress as you stage your car, corresponding lights are affixed to the Christmas Tree. The pre-stage bulb tells the driver that his or her car is about to enter the stage beam — which, in essence, is the dragstrip starting line. When the front tires of the car pass completely through the stage beam, the timers begin. If you start too soon, the evil red-light comes on and you go home early.

According to Jerry Bickel, "Increasing the rollout distance of a car gives the racer advantages that can make the difference between winning and losing. The added distance means that a little more time will elapse before the light beam reconnects. This makes it less likely that the driver will red-light, and the car gets a running start to cover the quarter-mile. The length of the track is also shortened slightly by the increased rollout distance.

"On the downside, increasing the rollout distance of a car will also increase your recorded reaction times. If your reaction times are good, you should increase the rollout distance as much as the rules allow." More on this topic later.

The connection

The folks at Port-A-Tree have done a considerable amount of research into rollout. I highly recommend the company's comprehensive video on the subject. According to Port-A-Tree, "Rollout is the ability of the car and the driver to react to the Christmas Tree lights and to leave the starting line at a precise time.

"No matter what class, the driver with a better reaction time has a better chance of winning the race. Reaction time, as a number on the e.t. slip, measures the driver and the vehicle performance at the starting line. The driver reacts first, with a foot off the clutch, a finger off the transbrake button, or a foot off the brake pedal. The response to this action is the vehicle reaction time, or rollout. Variables that influence reaction time include engine rpm, clutch or converter slippage, tire spin, engine performance, front tire diameter, suspension setup, staging technique, and any combination of the preceding.

"The movement of the tire out of the stage beam is what stops the reaction-time clock and starts the e.t. clock. The stage beam must be blocked by the vehicle tire at the beginning of the Tree sequence, and the beam must be unblocked the instant the green light comes on."

Time constraints

According to the folks at Port-A-Tree, a specific amount of time is required for the Christmas Tree bulbs to work. This is called trigger time, which equates to 0.040-second. Port-A-Tree has also determined that the average driver reaction time is 0.140-second, plus or minus 0.020-second. This means that, all told, a driver requires 0.180-second, plus or minus 0.020-second, to react to a given bulb on the Tree. When this is taken into account, the driver reaction time can, in fact, be taken out of the equation, leaving just the race car, the burnout process, and a few other items to influence overall reaction time.

What parts of the vehicle can you change to influence reaction time? As mentioned by those at Port-A-Tree, engine rpm, clutch or converter slippage, tire spin, engine performance, front tire diameter, suspension setup, and staging techniques affect overall reaction time. One of the easiest mechanical things to change is the front tire diameter.

According to Jerry Bickel, tire rollout is critical. "There are only two ways to legally increase the rollout distance: Use larger diameter tires or stagger the front wheels," he said. "Race sanctioning organization rule books [NHRA's included] allow a certain amount of wheelbase stagger. This means that one tire (usually the right front) is positioned slightly behind the other. Because the light beam is broken by the front wheels at the starting line, wheelbase stagger increases the rollout distance by the same amount."

Unless the car in question is a purpose-built drag machine (dragster, altered, Funny Car, Pro Stocker, and the like), it's extremely difficult (if not impossible) to change the front tire stagger. In cases such as this, the best bet is to physically change the overall diameter of the front tires. As you can imagine, the front tire diameter and, to a certain degree, tire pressure play a serious role in determining rollout.

By increasing the size (diameter) of the front tire, rollout is increased. For example, most of today's street cars are fitted with low-profile tires on all four corners, and these tires are substantially shorter than an old-fashioned 78-aspect ratio tire. By adding a tall tire, such as a 78-series or a dedicated drag race front tire, rollout is increased.

How much can rollout change? Take a look at the chart below from Goodyear. For the sake of comparison, only non-dragster tires are listed.

 

Size Diameter Overall Rollout Overall 23.0x5.0-15 23.0 inches 72.2 inches 24.0x5.0-15 24.0 inches 75.4 inches 25.0x4.5-15 25.0 inches 78.5 inches 26.0x4.5-15 26.0 inches 81.7 inches 27.0x4.5-15 27.0 inches 84.8 inches 28.0x4.5-15 28.0 inches 88.3 inches

 

Note that the rollout measured above is the total rollout of the tire. In essence, that measurement is how far the tire moves in one complete revolution. The chart does, however, show just how much rollout difference there is between various sizes of tires.

Running starts and red-lights

The bottom line is that an increase in the front tire diameter provides the racer with greater insurance against viewing the red eye on the Christmas Tree. In simple terms, the tall front tire will roll further without unblocking the stage beam, effectively fooling the starting system. In addition, increased rollout allows the car to literally take a running start (albeit a short running start measured in inches) when the Tree comes down.

If front tire pressure is increased, the overall diameter of the tire is increased, which in turn increases rollout (at least in theory). Conversely, if the front tire pressure is reduced, the rollout decreases. I should point out, however that a number of racers have tested this theory, and when kept within safe levels, it's often difficult to see much change by raising or lowering tire pressure. You'll also find that excessively lowering the front tire pressure can have an adverse effect on handling, especially at the big end of the dragstrip. Practically speaking, you're probably better off playing with front tires of a different diameter.

When using a tire diameter advantage on the starting line, be absolutely positive that you bump your car slowly into the pre-stage and stage beams. This is called shallow staging — a process that works well with street-strip vehicles (or footbrake cars) that do not have outstanding vehicle reaction times. If you drive right through the beams, the advantages of more rollout are tossed out the window.

In the end, you may find that by "adjusting" the rollout, you will be capable of cutting better lights (i.e., reaction times decrease) while at the same time lowering the elapsed times (i.e., the car now has a running start).

The price? In the big picture, next to nothing. Down the road, we'll take a close look at varied (and precise) starting line rpm, "adjustable" travel transmission brake switches, and other reaction-time factors. In the meantime, think long and hard about rollout. A simple front tire swap can often spell the difference between going home early and enjoying the spoils of competition.

 

http://www.nhra.net/dragster/1999/issue21/racing_technology.html

[Nightmare]

Deep staging?

[SlowerThanYou]

Deep staging?

 

What's the question?

[Nightmare]

What is it? I've been hearing it more and more now that i'm running on dirt. I never heard of it when i raced asphalt. This is only my second season on dirt so i'm still learning.

[SlowerThanYou]

What is it? I've been hearing it more and more now that i'm running on dirt. I never heard of it when i raced asphalt. This is only my second season on dirt so i'm still learning.

 

This is the procedure: you pre-stage, then stage & then continue to roll in further until the pre-stage light turns off.

 

This can be done only in certain classes on asphalt. It seems to be allowed in every class on the sand.

 

IMO, I would only use this technique as a last resort. Deep staging allows for a quicker reaction time, but you lose a little ET by doing it. We prefer to use other methods of speeding up reaction time. Some of them was mentioned in the above article.

[J-Madd]

The rollout info was interesting. I would like to ad, that adding rollout won't necessarily help win races unless you've got a very good reaction time. For example if your gonna have a 0.450 light and adding the rollout makes it a 0.550 that's gonna make your e.t. faster, but the guy your racing can have a 0.450 light with no rollout advantage and the faster bike is still gonna win. The first one to the end is gonna be the winner regardless of any manipulated e.t. advantage. Now if you are gonna cut a 0.350 (red) light and the rollout lets that be seen as a 0.450, that's where you will have an actual advantage in winning the race. Don't you agree Slower? The guys (Packard comes to mind) that put the number plate out front might stage with that and possibly run all the way through the tires before the timer starts. I don't know that for sure, but it seems feasible.

[SlowerThanYou]

The rollout info was interesting. I would like to ad, that adding rollout won't necessarily help win races unless you've got a very good reaction time. For example if your gonna have a 0.450 light and adding the rollout makes it a 0.550 that's gonna make your e.t. faster, but the guy your racing can have a 0.450 light with no rollout advantage and the faster bike is still gonna win. The first one to the end is gonna be the winner regardless of any manipulated e.t. advantage. Now if you are gonna cut a 0.350 (red) light and the rollout lets that be seen as a 0.450, that's where you will have an actual advantage in winning the race. Don't you agree Slower?

 

I agree with what has been said on this part, but want to take it a bit further. IMO, the best scenario is to have most rollout with-in reason with the front tire & still have the capability to go red. That way you have the adjustability to tune your reaction time to the conditions as needed. This is what's

primarily used for heads-up, .400 pro tree racing with NHRA.

 

While we are still rookies at 300'. We still follow our asphalt successes & try to apply them to the sand/dirt. 

 

Notes for next discussion:

 

Now, the second part of this that was not mentioned. Is Bracket & Index racing & what's referred to as a total package.

 

Also, I want to cover the second part of your post about Packard's Number plate.

[sheerider11]

Slower, are you a teacher or something?

[SlowerThanYou]

Slower, are you a teacher or something?

 

In a round about way, LOL!

 

I'll explain it a little more when I have time.

[J-Madd]

Slower, are you a teacher or something?

I took it as arrogance at first, but he's really just trying to share info to make everyone faster. But he does make every post sound like a syllabus. Lol.

[sheerider11]

I took it as arrogance at first, but he's really just trying to share info to make everyone faster. But he does make every post sound like a syllabus. Lol.

ive had classes taught like this. When I saw the break down, the question, to the upcoming subject, your teaching a class.

I'm all for it. Honestly I will never, ever use any of this. But you have a lot of knowledge and I like to know what more you have in store and willing to give up.

[SlowerThanYou]

Slower, are you a teacher or something?

 

I served this great country for 26 years (now retired). A good majority of that time was

teaching/speaking. The Air Force provided me a very good education/experience. There was even a program started & still may have it. Called Troops to Teacher's, for troops getting out to become a school teacher. I really wanted to do that, but I don't have the patience for todays children. Hope that gave a little insight.

 

I took it as arrogance at first, but he's really just trying to share info to make everyone faster. But he does make every post sound like a syllabus. Lol.

 

J-M, I can be very arrogant & most times I don't care what people think on forums. I'm trying to tone down my attitude, but it still comes out from time to time. Forums can be a little harsh. I tend to be more offensive than defensive when it comes to the HQ Circus. There are very few I give respect to & I'm sure that goes both ways.

 

You are right, for the most part I'm trying to pass along a little elderly teaching. If someone wants to use my information or not, it's all good with me.

 

At 1st you didn't know where I was going with this thread & I didn't know exactly either. I assumed the 1st few subjects wasn't going to generate much discussion, but it laid a foundation. Now the thread is starting to get some interaction. How far it goes or how long it last is dependent on the participant's; as with all good learning!  Plus, I'm learning from it also. 

 

ive had classes taught like this. When I saw the break down, the question, to the upcoming subject, your teaching a class.

I'm all for it. Honestly I will never, ever use any of this. But you have a lot of knowledge and I like to know what more you have in store and willing to give up.

 

In my opinion, the forums is very hard place to do something like this. That's part of the reason I'm doing this. Challenging myself, but at the same time passing along some of my 30+ years of drag racing. 

 

There are two other threads that pass along a bunch of information.

 

My baby is the Lock-out/Lock-up Tuning Thread. As far as I know, I'm the 1st to openly discuss ATV clutch tuning.

 

The 2nd is: 10mm DMX Testing Thread. That one surprised me the way it took off. The thing about that thread is it's not scripted/syllabus. Peeps are getting that information good or bad. No BS, just how/when it happens. 

 

Where will this thread go or the other 2 above. Like I said, "How far it goes or how long it last is dependent on the participant's".

[#1JUANstunna]

Is their a standard for how far off the ground the pre-stage and stage beams are or is it a user preference?

[SlowerThanYou]

Is their a standard for how far off the ground the pre-stage and stage beams are or is it a user preference?

 

For most asphalt tracks there's a standard, but a lot of time they aren't checked on a regular basis. For the big races like the NHRA Divisionals & Nationals. I'll provide an article below.

 

As for the 300' sand/dirt, I know of no rules. There should be some, but it would be hard, but not impossible with the grooming of the surfaces.

 

 

 

"It's the end of June and seven races since my last column. There has been a lot of racing, every type of weather (except snow), and a whole bunch of happenings and activity in and around the starting line.

Many of the safety issues I've discussed have improved, but some need further attention. One of the basics concerns the pre-stage and staging beams. There is no mystery about these beams that activate the pre-stage and staging lights, but I hear and read so much that is incorrect about width, height, and how to check rollout.

Two infrared beams are 11 1/2 inches wide with a 4 1/2-inch overlay. The beam height is 1 9/16 inches. These measurements are checked daily and maintained to the fraction of an inch. A 22-inch wheel and tire are used, and the measurements are made twice, in each lane, where the front wheels are positioned to the left and right in the middle of the groove.

After activating the pre-stage beam, a driver must move forward 7 inches to activate the staging light. To turn the pre-stage light off, a driver must move forward another 4 1/2 inches, leaving 7 inches to move out of the staging beam.

Drivers who stage carefully, consistently, and use the pre-stage light to locate their front wheels to utilize the consistent rollout will have 11 inches every run for consistent reaction times and elapsed times.

Deep staging is not allowed in the Super categories, but it does occur in all other categories some of the time. A few racers deep stage on purpose, and others just go in too fast or not carefully. The disadvantages of deep staging are a 40- to 80-percent reduction in rollout, which causes many red-lights; elapsed-time readings that will vary depending on how deep you're in; and the responsibility of staging first, because when both staging lights are activated, the starter believes that the drivers are ready.

Keep in mind that some tracks are using an auto-start system, though not at national events, and the computer is programmed to respond to the staging light coming on. Why do some people deep stage? You've got me.

A shallow stage is another way to get a big red-light. A driver will go in very slowly and stop at the slightest hint of activation of the staging light. If the staging beam has a front tire in 1/16-, 1/8-, or 1/4-inch, remember that is all the movement required to pull the front wheel back out of the beam. Torque from bringing up engine rpm can pull the front wheels back a small amount, especially on full-bodied, sprung cars.

Big rear slicks have more bite than treaded, small front tires, so you know what moves. My suggestion is to stage solid on each run, about 3/8- to 1/2-inch, so the shallow-stage red will not get you. I hope this explanation will keep a racer from ever saying again, "How could I have backed out of the light? The car didn't move!"

The staging light "rocker" is similar to the shallow stage except that the rocker is caused by the driver bumping in (using a quick and hard brake) and not going in smoothly. The rear slicks' sidewalls will wrinkle enough to allow the front tires to go in the staging beam and activate the staging light. As the car settles down, the racing slick will straighten out and may pull the front wheel back enough to cause the staging light to go off, and if the Tree is activated, a red-light results. Stage smoothly and carefully on each run, and be consistent.

While on the subject of staging, I'll define courtesy stage. The last paragraph of page 202 of the 1999 NHRA Rulebook states, "When staging for any of the Super categories, both contestants must activate their pre-stage lights before either may advance into the stage beams." If a driver lights both the pre-stage and stage lights before his or her opponent has the pre-stage light on, the starter will hold up the car not pre-staged, then back the driver out with both lights on and warn him, "Only the pre-stage light is to be on until the opponent lights his or her pre-stage."

If a driver lights both pre-stage and stage a second time before the driver in the other lane lights his or her pre-stage (not observing the courtesy stage rule), the driver will be disqualified if it occurs in eliminations.

While on definitions, try a "wheelie red." If a race car's first move is not forward but "popping," or raising, the front wheels up more than 1 and 9/16 inches, the car is out of the beam. The driver has lost about 9 and 7/16 inches of expected rollout, usually resulting in a red-light. The first move should be forward, not up.

A safety issue that needs to be brought up again concerns crewmembers who leave the starting-line area without looking both ways to make sure that cars are not leaving the burnout box or backing up from burnouts. Treat the racetrack like a busy freeway, and do not cross until it is clear.

Drivers who look over at their competition will sometimes move the steering wheel in the direction they are looking (toward the centerline) and get out of the groove. The problem is not the track condition but of getting out of the groove and not paying attention to keeping the race car in a straight line. Keep your priorities straight!

After having discussed definitions in this column, I offer these: To react is to respond. To anticipate is to expect. Drag races are won by driver reaction time and car performance, not driver anticipation and car performance. If a driver expects or anticipates a green light at exactly the same time run after run, he most likely will end up with a red-light and a loss. React to the amber lights coming on to win. 'Nuff said.

Thank you for the great communication, and keep it coming. I hope to see you at an NHRA national event real soon. Go straight, run quick, and stop safely."