thinking about trying the 4.10 ratio

[Craig 94 TA GT]

Hey Kevin, firstly, where did you get your info? If drag strips work that way nowadays (I wouldn't know how though...), then cool.
However, as far as I know and have researched, drag strips calculate the trap speed by giving the average speed of the last 66 feet. Yes, the average, hence the word "trap" not "top". You do not need 4 beams to calculate the average! Once you cross the first beam, the timer starts. Once you cross the last beam, the timer stops. Then you have, x number of seconds you were in the traps. Using this number, we get the average speed.
If the actual top speed can be calculated the way you said, then we wouldn't even need a beam 66 feet before the finish line. This is because we know the distance of the starting beam to the finish line, right? If we consider the starting beam the "first beam" and the finish line the "last beam", we still cannot calculate the top speed because it would be the average in the 1320! Believe me man, I didn't minor in math for nothing
You have to remember that all cars have different acceleration, where some are closer to linear, and others have clearly different growth rates. This is why the actual top speeds cannot be read unless you had a radar at the finish line.
BTW, this is what G-Tech uses as to what they claim sets them apart from the drag strip. It actually attempts to calculate the real top speed at the finish line, not the average speed at the traps.

[fastTa]

Craig do not make the mistake of confusing speed, velocity, and acceleration, which is precisely what you are doing. You are correct about their being "average" correlated to the mathematical computations of the trap computers and that is the average of acceleration. Dust off your old math books and look up the words "speed, velocity, and acceleration" it will swiftly end our argument. "Traps" are called traps because of the fact that they "trap" the elapsed time between beams, duh. "Top" speed is a term reserved to automobile testers who are referring to the maximum speed a vehicle can obtain once "acceleration" has ceased. Come on dude this isn't hard.

BTW my neighbor was an NHRA track director for 10+ years, I asked him this question just to make sure, and he of course verified my argument.

Believe me man, I didn't minor in math for nothing...

No offense Craig but maybe you did?

[Craig 94 TA GT]

Ouch, turning into an insult lol

Is anyone else reading this?? Are you kidding me? No offense or anything but ????

This is simple physics and math man. I know you will keep on insisting that I'm wrong and you're right, so I'll start adding quotes instead of explaining it myself..

This one is from Injuneer...
"Yes... it is true that your trap speed is the average over the last 60-ft."

"And to add a little more info... for just about every class of vehicle, the difference between the 'actual speed at the finsih line', and the NHRA 'average over the last 66-feet' is not very large. For cars running 100mph, and pulling 0.20 G's (typical of many LT1's), the difference is only about 1 mph.
OldSStroker is right... it used to be measured before and after the actual finish line, and it was changed because the big dog top fuelers and funny cars were delaying braking and chutes to pick up that extra couple mph. As you probably noticed from the past weekend NHRA Pomona on TV, the top fuel dragsters are having difficulty stopping before the sand traps with loss of chute or brakes......."

So there is only a small difference between the two "speeds", but there still is a difference. Maybe 1 MPH at the most, but 1 MPH is still 1 MPH.

Now if you were to measure the differences between 2 acceleration stages, you would need 4 trap sensors.

Dude, you can insult me or argue this thing to death with me, but before it goes on, ask anyone on this board and they'll agree with what I'm trying to say. So please, if I'm wrong, I'll owe you a brewski ok??

[fastTa]

Corona with lime

Did not mean any insult. Just a very commonly misunderstood principle.

[Craig 94 TA GT]

Thanks for the reply...I did work hard on my math minor so obviously if someone makes a remark about something that was worked hard for is gonna feel a little offended, right?
Anyways, we still have to remember one thing...we are not Mudstain owners lol

Here, let me try once more...if I understand your concept correctly, you're saying that using the two beams, we are able to calculate the exact MPH (speed) when you cross the second beam - the finish line. If this is so, try to imagine this... a car that crosses the first beam at 100 mph, and the second beam at 100 is going to measure 100 mph, right? I think we'll both agree on that. However, say theoretically a car goes through the traps at an evenly distributed acceleration (linear). It crosses the first line at 97, then the second at 103. Again, being that the MPH is evenly distributed the 2 cars will have the exact same time measured over the trap. Thus, they will have the same speed. However, the first car crossed the finish line at 100, while the second was 103. But the time between the traps will say 100 MPH. Thus, it is the average speed, not the average acceleration. Just my thoughts.

[fastTa]

Sounds good, but herein lies the flaw in that theory. We no doubt know that the average of the two speeds 103 and 97 equates to 100, however until NASA or another Einstein figures a way to measure speed here on earth without the use of a doppler shift measuring device(radar gun) or a laser gun, we must rely on current measurement methods. (A laser speed gun measures the round-trip time for light to reach a car and reflect back. Light from a laser speed gun moves a lot faster than sound -- about 984,000,000 feet per second (300,000,000 meters), or roughly 1 foot (30 cm) per nanosecond. A laser speed gun shoots a very short burst of infrared laser light and then waits for it to reflect off the vehicle. The gun counts the number of nanoseconds it takes for the round trip, and by dividing by 2 it can calculate the distance to the car. If the gun takes 1,000 samples per second, it can compare the change in distance between samples and calculate the speed of the car. By taking several hundred samples over the course of a third of a second or so, the accuracy can be very high.) My point here is even a laser gun uses an average speed therefore arguably technically inaccurate. Each trap beam does not have the unique ability to measure speed on it's own therefore nullifing any proposed averages. We know as humans that there is without a doubt a difference in vehicle velocity within the 66 feet of the 2 trap beams, but since speed is simply distance over time the trap speed calculations are oblivious as to whether a vehicles's acceleration is linear or not. So even as accurate as a radar gun or a laser gun may sound, they ironically are the ones that use a coefficient of averages to determine speed. This is why NHRA uses a trap speed type device. It provides irrefutable data.

[fastTa]

Craig how did we go from talking about a rearend to a physics debate
LOL

[Craig 94 TA GT]

Good stuff....
But firstly, I said the 2nd car was theoretical. It is nearly impossible to tell exactly how the distribution on the graph looks like, however, it is still possible. Remember here, physics is not of what has been measured, it is mathematically proven with formulas. So again, theoretically, an accelerating machine that has an even distribution of 97-103 mph will average 100 mph, thus having the same time of a machine travelling at a constant velocity, 100 mph. The 2 have different top speeds. By top, as before, I mean the top speed in the distance x given.

Now I'll take a look at the simple speed formula itself. Speed is the distance traveled per time length given. OK, so we're given time, right? The time is calculated by starting when the wheels break the first beam, and stopping when the wheels break the second beam. We are also given distance, which is 66 feet in this case. Say it takes 2 seconds to accomplish this, so we are going 66 feet/ 2 seconds, or 33 feet / second. That is the speed, right? Now I believe we're arguing that...you're saying this is the speed when the car crosses the second beam; I'm saying this is the average speed between the two points. Before we get into using and proving more formulas, let's take a longer distance and imagine it. Say someone takes a road trip from San Francisco to Los Angeles. That's 400 miles. Say it takes 7 hours to reach point A to point B. Thus, they're travelling at 400 miles per 7 hours, or ~57.14 MPH. Now if the driver wishes to slow down to a crawling 2 MPH at the finish line, his time will go up to say 7 hours 5 minutes depending on how hard he or she was braking. So now his speed is 400 miles per 7 hours 5 minutes, which is ~56.47 MPH. But he crossed the finish line at 2 MPH, thus it brought down the average speed a bit, but not the actual "finish line speed" to 2 MPH. This is the exact same concept as the 66 foot time calculation....just simply using the speed = distance/time formula.
Let me know your thoughts....

[Craig 94 TA GT]

lol, I guess it's late and we're tired and needed something better to do than drool at more mods lol. At least that's my point of view!

[Joe 1320]

Just to clarify something..... The two timing beams measure the time it takes for the tires to break the first beam and then travel to the second beam. Since we are doing an acceleration run, the car is accelerating , the speed that is displayed is an average speed not an averaged speed. Therin lies the misconception. It would be easier to comprehend this if we look at a top fuel or fuel coupe. There is often a 7 mph difference in their speed from the time that they break the first beam and the the time they break the 2nd beam. If an average speed wasn't targeted, the beams would only need to be a foot apart. Are they? no way. All those timers are displaying is the time it took to break the beams and it shows that as constant. Speed is calculated by distance over time and is a consistant unless the object is accelerating or decelerating. The speeds are not averaged from the speed at the first beam and the speed at the second beam, they are an average speed that given a certain acceleration constant, should occur at midpoint between the two beams.

Got it?

[Injuneer]

If you do the math, for a 100mph car pulling 0.20 G's over the last 66-ft, the difference between the average speed over the last 66-ft and the actual velocity at 1,320-ft is less than 1 MPH. You can also demonstrate there is not a whole lot of difference for a Top Fuel dragster running 300mph and pulling over 1 G in the traps.

[Injuneer]

Originally posted by N20LT4Bird
When I go through the traps in 4th gear, I am cranking around 6400 - 6500 rpm and I am doing just under 120 mph, thats with a 3.73 gear.

My guess is you actually have the 4.10's already.

[N20LT4Bird]

Originally posted by Injuneer
My guess is you actually have the 4.10's already.

Hmm....never thought of that. I bought the car with the gears done already. The guy told me that they were 3.73's (he had them done by somebody else) , but I have not had the cover off to check. However, when i bought the car it was an automatic and had no spray. So, I dont know why he would put 4.10's in the rear. But, I guess im gonna have to pull the cover and see.

[Joe 1320]

Originally posted by Injuneer
If you do the math, for a 100mph car pulling 0.20 G's over the last 66-ft, the difference between the average speed over the last 66-ft and the actual velocity at 1,320-ft is less than 1 MPH. You can also demonstrate there is not a whole lot of difference for a Top Fuel dragster running 300mph and pulling over 1 G in the traps.

Absolutely except in cases where you are dealing with less than expected parameters. You lose a cylinder and you are already in the decel mode as you cross through the traps, it's the negative that wreaks havok on mph average. Same in the brackets if you are hard on the brakes to avoid breaking out. Nasty things, those sanctioning rulemakers.

[fastTa]

Interesting stuff to say the least....but I would have to agree with Injuneer in that I wouldn't imagine there would be much difference in mph between trap beams with a top fuel dragster simply because they are so precisely geared to reach their peak acceleration right at the traps. What do you think? My $.02