Its come to my attention.....

[Feedman]

I have seen a certain movFast member, not mentioning any names....flying down Grand Central around the 10:00-11:00 p.m. I am assuming they were heading to work. Then again last night I saw them racing a red pickup truck...lol.

Just saying I saw you........lol.... :twisted:

[daveb91]

What the......... I have a Neon with a ricey exhaust 40mph sounds like a 300mph gas weed eater. lol
At least I wasnt making G-tech runs at around 100 mph on a public road! :lol:

[Feedman]

ha ha...lol....well you blew your cover.....lol.

I was just giving you a hard time....

Btw...the Gtech calculates the time...I never actually went 103 miles per hour...that would be unsafe, and everyone knows I obey all traffic laws.... 8)

[daveb91]

LOL!! No need to blow my cover I am a straight up guy. The red s10 was pissing me off he kept speeding up and slowing down next to me because you know if I have a fart can I must be constantly looking for a race :roll: and I am not in a good mood when I have to go to work anyways So I got in front of him so I wouldnt have to see him any more.

[RobbieNelson]

Btw...the Gtech calculates the time...I never actually went 103 miles per hour...that would be unsafe, and everyone knows I obey all traffic laws.... 8)

So, your saying it lied? It's usually fairly accurate on a good flat stretch of road.

[daveb91]

G-TECH is a very accurate machine, and the trap speed result that you get from the G-TECH is actually more accurate than the racetrack. Reason is that the racetrack averages your speed over a 60 feet stretch between two beams and G-TECH measures your speed at the exact 1/4 mile point.

Also it uses a accelerometer that measures distance by g's. 1g=32ft/sec so i would think to be accurate you would have to travel a 1/4 mile.

[daveb91]

http://www.gtechproforums.com/forums/

This should also help.

[Feedman]

http://www.gtechproforums.com/forums/

This should also help.

looked it over....didn't see much....?? 8)

[RobbieNelson]

Also it uses a accelerometer that measures distance by g's. 1g=32ft/sec so i would think to be accurate you would have to travel a 1/4 mile.

Close... its actually 32ft/(sec*sec) (32 feet per second squared). The derivitive of Acceleration is Speed and the derivitive of Speed is Distance. Don't want to get into an engineering discussion right now.

If you were using it correctly... you did go 1/4 mile and 108MPH. If you didn't... then, your ET was probably WRONG.

[ShortysTRM]

I've got video of it doing calculations before that many seconds were up and before I hit that trap speed. I wasn't far off, but I never got there. It does the same thing to 60...once it get all the info it needs, it tells you what you run.

[RobbieNelson]

108mph? Where did that number come from?

Gtech numbers were 14.xx @ 103mph. I don't know how close they were, but thats what it stated. No I went with another friend, using it, and when they let off they were @ like 60mph, and the Gtech stated there trap speed was 76mph...? So thats why I was saying that....A little more info please? 8)

This discussion my prompt some Gtech testing this evening. ;)

[jamesN272]

I never actually went 103 miles per hour...that would be unsafe, and everyone knows I obey all traffic laws.... 8)

bahahah http://www.ls2.com/forums/images/smilies/laugh.gif

:mrgreen:

[xjoewhitex]

I would like to G'tech mine when i get this little problem solved.. If that would be ok robbie? :)

[daveb91]

Close... its actually 32ft/(sec*sec) (32 feet per second squared). The derivitive of Acceleration is Speed and the derivitive of Speed is Distance. Don't want to get into an engineering discussion right now.


How dare you ruin my day by talking about derivitives! I have had enough derivitives, Thevenizing , kirchoffs , Ohms law, boolean to last me a life time dont make me have those bad dreams again.

[daveb91]

Since my day has been ruined by robbie i will ruin yours try this equation see how close it is.

ET=5.825*(weight/hp)^1/3

ET=estimated 1/4 mile time
weight= weight of the car
hp=is horsepower

and if you want to try this for your hp

hp=weight*(mph/234)^3

weight =weight of car
mph= mph in the 1/4


Have a nice Day!!!!! :)

[RobbieNelson]

I've got video of it doing calculations before that many seconds were up and before I hit that trap speed. I wasn't far off, but I never got there. It does the same thing to 60...once it get all the info it needs, it tells you what you run.

This is just not true. The time should be DEAD on! From the time it starts counting till the time it stops should match a stopwatch. You guys are probably experiencing the car tilting back at launch and shifting. If the Gtech isn't level for the whole run then you'll get bad numbers.

There is NO estimation of 1/4 ET and MPH. However, there are calulations. Calculation of Speed and Distance based on Acceleration. It has to have an accurate Acceleration of the cars forward direction. If the acceleration due to gravity interferes with it(tilted), then you'll get bad data.

Trust me. :wink:

[Feedman]

I've got video of it doing calculations before that many seconds were up and before I hit that trap speed. I wasn't far off, but I never got there. It does the same thing to 60...once it get all the info it needs, it tells you what you run.

This is just not true. The time should be DEAD on! From the time it starts counting till the time it stops should match a stopwatch. You guys are probably experiencing the car tilting back at launch and shifting. If the Gtech isn't level for the whole run then you'll get bad numbers.

There is NO estimation of 1/4 ET and MPH. However, there are calulations. Calculation of Speed and Distance based on Acceleration. It has to have an accurate Acceleration of the cars forward direction. If the acceleration due to gravity interferes with it(tilted), then you'll get bad data.

Trust me. :wink:

If I understand you correctly, the car cannot tilt back during launching or shifting or the calculations will be skewed....then how are you supposed to get a fair speed.....granny clutching and bogging the launch?

Also, since different cars take different amounts of times to cross the 1/4 mile mark, it would have no idea what to count? So it must take a measurement based on your accleration, find a constant, smooth the map some, and give you a reading.....

Still....we need to find a definate answer.... 8)

[Davis Silver Sti]

Still....we need to find a definate answer.... 8)

yea, take it to the track:)

[daveb91]

To get a true reading you would have to go a 1/4 mile. It knows when you have gone that far because the accelerometer is measuring your distance by calculating the g's. Also if you read any of the gtech sites it says if your car makes monsterous launches it could foul the reading. I doubt your making monsterous launches. You just have to make sure its sitting close to level.

[Feedman]

To get a true reading you would have to go a 1/4 mile. It knows when you have gone that far because the accelerometer is measuring your distance by calculating the g's. Also if you read any of the gtech sites it says if your car makes monsterous launches it could foul the reading. I doubt your making monsterous launches. You just have to make sure its sitting close to level.


boyyy...my car is the defintion of monsterous ...lol....

That settles it...track day it is....when....... 8)

[daveb91]

How does it work?
The heart of the G-TECH/Pro is a precision silicon accelerometer. An accelerometer is a sensor that measures acceleration, also known as G-Force. G-Force is what's keeping you in your seat as you are reading these words and if it wasn't for the seat you would be accelerating to the ground at 1G (32 feet per second per second).

G-TECH/Pro measures your speed and distance traveled by integrating acceleration over time. Basically, if you know how fast you are accelerating for a certain time period you'll know how much your speed has changed after that time period. So, if you start of from zero speed then you'll know what your speed is after every time period. These time periods are very small (2.5 milliseconds) and that's how G-TECH/Pro maintains its accuracy.

Distance is measured in the same fashion, if you know how fast you are going for a certain time period you will know what is the distance traveled during that time period.

G-TECH/Pro also measures delivered Horsepower, sometimes called Rear Wheel Horsepower. This horsepower includes the loss of power through the drivetrain which is usually 10-15%. The formula for Horsepower is speed times acceleration times the weight of the vehicle.



Why is my G-TECH/Pro consistently 2-3 mph above the track?
G-TECH/Pro is a very accurate machine, and the trap speed result that you get from the G-TECH/Pro is actually more accurate than the racetrack. Reason is that the racetrack averages your speed over a 60 feet stretch between two beams and G-TECH/Pro measures your speed at the exact 1/4 mile point.



The bracket tilts up and down so that the G-Tech can be made as level as possible. Because the unit measures G forces, if it is not level it will "feel" the gravitational pull of the earth, skewing the results.



I can find more its easy you use this little function called Google!

[Feedman]

Nice job Dave....still a little unsure if you have to drive the whole 1/4 mile or it can calcuate the distance and give you an accuare prediction?

me not good at using teh intraw3b.... 8)

[daveb91]

I pwn3d yo!

[Feedman]

I pwn3d yo!

umm...okay. 8)

[daveb91]

Ok, man this thread got turned around. :D Alright Adam i just emailed the g-tech support asking the 1/4 mile distance question I will let you know!

[Feedman]

Ok, man this thread got turned around. :D Alright Adam i just emailed the g-tech support asking the 1/4 mile distance question I will let you know!


lol....Sounds cool dude. I was just curious...sounds like you are as interested as I am...

Thanks buddy.... 8)

[RobbieNelson]

Nice job Dave....still a little unsure if you have to drive the whole 1/4 mile or it can calcuate the distance and give you an accuare prediction?)

Yes, you must do the whole 1/4 mile. How the hell else is it going to do it.

BTW... earlier I stated that it took the direvitive of the Acceleration. I screwed up... It integrates the Acceleration.

Lil rusty on my Calculus.

[xjoewhitex]

I so got Ignored :cry:

[RobbieNelson]

I would like to G'tech mine when i get this little problem solved.. If that would be ok robbie? :)

Sure! I'd like to attend to get it working properly.... If you don't mind.

[xjoewhitex]

I would like to G'tech mine when i get this little problem solved.. If that would be ok robbie? :)

Sure! I'd like to attend to get it working properly.... If you don't mind.

sounds good to me, also thanks for replying :D