Well I broke out the old G-Tech accelerometer today since my break in is over and thought I'd go get a baseline 1/4 mile time. Just for reference.

Now yes I know the G-tech isn't the same as the system at the track but it gives a person an idea what they have and if any mods they do give improvements. And I do know the trap speed on the G-Tech always registers about 7 to 8 mph high. But that would correspond to a 102.8 to 103.8 trap speed which is close to what the magazines have been getting.

I also know it starts timing the instant you accelerate, much like cutting a perfect start on the tree at the strip.

So 13.68 @ 110.8 (actually 102.8 to 103.8) mph as a baseline.

Breakdown:

Temp. about 75 to 80
Humidity: not bad, not good
Wind: a very slight tailwind
1/3 tank gas and just myself onboard
Showroom Stock (no mods!)

Turned TC off, everything else off too including AC
Put shifter in D
Braked torqued to 1500 rpm
I also had some moderate wheelspin on launch (no wheelhop!)
Feathered the throttle during the wheelspin then WOT
(I missed the 0-60 time during the run, would have been interesting but I was concentrating on keeping the Goat straight)

I was mildly pleased. All these low 14's I've been hearing the magazines run and some people at the strip too and I was getting worried a little. So I figure not too bad for a first time. Maybe after the engine loosens up a little (only 650 miles right now) it will have a little more. Plus I didn't try any of the other little tricks. I went on stock tire pressures, (could have dropped the rears down to aid traction and inflated the fronts more to reduce rolling resistance), ran with the jack and spare, floormats and I had been driving for about 15 minutes and the engine was getting warm. Would have been better if I had let it cool, drove for 5 minutes then ran.

And just as a comparison, the best time I ever ran on my G-Tech in the GTP was a 14.66 @ 101.5 (probably 93.5 to 94.5) mph. And I remember some of the first runs I made in the GTP
were like 15.1 or 15 flat. I got better over time with it so I figure I'd be able to trim some time off the 13.68 on the GTO over time with a few basic tricks.

So there's my run. I didn't run a second as the usually traffic free area of straight road I run on suddenly got busy. Anybody else run some G-Tech times? I know it's not as good as a real 1/4 mile timeslip but it's about as good as I can get in my area, with no 1/4 miles tracks (we have an 1/8 mile close) and not a lot of time to go racing either.

Way cool, OO!

Just as a "by the way", I've seen elsewhere that people are recommending sticking the car in "3" rather than "D" to bypass some of the torque management stuff. You might give it a try and see if it makes a difference for you.

Ahhh...you finally got your baby broke in! Nice run. ;)

Nice, its good to see the auto doesn't slow the car down at all.

Originally posted by Nocturn@Aug 5 2004, 06:28 PM
Nice, its good to see the auto doesn't slow the car down at all.
Yeah, I'm starting to have second thoughts about getting an M6.

BTW can anyone explain how the A4 "launch mode" works? I guess it sits down an inch when put into drive. That's the coolest thing I've heard about an automatic. B)

Thanks guys, I bet with a few little "race day" tweeks (tire pressure, no spare and jack , icing the intake) I could cut off 2 tenths. That run was made on a 2 lane road also, not a race prepped track. I know my tires had a lot of dust on them as well as the road itself. If I could hook it up better I know I could knock off a tenth.

BTW can anyone explain how the A4 "launch mode" works? I guess it sits down an inch when put into drive. That's the coolest thing I've heard about an automatic.

I'm still not sure of the mechanicals behind it. You must have your foot on the brake as you shift from neutral to drive. If you don't have your foot on the brake it won't do it. It is pretty sweet.

Just as a "by the way", I've seen elsewhere that people are recommending sticking the car in "3" rather than "D" to bypass some of the torque management stuff.

I thought about that actually. When I'd run my GTP I'd always run in 3rd as opposed to Drive. Next time I G-Tech it I'll try it. And wouldn't you know like an idiot I forgot to see what gear I was in as I hit the quarter mark. I was too busy trying to keep it straight and looking down the road to make sure there were no rabbits or woodchucks or DEER jumping out in front of me. :blink:

I'm thinking 4th by the feel of it now that I think about it. I wonder if staying in 3rd would keep me in the powerband at the end of the run.

I'm just happy it was in the 13's. I was really worried it would be low 14's. And this truly was my first run on the G-Tech. I'm not sandbagging some lousy 14 second times that "didn't count".

I'll keep anyone interested posted next time I make a timed run. Anyone else out there with the G-Tech or some other accelerometer??

Originally posted by Orbit Orange@Aug 5 2004, 08:57 PM
I'll keep anyone interested posted next time I make a timed run. Anyone else out there with the G-Tech or some other accelerometer??
I don't have one but I have been toying with the idea. I think I'd enjoy it. I'd be interested in what experiences other forum members might share about accelerometers..

Originally posted by Orbit Orange@Aug 5 2004, 03:33 PM
I also know it starts timing the instant you accelerate, much like cutting a perfect start on the tree at the strip.
The timer at the strip doesn't start until your car crosses the lights. Not when the tree goes green. You could sit there for 30 minutes after the green, then go, and still run the same 1/4 mile time. Just the R/T would be horrendous.

Originally posted by kevm14+Aug 6 2004, 10:02 AM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (kevm14 @ Aug 6 2004, 10:02 AM)</td></tr><tr><td id='QUOTE'><!--QuoteBegin-Orbit Orange@Aug 5 2004, 03:33 PM
I also know it starts timing the instant you accelerate, much like cutting a perfect start on the tree at the strip.
The timer at the strip doesn't start until your car crosses the lights. Not when the tree goes green. You could sit there for 30 minutes after the green, then go, and still run the same 1/4 mile time. Just the R/T would be horrendous.[/b][/quote]
That's what that means. Starting the instant you accelerate is basically the same as starting when you cross the light. Ala you can't accelerate without moving.

You could sit there for 30 minutes after the green, then go, and still run the same 1/4 mile time. Just the R/T would be horrendous.


I bet the track officials wouldn't be to happy with that. ;)

Maybe you guys could answer another quick question. I've heard that at the strip the trap speed that is given is actually the average speed over the last 60 ft. of the run. Is this true?

The G-Tech of course is actually giving you the ACTUAL speed at the end of the 1/4 mile distance, thereby the discrepancy between the two.

Is this correct?

There is a beam 60 ft before the finish and 60 ft after the finish and they calculate the speed by dividing the 120 ft by the time you take to cover that distance to get what your average speed at the finish line was. Note that this means if you don't run hard 60 ft past the finish line your speed will be lower.

Thank you! :)

How much $$$$$$ for a G-Tech??? :huh:

That thing sounds like a load of fun.

I've got the older version which I bought about 3 years ago. It ran me about 150 bucks at the time. It can also give you lateral g's, 0-60 and 60-0 braking distance, and an approximate rear wheel horsepower reading (haven't tried that one since you have to input weight for a correct measure). There is a newer version out now that has a lot more "bells and whistles" on it. I see it is 250 bucks in the Jegs catalog. I'd really like to have it over my older version as it is battery operated and mine I have to plug into the power outlet. Evidentally you can also plug it into your computer and download data from your runs too. Pretty cool.

Do a little shopping around and you might be able to pick one up. Heck try E-bay as somebody might have to get rid of theirs and you could get it for a fraction of the price.

G-Tech Pro Competition Meter is it's name.

Hope that helps.
:)

Originally posted by Orbit Orange@Aug 6 2004, 11:42 PM
[QUOTE]
...The G-Tech of course is actually giving you the ACTUAL speed at the end of the 1/4 mile distance...
Any accelerometer is actually going to use sampled acceleration measurements (that's all it does, remember) and the number of seconds it has been counting and do some arithmetic to calculate about how fast you are going and how far you've gone.

There is, by the way, no such thing as an instantaneous measurement...

AAAAAAAAAGGGGGGGGHHHHHHHHH!!!!!!!!!!!!!!!!!!!!!!!!

gto_in_nc just induced unwanted p-chem / quantam physics flashbacks! And first thing on a monday morning at that! You may just have ruined my whole week...

Dan

Sorry, Dan! Hey, I avoided detailed error analysis and talk of partial differentials and the whole "significant figures" issue. I resisted the temptaion to go "back to Newton" and derive equations of motion from first principles.

P.S. - Don't ever ask me why the sky is blue or what makes a rainbow or why bubbles are round or why a hurricane turns counterclockwise or how a mirror works or why a pencil sticking out of a glass of water looks bent or why there's no such thing as centrifugal force or... ;)

Originally posted by gto_in_nc@Aug 9 2004, 10:08 AM
no such thing as centrifugal force or... ;)
It's spelled centripetal :D

Originally posted by forestdweller+Aug 9 2004, 10:56 AM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (forestdweller @ Aug 9 2004, 10:56 AM)</td></tr><tr><td id='QUOTE'> <!--QuoteBegin-gto_in_nc@Aug 9 2004, 10:08 AM
no such thing as centrifugal force or... ;)
It's spelled centripetal :D [/b][/quote]
To be totally accurate, it is spelled "inertia" - but I'm being pedantic (again...) :o

Physicists, sheesh. ;)

Centripetal force (or "center-seeking" force) is the force your tires must supply to overcome the car's inertia in order to make it turn a corner. The tires push against the road in an attempt to accelerate the car radially, towards the certer of the curve. The car accelerates as Newton predicted; momentum being a vector, the momentum changes as a result of the change in direction even though speed (the magnitude of the velocity) may not. All comes back to Newton - a change in momentum is proportional to the force acting upon the body.

(yeah, we can be annoying as h3ll, can't we???)

As opposed to the inaccurate concept of centrifugal force, which should be more accurately stated as a lack of centripetal force..

BTW, I hope everyone knows why the sky is blue. We've all heard that little girl in that annoying commerical over and over and over :)

"Lack of..."? Yeah, I guess in a manner of speaking. Think about it this way, though. I have a weight on the end of a string and I am spinning it in circles overhead. When I have it going nice and fast and smoothly, you hold up a razor blade and cut my string (you b@st@rd!! ;) ) If there were such a thing as centrifugal force - a force pushing the weight to the outside of the circle - the weight would instantly make a right-angle turn and fly directly and radially away from me. Intuitively and from casual observation, however, we know that the weight, instead, would move tangentially, travelly in a straight line in exactly the direction it was moving at the moment the string was cut.

The "observed effect" of centrifugal force that people feel when a car goes around a corner, for example - the sensation of being pressed to the outside of the corner - is actually your brain's interpetation of the unnatural experience of having your body accelerated by a centripedal force. The car pulling you towards the center of curvature is the centripedal force in exactly the same way that me tugging the string is supplying a centripedal force to the weight. The feeling of being pushed to the outside of the corner is the same as the weight would feel (assuming weights have feelings, too.) Centripedal force (supplied by the tires pushing against the road in one case and by a hand pulling a string in the other) is overcoming inertia, changing the direction of the momentum vector of a body in motion.

Looks like we may have to open up a geek section to the forum :D

I fullfiled my obligation by duly warning everyone not to get me started, didn't I??? Y'all thought I was teasing, didn't you? I thought I exercised admirable restraint - and I let that whole "blue sky" thing pass right on by... ;)

Originally posted by forestdweller@Aug 10 2004, 05:58 PM
Looks like we may have to open up a geek section to the forum :D
You are on the internet reading about a car. Depending on who you ask - the whole forum would qualify you as a geek...

Now, as far as physics go - none of the discussions here really bother me. I have issues when i start thinking about physics that are not able to be modelled - only mathematically described (which, being a ChemE I obviously feel makes it more chemistry than physics - but we don't need that debate). It's not that I have a problem with understanding the concepts - it's just that I get so involved that the real world becomes blurred. I had my quantum physics class from like 5:30 to 7pm. If I tried to drive, or even walk across the street, too soon after the class - it resulted in near death experiences because my brain was so removed from the real world. I learned I had to give myself at least an hour 'lull' time after class before I could leave campus.
Dan

LOL! I can definitely empathize, Dan! Just as an aside, Newton's seminal work (other than Optiks, which was huge in its own right) is commently referred to as the Principia but its complete name is Philosophiae Naturalis Principia Mathematica. (Simply amazing what had already been figured out with astonding accuracy as far back as the late 1600s and a fascinating read, BTW.) My point is the name - physics is the study of "the mathematical principles of natural philosophy." Overlaps all over the freakin' place! (And a trail of floating cerebellums along the way... ;) )

Originally posted by gto_in_nc@Aug 10 2004, 07:14 AM
body in motion.
Uhhhhhhh hugh huh huh...he said "body in motion". :hysterical:

Just fugured I'd lighten things up a little. :P

Originally posted by DANSLS1@Aug 10 2004, 03:35 PM
it resulted in near death experiences because my brain was so removed from the real world. I learned I had to give myself at least an hour 'lull' time after class before I could leave campus.

Yeah, discussions of felines simultaneously both alive and dead can really mess w/your head ;)

I went to the university to Goodyear sends their test track engineers for physics brush ups. I've just suffered several flashbacks. Sadly, I think I liked it. :blink:

Now, I not only have to find a 10 step program for GTOholics but a self help program like Geeks Are People Too. :D

Originally posted by gto_in_nc@Aug 9 2004, 12:02 PM
Centripetal force (or "center-seeking" force) is the force your tires must supply to overcome the car's inertia in order to make it turn a corner. The tires push against the road in an attempt to accelerate the car radially, towards the certer of the curve. The car accelerates as Newton predicted; momentum being a vector, the momentum changes as a result of the change in direction even though speed (the magnitude of the velocity) may not. All comes back to Newton - a change in momentum is proportional to the force acting upon the body.

(yeah, we can be annoying as h3ll, can't we???)
Question, does centripetal force take gravity and wind resistance into account? Seems it might work in space where an applied force has no resistance and can continue untill it hits something or gets acting upon by another force.

Originally posted by Nocturn@Aug 11 2004, 02:10 AM
Question, does centripetal force take gravity and wind resistance into account? Seems it might work in space where an applied force has no resistance and can continue untill it hits something or gets acting upon by another force.
In the car turning scenario, gravity and friction is what is providing most of the centripetal force inward, so yes. Although this is not always the case. If you were a passenger in the car, the seatbelt/car door would be the significant provider of centripetal force (for you) since inertia would have you fly out of the car without them.

Exactly. Remember, Nocturn, a force is a force is a force. Remember, too, that forces are vectors (having both magnitude and direction) and as such they are additive. So when you have additional significant forces (such as those resulting from gravity or wind resistance (perhaps both in the case of a high-speed, high-banked superspeedway, for instance?)), the effects of the forces simply add together to give a "resultant force." Kinda like taking the price of something at the grocery store and then subtracting your coupon and your frequent-shopper discount before adding tax to get the final price.

Originally posted by gto_in_nc@Aug 17 2004, 08:00 AM
Exactly. Remember, Nocturn, a force is a force is a force. Remember, too, that forces are vectors (having both magnitude and direction) and as such they are additive. So when you have additional significant forces (such as those resulting from gravity or wind resistance (perhaps both in the case of a high-speed, high-banked superspeedway, for instance?)), the effects of the forces simply add together to give a "resultant force." Kinda like taking the price of something at the grocery store and then subtracting your coupon and your frequent-shopper discount before adding tax to get the final price.
ok proffesor :rolleyes:

Nice quater mile times. Its good to see that the automatic isnt much slower than the 6 speed. These low 14s that keep coming up are pretty sad in this car.

****. I didnt know it could do that. Ill have to get one of those. I have an auto so it should only g one thenth slower than the best runs on the manuals.

My brain is now :frankie: thanks guys <_<

I need some advil now.

I am going to bring this back from the dead - and I don't want to hear any more physics BS TYVM

I have the brand-new G-tech with data logging and all that jazz, it is VERY cool.