Gtech Results In - Page 2

302 LX Eric · 04-17-2001, 09:12 AM

Good points,Rev

I guess if the G-tech is consistent, then it would be good for monitoring items mentioned in your post.

E

sedanman · 04-17-2001, 03:53 PM

We used the Gtech at the track and it always came within about .1 of a sec, sure the MPH measuring is different. Like rev said it is a great tunning tool.

Lizard King · 04-17-2001, 06:59 PM

I usually try to get a cop to get my MPH ... hehehe

04-17-2001, 07:33 PM

I have one real quick question, but it doesn't really have anything to do with a GTech, at all. But anyways...If I beat a car by about 3-3.5 car lengths in a 1/4 mile, about how much difference would be in our times? I know this changes with your speed, but a rough estimate would be nice. Thanks in advance.

------------------
'69 Coupe with 351W
=========================
Edelbrock Performer-RPM intake manifold, Edelbrock Performer-RPM cam, Edelbrock lifters, Edelbrock 750 cfm carb, Accel coil, Moroso Blue-Max spark plug wires, Hedman headers, 2 1/2" pipe, glasspacks, Edelbrock double roller timing chain, Edelbrock valve springs, Flex fan, C4, Lakewood traction bars, 3:1 open rear-9" 3.89:1 posi coming this summer
=========================

Rev · 04-17-2001, 09:08 PM

If yor trap speed is around 100mph, each car length will be about .1 second.

Rev

------------------
'66 Coupe, 306, 300 HP, C-4, 13.97 e.t., 100.3 mph
1/4 mi.

john_86stang · 04-20-2001, 11:11 PM

I agree with Rev my G-Tech is a great tuning tool, because the track is so far away. It is nice to go out and let her eat after small mods: tires whatever then you know if it's any better. Just my .02.

------------------
John Welch
86 GT, 3.73's, H-pipe w/ 2-chamber Flows, No smog pump or A/C, crank pulley, K&N in stock box, adj. FPR, bypassed EGR(coolant) Best Run 14.34 @100.0 MPH (on G-Tech)

Nitrous Al · 04-21-2001, 08:27 PM

Is the Gtech worth the money or not?

Lou Lyman · 04-24-2001, 05:36 PM

Sorry to be ignorant on this subject but what is GTech? A software program, timing trap lights, what? Approximate cost? I'm new to this but trying to educate myself. Thanks.
Lou.

QuantumMotorsports · 04-24-2001, 10:38 PM

A GTech is a small electronic accelerometer that mounts in your car (on the windshield like a radar detector) and measures acceleration and elapsed time to come up with a 1/4 time. They are only as accurate as the accelerometer used in their circuit. The math they use is very accurate so like I said they are only as accurate as their accelerometer and timer can be. As far as GTechs or track times being more accurate, Unit, your math makes sense, but every car is different, that is why people say their GTechs are consistantly off. Every engine has a different torque curve and therefore a different HP curve. So, when you say that a car in 3rd gear will accelerate at a lower rate than the car in 2nd gear, you're correct, assuming that the torque curve of the engine is flat (a constant) This is only true for electric motors, hardly ever for a gasoline internal combustion engine. So, the mph change in the last 60 feet would be different for a car crossing the traps in it's power band and a car not in it's powerband, for instance, with my gears, I shift into 4th about 300 feet in front of the 1/4 mile. So I am crossing the traps at about 4000 rpm, I would accelerate differently in the 60' in front of the line than a car crossing at 6000 rpm. Therefore the difference between average speed over the 60' and instantaneous speed at the end of the track will be different for every car. In other words, the track will be off by a different amount for every car. Now, I feel that I must make a statement about somthing that someone else said. Something about being able to get actual speed with a radar gun at the end of the track. Did you mean instantaneous speed? speed is defined as the (change in distance)/(change in time). Instantaneous speed is defined as the speed when the change in time = 0. Everyone knows you can't divide by 0 so it is impossible to measure instantaneous velocity, unless you use calculus which is what a GTech uses. When the GTech integrates to get velocity the margin of error becomes exponentially greater, so if the accelerometer is off by a small bit, the velocity will be off by a lot. Anyway, like I was saying, even with a radar gun, you are by no means measuring instantaneous velocity. The radar gun measures doppler shift. The change in frequency of a wave when it hits a moving object (listen to a car horn as the car is moving towards and then away from you, it's higher and it gets lower as it goes by right?) doppler shift. Anyway, the radar gun knows the wavelength of it's sent signal, it measures the wavelength of the received signal, and subtracts them. Which is still measuring a distance over time. So anyway, even though a radar gun is more accurate than a 60' average, it is still an average. My main point here is, nothing is 100% accurate, and all of this is for fun anyway guys, so GTech times, track E/Ts whatever, believe what you want about accuracy, it's all relative.

Oh yeah, Lizard King, what does the weight of your car have to do with a GTech measuring a 1/4 mile time?

[This message has been edited by QuantumMotorsports (edited 04-24-2001).]

Lou Lyman · 04-25-2001, 01:39 PM

Thanks Quantum,

I found their website: http://www.gtechpro.com Price is $139.95
for the new (pro) model. Will upgrade origional for $40.00 Unit mounts to windshield and plugs into cigarette lighter. As long as it stays consistant seems like a great tool to have despite all this controversy.

Lou

Unit 5302 · 04-25-2001, 06:41 PM

The proper shift into the next gear should hold your acceleration curve nearly perfect, Quantum.

Sure your car will be making more torque at 4000rpms than 5500rpms, but I'm willing to bet the loss of torque multiplication due to a higher gear in the tranny will offset this. If you are shifting properly, it most certainly will.

From everything I've seen the Gtech's seem to be a pretty consistant 3-4mph off.

QuantumMotorsports · 04-25-2001, 07:06 PM

So you're trying to tell me that in each individual gear your acceration is a constant? Even though engine RPM is changing and when engine RPM changes your torque changes. Then why not run each gear to the rev limiter even on a stock motor? After you pass peak HP you will reach a point where your acceleration will be greater in a higher gear. My whole point is, the track times will be off by a different number for every car. And since the track times won't have a consistent error for every car, neither will the GTechs. I'm sure that there is some car that could run the 1/4 with a GTech in the car and the GTeck would match the ET and MPH exactly. It depends on the car. And given the amount of variables that are present when running a car down a track, you're never going to be able to accurately calculate acceleration. And using an average is not helpful because the range is so large and you are making a calculation of error using one end of the range (the end of the track)

About the change in RPM and difference in gear ratio. Not all engines make more torque at 4000 RPM than they do at 5500. My whole point is, without knowing the torque and power curves of the engine, you cannot accurately calculate acceleration.

------------------
Michael Black
Quantum Motorsports
Norman, Oklahoma

1988 Merc Cougar 5.0 HO, Ported and Polished E7TEs, 2.25" duals w/ 2 chamber flowmasters, T5 tranny
New E/T!!!
14.626 @ 94.94mph, 2.194 60' time, a little better than last time. Keep in mind this thang is heavy (3590lbs) Finally 14s!!!!

Rev · 04-25-2001, 07:37 PM

The G-Tech claims to check G force about 100 times a second. From these numerous samples, it calculates speed at any given instant. Since time is determined by a pretty accurate clock, the mph and distace can be pretty accuretly determined at any given instant. These "averages" are from one 1/00 second to another. That's the only reason these gadgets work as well as they do. The fact is that the G force meter works pretty well due I think to space exploration developement.

Rev

Rev

------------------
'66 Coupe, 306, 300 HP, C-4, 13.97 e.t., 100.3 mph
1/4 mi.

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04-17-2001, 09:12 AM	#21
302 LX Eric or '331 LX Eric' Join Date: Jan 1999 Location: Columbus, Ohio Posts: 2,142	Good points,Rev I guess if the G-tech is consistent, then it would be good for monitoring items mentioned in your post. E

04-17-2001, 03:53 PM	#22
sedanman Registered Member Join Date: Feb 1999 Location: Indianapolis, IN Posts: 963	We used the Gtech at the track and it always came within about .1 of a sec, sure the MPH measuring is different. Like rev said it is a great tunning tool.

04-17-2001, 06:59 PM	#23
Lizard King midnightruns.com Join Date: Dec 2000 Location: Ottawa, Ontario, Canada Posts: 584	I usually try to get a cop to get my MPH ... hehehe

04-17-2001, 07:33 PM	#24
BennyBoy Guest Posts: n/a	I have one real quick question, but it doesn't really have anything to do with a GTech, at all. But anyways...If I beat a car by about 3-3.5 car lengths in a 1/4 mile, about how much difference would be in our times? I know this changes with your speed, but a rough estimate would be nice. Thanks in advance. ------------------ '69 Coupe with 351W ========================= Edelbrock Performer-RPM intake manifold, Edelbrock Performer-RPM cam, Edelbrock lifters, Edelbrock 750 cfm carb, Accel coil, Moroso Blue-Max spark plug wires, Hedman headers, 2 1/2" pipe, glasspacks, Edelbrock double roller timing chain, Edelbrock valve springs, Flex fan, C4, Lakewood traction bars, 3:1 open rear-9" 3.89:1 posi coming this summer =========================

04-17-2001, 09:08 PM	#25
Rev Registered Member Join Date: Nov 1998 Location: Houston, Tx. Posts: 3,887	If yor trap speed is around 100mph, each car length will be about .1 second. Rev ------------------ '66 Coupe, 306, 300 HP, C-4, 13.97 e.t., 100.3 mph 1/4 mi.

04-20-2001, 11:11 PM	#26
john_86stang Registered Member Join Date: Jan 2001 Location: Crossett, Arkansas USA Posts: 45	I agree with Rev my G-Tech is a great tuning tool, because the track is so far away. It is nice to go out and let her eat after small mods: tires whatever then you know if it's any better. Just my .02. ------------------ John Welch 86 GT, 3.73's, H-pipe w/ 2-chamber Flows, No smog pump or A/C, crank pulley, K&N in stock box, adj. FPR, bypassed EGR(coolant) Best Run 14.34 @100.0 MPH (on G-Tech)

04-21-2001, 08:27 PM	#27
Nitrous Al Registered Member Join Date: May 2000 Location: Everett, MA Posts: 417	Is the Gtech worth the money or not?

04-24-2001, 05:36 PM	#28
Lou Lyman Registered Member Join Date: Dec 1998 Location: Tampa, FL Posts: 70	Sorry to be ignorant on this subject but what is GTech? A software program, timing trap lights, what? Approximate cost? I'm new to this but trying to educate myself. Thanks. Lou.

04-24-2001, 10:38 PM	#29
QuantumMotorsports Registered Member Join Date: Jul 2000 Location: Norman, Oklahoma, USA Posts: 597	A GTech is a small electronic accelerometer that mounts in your car (on the windshield like a radar detector) and measures acceleration and elapsed time to come up with a 1/4 time. They are only as accurate as the accelerometer used in their circuit. The math they use is very accurate so like I said they are only as accurate as their accelerometer and timer can be. As far as GTechs or track times being more accurate, Unit, your math makes sense, but every car is different, that is why people say their GTechs are consistantly off. Every engine has a different torque curve and therefore a different HP curve. So, when you say that a car in 3rd gear will accelerate at a lower rate than the car in 2nd gear, you're correct, assuming that the torque curve of the engine is flat (a constant) This is only true for electric motors, hardly ever for a gasoline internal combustion engine. So, the mph change in the last 60 feet would be different for a car crossing the traps in it's power band and a car not in it's powerband, for instance, with my gears, I shift into 4th about 300 feet in front of the 1/4 mile. So I am crossing the traps at about 4000 rpm, I would accelerate differently in the 60' in front of the line than a car crossing at 6000 rpm. Therefore the difference between average speed over the 60' and instantaneous speed at the end of the track will be different for every car. In other words, the track will be off by a different amount for every car. Now, I feel that I must make a statement about somthing that someone else said. Something about being able to get actual speed with a radar gun at the end of the track. Did you mean instantaneous speed? speed is defined as the (change in distance)/(change in time). Instantaneous speed is defined as the speed when the change in time = 0. Everyone knows you can't divide by 0 so it is impossible to measure instantaneous velocity, unless you use calculus which is what a GTech uses. When the GTech integrates to get velocity the margin of error becomes exponentially greater, so if the accelerometer is off by a small bit, the velocity will be off by a lot. Anyway, like I was saying, even with a radar gun, you are by no means measuring instantaneous velocity. The radar gun measures doppler shift. The change in frequency of a wave when it hits a moving object (listen to a car horn as the car is moving towards and then away from you, it's higher and it gets lower as it goes by right?) doppler shift. Anyway, the radar gun knows the wavelength of it's sent signal, it measures the wavelength of the received signal, and subtracts them. Which is still measuring a distance over time. So anyway, even though a radar gun is more accurate than a 60' average, it is still an average. My main point here is, nothing is 100% accurate, and all of this is for fun anyway guys, so GTech times, track E/Ts whatever, believe what you want about accuracy, it's all relative. Oh yeah, Lizard King, what does the weight of your car have to do with a GTech measuring a 1/4 mile time? [This message has been edited by QuantumMotorsports (edited 04-24-2001).]

04-25-2001, 01:39 PM	#30
Lou Lyman Registered Member Join Date: Dec 1998 Location: Tampa, FL Posts: 70	Thanks Quantum, I found their website: http://www.gtechpro.com Price is $139.95 for the new (pro) model. Will upgrade origional for $40.00 Unit mounts to windshield and plugs into cigarette lighter. As long as it stays consistant seems like a great tool to have despite all this controversy. Lou

04-25-2001, 06:41 PM	#31
Unit 5302 Registered Member Join Date: May 1999 Posts: 5,246	The proper shift into the next gear should hold your acceleration curve nearly perfect, Quantum. Sure your car will be making more torque at 4000rpms than 5500rpms, but I'm willing to bet the loss of torque multiplication due to a higher gear in the tranny will offset this. If you are shifting properly, it most certainly will. From everything I've seen the Gtech's seem to be a pretty consistant 3-4mph off.

04-25-2001, 07:06 PM	#32
QuantumMotorsports Registered Member Join Date: Jul 2000 Location: Norman, Oklahoma, USA Posts: 597	So you're trying to tell me that in each individual gear your acceration is a constant? Even though engine RPM is changing and when engine RPM changes your torque changes. Then why not run each gear to the rev limiter even on a stock motor? After you pass peak HP you will reach a point where your acceleration will be greater in a higher gear. My whole point is, the track times will be off by a different number for every car. And since the track times won't have a consistent error for every car, neither will the GTechs. I'm sure that there is some car that could run the 1/4 with a GTech in the car and the GTeck would match the ET and MPH exactly. It depends on the car. And given the amount of variables that are present when running a car down a track, you're never going to be able to accurately calculate acceleration. And using an average is not helpful because the range is so large and you are making a calculation of error using one end of the range (the end of the track) About the change in RPM and difference in gear ratio. Not all engines make more torque at 4000 RPM than they do at 5500. My whole point is, without knowing the torque and power curves of the engine, you cannot accurately calculate acceleration. ------------------ Michael Black Quantum Motorsports Norman, Oklahoma 1988 Merc Cougar 5.0 HO, Ported and Polished E7TEs, 2.25" duals w/ 2 chamber flowmasters, T5 tranny New E/T!!! 14.626 @ 94.94mph, 2.194 60' time, a little better than last time. Keep in mind this thang is heavy (3590lbs) Finally 14s!!!!

04-25-2001, 07:37 PM	#33
Rev Registered Member Join Date: Nov 1998 Location: Houston, Tx. Posts: 3,887	The G-Tech claims to check G force about 100 times a second. From these numerous samples, it calculates speed at any given instant. Since time is determined by a pretty accurate clock, the mph and distace can be pretty accuretly determined at any given instant. These "averages" are from one 1/00 second to another. That's the only reason these gadgets work as well as they do. The fact is that the G force meter works pretty well due I think to space exploration developement. Rev Rev ------------------ '66 Coupe, 306, 300 HP, C-4, 13.97 e.t., 100.3 mph 1/4 mi.