New G-Tech Pros SS G-Meter Discussion
12-25-2005, 09:34 AM
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Ever notice how us gentlemen of age (sometimes known as geezers) take the time to be thorough, providing details and well researched responses to questions? Maybe a little longer to read but don?t have to keep asking questions to get more info. Enjoy the company I can tell u that.
12-25-2005, 12:59 PM
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Originally Posted by cobradav' post='215517' date='Dec 25 2005, 01:34 PM
Ever notice how us gentlemen of age (sometimes known as geezers) take the time to be thorough, providing details and well researched responses to questions? Maybe a little longer to read but don?t have to keep asking questions to get more info. Enjoy the company I can tell u that.
I think your observation reflects fact since so few of us are above 60. In this regard, I seldomly read anything that is well supported, logical, objective, etc. There are exceptions, of course, but I won't name names. I don't think that the difference is simply experience (which is a function of age), although that probably has something to do with it. I think the difference is generational and reflects differences in the "goals" of communication, in general, and participation in discussions specifically. I enjoy the interaction with those of our generation especially. But, still, I also enjoy the interaction with those that are younger even though it is different. If I did not also enjoy the latter, then I would have a hard time hanging around. Merry Xmas cd.
12-25-2005, 05:27 PM
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Great to here from you vnod.my car is a totaly stock 545 without sport package and standard goodyear RSA tires(not runflats).had about 15000 miles when i ran these tests.i don't know if the miles improved performance or i just became more familiar with the car.when i get my data from work i'll also give you the setup i have in the GT2.i do know that i used a 10" rollout and i think all my other settings were the same as yours.also i saw a question on how some of the magazines obtain their times.C & D uses equipment that does not have a rollout thats why their times are about .3 sec slower than others.note that the quarter mile speed is about the same,rollout does not affect speed.I tried a couple of runs with 0 rollout,they consistantlt about .3 sec slower.the road i test on is rough blacktop and may have a slight grade to it thats why i test in both directions.i do have some traction problems but the method i previously described works best.torque braking to 1200 RPM should not cause a problem you only do it for a few seconds.heat is usually the cause for transmission failures but this causes very little heat unless you torque brake for several minutes.i find that torque braking does't shock the tires loose as easily as just mashing the gas.just curious about your age,i am 65 but don't let that fool you the need for speed and acceleration never goes away.
That's good to know about C&D. Sometimes I see mention of the mags procedures, but then forget what they said eventually. Interesting about what you say about rollout--.3 sec. Three tenths is the 1 foot roll-out rule of thumb I used to carry around, but the GT2 manual indicates that one should allow about .04 sec. per every 3 inches of rollout--which would mean about .16, rather than .3, for one foot of roll out. Oh well.
Also, you say that roll out won't affect 1/4 mile speed. Do you mean it won't affect it noticeably. I say "noticeably" because you still get a slight running start, which would affect speed a very small amount, if a roll-out distance is used. Right? Wrong? Why not?
[/quote]
I believe rollout figures mentioned in the GT2 instructions are based on serious drag racers using low axel ratio(4.88) and drag slicks which will you to greatly reduce the time required to go the 12" rollout.I show consistant .3 sec difference with no rollout.I agee there is a slight difference in speed at the end of 1/4 mile due to 12"rollout but is so small it is best to disregard.Due to the 12" rollout you will travel 1321'before you stop the GT2 timer,but at over 100mph you will be traveling about 150' a sec. so that extra 1' will only increase your speed marginally.Best that i can calculate about .02 mph.Will have to wait for Spring to run more tests.the roads here are covered with salt and grit due to fowl weather.
12-25-2005, 06:32 PM
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Originally Posted by grogan545' post='215239' date='Dec 24 2005, 12:05 PM
Great to here from you vnod.my car is a totaly stock 545 without sport package and standard goodyear RSA tires(not runflats).had about 15000 miles when i ran these tests.i don't know if the miles improved performance or i just became more familiar with the car.when i get my data from work i'll also give you the setup i have in the GT2.i do know that i used a 10" rollout and i think all my other settings were the same as yours.also i saw a question on how some of the magazines obtain their times.C & D uses equipment that does not have a rollout thats why their times are about .3 sec slower than others.note that the quarter mile speed is about the same,rollout does not affect speed.I tried a couple of runs with 0 rollout,they consistantlt about .3 sec slower.the road i test on is rough blacktop and may have a slight grade to it thats why i test in both directions.i do have some traction problems but the method i previously described works best.torque braking to 1200 RPM should not cause a problem you only do it for a few seconds.heat is usually the cause for transmission failures but this causes very little heat unless you torque brake for several minutes.i find that torque braking does't shock the tires loose as easily as just mashing the gas.just curious about your age,i am 65 but don't let that fool you the need for speed and acceleration never goes away.
That's good to know about C&D. Sometimes I see mention of the mags procedures, but then forget what they said eventually. Interesting about what you say about rollout--.3 sec. Three tenths is the 1 foot roll-out rule of thumb I used to carry around, but the GT2 manual indicates that one should allow about .04 sec. per every 3 inches of rollout--which would mean about .16, rather than .3, for one foot of roll out. Oh well.
Also, you say that roll out won't affect 1/4 mile speed. Do you mean it won't affect it noticeably. I say "noticeably" because you still get a slight running start, which would affect speed a very small amount, if a roll-out distance is used. Right? Wrong? Why not?
[/quote]
Thanks grogan. And, it will be great to see some more data. Your interpretation for the GT2 roll out is interesting and logical. I wonder if it is correct, however, since the manual seems to imply that its discussions apply to the "average" decent-performing car. On the other hand, it seems that the .3 figure is the more widely accepted value for the "average" decent-performing car.
Assuming .3 is the proper value, it makes me wonder about the appropriateness of GT2 times given a one-foot roll out. That is, I wonder if the GT2 (a) waits .16 sec before it starts timing (or subtracts .16 sec. from the measured time) or (b) actually attempts to determine when one foot has been covered before it starts timing. If (a), then our times, using a one foot roll out (or a 10 inch roll out) would be too slow since, for example, the GT2 should have delayed by about .3 sec., rather than .16 sec., before starting to time. If (b), then all is OK.
I'd like to be able to subtract .14 (.3 - .16) from the GT2's times for my 545i (and the Z06???) to make the results theoretically accurate.
After all, the auto mags make all sorts of adjustments to obtain theoretically accurate times. Any thoughts? grogran? cobradav? B32? realtyman? Centurion? ipsie dixit? Others?
12-26-2005, 03:59 AM
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Originally Posted by vnod' post='215322' date='Dec 24 2005, 04:09 PM
[quote name='grogan545' post='215239' date='Dec 24 2005, 12:05 PM']
Great to here from you vnod.my car is a totaly stock 545 without sport package and standard goodyear RSA tires(not runflats).had about 15000 miles when i ran these tests.i don't know if the miles improved performance or i just became more familiar with the car.when i get my data from work i'll also give you the setup i have in the GT2.i do know that i used a 10" rollout and i think all my other settings were the same as yours.also i saw a question on how some of the magazines obtain their times.C & D uses equipment that does not have a rollout thats why their times are about .3 sec slower than others.note that the quarter mile speed is about the same,rollout does not affect speed.I tried a couple of runs with 0 rollout,they consistantlt about .3 sec slower.the road i test on is rough blacktop and may have a slight grade to it thats why i test in both directions.i do have some traction problems but the method i previously described works best.torque braking to 1200 RPM should not cause a problem you only do it for a few seconds.heat is usually the cause for transmission failures but this causes very little heat unless you torque brake for several minutes.i find that torque braking does't shock the tires loose as easily as just mashing the gas.just curious about your age,i am 65 but don't let that fool you the need for speed and acceleration never goes away.
Great to here from you vnod.my car is a totaly stock 545 without sport package and standard goodyear RSA tires(not runflats).had about 15000 miles when i ran these tests.i don't know if the miles improved performance or i just became more familiar with the car.when i get my data from work i'll also give you the setup i have in the GT2.i do know that i used a 10" rollout and i think all my other settings were the same as yours.also i saw a question on how some of the magazines obtain their times.C & D uses equipment that does not have a rollout thats why their times are about .3 sec slower than others.note that the quarter mile speed is about the same,rollout does not affect speed.I tried a couple of runs with 0 rollout,they consistantlt about .3 sec slower.the road i test on is rough blacktop and may have a slight grade to it thats why i test in both directions.i do have some traction problems but the method i previously described works best.torque braking to 1200 RPM should not cause a problem you only do it for a few seconds.heat is usually the cause for transmission failures but this causes very little heat unless you torque brake for several minutes.i find that torque braking does't shock the tires loose as easily as just mashing the gas.just curious about your age,i am 65 but don't let that fool you the need for speed and acceleration never goes away.
That's good to know about C&D. Sometimes I see mention of the mags procedures, but then forget what they said eventually. Interesting about what you say about rollout--.3 sec. Three tenths is the 1 foot roll-out rule of thumb I used to carry around, but the GT2 manual indicates that one should allow about .04 sec. per every 3 inches of rollout--which would mean about .16, rather than .3, for one foot of roll out. Oh well.
Also, you say that roll out won't affect 1/4 mile speed. Do you mean it won't affect it noticeably. I say "noticeably" because you still get a slight running start, which would affect speed a very small amount, if a roll-out distance is used. Right? Wrong? Why not?
[/quote]
Thanks grogan. And, it will be great to see some more data. Your interpretation for the GT2 roll out is interesting and logical. I wonder if it is correct, however, since the manual seems to imply that its discussions apply to the "average" decent-performing car. On the other hand, it seems that the .3 figure is the more widely accepted value for the "average" decent-performing car.
Assuming .3 is the proper value, it makes me wonder about the appropriateness of GT2 times given a one-foot roll out. That is, I wonder if the GT2 (a) waits .16 sec before it starts timing (or subtracts .16 sec. from the measured time) or (b) actually attempts to determine when one foot has been covered before it starts timing. If (a), then our times, using a one foot roll out (or a 10 inch roll out) would be too slow since, for example, the GT2 should have delayed by about .3 sec., rather than .16 sec., before starting to time. If (b), then all is OK.
I'd like to be able to subtract .14 (.3 - .16) from the GT2's times for my 545i (and the Z06???) to make the results theoretically accurate.
After all, the auto mags make all sorts of adjustments to obtain theoretically accurate times. Any thoughts? grogran? cobradav? B32? realtyman? Centurion? ipsie dixit? Others?[/quote]
12-26-2005, 04:20 AM
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Originally Posted by vnod' post='215322' date='Dec 24 2005, 04:09 PM
[quote name='grogan545' post='215239' date='Dec 24 2005, 12:05 PM']
Great to here from you vnod.my car is a totaly stock 545 without sport package and standard goodyear RSA tires(not runflats).had about 15000 miles when i ran these tests.i don't know if the miles improved performance or i just became more familiar with the car.when i get my data from work i'll also give you the setup i have in the GT2.i do know that i used a 10" rollout and i think all my other settings were the same as yours.also i saw a question on how some of the magazines obtain their times.C & D uses equipment that does not have a rollout thats why their times are about .3 sec slower than others.note that the quarter mile speed is about the same,rollout does not affect speed.I tried a couple of runs with 0 rollout,they consistantlt about .3 sec slower.the road i test on is rough blacktop and may have a slight grade to it thats why i test in both directions.i do have some traction problems but the method i previously described works best.torque braking to 1200 RPM should not cause a problem you only do it for a few seconds.heat is usually the cause for transmission failures but this causes very little heat unless you torque brake for several minutes.i find that torque braking does't shock the tires loose as easily as just mashing the gas.just curious about your age,i am 65 but don't let that fool you the need for speed and acceleration never goes away.
Great to here from you vnod.my car is a totaly stock 545 without sport package and standard goodyear RSA tires(not runflats).had about 15000 miles when i ran these tests.i don't know if the miles improved performance or i just became more familiar with the car.when i get my data from work i'll also give you the setup i have in the GT2.i do know that i used a 10" rollout and i think all my other settings were the same as yours.also i saw a question on how some of the magazines obtain their times.C & D uses equipment that does not have a rollout thats why their times are about .3 sec slower than others.note that the quarter mile speed is about the same,rollout does not affect speed.I tried a couple of runs with 0 rollout,they consistantlt about .3 sec slower.the road i test on is rough blacktop and may have a slight grade to it thats why i test in both directions.i do have some traction problems but the method i previously described works best.torque braking to 1200 RPM should not cause a problem you only do it for a few seconds.heat is usually the cause for transmission failures but this causes very little heat unless you torque brake for several minutes.i find that torque braking does't shock the tires loose as easily as just mashing the gas.just curious about your age,i am 65 but don't let that fool you the need for speed and acceleration never goes away.
That's good to know about C&D. Sometimes I see mention of the mags procedures, but then forget what they said eventually. Interesting about what you say about rollout--.3 sec. Three tenths is the 1 foot roll-out rule of thumb I used to carry around, but the GT2 manual indicates that one should allow about .04 sec. per every 3 inches of rollout--which would mean about .16, rather than .3, for one foot of roll out. Oh well.
Also, you say that roll out won't affect 1/4 mile speed. Do you mean it won't affect it noticeably. I say "noticeably" because you still get a slight running start, which would affect speed a very small amount, if a roll-out distance is used. Right? Wrong? Why not?
[/quote]
Thanks grogan. And, it will be great to see some more data. Your interpretation for the GT2 roll out is interesting and logical. I wonder if it is correct, however, since the manual seems to imply that its discussions apply to the "average" decent-performing car. On the other hand, it seems that the .3 figure is the more widely accepted value for the "average" decent-performing car.
Assuming .3 is the proper value, it makes me wonder about the appropriateness of GT2 times given a one-foot roll out. That is, I wonder if the GT2 (a) waits .16 sec before it starts timing (or subtracts .16 sec. from the measured time) or (b) actually attempts to determine when one foot has been covered before it starts timing. If (a), then our times, using a one foot roll out (or a 10 inch roll out) would be too slow since, for example, the GT2 should have delayed by about .3 sec., rather than .16 sec., before starting to time. If (b), then all is OK.
I'd like to be able to subtract .14 (.3 - .16) from the GT2's times for my 545i (and the Z06???) to make the results theoretically accurate.
After all, the auto mags make all sorts of adjustments to obtain theoretically accurate times. Any thoughts? grogran? cobradav? B32? realtyman? Centurion? ipsie dixit? Others?[/quote]
I am sure the GT2 timer starts timing after you haved moved the rollout distance set in the timer.It will be apparent when i post my info later this week.The 1 run that i did at the drag strip using a 10" rollout were only about .02 sec difference.I think 14.11(strip)14.09(GT2).Yea i know that sucks.I was very depressed until i did some research on how weather affects acceleration.There is a site for serious drag racers(www.smokemup.com)that has mounds of info and formulas to calculate or correct for everything under the sun.I now realize that weather has a much larger effect on times than i originaly thought.I use a 10" rollout because when you "stage"at the dragstrip you usually drive into the staging beam a couple of inches.hope i have been helpful and am not getting to long winded in my replies.
12-26-2005, 07:00 AM
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Originally Posted by grogan545' post='215589' date='Dec 25 2005, 09:27 PM
[quote name='vnod' post='215322' date='Dec 24 2005, 04:09 PM']
[quote name='grogan545' post='215239' date='Dec 24 2005, 12:05 PM']
Great to here from you vnod.my car is a totaly stock 545 without sport package and standard goodyear RSA tires(not runflats).had about 15000 miles when i ran these tests.i don't know if the miles improved performance or i just became more familiar with the car.when i get my data from work i'll also give you the setup i have in the GT2.i do know that i used a 10" rollout and i think all my other settings were the same as yours.also i saw a question on how some of the magazines obtain their times.C & D uses equipment that does not have a rollout thats why their times are about .3 sec slower than others.note that the quarter mile speed is about the same,rollout does not affect speed.I tried a couple of runs with 0 rollout,they consistantlt about .3 sec slower.the road i test on is rough blacktop and may have a slight grade to it thats why i test in both directions.i do have some traction problems but the method i previously described works best.torque braking to 1200 RPM should not cause a problem you only do it for a few seconds.heat is usually the cause for transmission failures but this causes very little heat unless you torque brake for several minutes.i find that torque braking does't shock the tires loose as easily as just mashing the gas.just curious about your age,i am 65 but don't let that fool you the need for speed and acceleration never goes away.
[quote name='grogan545' post='215239' date='Dec 24 2005, 12:05 PM']
Great to here from you vnod.my car is a totaly stock 545 without sport package and standard goodyear RSA tires(not runflats).had about 15000 miles when i ran these tests.i don't know if the miles improved performance or i just became more familiar with the car.when i get my data from work i'll also give you the setup i have in the GT2.i do know that i used a 10" rollout and i think all my other settings were the same as yours.also i saw a question on how some of the magazines obtain their times.C & D uses equipment that does not have a rollout thats why their times are about .3 sec slower than others.note that the quarter mile speed is about the same,rollout does not affect speed.I tried a couple of runs with 0 rollout,they consistantlt about .3 sec slower.the road i test on is rough blacktop and may have a slight grade to it thats why i test in both directions.i do have some traction problems but the method i previously described works best.torque braking to 1200 RPM should not cause a problem you only do it for a few seconds.heat is usually the cause for transmission failures but this causes very little heat unless you torque brake for several minutes.i find that torque braking does't shock the tires loose as easily as just mashing the gas.just curious about your age,i am 65 but don't let that fool you the need for speed and acceleration never goes away.
That's good to know about C&D. Sometimes I see mention of the mags procedures, but then forget what they said eventually. Interesting about what you say about rollout--.3 sec. Three tenths is the 1 foot roll-out rule of thumb I used to carry around, but the GT2 manual indicates that one should allow about .04 sec. per every 3 inches of rollout--which would mean about .16, rather than .3, for one foot of roll out. Oh well.
Also, you say that roll out won't affect 1/4 mile speed. Do you mean it won't affect it noticeably. I say "noticeably" because you still get a slight running start, which would affect speed a very small amount, if a roll-out distance is used. Right? Wrong? Why not?
[/quote]
Thanks grogan. And, it will be great to see some more data. Your interpretation for the GT2 roll out is interesting and logical. I wonder if it is correct, however, since the manual seems to imply that its discussions apply to the "average" decent-performing car. On the other hand, it seems that the .3 figure is the more widely accepted value for the "average" decent-performing car.
Assuming .3 is the proper value, it makes me wonder about the appropriateness of GT2 times given a one-foot roll out. That is, I wonder if the GT2 (a) waits .16 sec before it starts timing (or subtracts .16 sec. from the measured time) or (b) actually attempts to determine when one foot has been covered before it starts timing. If (a), then our times, using a one foot roll out (or a 10 inch roll out) would be too slow since, for example, the GT2 should have delayed by about .3 sec., rather than .16 sec., before starting to time. If (b), then all is OK.
I'd like to be able to subtract .14 (.3 - .16) from the GT2's times for my 545i (and the Z06???) to make the results theoretically accurate.
After all, the auto mags make all sorts of adjustments to obtain theoretically accurate times. Any thoughts? grogran? cobradav? B32? realtyman? Centurion? ipsie dixit? Others?[/quote]
I am sure the GT2 timer starts timing after you haved moved the rollout distance set in the timer.It will be apparent when i post my info later this week.The 1 run that i did at the drag strip using a 10" rollout were only about .02 sec difference.I think 14.11(strip)14.09(GT2).Yea i know that sucks.I was very depressed until i did some research on how weather affects acceleration.There is a site for serious drag racers(www.smokemup.com)that has mounds of info and formulas to calculate or correct for everything under the sun.I now realize that weather has a much larger effect on times than i originaly thought.I use a 10" rollout because when you "stage"at the dragstrip you usually drive into the staging beam a couple of inches.hope i have been helpful and am not getting to long winded in my replies.
[/quote]Thanks grogan. Darn, I wanted to subtract .14 sec.
Your replies are not too long winded for me. I am the King of Long Winded. I will check out smokemup. We are on our way back to Phoenix in a few minutes. Later.
12-27-2005, 12:48 PM
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Originally Posted by vnod' post='215085' date='Dec 23 2005, 07:25 PM
Thanks heezy. Nope, I'm only interested in bolt-ons. Straight-line acceleration is my goal, but I have no interest in going all out. I'm just tinkering. And, I trust Dinan's claim. For example, Dinan certainly is not providing exaggerated claims for its throttle body and exhaust. If I get a measurable difference out of the Dinan CAI, then I'll be satisfied. And, I should be able to detect any effects of the Dinan CAI on average. So, at least, we all will have some idea if the CAI makes a difference. I appreciate your interest. Let me know if you have other thoughts.
Does Dinan offer any software at this time? To fully take advantage of your mods, some good tuning would be needed. With your exhaust, throttle body and CAI, you would look to have a dinan stage 3 car already. I don't see any software on their website, but think it's somewhat strange that they don't offer the software in conjuction with their other offerings.
If Dinan goes in line with other models, they'll soon offer a high flow air meter along with a high flow intake manifold. Do you plan on ordering these as well?
12-27-2005, 02:46 PM
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Thanks heezy. Nope, I'm only interested in bolt-ons. Straight-line acceleration is my goal, but I have no interest in going all out. I'm just tinkering. And, I trust Dinan's claim. For example, Dinan certainly is not providing exaggerated claims for its throttle body and exhaust. If I get a measurable difference out of the Dinan CAI, then I'll be satisfied. And, I should be able to detect any effects of the Dinan CAI on average. So, at least, we all will have some idea if the CAI makes a difference. I appreciate your interest. Let me know if you have other thoughts.
You might be right.
Does Dinan offer any software at this time? To fully take advantage of your mods, some good tuning would be needed. With your exhaust, throttle body and CAI, you would look to have a dinan stage 3 car already. I don't see any software on their website, but think it's somewhat strange that they don't offer the software in conjuction with their other offerings.
The software is supposed to be ready "soon." I am eager to see Dinan's claim for the software and its price.
If Dinan goes in line with other models, they'll soon offer a high flow air meter along with a high flow intake manifold. Do you plan on ordering these as well?
I think the revised MAF sensor is, indeed, coming next. Thanks for joining in. I am running late right now. CU
[/quote]
12-27-2005, 06:08 PM
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Originally Posted by vnod' post='215594' date='Dec 25 2005, 10:32 PM
[quote name='grogan545' post='215589' date='Dec 25 2005, 09:27 PM']
[quote name='vnod' post='215322' date='Dec 24 2005, 04:09 PM']
[quote name='grogan545' post='215239' date='Dec 24 2005, 12:05 PM']
Great to here from you vnod.my car is a totaly stock 545 without sport package and standard goodyear RSA tires(not runflats).had about 15000 miles when i ran these tests.i don't know if the miles improved performance or i just became more familiar with the car.when i get my data from work i'll also give you the setup i have in the GT2.i do know that i used a 10" rollout and i think all my other settings were the same as yours.also i saw a question on how some of the magazines obtain their times.C & D uses equipment that does not have a rollout thats why their times are about .3 sec slower than others.note that the quarter mile speed is about the same,rollout does not affect speed.I tried a couple of runs with 0 rollout,they consistantlt about .3 sec slower.the road i test on is rough blacktop and may have a slight grade to it thats why i test in both directions.i do have some traction problems but the method i previously described works best.torque braking to 1200 RPM should not cause a problem you only do it for a few seconds.heat is usually the cause for transmission failures but this causes very little heat unless you torque brake for several minutes.i find that torque braking does't shock the tires loose as easily as just mashing the gas.just curious about your age,i am 65 but don't let that fool you the need for speed and acceleration never goes away.
[quote name='vnod' post='215322' date='Dec 24 2005, 04:09 PM']
[quote name='grogan545' post='215239' date='Dec 24 2005, 12:05 PM']
Great to here from you vnod.my car is a totaly stock 545 without sport package and standard goodyear RSA tires(not runflats).had about 15000 miles when i ran these tests.i don't know if the miles improved performance or i just became more familiar with the car.when i get my data from work i'll also give you the setup i have in the GT2.i do know that i used a 10" rollout and i think all my other settings were the same as yours.also i saw a question on how some of the magazines obtain their times.C & D uses equipment that does not have a rollout thats why their times are about .3 sec slower than others.note that the quarter mile speed is about the same,rollout does not affect speed.I tried a couple of runs with 0 rollout,they consistantlt about .3 sec slower.the road i test on is rough blacktop and may have a slight grade to it thats why i test in both directions.i do have some traction problems but the method i previously described works best.torque braking to 1200 RPM should not cause a problem you only do it for a few seconds.heat is usually the cause for transmission failures but this causes very little heat unless you torque brake for several minutes.i find that torque braking does't shock the tires loose as easily as just mashing the gas.just curious about your age,i am 65 but don't let that fool you the need for speed and acceleration never goes away.
That's good to know about C&D. Sometimes I see mention of the mags procedures, but then forget what they said eventually. Interesting about what you say about rollout--.3 sec. Three tenths is the 1 foot roll-out rule of thumb I used to carry around, but the GT2 manual indicates that one should allow about .04 sec. per every 3 inches of rollout--which would mean about .16, rather than .3, for one foot of roll out. Oh well.
Also, you say that roll out won't affect 1/4 mile speed. Do you mean it won't affect it noticeably. I say "noticeably" because you still get a slight running start, which would affect speed a very small amount, if a roll-out distance is used. Right? Wrong? Why not?
[/quote]
Thanks grogan. And, it will be great to see some more data. Your interpretation for the GT2 roll out is interesting and logical. I wonder if it is correct, however, since the manual seems to imply that its discussions apply to the "average" decent-performing car. On the other hand, it seems that the .3 figure is the more widely accepted value for the "average" decent-performing car.
Assuming .3 is the proper value, it makes me wonder about the appropriateness of GT2 times given a one-foot roll out. That is, I wonder if the GT2 (a) waits .16 sec before it starts timing (or subtracts .16 sec. from the measured time) or (b) actually attempts to determine when one foot has been covered before it starts timing. If (a), then our times, using a one foot roll out (or a 10 inch roll out) would be too slow since, for example, the GT2 should have delayed by about .3 sec., rather than .16 sec., before starting to time. If (b), then all is OK.
I'd like to be able to subtract .14 (.3 - .16) from the GT2's times for my 545i (and the Z06???) to make the results theoretically accurate.
After all, the auto mags make all sorts of adjustments to obtain theoretically accurate times. Any thoughts? grogran? cobradav? B32? realtyman? Centurion? ipsie dixit? Others?[/quote]
I am sure the GT2 timer starts timing after you haved moved the rollout distance set in the timer.It will be apparent when i post my info later this week.The 1 run that i did at the drag strip using a 10" rollout were only about .02 sec difference.I think 14.11(strip)14.09(GT2).Yea i know that sucks.I was very depressed until i did some research on how weather affects acceleration.There is a site for serious drag racers(www.smokemup.com)that has mounds of info and formulas to calculate or correct for everything under the sun.I now realize that weather has a much larger effect on times than i originaly thought.I use a 10" rollout because when you "stage"at the dragstrip you usually drive into the staging beam a couple of inches.hope i have been helpful and am not getting to long winded in my replies.
[/quote]Thanks grogan. Darn, I wanted to subtract .14 sec.
Your replies are not too long winded for me. I am the King of Long Winded. I will check out smokemup. We are on our way back to Phoenix in a few minutes. Later.[/quote]
I checked instruction manual again for the GT2 and it seems to contradict itself on rollout.check out p.29 "does rollout really matter"it talks about a .35 sec diff for a 12" rollout.then check p.32 "fine tune rollout"it gives you the .04 sec for 3" number.
My GT2 is set up as follows.
weight-4000#
pitch-2.0
roll-3.0
driveline loss-.20
roll res-.013
CDA-7.00
1/4 rollout-10"
speed rollout-10"
I got the following results on 7-15-05 at maple grove raceway,weather conditions were,93o,96% humidity,and low barometer.
dragstrip GT2 timer
60' 2.121 2.10
330' 5.997 5.95
1/8 9.169 9.13
1/8 mph 78.11 78.00
1000' 11.852 11.83
1/4 14.109 14.10
1/4 mph 98.91 99.20
I believe this shows the GT2 to be very accurate,the biggest diff of.047 sec at the 330' mark.looking at these results again leeds me to believe that the 12" rollout may be the most accurate.