znod

Hi Friends:

It seems like I too often make a mistake in titles. In the title, "Pros" should be "Pro." And, I am not sure, from the GTech literature, if G-Tech or GTech is correct." I use "GTech" below. Whatever.

Anyway, my old GTech thread has become dated and cluttered. I have updated my experience and thinking below. Here are two discussions pertaining to Steptronic shifting issues that many be pertinent to you: Thread One and Thread Two.

"Mind-Candy" 545i Test Info

I have done no quarter miles because I believe I can learn what I want to learn with zero to sixty runs, and it is very difficulty to find a flat 1/4 mile without going to more trouble than it is worth--including going to a dragstrip. The main point of using a G-meter, IMO, is finding "the" optimal technique.

Unless trying some experimental technique or I had serious loss of traction, my runs have fallen into the range of 5.3 sec. (moved to new location= better traction) to 5.5 secs. The best technique with the Step, IMO, is to put the tranny into M1 and then let it shift itself--although starting in M1 may not really matter. I think this procedure turns out to be optimal because one must shift manually too soon to beat the tranny to it, and the tranny seems to shift at least as fast by itself in comparison to manually. This conclusion might change with tranny programming.

I know of only one other who has tried a G-meter--realtyman (B&B exhaust and K&N filter). He reported a best of 5.35 with his SMG not using the acceleration assistant. He uses the Escort GT2 meter, while I use, as mentioned, in the topic title, the GTech Pro SS meter. I am not sure if our meters are set up identically. I use the VTech's required one foot roll out (as though) and the default pitch setting. I would imagine that realtyman does the same.

In testing, I did not not alter my normal tire pressures (30 psi rear all around) and did not use brake torquing. My times likely would improve if I lowered my pressures or used brake torquing. Personally, I would not use brake torquing no matter what the improvement because I don't want to hurt my car. Besides, I have had a traction problem over most of my test period because of colder weather (I hope). Indeed, I that there is "more" in my car if I could get really good traction. I am going to give using the DSC and DTS possible settings another try because of the traction issue; my earlier attempt, using the default setting in warmer weather, was not promising.

My serious attempts produce results similar to those of three tests conducted by the big three US car-mags--5.3 to 5.5 (one test covered a manual). Note that the mags undoubtedly alter tire pressures, use brake torquing, or have superior "track" traction. And, unless there are data I am unaware of, neither realtyman nor I have been able to get a time as low as the 5.2 produced by R&T. I think the 5.2 time is bogus. Below is what the big three US auto-mag tests yield (with BMW's claim in parentheses):

BMW 545i--Manual C&D 5/04 5.5 14.1 103
BMW 545i--Step R&T 6/05 5.2 13.7 104.0
BMW 545i--Step MT 8/04 5.4 13.7 102.1
BMW 545i--Step MT11/05 5.5 13.8 102.8
(BMW claims 0 to 60 of 5.8 for the Step--which should be the average of a number of runs--not a best time as reported by the car mags.)

The 5.2 is suspicious to me because one of the other tests yields the same 1/4 mile time but a .2 sec slower 0 to 60. And, the Steptronic test yielding 0 to 60 of 5.5 yields a 1/4 mile time that is only .1 sec. slower than the test yielding the 5.2 0 to 60. Some of this reasoning gets fuzzier since the manual 545i gets a typical 5.5 0 to 60, but gets only 14.1 in the quarter. Go figure. Next, the 5.2 time is a full .6 sec. faster than BMW's claimed time--which seems like too much of a difference.

Z06 Test Info

I bought BFG drag radials for my Z06 because of time-devastating wheel spin in both 1st and 2nd gears. My safely-go-fast-in-a-straight-line-on-the-street procedure is to minimize wheel spin--which can be accomplished with new street tires just as well as with drag radials. I am not saying that my procedure is the fastest; it's just the one I prefer for consistency, to maximize tread life, for safety, and to reduce auto wear and tear. I am positive that one could launch at 4k RPM or so on the street, with good tires, and go faster than I can using my approach--assuming a good launch.

I have used my GTech for several runs in my Z06. My best result is 4.03 sec. I think I may be able to get below 4.0 using my easy-rider procedures, but I am not sure since my best run seemed pretty much optimal. I did not rev my engine at all, had almost zero wheel spin (with traction-control off), and shifted very quickly to second without powershifting. I have some auto mags containing tests for 2002 to 2004 Z06's--which for all practical purposes are identical cars. Below are the mag times/speeds to 60 and in the 1/4. The magazines, of course, use much more aggressive launch and possibly shift procedures than I do.

C5 Z06--2002 C&D 12/01 4.00 12.40 116.00
C5 Z06 MT 2/02 4.07 12.48 114.90
C5 Z06 MT 6/04 4.20 12.40 117.00
C5 Z06 MT 11/02 4.29 12.44 116.54
C5 Z06 MT 6/03 4.60 12.85 114.36
C5 Z06 R&T ?/02 4.30 12.70 112.10
C5 Z06 R&T 5/03 4.50 12.80 113.50

Who knows how comparable my best time is since I am using a VTech? I do know that my pitch and other settings are appropriate from data I have gathered.

cobradav

Good stuff and well reported. As to the magazines, they often times use weather data to correct for their times to adjust for different test times in their comparo tests. I believe they have some normalized standard but probably only within the individual publications standards. Sometimes they get challenged on their reports and provide greater detail on testing technique. I remember some great vaiability in one of the rags Z06 times that was very frustrating to some Corvette followers. You are in desert area, under normally very dry conditions. While being in FLorida I would see very humid conditions most of the time. Your testing of techniques is good for comparing against yourself and should translate to the optimum mode for us as well, but the actual times could and should vary with local, surface, and as u properly note, tire pressures, type and condition along as some other variables. Some will have modded car with lighter or heavier wheel/tire combos which will have some slight but real impact as well. And if you said it I may have run by it, but BMW is very conservative in their statements on times and HP. They appear never to want to be found overstating anything and want to be sure nobody ever cannot get the claimed times they publish. I don't think the same can be said for the US mfrs. They seem to push right up to the very best possible.

Anyway long ramble to say thanks for the time to do these tests and publish. I agree that for the Step tranny your results/experiments validate my own butt findings

znod

Hi cd:

Thank you for your insightful comments, and, yes, I agree with all you say. I just got back from another try. I waited for the day to warm up and changed to a different location. The ashphalt looked pretty much the same, but I got some decent traction--resulting in a 5.3. I feel like I finally made some sort of break through on finding a better place to test, but the day also had warmed up by about 20 degrees. I think the mags tend to give us something somewhat realistic to shoot for despite all the issues that can be raised about their procedures. And, in this regard, I think my current result has finally shown that it is likely that the "Mind-Candy" 545i mods have produced some, at least minor, benefit--with the Dinan CAI to come. I suspect that I still can improve on the 5.3 before adding the CAI given the better surface. I'll post back, of course, if I do. On the issue of BMW conservatism, do you know if, as I believe, that BMW reports averages. Doing so would be appropriately conservative IMO. And, yes, there is one Z06 set of test results that I left out of my info as mentioned above. It was goofy, but not upsetting to me. Thanks again.

cobradav

Hi cd:

Thank you for your insightful comments, and, yes, I agree with all you say. I just got back from another try. I waited for the day to warm up and changed to a different location. The ashphalt looked pretty much the same, but I got some decent traction--resulting in a 5.3. I feel like I finally made some sort of break through on finding a better place to test, but the day also had warmed up by about 20 degrees. I think the mags tend to give us something somewhat realistic to shoot for despite all the issues that can be raised about their procedures. And, in this regard, I think my current result has finally shown that it is likely that the "Mind-Candy" 545i mods have produced some, at least minor, benefit--with the Dinan CAI to come. I suspect that I still can improve on the 5.3 before adding the CAI given the better surface. I'll post back, of course, if I do. On the issue of BMW conservatism, do you know if, as I believe, that BMW reports averages. Doing so would be appropriately conservative IMO. And, yes, there is one Z06 set of test results that I left out of my info as mentioned above. It was goofy, but not upsetting to me. Thanks again.
[/quote]

I am not familiar with the actual BMW methodology, but if I had to guess I would say it is not average, but more than likely worst case. Just too much empirical data out there that consistently beats BMW claims, to simply be an ?average?. But in absence of true knowledge I could not rule it out.completely.

Again I must say you are doing an invaluable service to our members here by making this testing effort and documenting as meticulous as you are. Excellent reference material for future efforts as well. Of course it must be fun too Thanks

znod

I am not familiar with the actual BMW methodology, but if I had to guess I would say it is not average, but more than likely worst case. Just too much empirical data out there that consistently beats BMW claims, to simply be an ?average?. But in absence of true knowledge I could not rule it out.completely.

Again I must say you are doing an invaluable service to our members here by making this testing effort and documenting as meticulous as you are. Excellent reference material for future efforts as well. Of course it must be fun too Thanks
[/quote]
Thanks cd. And, you are very welcome. Given my experience, I can see how average could be about 5.8--expecially if testing at somewhat different times of the year and with different drivers, etc. It is fun, but I try not to over do it for the sake of my car and tires.

realtyman

Actually, that run was with the stock wheels & tires.
My light weight BBS RK's are my winter set up.

znod

Thanks for letting me know. I updated my original post for your new information.

I am going to have my stock wheels and RTFs on starting the day before we leave for Xmas in my car. I am going to get a few runs in with them on my car hoping for improved traction that is not offset by the increased weight. It would be interesting if the heavier wheels and tires are better in coldish weather in Phoenix on asphalt. Be sure and post any results you get with your lighter wheels and tires on this thread. We appear to be the only ones doing any testing. Well, actually there is one more who has not made his results public.

Edit: I never got around to trying my original wheels and tires. The car feels heavy with them on and not as agile.

znod

Hi Friends:

From looking at the results shown in the pic of the Passport GT2 G-meter posted by realtyman on my old VTech results thread, I realized that his meter gives lots of results that are not available on my VTech Pro SS G-meter without doing a full ? mile. So, I ordered a GT2 and received it a short while ago today.

After setting it up, I took the Mind-Candy 545i out for 2 runs. The first run seemed close to perfect, while a bit of not-too-bad wheel spin showed up in the second. The runs were done on the same asphalt ?strip,? but several blocks apart. My second run should not have been as good as my first, IMO, since I did not let my car cool at all after the first run. But, the effects of this factor, if any, probably were minimal (see below).

I think that my results confirm what I said earlier. My new location definitely provides better traction than the one I had been using?which resulted in some good and some not as good results. My first run?s results are better than my best with my Pro SS, while the second was slightly slower than with my Pro SS. Nevertheless, I think Pro SS and GT2 results are comparable since I got my best (by .2 secs.) Z06 results in the new location earlier today using my Pro SS.

My setup values for the time/speed related GT2 settings are as follows.

1. Rollout distance for both 0 to 60 and the ? mile?12??which is an acceptable standard that typically is used on drag strips and in magazine tests. Note that my manual indicates that an increase/decrease of 3? in the rollout distance will result in ?a .04 faster/slower ? mile time. So, in principle, my GT2 times should be about .16 secs. faster to, for example, 60 than if I had assumed no rollout.

2. Pitch correction?1.9?I used this correction factor because the GT2 manual indicates that, in trying to develop pitch correction factors for the C5 Z06 and the Audi S4, values of 1.5 and 2.0 had worked well. Note that my manual indicates that an increase/decrease in the pitch correction factor of .2 will result in ?a .03 slower/faster ? mile time. So, I am trying to be conservative in setting the pitch correction.

My setup values for the flywheel-horse power (FHP)-related GT2 settings are as follows.

1. Test weight of car, driver, and fluids?4,100 lbs. My FHP values may be high, low, or about right given that I pretty much guessed at my test weight. My weight estimate was 3,814 (base weight) ? 172 (equivalent sprung weight savings from wheel/tires, etc) + 175 lbs. (me, my clothes, and my book bag, etc.) + 70 lbs. (fluids) + 213 lbs (items not included in the base weight-besides me and fluids?comfort seats, AS, 18? wheels and tires, and who knows what else. In this regard, the recent Car and Driver test used a test weight of 4,150 lbs for a car equipped similarly to mine, as it came from the factory, but with a heavier driver (20 lbs), less fuel (maybe 60 lbs), no comfort seats (maybe an incremental weight of 100 lbs), and no book bag (10 lbs). Adjusting for these factors yields a second extimate of my cars weight of 4,150 - 20 - 60 + 100 +10 = 4,180.

2. Drive-train loss?.20?because of my Steptronic?the value recommended by my manual for an automatic transmission

3. Rolling resistance--.13?the GT2 default?left it alone since I had no idea what better to assume

4. Aerodynamic drag?6.5?I assumed a value .3 lower than the one that worked well for Passport on the Audi S4.

I really like the GT2 because of the data it provides without doing a full 1/4 mile. Here are my complete results for both tests.

The heading for what's below are: Test Statistic 1st Test 2nd Test

0-80 8.72 8.99
0-70 6.82 6.99
0-60 5.14 5.33
0-50 3.89 3.99
0-40 2.82 2.87
0-30 1.72 1.75
0-20 0.97 1.02
0-10 0.32 0.35
330 Feet 5.75 5.79
60 Feet 1.99 2.02
1/8 Mile Time 8.78 8.92
1/8 Mile Speed 80.40 79.50
HP @ Speed 333 @ 57 321 @ 54
Ave HP 282.00 273.00

Assuming a weight of 4,180 lbs for my car yields HP @ speed values of:
HP @ Speed 340 @ 57 327 @ 54
Ave HP 287.00 278.00

UPENN545

Thanks for your dilligent work donv.

znod

You are very welcome. The topic doesn't get much interest, but I hope some others will get interested and start doing some testing.