Originally Posted by vnod' post='213370' date='Dec 19 2005, 06:21 PM

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

Originally Posted by Salespunk' post='214831' date='Dec 23 2005, 02:06 AM

Just a side note on the 5.8 second 0-60 that BMW claims. They run all their tests with traction control ON. This slows the times down significantly.

Originally Posted by heezy545i' post='215026' date='Dec 23 2005, 05:15 PM

Donv,

If 0-60 and overall off the line performance is your goal, then something like a LSD or some gearing would have the biggest impact.

I see that you have the Dinan CAI on order. I'm sure it's a fine piece, but unless you have a full cat-back exhaust, headers and perhaps some high flow cats, I personally wouldn't expect much of a gain in hp regardless of the claims. The biggest difference you'll notice will likely be the sound.

If you're willing to spend the money on something like a LSD, try discovery automotive as they're quite reputable. http://www.discovery-automotive.com/portal...c_Content&id=94

Originally Posted by vnod' post='212991

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

Originally Posted by Salespunk' post='215129

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.

Originally Posted by vnod' post='215196

My information came from service tech that I ride with sometimes. He has also told me that internal numbers for the 550i 6 spd show it as quick (4.8 seconds) as the e39 M5 to 60 MPH.

Originally Posted by grogan545' post='215178

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.

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.