znod

Thanks much Eric. I am hoping the tread will be informative and enjoyable. Yes, definitely; gearing, of course, is highly pertinent to straight-line performance as you know.

And, yes, the Step's gearing is superior for straight-line performance--all other things equal. For example, just multiply corresponding single (e.g., first) gear ratios and rear-end ratios for the trannys being compared. When doing so for the Step versus the SMG/manual, one finds that the calculations for the Step imply, from an overall perspective, that the Step is better at producing rear-wheel torque for straight-line performance at least through the 1/4--other things equal.

However, a counteracting force is that the Step should, because of the inherent inefficiencies of autos, produce a greater loss in rear-wheel torque than the other trannys--about 5% more. So, considering matters for only first gear,

Step--4.17 X 3.38 = 14.1 (big advantage to the Step to this point)
SMG--4.17 X 2.93 = 12.42

14.1 - 12.42 = 1.68; 1.68 / 12.42 = 7.4% more rear-wheel torque for the Step other things equal.

Additionally, for example, .074(330 ft lbs) > .05(330); thus, even after factoring in torque losses from incremental auto tranny inefficiency, the Step comes out ahead, in theory, in rear-wheel torque and, thus, in straight-line performance in first gear. This sort of analysis holds, from an overall perspective, through at least the 1/4 mile.



Thanks very much g-man. And, I am glad you have found a good new site. Be careful. You have had a great start on the new site. I'll do the calculations and insert all results into post #1 above.

May I ask you to post results on the testing thread. Then, I'll repost whatever you want in post #1 of this thread. I am hoping to keep this thread somewhat uncomplicated by results and too much detail. Please don't feel the need to remove anything from your above post. Thanks much.

Have a great trip.

grogan545

Not a problem Zman.It is a good idea to keep this new site uncluttered.

znod

To All:

I have updated my bests in post #1 above for two runs today. They were good runs, but, initially, I thought they were not as good as yesterday. However, as shown above, they were very good on an adjusted basis. I am glad that we have stated adjusting for weather and altitude so we can see more clearly what is going on.

I will be posting grogan's undated data to post #1 later today since I have to do some other things now. Please check back for my update of his data.

grogan545

Looking better all the time Zman.It looks like you are back to or faster than pre 20.01 performance.
I found more info on weather corrections.Type in "national dragster weather 101"in search.There is an indepth disertation on weather effects on HP and ET.

SergeyM

Are the above numbers for a stock 545 auto? If so the car should be taken to a race track. The race track 1/4 time and speed will bring you back to reality. 545 is not mid-13th car.

znod

This one was close:

BMW 545i--Steptronic RT 6/05 3814 5.2 13.7 104.0.

The above times/speed have not been adjusted for either altitude or weather. And, we are better drivers than the magazine drivers. And, more seriously, we have spend a great deal more time than magazine drivers would in learning how to get the most out of a Step.

I do understand your concern, however. Here is what I observed when I started testing. The more I tested two things happened: (1) I got better at what I was doing and (2) My car got significantly faster. At the outset, my times/speeds were not as good as those of the magazines--even the ones getting the worse times/speed. So, I can see how the magazine times/speed might not adequately represent the capabilites of the 545i.

znod

Thanks for the ndw101 info. I can't tell if I am faster since I never did 1/4's using the other meter or altitude/weather corrections (which I couldn't have anyway without doing 1/4's). I have not equaled my earlier raw scores of three 8.71's for the 1/8. I have almost tied my previous best raw score 0 to 60--two 5.07's. But, faster, who knows?????

Incidentally, I misunderstood before. I'll put the corrections factors on the other thread right away. Sorry I misunderstood. But, let me know if you want me to do the corrections and post your new data above. If so, then should I correct your old data also?

I won't post any more data for you until you let me know for sure what you want me to do or to post. Sorry again that I misunderstood.

cobradav

Close but not quite correct:

Lets put these numbers over here for reference (also in another thread)


The final drive in SMG/Manual = 2.93
The final drive in Step = 3.38

First gear in SMG/Manual = 4.05
First gear in Step = 4.17


2nd gear in SMG/Manual = 2.4
2nd gear in Step = 2.34

Total ratio:
1st in SMG/Manual = 11.87
1st in Step = 14.09

2nd in SMG/Manual = 7.03
2nd in Step = 7.91

Each will get to 60 MPH in 2nd gear but you are getting into the power band quicker in the case of the Step. So there is an offset (tradeoff) to the slower shift in the Step and torque converter losses.

The Step gains in the economy area as both 5th (0.87) and 6th (0.69) are OD ratios while only 6th (0.87) in the SMG/Manual is an OD ratio.

For completness I'll repost a chart I made up. In this case I stripped out the 645 data so as not to confuse.

EBMCS03

DANG! should have gotten a Step!

Nah I love how the SMG feels! More sporty to me. Like the crisp shift feel knowing when it got into gear.

grogan545

I have already been to a race track.I went to Maple Grove Raceway(home of the NHRA Keystone Nationals)last July.I ran a weather corrected 13.47 at 103.73.I also had my GT2 timer log the the run.It was no more than .047 different than the drag strip timer(.047 diff at 330').At the end of the 1/4 it was .009 difference.The GT2 was .009 faster than the NHRA time.The speed was .29 mph faster on the GT2.