[Andy@Ross-Tech.com]

I took the MCS out today to log some data. My company is developing a BMW/Mini diagnostic program, but right now is in the early planning stages (no release date yet, and we WILL be banner advertisers when we have something to sell).

Anyway, one of our engineers whipped up a little logging program for me that saved wheel speeds as reported from the DSC computer. It worked pretty well, and resulted in about 13 samples/second.

Here's an acceleration plot (simply change in speed over change in time) for the MCS in 1st and 2nd, as compared to some other vehicles.



Here is a full throttle run up through 1st with a bark into second:



Interestingly, you can see the difference in speeds between the front and rear wheels under acceleration (remember that to have friction, you must have slippage).

[Grinder]

Very interesting data there. Just out of curiosity...why did you compare vs 2nd gear in those other cars?

[Andy@Ross-Tech.com]

So, now we know the optimal 1>2 shiftpoint for a stock MCS (42 mph). I am astounded at how long-legged this car is. 1st gear is comparable to 2nd gear in a Golf TDI! With a chip that raises the rev limiter to 7500 rpm, it may be possible to go almost 80 mph in 2nd gear!

More to follow ...

[Andy@Ross-Tech.com]

Quote:

Originally posted by Grinder
Very interesting data there. Just out of curiosity...why did you compare vs 2nd gear in those other cars?

Well, those were cars for which I had data on my PC. The lucky S4 owner had just sent his data to me to make some graphs. Gotta use whatcha got. This may come in very handy for doing real-world performance comparisons to back up dyno testing.

[macncheese]

Very cool. Much prettier than my data logs

[Grinder]

Whoa! Didn't notice that before. Could this by why 0-60 times vary so much?? Some shift at the redline, others shift earlier?

[Andy@Ross-Tech.com]

Aw shucks, your boost plot was plenty pretty!

The really cool thing is the hundreds of different measurements possible using the BMW protocol, way above and beyond OBD-II government-mandated stuff. For example, in the VW/Audi world, we can see requested and delivered boost, individual solenoids and actuators, even calculated torque in Nm!

[BruceK]

Quote:

Originally posted by Andy@Ross-Tech.com
...(no release date yet, and we WILL be banner advertisers when we have something to sell)...

[DaveNagy]

Great plots. Many thanks. I plan to try to generate similar plots from the output of my accelerometer, but you really can't beat reading the wheel-RPM directly.

My God, the MCS has a looong flat torque curve. In fact the term "curve" seems inappropriate! No wonder people think of this car as sneaky-fast.

Any chance you could give us overlapping plots of all 6 MCS gears? We might be able to figure out some more ideal shift points. (Oh wait, this would involve some seriously trans-legal speeds. Maybe the first four gears would be adequate!)

-Dave

[Andy@Ross-Tech.com]

Quote:

Originally posted by DaveNagy
Great plots. Many thanks. I plan to try to generate similar plots from the output of my accelerometer, but you really can't beat reading the wheel-RPM directly.

My God, the MCS has a looong flat torque curve. In fact the term "curve" seems inappropriate! No wonder people think of this car as sneaky-fast.

Any chance you could give us overlapping plots of all 6 MCS gears? We might be able to figure out some more ideal shift points. (Oh wait, this would involve some seriously trans-legal speeds. Maybe the first four gears would be adequate!)

-Dave

That's exactly what I did with my GTI:

[IMG]http://andy.lasvegastech.com/vwfiles/shiftpoints.gif[/IMG}

Definitely came in handy at the dragstrip (I was shifting too early). I love doing this kind of stuff. Once I get some acceleration and coast-down logs done, I'll plug them into my "Butt Dyno" spreadsheet:

[url]http://andy.lasvegastech.com/vwfiles/dynoplot4.xls[/url}

[IMG]http://andy.lasvegastech.com/vwfiles/dynoplot4.gif[/IMG}

You need an accurate mass of the vehicle with driver, then a full throttle run is done in a single gear (2nd in the above example). At redline, the clutch is pushed in and the car is allowed to coast as far as possible. As long as the road is straight and flat, the power at the wheels can be computed quite accurately. My GTI pulled 172 whp on a DynoJet and 174 whp using the Butt-Dyno (same configuration for both).

[jlm]

please explain how to make sense out of those curves; I'm mystified.

[Mini S]

Im as clueless as a two-dollar hooker in church.

Mini S

[BrantV]

[quote]Originally posted by Andy@Ross-Tech.com
[b]

That graph makes it very easy to spot the correct shift points for your GTI. Basically prioritizing for maximum acceleration the shift points look like they'd be:

1->2 at ~ 33 MPH at ~ 6500 RPM.
2->3 at ~ 61 MPH at ~ 6700 RPM
3->4 at ~ 88 MPH at ~ 6400 RPM.

Very nice indeed. Any chance of seeing one for the Cooper S?

If you ever get access to a track, it'd be interesting to see the same graph all the way through 6th gear.

Thanks,
Brant

[Mugami]

and for in laymen terms. best shift point is where one line crosses then next. 1st gear line crosses second gear is the shift point since at that time your no longer accelerating faster than if you were in second vs first. the torq is there for showing the exact rpm.. if you draw a straight line up and down from the point of the other two crossing. in estimates for the MCS i would say at 42-43 mph roughly 6500-6700 rpm looking at his graph.

[macncheese]

Quote:

Originally posted by jlm
please explain how to make sense out of those curves; I'm mystified.

The bright colored graphs are acceleration (left vertical axis), the darker ones are engine RPM (right vertical axis).

The idea is to always be accelerating as fast as you can. Compare first gear with second gear and you'll find the point where second gear is better than first (at the intersection of the blue and red lines). You can look down at the horizontal axis and thats what speed you should be shifting at, or better yet, look up at the RPM graphs, and read off the right vertical axis to determine the engine RPM to shift at.

Its hard to explain graphs in words

[Andy@Ross-Tech.com]

Exactly! For maximum acceleration, shifts should be made where the acceleration curves for each gear cross one another. I'll do some more logging with other gears, but I don't think I will be able to do 5th and 6th

I did some logging at the dragstrip with my GTI as well:

[IMG]http://andy.lasvegastech.com/vwfiles/14793c.gif[/IMG}

I'll be doing some logging when I take my MCS to the dragstrip to see how it goes!

[DaveNagy]

Without giving away any trade secrets, how are you creating those graphs? I planned on using a spreadsheet (Excel) to massage and then graph my raw data. Is that what you're doing, or is some different software necessary to get everything all prettied up?

-Dave

[Andy@Ross-Tech.com]

Nothin special, just Excel. It's the SOURCE of the data that is a trade secret.