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      12-10-2011, 06:59 PM   #102
MFGJR
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Drives: 2007 Z4 M Coupe
Join Date: Sep 2008
Location: Richmond, VA

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Quote:
Originally Posted by RandysV10 View Post
Hey Frank,

I'll keep a mental note on that segment and see if I can clean up the braking there, it does tend to lean to the right. Going to be interesting on the data after the next run, just hope the weather is not a factor as that will probably change everything.
Randy,

I hope you don’t mind me using your data as a test bed for analysis. I’m not AT ALL criticizing the driving—you’re going faster than the 2:30+ish times that have been my best at VIR. It’s just really useful to have real-world, relevant data to use when thinking about the things that I know I need to work on, and how to see the related good or not-so-good in the data.

That said, yeah, it’ll be enlightening to have the new data, and I’ll have my fingers crossed that it’s dry for you.

The brake pad differences between the two track days should be real interesting. I know your brakes weren’t very confidence inspiring last time out, and I think we can see that in the data.

RS2’s “Toggle Delta” feature lets us easily measure the distance and duration between two points on the graph. If you haven’t already figured out how to use it, first click the red delta button on the tool bar (circled in the below screen shot). Then click the first location on the graph—that point then becomes fixed. When you click a second point, RS2 measures the time and distance between the two, and also in the legend(s) provides the delta for any channels you have on the graph. You can move the second point around by clicking at another point, but you can’t move the first point without turning the Toggle Delta feature off, and then on again, using the tool bar button.

In the below graph, which has a pretty representative lap from run 14, I measured between getting off the throttle coming down the front straight approaching Turn 1, and getting off the brakes and back on the gas right around the turn-in point. RS2 measures that as 5.832 seconds in duration, and 792.299 feet in distance. The brake markers at VIR are, I believe, measured in 100 foot increments, so this is starting the braking before even the 6 marker. (Had it been me, the way those brakes were complaining, I’d have started braking for Turn 1 at, say, Oak Tree!)

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Further, if you look at the throttle on the front straight—which is divided between the right and left sides of the graph as start/finish is in the middle—you were full-throttle for about 1,000 feet out of Hog Pen, and then started steadily coming out the gas for the next 650 feet/6 seconds before going to brakes. Should be a good bit of speed to be had with another 5-6 seconds of 100% throttle, vs. the 65% that you averaged across that time. Of course, there’s the resultant trade-off in braking point.

Similarly, braking on the back straight was 800+ feet and 5+ seconds, though here you weren’t trailing off the throttle prior to braking.

So, next time out with the Big Boy Brakes, it will make for an interesting contrast in terms of how much longer you’re comfortable staying in the throttle, and how much you can compress the braking zones. Now, we just have to remember what Jay’s taught us about keeping the car settled on the brakes…

Next thing I'm going to try to look at is consistent and accurate turn-in at Nascar, which seems to elude me.
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