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(Don't miss "M3 vs Mcoupe at Glen part II, the revenge!")
It is fascinating to analyze the GPS telemetry data from Stee's Traqmate.
Looking at our laps compared it seems that even on the track, shortest line wins but overdriving loses: the essential lesson of autocrossing, what do you know?...
The session data graph is below
We both start the lap at 106mph across the start finish line. The M3 is the Blue trace, the MC the RED.
In turn 1 the M Coupe loses out as I either turned in too early or my front
end washed out too much. Perhaps I was too ambitious for the tires. the M3 takes a cleaner line.
Turn in speeds M3 76mph, MCoupe 79mph
Apex speeds M3 67mph MCoupe 65mph
Exit speeds M3 78mph MCoupe 74mph
Between 1 and two though, I used more of the track and I get a
better angle into 2 and especially up the esses where I take a straighter,
shorter line (the scary aim for the blue line). As a result I make up
dramatically on Stee.
Turn in speeds M3 98mph, MCoupe 97mph
Apex speeds M3 102mph MCoupe 104mph (turn2)
Apex speeds M3 104mph MCoupe 107mph (turn3)
Apex speeds M3 119mph MCoupe 121mph (turn4)
Exit speeds M3 128mph MCoupe 128mph
On the back stretch I'm real slow shifting to fifth (lack of
practice for sure) and I lose a ton to the M3. Also Steve is much
quicker from throttle to brake. At the bus stop braking area I top out at 132mph when I get on the brakes, Stee is 6 feet ahead of me. When Stee hits the brakes he is going 135mph and is 14 feet ahead of me!
(advantage SMG and left foot braking and Stee)
Now here is the interesting part: when I get off the brakes at 86MPH,
Stee is a full 50 feet ahead of me and gets off the brakes about 70
feet after I did. We are both trail braking but I am able to take a earlier straighter arc into the bus stop.
The results are dramatic: my turn in speed is a full 5MPH faster, my exit speed 4 mph faster.
My line through the bus stop is 731.2 feet, Steve's 743 feet. (advantage AC).
Turn in speeds M3 106mph, MCoupe 97mph
Apex speeds M3 75mph MCoupe 81mph (bus stop a)
Apex speeds M3 75mph MCoupe 79mph (bus stop b)
Apex speeds M3 76mph MCoupe 80mph (bus stop c)
Exit speeds M3 80mph MCoupe 87mph
The outer loop is also interesting: I'm turning in at a full 5mph
faster at 88mph but I scrub off speed down to 83mph. I'm managing
the push with the throttle. Steve enters slower and later and he is
able to get on the throttle sooner but his line is much longer (1280
feet vs 1251 feet).
Turn in speeds M3 85mph, MCoupe 88mph
Apex speeds M3 86mph MCoupe 84mph
Exit speeds M3 97mph MCoupe 95mph
Coming into turn 6 a downhill left. Stee brakes much later than AC and gains back all he has lost in turn 5. However, he turns in very early and while he has plenty of grip, he cannot quite get on the power as soon as I did. Again small differences can have big consequences. That fraction of a second allwed me to accellerate downhill a touch faster and catch back up again. The big M3's weight plays a role at the end of the downhill, we are both on the brakes at exactly the same time before turn 7 (the toe) but the results are quite different:
Turn in speeds M3 81mph, MCoupe 78mph
Apex speeds M3 71mph MCoupe 72mph
Exit speeds M3 86mph MCoupe 88mph
In turn 7 there is another dramatic demonstration that taking the shorter line can pay. The MCoupe is a couple of MPH slower but picks up dramatically by the end of the turn: 780' vs 807' radius, a gain of 10.6 feet for the MCoupe.
Turn in speeds M3 81mph, MCoupe 85mph
Apex speeds M3 64mph MCoupe 62mph
Exit speeds M3 76mph MCoupe 75mph
Now coming to turn 8 is where Stee really drove well and the car really stuck. The MCoupe struggles with front end grip and goes a tad wide, a 608 foot arc vs a 601 for the M3...all the previous advantage is lost.
Turn in speeds M3 72mph, MCoupe 75mph
Apex speeds M3 61mph MCoupe 59mph
Exit speeds M3 80mph MCoupe 79mph
The consequent better exit brings the M3 to turn 9 faster and there again he drives well and takes a later entry into the corner for a smoother exit. The MCoupe is pinched a little by the slower car.
Turn in speeds M3 78mph, MCoupe 74mph
Apex speeds M3 65mph MCoupe 64mph
Exit speeds M3 77mph MCoupe 75mph
turn 10, I just cannot get to the ideal turn in position and I coast through most of the corner, Stee is on the power before the apex, a beautiful job.
Turn in speeds M3 93mph, MCoupe 95mph
Apex speeds M3 85mph MCoupe 82mph
Exit speeds M3 93mph MCoupe 92mph
now between turn 10 and the start finish I catch up again ever so slightly but by then it's all over. Stee has got me by 2/10th!
Turn in speeds M3 94mph, MCoupe 91mph
Apex speeds M3 73mph MCoupe 74mph
Exit speeds M3 89mph MCoupe 90mph
total lap distance: M3 17996.1 feet M Coupe 17939.2 feet
interesting device AC.. thanks for the link. i can see it being really useful for a road car because it's so portable, but not sure about racecars where you have a dedicated data analysis hardware with more functionality. but for team's on a budget, at least there is another option.
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