NCM Motorsports Park BMW E30 Data Analysis
At the last AER event of 2017 at National Corvette Museum Motorsports Park our team has had several drivers running very close lap times. I decided to look at the data to see if there are any differences between the drivers that I can learn from, potentially picking up some speed in the process.
To give an overview of the track, NCM Motorsports Park features several tight, narrow and long corners leading onto long straights, many transitions and several confidence sections which challenge the driver's estimation of how much grip the car has, exactly. I was specifically looking for better exit speed out of the tight corners leading onto straights and higher speed carried through the confidence corners.
Conditions were dry and cool, with ambient temperature in the 50-60°F range. The car was on Nexen or Star Spec tires, I am not entirely sure which and there have been tire changes throughout the day. Based on me driving this car at other events I would say despite tire changes its handling characteristics remained consistent.
I've looked at second fastest laps for the sessions shown, and while there are some minor differences I feel the plotted laps sufficiently well represent the best lap of each driver. Keep in mind also that the event, being an endurance race, has car preservation as the top priority. Of the three drivers, Joel has the most familiarity with the car and myself and John are, in my estimation, similar.
Different driving styles are evident. John brakes earlier but it looks like travels less distance going into the chicane. I have a higher minimum speed but I imagine travel more distance at the exit. Interestingly enough, all three drivers match one another in track position once the chicane is over.
John looks to have a significantly lower minimum speed but compared to Joel, only loses about 0.2 seconds, and makes the speed back. This usually indicates less distance traveled - a tighter line around the corner. I have a later power application and lose about half a second by turn 5.
This is a high speed confidence corner. Speed is available for those brave enough to go after it.
John is taking this section conservatively with the earliest and hardest braking and lowest minimum corner speed, and it costs him dearly - nearly half a second that is not recovered until Deception. I am surprised to have outdone Joel there, though he is still ahead of me overall on the lap.
Another interesting corner with respect to deltas. John has the highest minimum speed but is losing ground in track position indicating again larger distance traveled. He is also applying power partially in the corner which is consistent with being on a wide arc, i.e., close to the outside edge of the track for longer. Joel overbrakes somewhat allowing me to catch him at the exit even with a later throttle application.
The battle of speed vs distance continues with me having a significantly slower entry but not losing ground in track position. I know that I turn quite early for turn 8 and as a result probably drive less distance compared to drivers who brake later and go deeper.
I do carry more speed through the corner which is combined with a later throttle application; the "straight" through turns 8 and 9, however short it seems, does matter to the tune of a about a fifth of a second in lost time.
Possibly the single most important corner on the track and also the most difficult one to drive fast, I call it the impossible left. John does the best here with the highest minimum speed and early throttle application and you can see that the speed loss on the entry is not really recoverable, as despite much earlier throttle application Joel is not any faster between turns 10 and 11 than John.
I overbrake for Deception and pay for it on the remainder of the straight. Joel carries the most speed through the corner itself which puts him ahead momentarily but John's earlier throttle application comes through as we approach Faux Rouge.
Again I am surprised that I carry the speed for longer going into this confidence right hander, as I thought I was quite conservative when I was in the car. I do get on throttle the latest but overall I am still gaining on both drivers.
Another corner where I thought I was conservative but actually was faster than the other drivers, I finally catch Joel after the slower exit from Deception.
A reversal of fortunes - I thought I was doing well going into turn 18 but data shows that this is not the case, with John carrying a good amount of speed more into the corner.
If the benefits of early throttle application are demonstrated anywhere, it's in this corner where John gets the car rotated much earlier than either Joel or myself and gets on the gas a good 70 feet before we do which is about 4 car lengths. That coupled with an amazing drive through turns 21 and 22 gets John nearly three quarters of a second on me and half a second on Joel, putting all three drivers within two tenths of one another by the start/finish.
Cornering speed matters. I gain about a second on the other drivers between turns 5 and 15.
Exit speed matters. I lose that second back in turns 2, 6, 12 and 20.
A balanced car is fast. Combining high entry speed with early throttle applications - and doing it consistently lap after lap - requires an agile and balanced car. The more a car is prone to chronic understeer, oversteer or unpredictability the slower it is, on average.
Effect Of Draft
My best lap time was actually 3/4 second quicker than the lap posted above, but that lap ended with me drafting behind a higher class car for most of the front straight. Especially in the convertible which is the car we were driving drag is a big factor. Let's look at the difference between my 1:31 lap and my 1:32 lap to appreciate the gains due to draft:
My draft lap started off as a hot one, although I did not beat my previous best everywhere I was ahead by about 0.2 seconds by the sinkhole exit. But the tow behind a higher class car on the main straight netted another half a second with me doing nothing but holding the steering wheel straight. With me having nearly identical exit speeds out of the sinkhole, by the start/finish the speed delta was 4.5 mph in favor of the draft lap.