Suprised it hasnt been mentioned yet but DATA. I agree that getting more time on track (HPDE) and instruction will help. After that, the next step is data.
The setup we use at Charnal House;
Equipment:
1) 10hz bluetooth GPS (qstarz bt818). You need 10hz minimum to get meaningful data
2) Old Android cellphone with RaceChrono App
3) Ram Mount, holding cellphone in plain view of the driver.
How we use it:
When in car, the main thing to look at is the predictive split timer. This function compares your current lap to your best lap and predicts the outcome of the current lap. Green and "negative number" means you are currently going faster than your best lap. Red and positive number means you are currently going slower than your best lap.
Once you complete a turn (and safely on the straight), glance over at the split time (predictive). If its green and -0.7, that means your 7 tenths up on the best lap. After the next turn if it's green and -0.4, that means you just lost 3 tenths. Then while you're going down the straight, you try to figure out where you lost that 0.3 tenths, and make a mental note of that turn for your next lap.
By reviewing this data at each turn, you get instant feedback. Then through experimentation, you learn the fastest way around each turn.
after the session
Upload the data to the serious-racing.com website and you can now compare laps. For my team, we generally grab everyones single best lap and graph them together. From here you can quickly see and compare these three important points:
1) The line everyone is taking through the turns
2) The braking performance (deceleration rate and braking point)
3) The mid-corner speeds
^It is also possible to sync video of the fast lap with the data analysis. We don't often do this, but it can be useful to look at later.
If you review this data before your next session, and just make a couple mental notes, like "I need to apex later in T2" or "Try to brake harder and later at the end of the long straight", or "Bob is getting on the throttle sooner at turn 8 exit". Just focus on a couple small improvements each session. You could even write them on a sticky note and place it on the dashboard for your next session. The most important turns are the ones before the longest straights (for any track) - so work on these first.
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I am sure there are other apps and equipment which can be used, but these are kind of the "basics" of data analysis that we have been honing in on over the last few years.
Mike @ Charnal House Inc. Like us on Facebook! Or send us a message at CharnalHouse@gmail.com