Here's how the ballast worked, to good effect, in our old netKar PRO league, fro your information. This is what I'll be doing in AC as well, when we decide to use ballast. This is a proven technique that worked well for years in our netKar PRO league. We won't necessarily be using ballast every season.
The important stuffIn a nutshell, the faster you are in a race, the next race you will carry more ballast to slow you down. If you're not so fast, you might lose ballast. Your ballast changes from race to race (not round to round). The more often you adjust the ballast, the more accurate it becomes.
At the end of each race, my program works out the average fastest
race lap time for each racer, who was within 6% of the fastest lap time (this excludes lap times of people who are too slow, so that everyone else doesn't get masses of ballast piled on). Basically, the
faster your best lap time is compared to the average, the
more ballast you get. The
slower your best lap time is compared to the average, the
less ballast you get.
How much ballast?The amount of ballast you need to achieve a certain percentage slow down in lap time varies from car to car (as cars are different weights). This base amount gets set by experimentation before round 1 of a season and then gets refined each round as we see how different people are slowed down, on average, by the ballast in practice. Some people will be slowed down more by the same amount of ballast; some less, due to driving style. It all gets average out.
Bonus pointsThe ballast tightens up the field, but people who are carrying more ballast get bonus points, e.g. 0.5 points for every 25kg of ballast. This way, faster people are still rewarded on the leader board.
The fine printIf a racer didn't get to complete 4 laps or more in a race, their ballast won't change for the next race, because they haven't done enough laps to calculate a decent average. This avoids unexpected skewing of your ballast.
In the first two rounds, your ballast can jump up and down a bit before it settles on an average. To "smooth out" ballast changes
after the first two rounds, your ballast changes are reduced to 70% of the calculated ballast change. This stops your ballast from jumping too dramatically up or down. E.g. if it's calculated that you need 100kg of extra ballast after the first two rounds, the program will only give you 70% of this i.e. 70kg. Likewise for decreases.
An exampleHere's what happens in my program after a race:
The average fastest race lap was 1:47.639. Looking at Guybrush's line, his best time was 1:45.691, which was 1.948 seconds faster than the average. As a result, he gets 46kg of extra ballast for the next race (he started on 0).
The people like Rob who were slower than the average (0.272 seconds slower, in Rob's case), lose some ballast from their starting weight.