First and foremost I want to thank all those that are spending time and resources to create such a concept and a race series. I know it must be far more difficult and time consuming that we can start to imagine. Thanks for promoting racing!
Deciding on a ruleset really is a done after the decision of what the goal of the series is. I think it would help to know what the end goal is as this will refine your conversation to better discuss rules.
From my perspective you have a few options on how to approach time attacks, as others have tried:
Option #1 - GT LIVE (aka "the culture"). There might not be the breath and depth as other series, but it's about spreading a culture and style just as much as the racing. It's what happens off the track as much as what goes on. It's glitz and glam - but hey, it makes headlines, creates internet chatter, and makes the magazines.
Option #2 - Redline Time Attack (aka "the grassroot series"). This is a grassroots series that caters to the drivers and the purity of the sport more than other options. The rules are flexible, but are getting more and more strict as they mature their series. It doesn't have the glam, but most of the best drivers and cars come out and so do the press coverage and the sponsors.
Option #3 - Super Lap Battle (aka "The sellouts") This is Super Street's concoction but has grown to something more over time. It's more about selling parts and magazine subsciptions - oh and sometimes there is good racing. The rules are catered about surfacing a product, satisfying sponsors, and making great headlines. For example, keeping information like the HKS EVO being completely illegal in any other sactioned time attack series in the U.S. is kept more "hush hush" because, well, it's fast. Or eliminating Porsches because it doesn't help you sell magazines. Or V8s. Or pushrod anything. Or anything else that makes your demographic look bad. I think Matt Guiver said it best, "[T]he big draw for media events is incredibly fast cars, so I also want to see race cars, and track only cars putting down untouchable times." Well, he's got a point. Fast cars are what create buzz for their respective audience. These guys have figured this out better than anyone.
Option #4 - NASA TT (aka "Old Skool" or "HeyWeDidThisWayBeforeYouThoughtThisWasPopularSoThanksForComingOutYouNoob") - National, organized, only one with actual membership and dues. Rules are different than the Unlimited/Limited AWD/RWD/FWD classing of the other series. Doesn't have the appeal or glam as the other options, but the structure works and is supported to a broad range of cars (read v8s) with classes for anything under the sun.
Option #5 - Cobb Track day or Subiefest (aka "the festival") - since these are fewer, more annual/semi-annual events they are seen as a "family/make/model reunion" or a "celebration of racing" more so than trying to approach it as a full competition or a substainable series. But they do bring crowds and a happy bunch of enthusisasts showing off their improvements since their last gathering. Sometimes the races aren't timed - so everyone is fast and says so for the next few months on the internetz. Other times they are - so everyone is fast and says so for the next few months on the internetz.
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While you think about goals and then rules around those goals, here are some questions I hope you answer along the way:
- What the reason I'm in the series? Is it for fun? Is it to improve my driver skills? Is it to engineer a car? All the above?
- Are you a feeder series? Are you anticpating my skills useful in another series? If so, which ones? Is my car for a feeder series? If so, which ones?
- Great, you have a series - but I hate spending my $10k and losing to guys with 3,4,5 times as much money. What are you going to do to make me want to come back and lose every time to someone in my class with more money and be happy about it?
- Great, I'm in a class with 6 guys, and I'm 4th every time and 3rd when someone can't come. The guys in front of me are far better drivers than me and very consistent, making the class "locked up". So if I go the next event I'm probably going to come in, well, 4th. What are you going to do to make me want to spend $150 each time to enjoy being a runner up to the podium yet again?
- What is more important when it comes to points, press, prizes, and sponsors - promoting each driver to improve their skills, for me to spend more money to improve my car, me getting money in prizes, or sastisfying sponsors?
- What's more important, keeping the series alive at any cost, or sticking to the original goals and values of the series?
- V8s - in or out? Porsche Cup cars - in or out?
- If I build a street legal locust car or I have an ariel atom, am I legal to compete even if it's a low quantity production or kit car? what if I tube frame a 2000 pound racecar, get some backwater county to give me a license plate, am I able to compete in the street legal class?
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The more I think about it I like the NASA TT based style of classifying cars with each car getting a "point" score and then moving up classes due to their upgrades and modifications. I see the possible benefits:
- It can allow for v8s, porsche cup cars, race cars as well as the street cars because the "point" system moves cars up from "base" classes to their respective racing classes.
- It follows generally (but not specifically) jid2's "slow,medium,fast" concept of bunching cars appropriately. By using points to rate cars it discourages sandbagging because they are already classed before racing with no benefit to going slower.
- It also allows Biggie's argument of "It's not our fault ______ car can only run ____ size tire" or "It's not our fault ______ car wieghs ____ pounds" resolved. Each car can run whatever tire / weight they want, but gain points based on how extreme they go respective of their base car and class.
- It allows for an "unlimited" class with your crazy lappers. It's what you use as your flagship cars for the sponsors and advertising.
- It allows a newcomer to race without being intimidated by bigger competitors/more modified cars.
- It allows AWD,FWD, and RWD able to run in the same class.
- It (potentially) allows for a wide range of type of tires and widths, since each would come with their respective "point" penalty (and potential class upgrades).
- By sanctioning rules similar to a series like NASA you still leave cars potentially eligible for other local/regional/national series as well as other noterized time attack series in the country. (And allow me to fulfill my lifelong goal of making it into Super Street Magazine and next to it have a joke from the editors I heard in the 5th grade as the caption

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A few last notes:
- I like the idea of rewarding top competitors as well as the most consistent lapper in each class. This way the top racer wins, but the "little guy" can still have a chance for prizes by improving his skills and better knowing his car - and makes him want to come back and spend $150 to come in 5th again.

- I like the idea of points given throughout the season per class. This also promotes competitors to keep their car running, keep it coming to the events, and rewards consistency.
Hope this helps. Good luck with the series. I really look forward to its formation and success.
Thanks.