We all know it's basically impossible for three main reasons. First with no rules you can easily build a car that can corner so fast that the squishy meat sack steering wheel to seat back spacer will pass out. Secondly, I don't see how any open rules series could last more than a few years. We've seen it time and time again. Give people an open rule book with the intention of making it easier for people to build something and it starts out great, then after a year or two it becomes an open checkbook series as with the biggest spender winning, then it get's so expensive that the original guys drop out, you have one or two teams left, the the board of directors pulls the plug and it's all over. Most recently LMP1, when the hybrid era started everyone was over the moon at the different configurations of engine and hybrid system. For a short time it was awesome, then it got so expensive that everyone left. Yes, diesel gate helped, but it was already failing fast. It can work up to a point at the club level right up until you get a Scott Tucker who comes along and throws a couple of million at building a D sport racer just to beat the lap record. He managed it easily and made a mockery of the class. You have guys scrimping and saving, even the 'big' guys who had actual sponsorship (normally from personal company sponsorship, friends companies, or industry) may have been spending $100k a year and he drops literally millions on obliterating the class. While a complete douche bag Scott was a pretty good 'AM' driver, his 'Pro' driver who did the testing was approaching LMP1 times in a freaking D sports racer at Elkhart lake. There's an outstanding Dinner With Racers podcast about that car with Jeff Braun his team principle. Ep5 from Nov 2015 about that car. Finally, at a pro level, no manufacturer is going to sign up to an open rule book. It just has too many options and unknowns for them to build a business plan and go to the BoD and ask for an 8-9 figure budget. That's why in Indy car and F1 they don't just say an X capacity engine, or even an X capacity V6 engine. They have to specify limits on V angles, bore spacing, materials, valve angles etc. etc. This was why F1 went to specifying V10's 3.0L engines back at the turn of the century. The prior regs had started with V8, V10, and V12 with different angles and configurations, by the end of the tenure everyone was using V10's and those that had started with V8's and V10's had to throw away tens of millions of research $$ and start again when the V10 proved to be the best overall compromise of cylinders, size, weight etc. No one likes uncertainty.
Now, having been a Debbie downer, here's what I'd do assuming a professional closed wheel series:
- Mandate a spec pump fuel
- Max fuel capacity
- Max fuel fill flow rate
- Max fuel flow rate
- Minimum weight for hybrid unit to be deployed only over 100mph to front wheels only
- Spec underfloor
- MAx wing surface area. Only single (or double) element wings allowed which must be in a single plane (no curved wings like the front of single seaters or what's coming this year in F1 for the rear.
- Min body surface area
- Max down force limit, max turbulent air
- Min vehicle weight
- Spec tires
- Steel coil springs only. Max 4 per car, no firth elements etc.
- Steel sway bars, can only be straight solid steel
- Spec steel brake discs <- single biggest thing you can do to help passing, increase the braking zone distance.
- Min weight for brake calipers
- All suspension components must be metal
- Shocks cannot be adjustable in anyway while on the vehicle and must not have any sensors or control at any time
- Mandated safety spec
- Max price for customer cars and manufacturers must sell to anyone who asks, even competitors
- Max cost of spares such that a car built from spares can't cost more than three times a new car, excluding off the shelf parts like fasteners.
And I bet that not a single manufacturer will sign up.
For club racing, we're kind of there with things like D sports etc. It becomes self regulation on the upper end of the spending curve as it's all hobbyists unless a once in a generation a Scott Tucker comes along, but they don't stay around long.
Even at the club level the customer has spoken. Classes like the various SCCA sports car ones are light on entries, while the more tightly regulated classes are far more popular. Or look at something like NASA where they haver much more of a run what you brung classing, but even then they give you points for changes and too many points put you in a higher category. That is effectively their own BOP. 'Do what you like, but if its too much you move up a class'.
The only place left for really open competition is Pikes Peak and Rally Raid