See the rule book at the very bottom of this page for all official rules. Here’s just a quick summary to get you started:
- Front Wheel Drive production vehicles. (AWD->FWD conversions allowed)
- 4-cylinder Naturally Aspirated engine. No turbos, superchargers, nitrous, etc.
- Manual transmission (stick shift). No dog box, no sequential shifters.
- 100 or higher treadwear tires
- Up to 205 largest tire width, or 215 or 225 with a weight penalty
- Wheels weighing at least 11 lbs each (bare; without tire, weights, etc)
- Non-adjustable or single-adjustable shocks (ie Koni Yellow / 8041 and similar)
- No metal or spherical / “pillowball” suspension arm bushings
- Limited body and aerodynamic modifications
- Minimum race weight with driver is calculated based on your dyno, using this calculator: Official Front4 Minimum Weight Calculator
- Our most competitive cars generally come out to around 130-150 peak whp and a 2300-2500 lb minimum weight
- Competitors are required to submit a recent dyno sheet
The goal here is to build cars that are reasonably competitive with each other, while allowing for some variety and choice, and without making this all about spending money.
While we pride ourselves in competitive driving skill, this is also a mild builder’s class, so you’ll want to put some thought into car choice and setup. Our rules don’t dictate a “spec” build, and will not try to make every conceivable car or setup competitive. Instead, they provide some simple parameters and limits, and it’s up to you to choose a car and setup that will be competitive. Many of us are also happy to share the details of our own car builds, so that new drivers don’t have to reinvent the wheel.
We’ll adjust the rules from time to time in order to promote a balance that suits the majority of our competitors and our core mission, and disallow things that are overly advantageous, costly, or otherwise problematic.
Cars that fall on the lower weight / lower power end of things may be able to corner faster (depending on driver, tires, and suspension), while those with higher weight / higher power will attempt to make up for that with higher straightaway speeds, but the difference between the two shouldn’t be huge. Which approach is better can vary depending on the track or course driven at each event, as well as driver preference, style, and strategy. This also helps keep the same car from winning every event.
Official Front4 Rule Book
IMPORTANT: Click Here for 2020 Mid-Season Rules Update