Series Regulations

Version: 20260205

The Formula Pro USA Western Championships is a West Coast-based open-wheel racing series, designed to serve as a vital step on the motorsports development ladder. The series fields identical Ligier JS F3 and F4 chassis powered by Honda engines, ensuring a level playing field where driver talent is the primary differentiator. Competitors race at some of the most iconic circuits in the United States, including WeatherTech Raceway Laguna Seca, Sonoma Raceway, and Thunderhill Raceway Park. This platform provides aspiring professional drivers and serious enthusiasts with an affordable and competitive environment to gain experience before advancing to higher tiers of motorsport.

It is the explicit intention of these rules and associated regulations to prohibit innovation and alteration of the cars. Anything not expressly permitted by these regulations and related supplements are prohibited. Modifications, Substitutions and Omissions are only permitted as expressly allowed in these Regulations, related supplements, or by written consent of the Race Director.

• Modifications are defined as “Any alteration to a part or component that changes its design, material, shape, finish of a working surface, function, and/or weight from that originally designed and manufactured”.
• Substitutions are defined as “Any part or component that may be exchanged with an existing part of equal or different specifications that are directly interchangeable without modification to adjoining components” this includes direct exchanges of commonly available parts and reproductions.
• Omissions are defined as “The removal of any part or component from the vehicle for any reason.”

• JSF3 – The minimum weight of the car plus driver with all required safety equipment at any time during competition shall be 1,670 lbs (757.5 kg).
• JSF4 – The minimum weight of the car plus driver with all required safety equipment at any time during competition shall be 1,455 lbs (660 kg).

Hankook Motorsports, Inc. is an official sponsor of Exclusive Racing’s Formula Pro USA Western Championships. Race Competitors competing in the Formula Pro USA Western Championships shall use Hankook Race Tires in ALL Events. Event(s): means each event, including practices (free and timed), test sessions, qualifying sessions and races, promoted and/or organized by and/or on behalf of Formula Pro USA as part of the Formula Pro USA Western Championships Series. Hankook race tires must be ordered through Exclusive Racing to ensure the series gets appropriate sponsorship credit. All tires are price controlled by Hankook. Exclusive Racing will provide Hankook race tires at each event. There is normally a third-party tire mounting service at each event.

To order tires email ZDM@ExclusiveRacing.com with your tire order at least two weeks in advance to the event date. All tire orders must be paid for in full prior to shipment or delivery at the track. Please reach out to Info@ExclusiveRacing.com with any questions.

Series Tire Size:

• JSF3 Front Slick 230/560R13
• JSF3 Rear Slick 280/580R13
• JSF3 Front Wet 230/560R13
• JSF3 Rear Wet 280/580R13

• JSF4 Front Slick 180/550R13
• JSF4 Rear Slick 240/570R13
• JSF4 Front Wet 180/550R13
• JSF4 Rear Wet 240/570R13

FPUSA-3 Championship Tire Allotment (Two-Set Rule)

• Event Allotment: Competitors are permitted a maximum of two (2) sets of official dry-weather tires (four fronts, four rears) for use during all official Qualifying and Race sessions per event weekend.
• Practice and Testing: There are NO tire quantity limitations for practice and testing.
• Declaration & Marking: All competition tires must be declared by the competitor and officially marked by Series Scrutineers. It is the sole responsibility of the competitor to ensure all eight (8) tires are appropriately marked prior to the commencement of the first Qualifying session.
• Tire Replacement (Single): If a single marked tire from the allotted eight is damaged or defective after the start of a session, the competitor may—upon verification and approval by the Race Director—replace it with another tire. This exception is granted once per weekend without penalty.
• Tire Replacement (Multiple): If a competitor must change a second marked tire, or more than one tire beyond the initial approved replacement, the competitor will be penalized two (2) finishing positions for FPUSA scoring and season points purposes. This penalty does not affect starting grid positions.
• Restricted Use: Tires may not be changed for the purpose of gaining a competitive advantage. The Race Director reserves the right to increase or modify penalties at their discretion.
• Wet Weather: Rain tires are unrestricted and may be utilized at any time during the event.

FPUSA-4 Championship Tire Allotment (One-Set Rule)

• Event Allotment: Competitors are permitted a maximum of one (1) set of official dry-weather tires (two fronts, two rears) for use during all official Qualifying and Race sessions per event weekend.
• Practice and Testing: There are NO tire quantity limitations for practice and testing.
• Declaration & Marking: All competition tires must be declared by the competitor and officially marked by Series Scrutineers. It is the sole responsibility of the competitor to ensure all tires are appropriately marked prior to the commencement of the first Qualifying session.
• Tire Replacement (Single): If a single marked tire is damaged, defective, or deemed unfit for use after the start of any Qualifying or Race session, the competitor may—upon verification and approval by the Race Director—replace that tire with another tire. This exception is granted once per weekend without penalty.
• Tire Replacement (Multiple): If a competitor must change a second marked tire, or more than one tire simultaneously, for any reason (damage, defect, etc.), the competitor will be penalized two (2) finishing positions for FPUSA scoring and season points purposes. This penalty does not affect starting grid positions.
• Restricted Use: Tires may not be changed for the purpose of gaining a competitive advantage. The Race Director reserves the right to increase or modify penalties at their discretion.
• Wet Weather: Rain tires are unrestricted and may be utilized at any time during the event.

• 1. General Principles
  • 1.1 One-Make Specification: The car must be a Ligier JS F4. No structural modifications, machining, or lightening of stock parts is permitted unless explicitly stated.
  • 1.2 Data Logging: Standard GEMS data logging system is permitted. Telemetry (real-time data transmission to the pits) is forbidden. The updated Aim system with SmartyCam is optional as is the AiM steering wheel in X4 Pro spec. AiM system can only be used for data logging, using this system for any other purposes is strictly forbidden.
  • 1.3 Overarching concept: Everything that is not explicitly authorized in these regulations, or in the technical bulletins which may be issued by the series during the season, is strictly forbidden.
• 2. Chassis & Dimensions
  • 2.1 Survival Cell: Carbon composite monocoque meeting 2016 FIA F4 safety standards.
  • 2.2 Dimensions:
    • Wheelbase: 2,750 mm ± 10 mm
    • Minimum track: 1,200 mm
  • 2.3 Minimum Weight: 660 kg (1,455 lbs) Including driver and all gear. Ballast must be mounted to the cockpit floor.
  • 2.4 Ride Height Skid block minimum thickness of 2.0 mm. Thickness will be measured only around the three 80 mm diameter holes; the minimum thickness must be respected in at least one place on the circumference of all three holes.
  • 2.5 X4 Pro Upgrades: Halo, AiM wheel/data/camera, rear end fences are all authorized. Teams can add all or any upgrades individually.
• 3. Engine
  • 3.1 Type: Sealed from Mountune Honda K20 C1 (2.0 Litre, 4-cylinder).
  • 3.2 Power Output: Restricted to approximately 160 BHP via mandatory ECU map.
  • 3.3 Tuning: Strictly forbidden. Air intake, exhaust, and cooling systems must remain stock.
  • 3.4 Engine Oil: All JSF4 cars MUST have a minimum oil level to be considered legal to compete.
  • The Standard: The oil level must be at or above the “MIN” line on the official Ligier dipstick (P/N: OA11-18-002). The oil must completely cover the line directly above the arrowhead at the “MIN” mark.
  • The Mandatory Procedure:
    • Step 1: Start the engine
    • Step 2: Idle the engine for exactly 1 minute
    • Step 3: Shut off the engine
    • Step 4: Check the dipstick immediately after shut-off
• 4. Transmission
  • 4.1 Gearbox: SADEV SL75 6-speed sequential gearbox. Fixed ratios.
  • 4.2 Shifting: Pneumatic paddle-shift system (actuated by steering wheel paddles).
  • 4.3 Reverse: The car must have a functional reverse gear which can be operated by the driver from the cockpit.
  • 4.4 As Delivered: The gearbox must remain as supplied by Sadev, with all gears installed and without any modification, coating, or treatment. The gearbox is subject to technical inspection at any time during the race weekend to verify oil level and detect any unauthorized modification.
• 5. Suspension & Steering
  • 5.1 Type: Double wishbone front and rear with pushrods.
  • 5.2 Dampers (Shocks): JRi 2-way adjustable dampers.
    • Allowed Adjustments: Bump and Rebound settings may be changed. Springs may be swapped for different stiffness rates (from Ligier dealer only).
  • 5.3 Setup: Teams are permitted to adjust:
    • Ride Height
    • Camber
    • Toe (Front and Rear)
    • Anti-Roll Bar stiffness (Front and Rear)
• 6. Brakes & Wheels
  • 6.1 Calipers: Brembo 2-piston calipers (Front and Rear).
  • 6.2 Rotors: Steel ventilated discs.
  • 6.3 Bias: Driver-adjustable brake bias is permitted via a cockpit knob.
  • 6.4 Wheels: Cast aluminum, 13-inch rims (8″ wide front / 10″ wide rear).
  • 6.5 Tires: Spec tire (per Exclusive Racing). Tire warming blankets are forbidden.
• 7. Safety Features
  • 7.1 Crash Structures: Mandatory front nose box and rear impact attenuator.
  • 7.2 Extinguisher: On-board electrically activated fire suppression system.
  • 7.3 Wheel Tethers: Cables attaching the wheel hubs to the chassis.
  • 7.4 Halo: X4 Pro upgraded JSF4 features J-Lo cockpit protection systems.

• 1. General Principles
  • 1.1 One-Make Specification: The car must be a Ligier JS F3 (Chassis ID: FIA F3 Regional 2018 Spec). No structural modifications, machining, or lightening of stock parts is permitted unless explicitly stated.
  • 1.2 Sealed Components: The engine is a sealed unit. Teams are forbidden from breaking seals or modifying internals.
  • 1.3 Data Logging: Standard GEMS data logging system is permitted. Telemetry (real-time data transmission to the pits) is forbidden. The updated Aim system with SmartyCam is optional as is the AiM steering wheel in F3 spec. AiM system can only be used for data logging, using this system for any other purposes is strictly forbidden.
  • 1.4 Overarching concept: Everything that is not explicitly authorized in these regulations, or in the technical bulletins which may be issued by the series during the season, is strictly forbidden.
• 2. Chassis & Dimensions
  • 2.1 Survival Cell: Carbon composite monocoque meeting FIA F3 Regional 2018 standards. Includes the Ligier Halo device.
  • 2.2 Dimensions:
    • Wheelbase: 2,750 mm ± 10 mm
    • Minimum track: 1,200 mm
  • 2.3 Minimum Weight: 757.5 kg (1,670lbs). Includes driver and gear. Ballast must be secured to the cockpit floor.
  • 2.4 Ride Height Skid block minimum thickness of 2.0 mm. Thickness will be measured only around the three 80 mm diameter holes; the minimum thickness must be respected in at least one place on the circumference of all three holes.
• 3. Engine
  • 3.1 Type: Sealed Honda K20 C1 (2.0 Litre, 4-cylinder, Turbocharged).
  • 3.2 Power Output: Approximately 303 BHP (226 kW).
  • 3.3 Tuning: Restricted via mandatory ECU map.
  • 3.4 Exhaust: Turbo-specific exhaust system; no modifications permitted.
• 4. Transmission
  • 4.1 Gearbox: SADEV 6-speed sequential gearbox.
  • 4.2 Shifting: Pneumatic paddle-shift system.
  • 4.3 Differential: Limited-slip differential.
  • 4.4 As Delivered: The gearbox must remain as supplied by Sadev, with all fixed ratio gears installed and without any modification, coating, or treatment. The gearbox is subject to technical inspection at any time during the race weekend to verify oil level and detect any unauthorized modification.
• 5. Suspension & Steering
  • 5.1 Type: Double wishbone front and rear with pushrods.
  • 5.2 Dampers (Shocks): JRi 2-way adjustable dampers.
  • 5.3 Setup: Teams are permitted to adjust:
    • Ride Height
    • Camber & Caster
    • Toe (Front and Rear)
    • Anti-Roll Bars (Adjustable blades)
    • Shocks within adjustment range
  • 5.4 Steering: Rack and pinion, height and reach adjustable column.
• 6. Brakes & Wheels
  • 6.1 Calipers: Alcon 4-piston monobloc calipers (Front and Rear).
  • 6.2 Rotors: Steel ventilated discs.
  • 6.3 Bias: Driver-adjustable brake bias permitted.
  • 6.4 Wheels: Aluminum monoblock, 13-inch rims.
  • 6.5 Tires: Spec tire (per Exclusive Racing). Tire warming blankets are forbidden.
• 7. Safety Features
  • 7.1 Halo: Mandatory Ligier Halo structure for head protection.
  • 7.2 Impact Structures: Front, Rear, and Side impact structures.
  • 7.3 Wheel Tethers: tethers on all four corners.
  • 7.4 Extraction: Removable seat shell for driver extraction.