Race Format
- There are no Masters or Pro divisions. All racers compete together.
- There is no qualifying.
- All heats are three minutes.
Monthly · Third Saturday
GTP Open
Series Rules
Saturday racing with a 4-inch metal flexi chassis, open 64-pitch gearing, and an approved GTP body. All racers compete together, with no qualifying and three-minute heats.
Latest revisionOctober 30, 2026
Race format and procedures
Saturday Series Racing Guidelines
Main Assignments
- If more than eight racers enter, mains will be assigned using finishing positions from the previous race in the same series.
- Racers who missed the previous race will start at the back of the grid in the lowest main.
- For the first race, mains will be assigned using racers’ Pro / Masters classifications and, where needed, finishing positions in the most recently completed series.
- The race director has final authority over all initial main assignments.
Series Points and Standings
- Each racer earns one point for entering a race, plus one point for every competitor beaten in the overall race results.
- Each racer’s lowest race score is dropped from the series total.
- Series ties are broken by the most wins, followed by the most second-place finishes, then the most third-place finishes.
Backup Cars
- Backup cars are permitted and must comply with the applicable series specifications.
- Backup cars must pass tech inspection before the race and remain in parc fermé until used.
- Only one backup car switch is allowed per racer per race.
- Using a backup car results in a five-lap penalty.
- Once switched, the racer may not return to the original car.
Repair Pauses
- The race director, at their sole discretion, may briefly pause racing to allow a racer to repair their car.
- The goal is for everyone to have fun and get the opportunity to race.
Complete requirements
GTP Open Series Specifications
Frame / Chassis
- Must use a 4" commercially-available two- or three-piece metal flexi frame.
- No chassis cutting is allowed except a very small amount at the pillow blocks to fit rear bearings, oilites, or bushings.
- The motor may be soldered in place. Motor braces and pin tubes are permitted.
- A 3/32" solid metal rear axle is required. No exotic materials. Flatted axles are permitted.
- Bushings, oilites, or ball bearings are permitted at the rear axle.
- Cars must meet the following dimensions, measured with the entire car resting on a slotted tech plate:
- Maximum width: 83 mm (approximately 3.26").
- Minimum rear clearance, including the motor: 0.047".
- Minimum front pan and center section clearance: 0.010".
- Weight may be added to the top of the chassis.
- Any commercially available light weight pan may be used.
Guide Flag
- Weighted and unweighted guide flags are permitted.
Tires / Wheels
- Front tires and wheels are optional.
- If used, 3/8", 1/2", or 5/8" fronts are permitted. Wing car “thingies” are not permitted.
- Rear Tires – no speed rubber or Kelly Bulldogs
Motor
- Approved motors: Chicagoland Stage 2 CR102 or Mid-America Road Runner, Mid-America Eagle
- All motors must remain factory sealed and unopened.
- No internal motor modifications are allowed.
- The motor shaft may be shortened.
- All motors must bear the manufacturer’s permanent etching on the motor can for identification.
Gearing
- Gearing is open. Must be 64 pitch.
Body
- Do not cut into its top surface; retain some front and rear turn-down.
- Minimum stock thickness: sold as .007 in.
- No interior or driver is required.
- Unless otherwise specified, minimum unpainted body thickness is .007".
- No aero-effect modifications or add-ons are permitted.
- Approved bodies:
- Kelly Racing Falcon 1874A/B
- Mid-America Evolution 953
- Speed Max 954
- Outisight B3 OS-363
- Bentley OS-069 (2002 ‘HI SPEED’ version)
- Ralph Thorne Racing Revolution 1275-2, Viking 96-21
- Ralph Thorne Racing Viking 96-21
- JK Dagger Concept GTP HD B167A
- Ultimate Peugeot 908HDI B25A/B