Event Overview
August 15, 2026Classes
Box Stock
Entry-level hard-body class using near-stock RTR Mini-Z hardware.
Spec LM
House spec class based on Box Stock with 102 mm Kyosho LM cars.
Lipo 2500
2WD hard-body class with 2500-class sensored power and blinky ESC.
Lipo 2500 Pan
Open 2WD pan chassis with 2500-class power and approved pan bodies.
Formula 1
112–116 mm Formula class with 2500-class sensored power and blinky ESC.
Pan Open
Open-power 2WD pan class for 94, 98 and 102 mm cars.
Race Format
Qualifying
Two qualifiers are guaranteed. A third qualifying round may be run if time permits.
Main Events
Each class advances to its main following qualifying. Exact main structure may be adjusted to entry count and event timing.
Staging
Cars must be placed in the pit lane, not directly on the active racing line.
Six Classes
Box Stock, Spec LM, Lipo 2500, Lipo 2500 Pan, Formula 1 and Pan Open.
Controlled Practice
4 MinutesGroup 1
Box Stock
Spec LM
Group 2
Lipo 2500
Formula 1
Group 3
Lipo 2500 Pan
Pan Open
Technical Inspection
Every Race
Cars are subject to tech before each qualifier and main.
Blinky KV Check
Every class requiring blinky ESC operation must pass the event KV check before being allowed to race.
Digital Tech
The event tech system is viewable by anyone. A password is required to enter edit mode and change official tech records.
Official Class Rules
Working event rules based on the current 28SRA specifications, with the Small Scale Speedway Spec LM house rules retained.
Box Stock28SRA 2026
Entry-level hard-body class using near-stock RTR Mini-Z hardware.
- Driver restriction: drivers competing in Lipo 3500, 2WD Mod, AWD Mod, Lipo 2500 Pan or Open Pan are not eligible for Box Stock.
- Chassis: Kyosho MR03S, MR03S2, MR03 RTR, MR04 RWD, or Associated SR27 in RWD form. Chassis must remain as manufactured; no material removal for weight reduction.
- Wheelbase: 90, 94, 98 or 102 mm.
- Motor/board: Kyosho MZ9P or MZ9E RTR brushed motor with the stock RTR electronics. Motor wire replacement up to 20 AWG and safety-switch removal are permitted; EVO/upgraded boards are not.
- Gearing: 6T–9T RTR pinions with the stock Kyosho gear differential.
- Wheels: production 1/28 plastic or aluminum wheels; front max 8.5 mm, rear max 11 mm, diameter 19–20 mm; wheel/tire package must remain inside the body.
- Tires: rubber production tires only, max 25.5 mm mounted diameter; front 8.5 mm/rear 11 mm. No tire warmers, traction compound, foam, silicone, urethane, ethyl-carbamate tires or inserts. Water or 70% alcohol may be used for cleaning.
- Battery: four AAA cells (alkaline, NiMH or NiCd). A separate battery may be used only for the transponder.
- Radio/electronics: stock RTR radio/electronics only; no radio modification.
- Body: manufactured molded hard shell fitting the legal wheelbase, max 180 mm long and 83 mm wide. Original shell components are generally required, with limited race-damage omissions permitted.
- Options: bearings, wheel nuts, springs and T-plates from any manufacturer are allowed. Suspension parts otherwise remain original Kyosho. No added ballast.
- Kingpin flip is allowed if the lower pin is shortened so it cannot damage the track.
Spec LMSmall Scale Speedway
House spec class based on Box Stock with 102 mm Kyosho LM cars.
- All Box Stock rules apply except where specifically changed below.
- Chassis: Kyosho LM configuration only.
- Wheelbase: 102 mm only.
- Body: Kyosho LM hard bodies only.
- Motor: stock Kyosho RTR motor or PN Racing 70T brushed motor.
- Front springs may be changed.
- Aftermarket rear damper plate is permitted.
- All remaining Box Stock restrictions and allowances remain in effect.
Lipo 250028SRA 2026
2WD hard-body LiPo stock class with 2500-class sensored power and blinky ESC.
- Chassis: current 28SRA-approved 2WD Mini-Z-size chassis including Kyosho, Jomurema, GL Racing, MRC, PN, RTRC, Atomic, Reflex/RX28, Nexx, Specter, MWX, G-Force, Xbility and AE RC28 platforms listed in the 2026 rules.
- Wheelbase: 98 or 102 mm.
- Motor: 1/28-scale 2500Kv sensored motor, max 15 mm can diameter, 2800Kv ceiling. No aftermarket rotors or motor tampering.
- Gearing: 1/28 pinion/spur gears permitted; tooth count must be identifiable. Standard event ratio is 12T/53T unless the race director announces a track-specific change.
- Wheels: production 1/28 plastic or aluminum; front max 8.5 mm, rear max 11 mm, 19–20 mm diameter.
- Tires: rubber production tires, max 25.5 mm mounted diameter. Tire warmers allowed. No traction compound, homemade, foam, silicone, urethane, ethyl-carbamate tires or inserts.
- Battery: 2S LiPo or two 1S cells in parallel; max 8.40 V, max 45×24×13 mm, max 500 mAh, original production labeling required.
- ESC/receiver: any 1/28 ESC and receiver; ESC must have timing/turbo/boost disabled and show blinky mode. No gyro or gyro-equipped receiver.
- Body: manufactured hard shell for the legal wheelbase; max 180 mm long, 83 mm wide and 24 g minimum body weight; limited clearance modifications permitted.
- Options: publicly available production/3D-printed 1/28 parts allowed under the 28SRA availability requirements; ballast is allowed.
- Minimum race-ready weight: 160 g.
- Summer Nationals: blinky motor/ESC combinations must pass the event KV check before being allowed to race.
Lipo 2500 Pan28SRA 2026
Open 2WD pan chassis with 2500-class power and approved pan bodies.
- Chassis: any 1/28-scale 2WD chassis. Prototype and pre-production chassis are allowed.
- Wheelbase: 94, 98 or 102 mm.
- Motor: any manufacturer 2500 motor, sensored or sensorless, max 15 mm can diameter and 2800Kv ceiling.
- Gearing: open 1/28-scale gearing.
- Wheels: production 1/28 plastic or aluminum; front max 11 mm, rear max 14 mm, 19–20.5 mm diameter; wheel/tire package must fit inside the body.
- Tires: production rubber tires; front max 11 mm and rear max 14 mm. Tire warmers allowed. No traction compound, homemade, foam, silicone, urethane, ethyl-carbamate tires or inserts.
- Battery: 2S LiPo or two 1S cells in parallel, max 8.40 V. A separate battery may be used only for the transponder.
- ESC/receiver: any manufacturer sensored or sensorless ESC and receiver. Gyros and gyro-equipped receivers are prohibited.
- Body: approved 28SRA Lexan/LMP pan body. Cutting the rear panel is allowed.
- Options: open; homemade, 3D-printed and prototype parts are allowed.
Formula 128SRA 2026
112–116 mm Formula class with 2500-class sensored power and blinky ESC.
- Chassis: GL Racing GLF-1, G-Force Formula, PN PNR 3.0F1, MWX R1F1, Atomic SF-F1 conversion, Reflex FX28 or Xbility XB-F1.
- Wheelbase: 112–116 mm.
- Motor: 2500Kv sensored 1/28 motor, max 15 mm can, 2800Kv ceiling. No aftermarket rotors or motor tampering.
- Gearing: any pinion/spur; standard event ratio 12T/53T unless announced otherwise. Gear tooth counts must be identifiable.
- Wheels: front 11 mm, rear 14 mm, 19–20 mm diameter.
- Tires: production rubber tires, max 25.5 mm mounted diameter. Tire warmers allowed; no traction compound, homemade/foam/silicone/urethane/ethyl-carbamate tires or inserts.
- Battery: 2S LiPo or two 1S cells in parallel; max 8.40 V, max 45×24×13 mm, max 500 mAh, original production labeling required.
- ESC/receiver: any manufacturer, but ESC must be in blinky mode. Gyros and gyro-equipped receivers prohibited.
- Body: approved Lexan Formula bodies; aftermarket F1-style front/rear wings allowed. Bearings in the front wing are prohibited.
- Minimum race-ready weight: 140 g.
- Summer Nationals: blinky motor/ESC combinations must pass the event KV check before being allowed to race.
Pan Open28SRA 2026
Open-power 2WD pan class.
- Chassis: any 1/28-scale 2WD chassis. Production, prototype and pre-production chassis are allowed.
- Wheelbase: 94, 98 or 102 mm.
- Motor: any manufacturer motor, sensored or sensorless, max 16 mm can diameter.
- Gearing: open.
- Wheels: production 1/28 plastic or aluminum; front max 11 mm, rear max 14 mm, 19–20.5 mm diameter; wheel/tire package must fit inside the body.
- Tires: production rubber tires; front max 11 mm and rear max 14 mm. Tire warmers allowed. No traction compound, homemade, foam, silicone, urethane, ethyl-carbamate tires or inserts.
- Battery: 2S LiPo or two 1S cells in parallel, max 8.40 V. A separate battery may be used only for the transponder.
- ESC/receiver: any manufacturer sensored or sensorless ESC and receiver. Gyros and gyro-equipped receivers are prohibited.
- Body: approved 28SRA Lexan pan body. Cutting the rear panel is allowed.
- Options: open; homemade, 3D-printed and prototype parts are allowed.
Tech Quick Reference
| Class | Motor / ESC | Battery | Weight | Key checks |
|---|---|---|---|---|
| Box Stock | Kyosho RTR brushed / stock RTR board | 4×AAA | No added ballast | RTR chassis, hard body, wheels/tires, stock electronics |
| Spec LM | Kyosho stock or PN 70T | Per Box Stock | Per Box Stock | Kyosho LM, 102 mm, LM hard body, allowed spring/damper changes |
| Lipo 2500 | 2500 class, ≤2800Kv, blinky; 12/53 | 2S, ≤8.40V, ≤500mAh | ≥160g | KV, blinky, gearing, weight, body ≥24g |
| Lipo 2500 Pan | 2500 class, ≤2800Kv; open gearing | 2S, ≤8.40V | No minimum listed | KV, pan body, wheelbase, wheels/tires, no gyro |
| Formula 1 | 2500 class, ≤2800Kv, blinky | 2S, ≤8.40V, ≤500mAh | ≥140g | KV, blinky, 112–116 mm, F1 body/wings |
| Pan Open | Open, ≤16 mm can; open gearing | 2S, ≤8.40V | No minimum listed | Pan body, wheelbase, wheels/tires, no gyro |
FAQ
How many qualifiers are guaranteed?
Two. A third may be added if the event schedule allows.
Is tech required before every race?
Yes. Cars are subject to technical inspection before each qualifier and main.
Do blinky classes get checked for KV?
Yes. All blinky classes must pass the event KV check to race.
Which classes receive a KV check?
Lipo 2500, Lipo 2500 Pan and Formula 1 must meet the published 2800Kv ceiling. Blinky operation is additionally required for Lipo 2500 and Formula 1.
Where do I place my car before a race?
In the pit lane. Do not place the car directly on the driving line.
Share The Rules
Summer Nationals Rules & Tech
Scan the QR code or visit vector28.org/summer-nationals/.
Useful for posting at the track, registration table or on social media.
Race replay, setup analysis and RC race tools. Return to the Vector28 home page anytime from the sponsor link at the top of this page.