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Big Daddy's Indoor Motorsports rules

1/12 Losi Dirt Late Model Rules

v1
Class Rules1/12 Losi Dirt Late ModelEffective Aug 15, 2026· Updated 2 months ago

Summary of recent changes

1/12 NASCAR Losi chassis run with a dirt late model body — same spec as Losi NASCAR.

Spec sheet

Governing
Notes
Stock RTR, no option parts besides heatsink
Motor & ESC
Motor type
Spec brushed
Motor turn
N/A (brushed)
Spec motor
Losi LOS-1907 28-turn 380 (or ARRMA ARA390305)
ESC
Stock 25A brushed (IC2)
Battery & power
Battery chemistry
LiPo
Cells
2S
Max voltage
8.40V
Tires
Spec tire
Losi spec (LOS-1914/1937/3779)
Tire additive
Spec sauce only
Weight & body
Min weight
945 g
Body
Pro-Line Dirt Late Model or Losi ZL1 Asphalt Late Model
Chassis & Suspension
Chassis
RTR Losi NASCAR / ZL1 Asphalt Late Model (unmodified)

1.Chassis Spec

RTR LOSI Nascar with stock body mounts, front and rear splitter, OR RTR LOSI ZL1 Asphalt Late Model with stock body mounts, front and rear splitter. Un-modified. No removing any parts. No heating or bending parts.

2.Weight Spec

Minimum 945g in race-ready trim.

3.ESC / Receiver

Stock SPMXE3125RX / Stock SPMXSE3325RX / SLT RX / 25A Brushed ESC IC2 plug.

4.Battery Spec

Stock SPMX142S30H2 Spektrum 1400 2S 7.4V Smart G2 30C lipo / Ovonic 1700 2S with IC2 plug / Ovonic 1400 2S with IC2 plug. MAX temp 90F at tech table. 8.40 MAX VOLTAGE. Battery in stock battery box location.

5.Tire and Wheel Spec

LOS-1914 (medium) or LOS-1937 (soft) / LOS-3779 (medium) Asphalt Late Model. Sidewall glueing allowed.

6.Motor Spec

Stock LOS-1907 28-turn 380 or ARRMA ARA390305 28-turn 380 with original bullet plugs from LOS-1907 installed. LOSI Nascar 380 Aluminum Motor Heatsink LOS-1920 allowed.

7.Body Spec

Dirt late model body: Pro-Line Dirt Late Model or Losi ZL1 Asphalt Late Model. All bodies precut, no body trimming. Mounted at stock height, not lowered.

8.Miscellaneous

Shock oil & diff grease open. Motor fan may be any 25mm x 25mm fan. Stock springs, bearings, pinion, spur, servo & RTR radio only. No LOSI option parts besides heatsink. All chassis screws must be installed.

9.Race Spec

2-4 minute heats – 60-250 lap mains (OVAL) / 5 minute qualifiers – 5 minute mains (ON-ROAD).

10.Tire Sauce

SXT Black ONLY.

Version history

v1Published.
Aug 15, 2026