New Hampshire's Original Diesel Performance and Repair Specialists



4 Cylinder Mini Tractors


4 Cylinder Mini Modified Tractor Class Rules

  1. Weight classes to be 1650 and 1800 lbs.
  2. Must be automotive water or air cooled, 4-cylinder 4 stroke engine. Y you must start with an engine no more than 2500 cc or 153 CI. You may do anything you wish inside the engine.
  3. You may use any intake manifold but carburetion is limited to a maximum of 500 CFM of any combination, naturally aspirated, allow fuel injection systems.
  4. Engine and first transmission must be compatible.
  5. Engines with stock intake manifold and carburetor must be equipped with a 3/16 thick steel bell housing safety shield. It must be a 180-degree design to the bottom of the flywheel and securely attached to the tractor starting one inch ahead of the flywheel or against the face of the engine block and be a minimum of 6 inches wide or this area must be covered with approved SF1 safety blanket.
  6. Engines with non-stock manifolds or carburetors must run one of the following:
    1. An approved SF1 steel bell housing
    2. A bell housing covered with an approved SF1 safety blanket
    3. A stock bell housing covered with a fabricated shield of at least 3/16 steel starting at the rear face of the engine block and extending at least rearward of the front of the transmission it is to be of a 360-degree design and also to include the front of the bell housing that extends below the engine block as much as possible. The lower portion of the shield may be of the bold on type. The intent of the shield is to fully encase the bell housing and to contain a failure in the area.
  7. All automatic transmissions must b covered with an approved safety blanket (blanket must meet SEMA standards) or be covered with steel as in standard transmissions specifications.
  8. Any ignition system allowed. Quick change rear ends allowed.
  9. No alcohol fuel allowed.
  10. All u joints and drive shafts must have 360-degree design shielding made of 1/8 steel. All fans and belts must be covered by 1/6 steel shielding 360 degrees.
  11. Harmonic balancer shall be solid steel or shrouded with ¼ steel no more than one inch away in direction of rotation, 360 degrees to be securely fastened.
  12. Tires will not be any larger than 31 inches high, no dual wheels. All tractors will pull in 2-wheel drive.
  13. All tractors must meet mini specifications on following
    1. Ignition kill switches
    2. Safety specifications
    3. Exhaust system
    4. Clutches, flywheels, and automatics #2 & #3 only
    5. Engine side shields (rules #2 & #3 engines)
  14. All tractors will have fenders suitable for protecting the driver.
  15. Hitch height is 13 inches at the hitch point.
    1. Draw bar must be horizontal
    2. Must have a 2’ or larger hole
    3. Minimum ¾ from pulling point to edge of the hitching device.
    4. Minimum ¾ thick steel at the hooking point. Any steel tubing used in the hitch must have a minimum of 160 wall thickness, all other steel must be minimum 250. The hitch must be rigid in all directions, not having more than ½ play.
    5. No portion of vehicle may interfere with sled, chain or hood during a pull or while being hooked or unhooked.
    6. Draw bars to have no provisions to be made shorter than 6: from center of rear axle.
    7. Draw bars and wheelie bars are not to be connected
  16. All tractors shall have wheelie pads. Pads are to be 4”X4” maximum height to be 6 inches. Rear of pads are to measure a minimum of 6 inches from outer rear circumference of the tire. Wheelie bars to be tested at a maximum weight and stamped as such by the board.
  17. No portion of any tractor may exceed 8 feet forward of the center of the rear wheel. Nor will it exceed 6 feet maximum in width.