■Limited to automotive type - maximum of eight cylinders per engine - two valves and one spark plug per cylinder.
■One blown or two naturally aspirated engines per vehicle.
■Maximum size blown - 575 cubic inch, naturally aspirated - combined 1100 cu. in.
■maximum blower size 8-71. No high helix rotors or cases.
■Aluminum blocks are allowed.
■Blower belt shield required. Blower restraint required if no waste gate installed.
■No Super Stock tractors allowed
2.On vehicles with multi-cylinder engines using starter ring between engines - the starter ring must be 360 degree shielded with 1/4" steel and have both ends enclosed.
3.Multi-cylinder engines that are coupled together the coupler must be 360 degree shielded.
4.Harmonic balancers must be 360 degree shielded and fastened with bolt. SFI approved balancers exempt from shielding.
5.Vehicles equipped with any type of clutch must have steel or aluminum flywheel and use a blowproof bellhousing having no non-factory holes, drilled or cut in it - exception of a clutch maintenance/inspection hole and one 1" cooling hole, and be equipped with a block saver plate of 3/16 steel or 14" aluminum. No cast iron components permitted - components defined as flywheel, pressure plate, floaters/clutch disc(s). All automatic transmissions must have positive reverse gear lockout and a safety blanket installed (blanket must be in good condition).
6.Maximum length of vehicle is 15' from center of rear axle housing to the further most point of vehicle. Vehicle must have wide front axles. Front wheels must track within rear wheels.
7.Hitch height is 20" for all vehicles in Modified class and length is minimum of 18" from center of rear axle to hook point. No clevis allowed on drawbar. Hitches must be rigid, in all directions. No movement is allowed while pulling. HITCH HOLE TO BE 3.75" x 3.0" Drawbars must be parallel to the ground. Hitch must be horizontal - Not vertical. Do not connect drawbars and stabilizer bars.
8.Maximum tire size of 30.5" x 32". Single cut or double cut tires allowed.
9.Competing vehicles must have working rear wheel brakes.
10.Two wheel drive trucks using non-planetary rears must use hub shields.
11.No four-wheel drive trucks or classic modified tractors allowed to pull in Modified class.
12.No turbine tractors or super stock tractors allowed allowed to pull in the Modified class.
13.All exhaust systems must discharge vertically - Vertically is defined as being within 10 degrees (any direction) of "being plumb". Height shall be a minimum of 12" above the bend in the pipe which discharges vertically, measured from the top of the pipe to the bottom of the bend.
14.Pulling vehicles must have an automatic ignition kill switch and/or shut off. Kill switch must be mounted independently of drawbar and/or wheelie bars. Kill switch to be mounted in rear center of vehicle, 48" above and within 6" off center of point of hook. Kill switch for spark ignition engines must break or ground the ignition circuit and must break electric power to an electric fuel pump(s) if so equipped.
15.Pulling vehicles must have a shield between the driver and the tires that consists of a solid barrier between the driver and any part of the rear tires. The barrier must be able to sufficiently support the wieght of the driver and must extend a minimum of 6" horizontally at the top, and be a minimum of 36" wide at the top.
16.All vehicles must be equipped with stabilizer bars. Stabilizer bars to have pads, not wheels, on bottom of baars. Pads to be a minimum of 5 sq. in. Pads to be a minimum of 32" rearward from the center of the rearend housing. Pads maximum of 10" off the ground. Outside to outside length of pads to be a minimum of 20". Minimum 12" high bumper bars - Top to be fastened to stabilizer bar framing. Bars must support weight of tractor for weight class being pulled.
17.All vehicles must have front skid bars. For examples: >>>CLICK HERE<<<
18.All weight frames and weights must be stationary and safely secured to the vehicle. Frames or weights must not extend rearward beyond the rear tires or exceed the width of the rear tires. No weights on vehicle seat or deck or within 8" of top of drawbar.
19.All driveshafts must be inclosed. Any continuous section cannot be longer than 48".
20.Legal fuels are gasoline, and alcohol. All forms of nitro-methane, including nitrous oxide and propylene oxide are illegal.
21.Vehicle must have a rollover protection bar or cage that is at least as high as the top of the drivers head/helmet. Rollover protection must be fastened at least two points to the rear axle housing. Factory style flip down tops allowed. Rollover protection must be able to lift one rear wheel when pulled horizontally from the top of the bar/cage without damage to the rollbar/cage.
22.Fire extinguisher is required.
23.Driver must wear helmet and fire suit (jacket and pants).