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Section 20 - PRO STOCK SEMI TRUCKS (PSS)

Unless specifically outlined below in the class specific rules, the Truck General Rules and the overall General rules outlined above will apply.

20.1 - General Rules

  1. Pro Stock Semi Trucks will compete at a maximum weight of 20,000 lbs.

  2. Truck must be stock appearing for the year, model and make of truck.

  3. All trucks must have working brakes on all rear wheels.

  4. Drivers must use a seatbelt and/or shoulder harness when hooked to the sled.

  5. Cabover (COE) type trucks are not accepted in OTTPA competition.

20.2 - Drawbar / Hitch

  1. Trucks are required to have their own hitching device that is subject to approval by the head tech official at each event. The hitch must be adjustable so that the height from the ground to the point of hook is between 18” and 14’’

  2. Centerline of the rear axle to the hook point on the hitch must be no greater than 7 feet.

  3. Trucks running 4.1 and smaller turbocharger has a 18 inch maximum hitch height

  4. Trucks running 4.2 - 4.6 turbocharger has a 16-inch maximum hitch height

20.3 - Chassis / Body

  1. All competition vehicles must have a firewall between the engine compartment and the driver's compartment. No holes except for controls. Holes must be no larger than one-half inch larger in diameter than the control that passes through.

  2. All hoods must be securely fastened closed while in competition.

20.4 - Tires & Wheels

  1. Maximum tire size limited to 11x24.5 x 8.25 (or) 10 x 22 x 8.25.

  2. All tires must be road use approved tires and available to the public.

  3. Dual wheels and dual tires must be used on the rear axles.

  4. No chains or cables permitted.

  5. No tire cutting permitted.

  6. No split rim or wedge lug type wheel allowed.

  7. No spoke type wheels. Wheels must be bud type.

20.5 - Weights / Weight Box

  1. Weights cannot extend rearward more than 51 inches from the center of the rear axle.

  2. Weights cannot extend more than 24 inches from the farthest point forward of the vehicle.

  3. Weights must not interfere with the hooking of the sled to the hitch.

20.6 - Engine

  1. Only one production available commercial truck engine will be permitted.

  2. The engine must have been available for over the highway road use trucks.

  3. No recast, billet steel, or aluminum blocks.

  4. No recast, aluminum, or billet heads permitted.

  5. All fans must have fiberglass blades. A complete shroud must encircle the fan area (360 degrees) and be securely attached.

  6. Mechanically operated throttles must have two springs attached to the throttle arm on pump to aid in returning to idle position.

  7. Electronic engine control (ECM) may be OEM or aftermarket.

  8. Factory fuel pump or P-Pump is allowed for all trucks. It must not be larger than a P7100. No pump may be modified with Sigma parts. No Billet fuel pumps.

20.7 - Kill Switch / Air Shutoff

  1. A 3-way dump valve is required in the fuel supply line on mechanical fuel injection systems. It must be easily accessible to the driver to operate while restraints are worn.

  2. Air shut off must be able to be activated from the driver’s position and must also be connected to a cable run to the rear of the vehicle.

  3. Kill connection at rear of vehicle must be within 6 inches of centerline of truck, and 36 inches above hook point. A 2-inch solid ring attached to end of this cable

20.8 - Turbocharger

  1. Turbos are limited to single turbocharger with a 4.6” inch maximum inducer bore.

20.9 - Transmission

  1. Transmissions and rear ends must be commercial semi-truck factory components.
  1. Only mechanically activated clutches are permitted. (Hydraulic assists are permitted)

20.10 - Axles & Suspension

  1. Only tandem drive axle bobtail semi-trucks will be permitted to compete.

  2. Tandem axle spacing must be between 60” and 52”.

  3. No front wheel drive will be permitted.

  4. Airbags or air springs and/or all mechanical lift mechanisms on front steering axles are NOT permitted.

  5. Trucks with air ride suspension must be equipped with chains or some type of limiting device on both drive axles to prevent the height of the frame from changing during the pull. Limiting devices must not have any ‘give’ built in. Solid rear drive axle suspension permitted, however all drives must be chained or limited. Chains or limiting devices must be tight (no slack) when the hitch is measured. Four short chains or cables from the side of the frame down to the axle housings is recommended. No chains and binders going up and over the frame rails are allowed.

20.11 - Driveline / Shielding

  1. Universal joint shields are required beyond the rear of the transmission. Must be a solid construction, 5/16” thick steel minimum and be able to contain debris or direct debris toward the ground. U-joint shields not required on the inter-axle drive shaft provided the top of the frame between the rears is securely covered with minimum 1/8” aluminum or steel. Front driveshaft to have a 5/16-inch x 2-inch wide steel, 360-degree safety loop installed at center of driveshaft between transmission and front drive axle and be securely mounted to each frame rail by two (2) – 3/8-inch grade 5 bolts evenly spaced on each side.

  2. SFI 4.1 or 4.2 blanket that completely covers the bellhousing. It must be attached to the block and extend rearward to the transmission with a minimum six-inch overlap where it is fastened. Must have SFI tag and be within the expiration date. A fabricated Bellhousing can be used based on the following:

    1. On a vehicle where an SFI bellhousing is not available to cover the flywheel and clutch assembly, an SFI type bellhousing may be fabricated using a minimum 1/4-inch steel and covered 360 degrees with an SFI 4.2 blanket.

    2. Use of fabricated bellhousings limited to applications where a SFI 6.2, 6.3 or 6.4 bellhousing is not available or feasible for application (i.e. flywheel/clutch assembly larger than 14 inches).

20.12 - Fuel & Water

  1. VP Racing Fuel is the only fuel that is allowed for use in all pulling vehicles. VP DX fuel is allowed.

  2. VGM water is the only water injected water that is allowed. All water injected vehicles must run VGM water only.

  3. A \$50 fine will be assessed for lack of fuel and water test ports for all classes.

  4. A \$50 fine will be assessed for any minor infractions of fuel or water quality.