SECTION 8

MODIFIED EQUIPMENT RULES

 8-1 MODIFIED ENGINES

PART A – ENGINES The following list constitutes legal engines:

NOTE: See class weight rule (rule 2-1) for tractor weight limits according to engine size.

ENGINES – AUTOMOTIVE

One automotive engine of 600 cubic inch. Maximum supercharger size 14-71. Helix restricted to a maximum rotor spiral of 6.5 degrees per inch of rotor length. Variable multi speed supercharger devices prohibited.

All superchargers must be mounted to the intake manifold by use of aluminum studs only (No steel studs allowed.) All modifieds must have an explosion blanket around the supercharger.

Supercharger restraint system is mandatory and shall consist of four separate straps, one on each corner of the supercharger, with each strap securely fastened to the engine by means of its own attachment bracket. The top attachment bracket is to be sandwiched between the lower surface of the injector body and the upper surface of the supercharger case. The bottom attachment bracket for each strap shall be connected to the engine by a minimum of one 5/16 inch bolt or stud (SAE Grade 5 or better).

Blower belt shield must be wider than all components, idler, belt pulleys, etc. and extend to the bottom of bottom pulley or below.

Screw-type superchargers are not permitted for competition vehicles.                                                                                                                                                                                                                                                                                  Any specifications not listed will follow NTPA rules.

ENGINES – TURBINES

One T-53 or one GE T-58 allowed.

1.       Any turbine engine is not allowed to run a clutch/flywheel assembly or any automatic transmission.

2.       Exhaust pipes of turbines must extend a minimum of 6 inches above the top of the exhaust opening.

3.       Exhaust stack diameter to be no smaller than 1 inch of engine outlet.

4.       No turbine engine will be operated beyond military temperature and RPM limits.

5.       Turbine air intake must be screened with metal screen that has openings no larger than 3/16 inch.

6.       Engines must have a 3/8 inch steel shroud that surrounds the engine. Shroud must extend a minimum of 5 inches forward and ten inches aft of the turbine section. The shroud must incorporate a minimum of 3/8 inch thick flanges that extend radially inward from the shroud on both ends of the shroud within a maximum of 1 inch of the engine casing. A ½ inch gap between the engine and the ID of the flange must be maintained for air circulation inside the shroud. The flanges may be scalloped out to clear turbine accessories, brackets, etc. and may be either rolled edged of the shroud or steel rings attached by welding or rivited to the shroud.

Two independent over speed protection devices are required for power turbine wheel.

The governor setting must not exceed manufacturer’s maximum specs. Over speed shutdown – consists of speed monitor that activates a normally closed solenoid valve located between fuel control and fuel manifold. Trip setting to be low enough to prevent overspeed in event of driveline failure. No TF-35 engine allowed.

Turbine engines allowed starter motor onboard, or auxiliary power unit to be carried on board and running during a competitive attempt but must not be hooked into the drive train during competition attempt.                                                                                                                                                                                                                                              Any specifications not listed will follow NTPA rules. 

ENGINES – AVIATION, MARINE, INDUSTRIAL

One  Allison naturally aspirated motor. The gearbox output shaft must not exceed one and one-half the speed of the crankshaft. Clutch and bell housing used in this application must be NBPI approved. Bell housing must be bolted to a ¼ inch or greater steel plate with a minimum of (12) 3/8 inch bolts (grade #5) evenly spaced around bell housing.

The plate must be securely fastened to the frame by (8) 3/8 inch bolts (grade #5) with (4) bolts on each side of the frame.

The blower housing must be covered by 3/8 inch steel, or approved blanket 360 degrees, extending 8 inches forward of blower housing.                                                                                                                                                                                                                                                                                                                                                             Any specifications not listed will follow NTPA rules.                                                                                                                                                                                                                                                                                                                ENGINES - NATURALLY ASPIRATED                                                                                                                                                                                                                                                                                          Any motor configuration can be used. Engines must remain naturally aspirated. The sum of the cubes of all the engines added together cannot exceed 1420 c.i.                                                                                                                                                                                                                                                                                                                      Engines-Agricultural 

Any  agricultural engine with a cubic inch of 505 or less on alcohol, or any cubic inch diesel may be used. Turbocharger size is limited ot the specifications as listed in rule 7-4(1). No aluminum heads allowed. 

ENGINES – TURBOCHARGER

Turbo engines are allowed to run (1) 3” in and out non-staged turbo per bank on (1) V8 automotive engine with maximum of 600 cubic inches. Must also follow  Super Farm rule 7-4 for turbochargers.

Turbochargers that are not under hood must be completely shrouded, except for inlet and exhaust pipes, with steel or aluminum of at least .060 thickness.

PART B – ENGINE PROTEST

To protest a tractor under the cubic inch rule, first contact a modified rules officer. Protester and driver being protested must first put up $250.00 each.

Protester must pay for cost of getting meter, if there is a cost.

On a protest, all tractors in the class will be checked if the tractor being protested fails the test.

PART C – IF YOU ARE ILLEGAL

1.       Forfeit the year’s points.

2.       Refund any prize money received that year.

3.       Tractor and all drivers connected with that tractor are suspended one year and one day from the day prize money is refunded. (Refunded prize money goes into Association treasury.)

8-2 DEFLECTION SHIELD

Deflection shield is required on both sides of the engine from the bottom of the head and extend to 2” below bottom center throw of crankshaft.

 

8-3 DEADMAN THROTTLE

Tractor will be equipped with a deadman throttle. All throttles working in a forward-rearward direction shall be closed in the uppermost position. No hydraulic linkage allowed. Must be positive two-way linkage. All foot throttles must have toe strap. All injection or butterfly shafts of blown engines must have dual return-to-idle arms and springs.

8-4 HARMONIC BALANCERS

Harmonic balancers that  are non-SFI approved shall be shrouded with  ¼ inch steel no more than 1 inch away in any direction of rotation, 360 degrees and securely fastened, or shall be solid steel. A bolt in the crankshaft to hold  dampner is required. All balancers or steel hubs required to have a retainer to restrict forward movement. 

8-5 FANS

All fans must be shrouded with steel 1/16 inch or thicker, 360 degrees. Electric fans excluded.

8-6 EXHAUST

Exhaust must be discharged vertically, 11 inches above the bend in the pipe. Vertical is defined as within 45 degrees of plum. No rain caps.

8-7 FUELS

All forms of nitro-methane (including nitrous oxide) are illegal as a fuel or fuel additive. Legal fuels are gasoline, alcohol, aviation gas, kerosene and diesel.

8-8 FUEL DELIVERY

Fuel delivery must match engine type.

8-9 KILL SWITCH

Kill switches must be located in the rear center of the tractor. Kill switches must break the entire electrical system.

CABLE CONSTRUCTION

Kill switch cable must be enclosed, so that if tractor unhooks from sled cable can be separated from tractor without obstruction from the tractor.

8-10 TRACTOR SEAT

All tractors must have a strong and rigid seat and be independent of the fenders.

8-11 FENDERS

All modified tractors are required to have fenders or a shield or both, between driver and any part of the rear tire. Fenders must curl a minimum of 6 inches from vertical, out over the tire in the same configuration as the tire. Fenders or shield must be able to support weight of driver. They must be constructed so that when the driver is seated and hands are on the wheel he/she cannot touch the rear tire with any part of the body.

8-12 WHEELIE BARS

Wheelie bars are required and shall be able to support the tractor’s weight and be more than 10 inches off the ground and have a pad at least 5 inches square, located 32 inches from center of axle.

8-13 TRACTOR LENGTH

No portion of tractor, including weights, may exceed 14 feet forward of the center of the rear axle.

8-14 FRAME BRACES

Tractor frames will be braced from the front frame to the rear axle.

8-15 BRAKES

All tractors must have working brakes.

8-16 DRAWBAR CONSTRUCTION AND PLACEMENT

Minimum length of drawbars will be 18 inches from center of the axle to point of hook, and have a maximum height of 20 inches from top of hitch to the ground. Drawbars shall be constructed so that in the event of breakage, the drawbar supports do not pull from a top link or brace above the centerline of the rear axle. Drawbars must be rigid in all directions.

DRAWBAR CHECK – Mandatory drawbar height check will be done at the beginning of the track before each pull attempt. This applies to all classes and all tractors. Measurement for each tractor will be done in the same location.

8-17 CLUTCH AND FLYWHEEL

Tractors using a manual clutch shall be equipped with a blow proof flywheel and clutch assembly, and be in a blow proof bell housing of 360 degree type. It is the responsability of each member to  inspect their own  clutch annually and provide a signed Warrant of Clutch ,Flywheel and Bell housing (or Automatic) Components waiver to compete.

8-18 AUTOMATIC TRANSMISSION COVER

Automatic transmissions will be completely covered, 360 degrees, with two safety blankets from the back of the engine block to where the tail shaft bolts to the main housing. Flywheel inspection cover must be in place.

8-19 DRIVE SHAFTS

Drive shafts will be enclosed in 5/16 inch minimum steel. Round inside diameter not to exceed 2 inch more than the largest universal joint, fastened every 6 inches or closed with 3/8 inch or larger bolts, or butt and seam welded, and securely mounted to the tractor frame.

8-20 ENGINE SUPPORT

Engines must have a support saddle at the rear of the engine, and in front of any auxiliary transmission; 3/8 inch steel, 5/16 inch chain or cable, or rear block plate.

8-21 TRACTOR FRONT END

Tractors shall have a wide front axle. Front wheels shall track within the rear wheels.

8-22 TIRE SIZE

Rear tires shall be no bigger than 30.5x32.

8-23 STARTER INTERRUPT SWITCH

All tractors must be equipped with a starter interrupt switch on the gear-shift which will allow starter engagement only in a neutral gear-shift position.

8-24 REVERSE LOCK OUT

All tractors using an automatic transmission must be equipped with a positive reverse gear lockout.

8-25 INTERFERENCE

No portion of the tractor may interfere with the sled during the pull.