Jump to content
Sign in to follow this  

XIII Modified 4WD Trucks - 2010 NTPA

Sponsored By:  

Recommended Posts

A. Body/Chassis

1. Vehicle must have hood, grill, and fenders in place as intended by manufacturer.

2. Vehicle body style must be or have been available from a dealer as a mass produced model.

3. Vehicle must maintain original appearance.

4. Vehicle appearance.

a. Must have metal cab and outer skin

b. No cab and bare chassis, or flatbeds permitted.

c. Must have metal fenders, doors, frame, hood and bed shell.

d. Non-metal floor allowed in bed.

e. Fiberglass hood scoops, spoilers, fender flares are allowed.

f. Allowed to use stock appearing pickup truck and van fiberglass bodies and body parts.

5. Side doors must be mounted and closed if vehicle was manufactured with doors.

6. Truck doors must have a single latch design, allowing the door to be opened from both inside and outside.

7. Flip-top-body type vehicles and vehicles that do not have two (2) working doors must have door glass lowered or

8. Vehicles with less than stock size window openings must have an escape hatch with a minimum size of 17" x 18"

note: Escape hatch will not be counted as a working door.

9. Adjustable front shocks or suspension stops must be mechanical. Pneumatic, hydraulic, electrical adjustable stops are not allowed.

10. Vehicles must have safety glass or plexiglass in windshield and rear window. Factory tint is permitted.

11. Stained or smoked glass is not allowed.

12. Tinted windows that impair the track officials view of the drivers compartment are not allowed.

13. Vehicles in this division must have vertical bumpers at the rear most point of the vehicle. Bottom of bumper to be a minimum of 8" vertically. Must be rigid.

14. Hood line variance: original hood line should be kept and a 3" maximum clearance opening will be allowed for speed equipment.

15. Truck or floor must have floor or bed cover.

16. Truck may compete without tailgate or rear door(s) for greater hook point visibility.


B. Drawbars

No drawbar greater than the angle of the sled chain. (Acceptable angle: 0° to a maximum of 25°)


C. Driveline/Driveline Shielding

1. Vehicles must have three (3) round metal shielding loops.

a. 360° loop must be a minimum of 3/8" aluminum or 5/16" steel, 3/4" wide (or wider) and not more than 2" from the shaft in any direction.

b. End loops to be placed no farther than 6" from universal joints, with third loop in center of shaft.

c. May use a solid tube (3/8" aluminum or 5/15" steel) to meet the above requirements.

2. If planetary reductions at wheels are used, the following drive shaft shielding criteria will apply. No cast metal.

a. All remaining drive train, excluding additional manual transmissions, must be encased in 5/16" minimum steel or 3/8" aluminum, round, inside diameter not to exceed 2" inches more than the outside diameter of the largest universal joint, fastened every 6" or closer with 3/8" or larger bolts, Grade #5, or butt and seam welded, and securely mounted to vehicles frame. Applies to all vehicles with exposed drive shaft. No more than 1/4" of end of driveline shall be visible with driveline shielding in place.

note: If U-Joints are used in any drive shaft application, the shielding must be 5/16" steel or 3/8" aluminum with 1/8" steel insert in aluminum. The insert must be a minimum of 6" wide.

b. Shield over any yoke or U-Joint must be within 1/4" of gearcase and extended a minimum of 4" past center line of U-Joint.

c. All FWD vehicles engine/automatic transmission combination must have either (1). Two front engine mounts, two rear engine mounts, and a support saddle for rear of transmission, with 1/2" maximum clearance; OR (2). Two front engine mounts, support saddle at rear of engine, with 1/2" clearance, and a mount at rear of transmission.

note: this is to prevent engine or transmission from dropping if breakage occurs.

3. Drive shafts between engine and transfer case must have solid shielding a minimum of 3/8" aluminum or 5/16" steel.

4. Vehicle must have 360° metal shield around the universal joints, 3/8" aluminum or 5/16" steel, minimum 6"wide.

note: if a split design is used, mount as in rule 2:a. above.

5. Axle and hub bolt shield required, except where planetary final drives are used.

a. Shield must be at least 0.060" inch think.

b. Minimum diameter of axle end or hub bolts to be covered on both front and rear axles.

c. Mounting shield cannot be mounted to axle end or hubbolts.

d. A hole may be installed in center of front shield so lock can be operated, so long as hub end or axle bolts are covered.

6. No counter balancers permitted in driveline.


D. Engines/Engine Limitations

1. Vehicles are limited to a single automotive-type engine.

note: automotive engine is any engine or it's replica available in a passenger car. Maximum eight (8) cylinders. No diesel engines permitted.

2. Engines must be naturally aspirated only.

3. Acceptable fuels are gasoline and alcohol.

4. Engine must be in stock location, which is defined as being within engine compartment as manufactured, behind stock grill and in front of stock firewall.

5. Vehicle may run without radiator, and engine may be moved forward, but must stay behind grill.

note: entire engine to mean anything that is bolted to the engine block.

6. Except for high performance type starters with crackshaft drive, rear of engine block may not be moved forward of center line of front axle.

7. Not superchargers or turbochargers allowed.

8. Automotive engines at all levels of competition are only allowed to run a maximum of two (2) valves per cylinder and one spark plug per cylinder.

9. Fuel injection (and carburetors) and headers may protrude through to hood.

note: bubble or scoop is optional, but if used, the scoop or bubble must cover the carburetor(s) of fuel injection, if induction system protrudes through the hood.

10. Maximum boring space is to be 5.0" on center.

11. Vehicle must have vertical exiting exhaust. Height of pipe must be a minimum of 1' above the bend.

note: vertical is defined as "being in plumb" with a 10° variance in any direction permitted.

12. Vehicles to conform to provisions of Modified Tractor engine shielding.*

13. FWD vehicles must have provision on crankshaft to accommodate 1/2" square drive at 1 to 1 ratio for use in cubic inch test.


E. Frames

1. May be different than the make and model of truck body.

2. Must be main supporting member of chassis, OEM truck frame.

3. Tubular steel frame is allowed.

4. Center of wheels cannot exceed plus or minus 6" of fender wells for wheelbase being used, which means that a vehicle may run up to a maximum of 133" wheelbase.

5. Wheels must be in fender wells as described above. Body may be stretched in middles to accommodate this.

6. The outside edge of the tire on the narrow axle must overlap the center line of the tire on the wide axle by at least 1".


F. Hitch

1. No portion of the truck may interfere with sled, chain or hook during pull or while being hooked or unhooked.

2. An area 5" wide and 12" high immediately above the drawbar must be free of all obstructions (including weights, wheelie bars and second drawbars) for ease of hooking and unhooking.

a. If body extends more than 12" behind point of hook, the open area must be 18" above the drawbar and 24" wide at rear most point of body.

3. Vehicles must have tow hitch of front of vehicle.

a. It can extend no further than 6" past the farthermost front portion of the vehicle.

b. It will not be counted when measuring the length of the vehicle.

c. It must have a 3" diameter hole, positioned horizontally.

d. It must be strong enough to push or pull the vehicle at it heaviest weight.

e. It is to be used only for pushing or pulling the vehicle.


G. Safety

1. Vehicle must have complete firewall with no holes except for controls. Holes not to exceed, 1/2" larger than control.

2. Vehicle that do not have working doors must carry an on board halon fire system with a minimum of 3 nozzles located within the driver's compartment/engine compartment.

3. Flip top funny car type vehicles must have body in lowered position before vehicle may be moved under it's own power.

4. Flip type bodies must have a safety lock to hold up the body.

5. Body may be raised to start engine and may stay raised while engine is running as long as the vehicle is not in motion.

6. Operator"s compartment.

a. No fuel tanks, fuel pressure gauges, fuel pumps and/or fuel lines are allowed in the operator's compartment.

b. If the fuel tank is located behind the driver, a fire barrier is required from the firewall to the rear of the drivers seat. (0.060" aluminum or steel is acceptable fire barrier material.)

7. Vehicles must use wheels no more than 6" of the ground, within 6" of the forward most part of the vehicle.

a. Wheels must be a minimum of 6" in diameter by 2" wide.

b. Wheels must support the weight of the vehicle.

c. Wheels must be raised or removed for the purpose of ground clearance when the vehicle is not on the competition track.

d. Wheels must be at least 3' apart.

8. Weights must be safely secured to vehicle, and must not extend forward more than 60" from the center line of the front wheel.


H. Tires.

Maximum tire size to be 112" circumference when mounted on a 20" wide rim and inflated to 30psi with original bar, not to exceed 18" in tread width before cutting.


* Engine Shielding (it's late, I will complete this portion later)..........


Share this post

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

  • Create New...