Tech Information

Summary of new rules and procedures approved by WPI and NTPA Executive Board of Directors for 2025
season. The following is a description of all new rules or changes to existing rules. Each new or updated
rule is noted as NEW’25 in rule book index. For more details, refer to the 2025 NTPA Pulling Rules
referencing page numbers shown.

Drawbar Measurement – pg.31

• Drawbar to be measured using a NTPA approved drawbar stand on a hard, flat surface as level as
  possible. Concrete pad is preferred as recommended to promoter. Scale is also an acceptable
  measuring surface if long enough and level to measure drawbar accurately using drawbar stand.
• Tire air pressure can be altered and drawbar can be lowered after the drawbar is measured but all
  vehicles are subject to drawbar check after competition.
• Drawbar re‐measurement after competition pull is at the discretion of the Event Manager or Head
  Official.
  • TWD Hitch Locking Device rule remains as currently written.
  • Rule requiring drawbar adjustment on pad 3 to 5 vehicles ahead of hooking is deleted.

Breakage and Points Clarification – pg.31,32

• New rule implemented for 2024 season applied to the second session when a competitor broke
  during first session of a multi‐session event.
• Last place points for second session are awarded when there are 15 or less total competitors in the
  class and breakage occurred in competition during first session. Must pull a measureable distance for
  this rule to apply.
• Last place points will not be awarded if entered in a second class and vehicle has not made a
  measurable attempt in that division during the first session of competition.
• Competitor must hook in first session in order to earn last place points in a second session for each
  division entered.

C. Disqualifications – pg.39

• 7. Penalties
  Penalties for illegal vehicles shall be as follows:

  a. Illegal engine, drawbar, ignition, traction control, data recorders, and cubic inch violations shall
  result in a penalty of up to loss of all points accumulated for the competition season by that
  NTPA license numbered vehicle and suspension of membership for up to five (5) years and ten
  (10) days for the driver and owner of that vehicle. Penalty applies whether or not the owner is
  the driver of the vehicle. Upon appeal by competitor or owner and review, final penalty
  determination is at the discretion of WPI/NTPA Executive Boards along with WPI / NTPA
  Technical Services.

NTPA Stamp – General Rules – pg.43

• Notice: Any flywheel or component engraved with NTPA stamp is not recognized as an approved
  component for NTPA competition.

Tractor Drawbar – includes 7,700 lbs. up to 10,000 lbs. – pg.54

• Tractors (including OEM chassis) must utilize a single piece drawbar design, billet steel, incorporating
  a minimum 15/16‐inch diameter pivot pin located on same plane as the point of hook.
• No interference to anti‐unhook device welded to nose of sled hook while vehicle is hooked to the
  sled or when hook is inserted or removed from drawbar.
• Top and bottom of drawbar must be flat the entire length, no step up or down ahead of 3 ¾‐inch
  long by 3‐inch wide hole for hook.
• Any request to machine drawbar or bottom of rear differential housing to increase drawbar height
  must be submitted to NTPA Technical Services for approval.

Semis – Drawbar Access – pg.55

• Area 7 inches wide and 5 inches forward from drawbar point of hook extending vertically must be
  open and clear of any obstruction including weights, weight boxes, and etc.

Electrical / Electronics / Ignition Systems – pg.58

• Ignition System:
  • Any ignition system that incorporates a means to control/vary/manipulate ignition timing
    based on feedback in any form is prohibited.
  • Multi‐coil (coil on spark plug or near spark plug) systems (ie. Fuel Tech), are accepted in Open
    Super Stock, Light Super Stock, and Modified Mini divisions until end of 2025 NTPA Pulling
    season where further evaluation and consideration will be given.
  • Ignition system and/or components, including ignition module, wiring harness, and
    attachments must be utilized in an unaltered manner consistent with the manufacturer’s
    installation and instruction manuals unless otherwise approved.
  • Ignition control modules (boxes) must not be tampered with in any way. Control module or
    box must be factory sealed with no indication that component has been tampered with
    including indication of factory installed screw(s) being loosened or gaskets and seals broken.
  • Any ignition system that incorporates vehicle performance data via measurement, sensing,
    processing, inference, etc., to activate or deactivate any function or capability of the ignition
    system is prohibited.
  • Any sensor or wiring that connects or transmits vehicle performance data directly, or
    indirectly, to the ignition system is prohibited.
  • The use of any automated rpm‐control device is prohibited.
  • Any microprocessor (computerized) ignition components or control are prohibited.
  • All wiring associated with the ignition system must be fully visible and traceable.
• Traction Control:
  • Any form of automated or computer controlled torque management (ie. traction control) is
    prohibited.
  • The use of any programmable multi‐point rev limiter and/or rate‐of‐acceleration rpm limiter,
    either by themselves or integrated into the ignition system is prohibited.
• Data Recorders:
  • Data recorders may be used (as accepted by division) to record engine and vehicle functions
    (ie. rpm, temp, pressure, etc.) provided data recorder does not activate or affect vehicle
    control or engine ignition and fuel systems.
  • Fifth‐wheel sensing devices prohibited on all vehicles. Includes any additional wheels
    contacting the track other than the four wheels and tires for moving the vehicle.
  • All lines sensing flow, pressure, etc. for fuel or oil must be metallic or steel braided.
  • Any transmitting device (mechanical, hydraulic, pneumatic, electrical, optical, etc.) that
    assists in determining track boundary or location of competition vehicle on track is
    prohibited.
  • For data recorder applications, the transmission or display of any vehicle performance data
    (ie. wheel speed, driveshaft speed, engine data, etc.) gathered or processed by the data
    recorder cannot be broadcast to any remote location or device while under green flag. This
    data may be reviewed manually via (download, printout, replay, etc.) only after the run is
    complete and vehicle is off the pulling track and clear of runout area.

Hypermax Fuel Injection Pumps – pg.59

• Hypermax approved injection pump is an accepted replacement for any Bosch P7100 type pump
  application except in Light Pro Stock division
• Hypermax Mark 2 approved injection pump is an acceptable replacement for any Bosch P8600 type
  pump application

Aftermarket Blocks – (tractor and diesel truck divisions) – pg.60

•  Aftermarket billet or cast aluminum engine blocks are limited to Open Super Stock, Light Super Stock
  Tractors and Super Stock Diesel 4X4 Truck divisions.
• Diesel Super Stock, Heavy Super Stock, Pro Stock, and Pro Stock 5.0 ‐ cast steel or billet steel blocks
  only, no aluminum.
• Pro Stock 4.1 ‐ cast steel or billet steel only, no aluminum.
  • OEM head bolt pattern and OEM head gasket must be used.
• Light Pro Stock, Super Farm, and Hot Farm ‐ cast steel only, no billet steel or aluminum.
  • OEM head bolt pattern and OEM head gasket must be used.

OEM Tractor Tie Bars – pg.72

• No provision for splitting or separating Tie Bar assembly is permitted. Tie Bar assembly must be
  constructed and welded as a one‐piece continuous design capable of keeping OEM tractor chassis
  horizontal when bolts for splitting tractor are removed.
• Tie Bar material type, thickness, and acceptable design(s) to be determined and approved by
  WPI/NTPA Technical Services and Safety Committee.

Diesel Super Stock Tractor ‐ Crankcase Pressure Relief Device – pg.77

• Two aluminum burst panels approved by NTPA must be mounted to side of oil pan, as high above oil
  level as possible, using standard burst panel frame.
• Approved burst panel must be installed as a single thickness into each frame as received from
  supplier. No repair or modification to burst panel allowed.
• Only approved manufacturer is Bonnifante. Distributor for NTPA crankcase burst panel will be
  designated by NTPA Technical Services.
• Contents from burst panel must be deflected downward using a commercially available burst panel
  deflector that fits the burst panel frame and covers the entire burst panel. Deflector cannot be
  fabricated.
• Engines equipped with a steel oil pan are exempt from crankcase pressure relief device requirement.

NEW ‐ SFI Identification Access – pg.78

• Any SFI certification tag or decal along with any manufacturer’s identification or expiration tag or
  decal must be easily accessible and openly visible for inspection at any time.
• Components such as SFI bellhousing, SFI 4.2 clutch housing blanket, and SFI 4.1 automatic
  transmission blanket and etc. are examples of this requirement.
• Removal of a panel or shield for clear visibility is acceptable.

Hemi Spark Plug Retainer – Safety pg.80

• Any Hemi type engine valve cover that is not equipped with a hold down device (ie. snap ring or billet
  ring) for the spark plug tube must install a retaining kit accepted by NTPA Technical Services.
• Any Hemi valve cover that uses only the nut on top of valve cover to secure the spark plug tube
  requires this device.
• K&I Newberry design has been approved for this purpose. Modern Machine and Tool is a
  manufacturer and supplier of kits accepted by NTPA Technical Services.
• Any Hemi type engine spark plug tube retainer that is SFI 14.4 rated is accepted.

Supercharger Burst Panel Deflector – pg.86

• A burst panel deflection shield (commercially available only) must be placed in front of any
  supercharger burst panel whenever a fuel system component(s) are located directly in the path of
  contents escaping the burst panel.
• Fuel System components include but not limited to fuel lines, connection blocks, valves, fuel tank or
  vent.
• Deflection shield must cover the entire area of the burst panel and be enclosed on both ends.
• Contents from burst panel must be deflected upward or downward whichever is the clearest path.
• Deflection shield cannot be fabricated, but must be obtained from an aftermarket supplier and
  installed as intended by supplier, no modifications.

Pro Stock 5.0 and 4.1 – Tires – pg.88

• Mitas or any 24.5 x 32 brand tire approved for NTPA competition is accepted in Pro Stock 5.0 and 4.1
  divisions at Region and State levels
• No limit on number of lugs on any approved tire used in these divisions

Modified FWD Trucks – Tire Circumference – pg.88

• Any tire used in Modified FWD division is limited to 112‐inch maximum circumference when
  mounted on rim after cutting.
• Tire circumference to be measured as installed on pulling vehicle in ready to compete condition using
  NTPA template.

Diesel Engine ‐ Turbocharger Compressor Housing Blanket – pg.91‐92

• Any turbocharger mounted directly to exhaust manifold or bottom (high pressure) turbocharger on a
  multi‐turbo setup in a diesel engine application must have a NTPA approved blanket that completely
  encloses compressor housing.
• Blanket must contain a minimum 5 layers of Kevlar.
• Blanket displaying a SFI 4.1 certification is accepted but not required.
• Blankets manufactured by the following suppliers are accepted by NTPA:
  • Taylor Motorsports Products
  • Stroud Safety
  • Ram Jet

Diesel Super Stock Tractor – Fuel Injection Line Length – pg.94

• All fuel injection lines must be a minimum 24 inches in length from injection pump to injector

Semis – Cab Over Trucks (COE) ‐ pg.102

• Note: Cab Over (COE) type trucks are not permitted in NTPA competition at any level.

Semis – Rear Drive Axles – pg.103

Current Rules

• Rear drive axle must be rigid to the frame in all directions. Axle must not move from main frame of
  the truck.
• If tires on rear drive axle lose contact with the ground while hooked to the sled, this is grounds for
  disqualification.

  Additional Rules Consideration
  
  Note: The following competition rules are optional for 2025 NTPA pulling season. New rules listed
  have been proposed and accepted by WPI/NTPA for the 2026 season. Further evaluation and
  consideration will be given at the end of the 2025 season.

  • Both rear drive axles must be mounted rigid to chassis.
  • Any form of variable suspension on the front drive axle (air, hydraulic, springs and etc.) is
    prohibited in Semi division at all levels of NTPA competition.
  • Front drive axle can be mechanically adjusted up or down only. Adjustment must be by
    mechanical device (screw, lever, linkage, etc.)
  • Suspension adjustment must be locked in place before drawbar is measured and remain locked
    until competition run is completed.
     No drive axle adjustment from cab allowed.

Modified – Supercharger Overdrive (Pro National / Regional National levels) – pg.104

• Any engine equipped with a wedge type cylinder head that does not accept a stock OEM intake
  manifold bolt pattern, excluding Big Chief wedge type cylinder heads, allowed up to a maximum of
  60.0% supercharger overdrive ratio.
• Engines with Big Chief wedge type cylinder heads, overdrive will remain at 42.0% overdrive ratio.
• Engines with wedge type cylinder heads that accept a stock OEM intake manifold bolt pattern,
  supercharger overdrive will remain at 70.0% overdrive ratio.

Light Limited Super Stock – Chassis Rules Update – pg.107, 108

• Chassis / General (current rule book)
  • Front axle suspension is permitted
  • Swivel axle front ends are permitted
  • Aftermarket transmission is permitted.
• NEW ‐ Chassis / OEM
  • OEM tractor chassis is described as having engine, clutch/torque housing, transmission, and
    rear axle housing assembly bolted solidly together as one continuous assembly as configured
    by OEM.
  • OEM tractor chassis built to this configuration must be equipped with a Tie Bar assembly
    constructed and fastened to each axle housing and extend forward ahead of clutch and
    flywheel assembly. Refer to F. General Rules, Section 19. Safety, sub‐section o. Tractor Tie
    Bars for complete details.
• NEW ‐ Chassis / Full Frame
  • Any 2WD OEM farm tractor manufactured without a continuous cast iron housing from rear
    of engine block to transmission or rear differential housing (i.e. 7000 Series JD or Case IH
    MX100) will be permitted to remove any OEM driveline components from rear of engine to
    OEM rear axle and differential housing.
  • OEM farm tractor rear differential and axle housings used must be steel or cast iron and
    retained in chassis assembly. Housings must be used as manufactured by OEM. Only
    modification for installation of internal aftermarket gears, shafts, or bearings allowed. No
    removal of differential housing material for lightening purposes permitted. Only OEM
    replacement housings permitted, no aluminum.
  • Any tractor with the OEM cast iron tub (belly) type frame or OEM driveline assembly
    removed must be equipped with a full steel, channel or tube type frame, bolted to each rear
    axle housing with a minimum qty. 4 (four), grade 8 rear axle housing bolts and extend
    forward continuously to furthest most point of chassis less any external weight rack, tow
    hitch, and etc.
  • No provision for splitting chassis apart is allowed. Frame on each side of chassis must be
    constructed or welded together as a one‐piece continuous design. Chassis design, material
    type and thickness to be determined and approved by WPI/NTPA Technical Services.
  • Brand of tractor sheet metal must match same brand rear axle housing and engine. (i.e. IH
    and Case IH, Ford and HN, and etc.)
  • SFI 6.2, 6.3, or 6.4 bellhousing must be installed along with required driveline shielding and
    tethers meeting Component Tractor requirements.
  • Engine must be mounted no further forward then 60 inches measured from centerline of
    rear axle to rear face of engine block. Engine mounting position must follow Component
    Tractor requirements found in F. General Rules, section 5. Chassis, sub‐section c. Engine
    Mounting Position, 1) Component Tractor.
  • Tractors that competed in 2024 or previous with cast iron tub (belly) type frame (i.e. Oliver,
    White, Cockshutt, etc.) removed, will have until the 2026 NTPA season to mount engine no
    further forward than 60 inches from centerline of the rear axle to rear face of engine block.
  • Optional: Tractors currently competing in Light Limited Super Stock division with a full cast
    iron OEM torque housing as described in OEM chassis rules previous, are permitted to install
    a full frame chassis as described in Chassis/Full Frame. Tractors configured with a full frame
    chassis must retain the cast iron or steel OEM rear axle and differential housings and place
    the engine no farther forward than 60 inches from centerline of rear axle to rear face of
    engine block. This option does not apply to tractors previously built with cast iron tub
    removed where engine location remains unchanged until 2026.
  • If a situation arises concerning safety, a full frame chassis for this division could be
    implemented at any time by the WPI/NTPA Executive Boards.

4.1 Pro Stock ‐ pg. 111

•  2. Turbocharger
  a) Turbocharger air inlet limited to 4.100‐inch smooth bore housing (no MAP ring).
  b) Exhaust outlet limited to 4.500‐inch diameter exhaust restriction to be measured at the face of the
  wheel. All exhaust must exit through the 4.500‐inch restriction.
  c) Inlet and exhaust restricted bores must be perfectly round and straight. No oblong shape or
  tapered restriction area accepted.
  d) Compressor wheel inducer blade outer tips must protrude into air inlet restriction by a minimum
  1/8‐inch (.125‐inch) and be a minimum of 4 inches in diameter
  e) Exhaust wheel must protrude into the 4.500‐inch restriction by a minimum 1/8‐inch (.125‐inch).
  f) NTPA Technical Services must be able to access and measure the 4.100‐inch air inlet restriction
  without making contact with any inducer blade and without removing compressor housing.
  g) Maximum distance from compressor housing mounting flange to face of air inlet opening is 4.760
  inches.
  h) Furthest point of compressor wheel inducer blade(s) must be behind the face of compressor
  housing air inlet opening.
  i) Measurement: A 2‐point NTPA tool with a 1‐inch center opening machined at 30‐degree
  maximum face angle will be used to verify compliance. The NTPA tool must fit the housing air inlet
  bore and stop at the 4.100 restriction without touching any portion of the inducer blade.
  Turbocharger air inlet restriction and related compressor wheel dimensions will be further
  considered and evaluated before the 2026 season.
• 3. Turbocharger Compressor Wheel Retaining Device
  a) Compressor wheel retaining device required at face of compressor housing intake opening.
  b) Retaining device must be mounted solidly to compressor housing air inlet opening by double‐type
  V band clamp before the air shutoff. Face of retaining device limited to a maximum of 8 inches from
  furthest point of compressor wheel excluding center hub or shaft. Maximum diameter of retaining
  device is 8 inches.
  c) Retaining device must be installed as manufactured and supplied by turbo manufacturer.
  d) Retaining device must be a single piece design machined from billet steel or aluminum – no multi‐
  piece welded assemblies.
• 4. Turbocharger Pressure Pipe Blanket
  a) Pro Stock 4.1 turbochargers, the turbo pressure pipe between the turbocharger and the intake
  manifold must be wrapped 360 degrees with a NTPA accepted blanket.
  b) Blanket must be placed as close to compressor housing outlet neck as possible and extend at least
  6 (six) inches beyond the first bend in pipe or a minimum blanket length of 18 inches, whichever is
  longest.
  c) Any pressure pipe shorter than 18‐inches must have blanket covering the entire length of pipe.
  d) Blanket must be manufactured with a minimum of 5 (five) layers of Kevlar.

Pro Farm – Recast Cylinder Head – pg.112

• Engine cylinder head must be OEM style (recast steel cylinder heads accepted) for brand of engine
  and retain stock dimensions (ie. height, width, and length). No billet cylinder heads allowed.
• Bolt patterns of OEM cylinder head must be retained including:
  • Intake and exhaust manifolds
  • Head bolt pattern
• OEM manifolds must fit cylinder head without modification
• No overhead cams allowed. Maximum of two (2) valves per cylinder.

Super Stock FWD Trucks – Engine Mounting, Front Axle – pg.116

• All engines must be placed no further forward than 12 inches rearward of front axle center line to
  rear face of engine block.
• Any OEM, military, or automotive/truck type replacement front axle is acceptable in this division.

Pro Street Diesel 4X4 – 2.6 Trucks – Drivetrain – pg.118

• When OEM drivetrain utilizes a manual type clutch, the OEM clutch housing must be shielded with a
  made to fit SFI 4.2 rated blanket.
• Blanket must be constructed the same as a SFI 4.2 Tractor Blanket with 4 straps that are fastened
  forward to keep blanket tight to rear of engine block.
• Option: OEM drivetrain can be replaced with a Modified FWD Truck type drivetrain including a SFI
  bellhousing, SFI approved clutch, driveline shielding, along with required safety hoops and tethers.
• Reference to Modified FWD driveline rules relate to drivetrain only and does not infer any change to
  chassis rules. Cab, truck box, and chassis must remain as currently required.

Pro Stock 4X4 Truck 3.0 – Cab Floor Pan – pg.119

• Rule c. is deleted – floor pan in cab is not required.

NEW ‐ Hot Rod Big Block Tractors – pg.113, 114, 115

All OEM tractor chassis rules, including shielding, safety, and SFI requirements apply to this class plus
the following rules.

• Engine:
  a. Maximum engine displacement: 521 cid.
  b. Engine must be naturally aspirated V‐8, no turbocharger or any type of forced air induction.
  c. Engine block and cylinder heads must be cast iron.
  d. Single carburetor, no fuel injection of any type.
  e. No tunnel ram, sheet metal, cast sheet metal, welded, or fabricated aluminum intake
  manifolds allowed. Aftermarket aluminum intake manifolds are permitted.
  f. Spark plug deflectors are required to divert the spark plug downward.
  g. No engine driven cooling fans, electrically driven cooling fans only.
  h. Crankshaft harmonic damper must be SFI 18.1 rated with crankshaft retaining bolt.
  i. Air cleaners must be under tractor hood.
  j. Diesel engine conversions are allowed but must run on gasoline only
  k. Maximum engine RPM: 7200rpm – maximum 50rpm tolerance.
  l. MSD ignition box required with maximum 7200rpm chip installed or a limiter box.
  1) No switches or dial operated devices that can control engine rpm from the driver’s
  seat.
  2) MSD box cannot be tampered with or modified in any way.
  3) Rivets must be original and factory installed.
  4) If sealant or sticker are broken, MSD box must be replaced.
  5) Only wiring per the MSD diagram is allowed and clearly visible.
  6) No additional wires can be attached to the MSD factory wires other than what is
  specified per MSD’s wiring diagram.
  7) Tech inspection performed using MSD model 89952 RPM Module/Chip Tester, MSD
  model 8998 Digital Ignition Tester, and/or Datalog Peak Performance Recorder P/N
  2347.
  8) All tractors must have a Datalog RPM Plug Kit P/N 3316.
  9) MDS boxes must be located for easy access and inspection by Tech Official.
• Fuel:
  a. Gasoline only measuring a maximum specific gravity of 750.
  b. No alcohol, ethanol, or oxygen enhancing agents allowed.
• Electronics:
  a. Use of Datalogger and MAP sensors are not permitted.
  b. Use of Electronic Control for ignition timing ie. (MSD 8973, Power Grid, Six Shooter, MSD
  Digital, and Davis Electronics) is not allowed.
  c. Engine must be controlled directly by manual throttle utilizing a mechanical lever and
  linkage or cable only.
• Sheet Metal:
  a. Any farm tractor sheet metal is allowed.
  b. Sheet metal must be stock appearing in dimension, must be in stock location as original as
  measured from the centerline of the rear axle.
  c. Fenders are required but do not have to match the sheet metal used. Fenders can be
  fabricated.
• Chassis:
  a. Maximum overall length: 12 ft. measured from center of the rear axle to furthest point
  forward including weights.
  b. Maximum tractor wheelbase: 102 inches.
  c. Frame rails, front end, and front axle assembly can be fabricated.
  d. Front tire tread must overlap the tread the rear tires.
  e. Tractor must have Tie Bars unless equipped with a full frame rail on each side of the tractor
  starting at the rear axle housing and extending forward to the furthest part of the tractor
  excluding any weight brackets, tow hitch, and etc. Refer to F. General Rules, section
  19.Safety, sub‐section o. Tractor Tire Bars for complete details.
  f. Tractor with cast iron tub removed must have a full frame rail on each side of tractor.
  g. Steering may be rack and pinion or hydraulic.
  h. Swivel front axles and suspension are allowed.
  i. Engine must be parallel to the input of transmission and be mounted in center of frame.
• Drivetrain:
  a. All tractors in this division must be equipped with a block saver plate along with a SFI 6.2,
  6.3, or 6.4 rated bellhousing. See F. General Rules, section 3.Bellhousings, sub‐section c.
  Bellhousing Attachment for more details.
  b. Flywheel and clutch assembly must be SFI 1.1 or 1.2 rated.
  c. SFI 4.2 Tractor Blanket is not an acceptable replacement for the required SFI bellhousing.
• Transmission / Differential:
  a. Rear axle/differential can be an agricultural tractor type OR a planetary type rear axle with a
  truck type differential center section.
  b. When a planetary type rear axle with a truck type differential is used a full frame on each
  side of the tractor is required.
  c. Internal modifications to the stock transmission are allowed.
  d. Aftermarket transmissions are allowed.
  e. No automatic or power‐shift transmissions allowed.
  f. No TA’s allowed.
  g. OEM torque housing and transmission can be removed if option to unbolt from rear
  axle/differential housing as designed from the factory.
  h. Rear differential lock is not permitted.
  i. Refer to F. General Rules, section 10. Drivelines, Driveline Shielding, Tethers for details
  related to driveline safety requirements.
• Competition:
  a. Hot Rod Big Block Tractor are allowed to compete in their own division only at Region and
  State levels of NTPA competition.