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MX235 Rules

Updated: 13.12.16

FORMAT: This is a heads up 1/8th mile class run on a .400 Pro tree with a Professional Pairing Ladder. Auto-Start and Courtesy Staging is in effect. MX235 Top 16 Qualifiers will run in the "Front Runner" class while cars that did not qualify in the 16 car field may be eligible for a "Second Chance" Race. (32 Car Field or All Run Format may be used at certain events.)

SAFETY: All NHRA/IHRA and Local Track Safety rules apply for driver and car, the use of an oil retention device is MANDATORY.

CHASSIS: Complete stock chassis and front frame rails must be retained from motor plate/shock tower to behind the rear wheel opening (for non back-halved cars only). Back-halved cars are permitted. All aftermarket front suspension components are allowed. All replacement parts must be in stock location. Aftermarket bolt-on replacement front k-members/sub frames are allowed. Struts or relocated shocks are permitted. All aftermarket bolt-on front ends are legal. Mini tubs are allowed. Anti-sway bars allowed. Rear leaf springs, springs, shocks and coil-overs may be moved to accommodate tire clearance and do not need to be mounted in stock location. Stock suspension, ladder bar, and torque arm only. Aftermarket 4-links are prohibited. No Wheelie Bars. Factory wheelbase must be maintained within +/- 1 inch. 

INTERIOR/BODY: Factory appearing (aftermarket parts are allowed) interior is required. Factory floor pan on driver and passenger side required from firewall to rear of door jamb. Firewall must be in stock location; minor modifications for transmission, etc. are permitted. Headlights and taillights must be functional. Aftermarket fiberglass or carbon fiber replacement panels are allowed. All front ends must be factory appearance and cannot be stretched. No extenders or stripe takers. Lexan or OEM Glass windows.

ENGINE: Maximum displacement for all engines is 640 cu. in. Small Blocks are allowed any deck height, but must remain stock bore spacing. GM Big Blocks are limited to 10.2 deck height. Ford Big Blocks are limited to 10.3 deck height. Mopar Big Blocks are limited to 10.7 deck height. Billet heads are prohibited for both SB and BB combinations.

TRANSMISSION: Any transmission permitted.

TURBOCHARGERS: Single turbocharger limited to 88mm maximum. Twin turbochargers limited to 72mm maximum. Inducer dimensions will not exceed 3.5039 inches. Turbocharger size will be verified by the measurement of the housing bore at the impeller wheels leading edge. The housing bores diameter at the leading edge of the wheel may not exceed 2mm more than the maximum allowable. Inserts or reducers to achieve inlet dimensions are prohibited. Turbochargers with nitrous oxide are permitted only on rotary, 4-cylinder, and 6-cylinder engines.

SUPERCHARGERS: Centrifugal and roots superchargers are permitted, must meet factory housing dimensions. Inserts or reducers to achieve inlet dimensions are prohibited. F-2 or equivalent allowed. Roots supercharger limited to 14-71. Screw superchargers are prohibited. Cannot combine supercharger with nitrous.

NITROUS: Multiple bottles must WYE together to a single -6 line. Small block nitrous is permitted to run any multi-stage nitrous system. Big block nitrous as a single stage fogger, must use -4 nitrous line maximum from WYE to solenoids. Electronic fuel injection allowed, only 8 nitrous feed lines on engine. Two stage nitrous plate allowed. Push nitrous systems are prohibited.

EXHAUST: Mufflers or inserts are required on all cars except for turbo cars. Exhaust may exit underneath car or out the front fenders but must not affect timing or staging beams.

FUEL: Gasoline, methanol, or E-85 is allowed.

TIRES: All cars must compete on a 235/60/15 radial, 26/8.5/15 radial, or 26/8.5/15 slick.

All minimum weights include the driver.

Naturally Aspirated:
 - Small Block - 2,350 lbs.
 - Big Block - 2,600 lbs.


 - Small Block Nitrous (Inline Head) - 2,650 lbs.
 - Small Block Nitrous (Non-Inline Head) - 2,700 lbs.
 - Big Block Nitrous (Up to 604 cu. in.) - 3,100 lbs.
 - Big Block Nitrous (605 to 640 cu. in.) - 3,150 lbs.

 - Single YSI/F1A/8-71 Supercharger (Small Block) - 2,800 lbs.
 - Single F1C/10-71 Supercharger (Small Block) - 2,950 lbs. (Deduct 50 lbs. for 8.2/8.7 Deck) (Deduct 50 lbs. for Cast Stock Valve Angle) (Add 50 lbs. for F1C-10.5)
 - Single F1R/Xi/12-71 Supercharger (Small Block) - 3,100 lbs. (Deduct 50 lbs. for 8.2/8.7 Deck) (Deduct 50 lbs. for Cast Stock Valve Angle)
 - Single F1X/F2/XB105/14-71 Supercharger (Small Block) - 3,200 lbs. (Deduct 50 lbs. for 8.2/8.7 Deck) (Deduct 50 lbs. for Cast Stock Valve Angle)

 - Single 76mm T6 Turbocharger (Small Block) (Mid Frame) - 2,900 lbs.
 - Single 80mm T6 Turbocharger (Small Block) (Mid Frame) - 2,950 lbs.
 - Single 82mm T6 Turbocharger (Small Block) (Mid Frame) - 3,000 lbs.
 - Single 84mm T6 Turbocharger (Small Block) (Mid Frame) - 3,050 lbs.
 - Single 88mm T6 Turbocharger (Small Block) (Y2K, GT47-88) (Cast Mid Frame) - 2,900 lbs. (Deduct 50 lbs. for 8.2 Deck)
 - Single 85mm T6 Turbocharger (Small Block) (Pro Mod 85) (Mid Frame) - 3,250 lbs. (Deduct 50 lbs. for 8.2 Deck and/or Cast Stock Valve Angle)
 - Single 88mm T6 Turbocharger (Small Block) (GTX55-88, Pro Mod 88, etc.) (Mid Frame) - 3,300 lbs. (Deduct 50 lbs. for 8.2 Deck and/or Cast Stock Valve Angle)
 - Single 85mm T6 Turbocharger (Small Block) (Large Frame 85/GTX55-85) - 3,150 lbs. (Deduct 50 lbs. for 8.2 Deck and/or Cast Stock Valve Angle)
 - Single 88mm T6 Turbocharger (Small Block) (Large Frame 88) - 3,200 lbs. (Deduct 50 lbs. for 8.2 Deck and/or Cast Stock Valve Angle)
 - Twin 67mm Turbochargers (Small Block) - 3,200 lbs. (Deduct 50 lbs. for Cast Stock Valve Angle)
 - Twin 72mm Turbochargers (Small Block) - 3,250 lbs. (Deduct 50 lbs. for Cast Stock Valve Angle)

Weight Additions and Deductions:
 - Deduct 200 lbs. for Mod Motor
 - Deduct 50 lbs. for Leaf Spring

 - Deduct 50 lbs. for Any Nitrous Plate System
 - Add 50 lbs. for Small Blocks (Nitrous Only) with Cast Tunnel Ram/Sheet Metal/2 Carbs or 2 Throttle Bodies
 - Deduct 100 lbs. for Blow Through Carburetor on Boosted Applications
 - Deduct 150 lbs. for Single T4 Turbocharger
 - Deduct 100 lbs. for Twin Turbochargers smaller than 67mm.
 - Deduct 500 lbs. for 4-Rotor and Inline 6-Cylinder Combinations
 - Deduct 300 lbs. for V6 Combination

 - Deduct 800 lbs. for 2/3-Rotor and 4-Cylinder Combinations

 - Deduct 250 lbs. for any Buick, Olds, or Pontiac combination.

 - Deduct 100 lbs. for IRS

 - Deduct 300 lbs. for Front Wheel Drive