X275 Rules


1.1 Rear chassis rails may be notched for tyre clearance but not moved or rerouted. Inner chassis rail cannot be moved and must remain in factory position. Any metal cut away must be replaced with the same thickness material or thicker. Special permission may be given to existing cars with rails moved if standard points are retained and tyre is within the limits, but must be checked with a delegate or scrutineer.
1.2 Rear suspension mounting points may be reinforced or fabricated in standard size in the standard location on the chassis only, adjustable/multiple points on the differential end acceptable, shock absorber location can be moved (IE inboard coilovers), and leaf springs can be moved inwards.
1.3 Adjustable tubular control arms may be used on rear ends but must retain factory mounting points and original manufacturer style suspension design. Tramp rods, Slapper bars, Caltrac bars or any other similar devices may be used. Anti roll or sway bars permitted.
1.4 Coil over shocks are permitted.
1.5 Fibreglass/Carbon panels limited to bolt on panels only ie: bonnet, boot lid, bumpers and doors.
1.6 Mini tubs, chassis connectors and bar work in/under floor permitted (providing above rules are met)
1.7 No removable transmission tunnels
1.8 Tube front cross members allowed.
1.9 Ladder bars allowed on Late model IRS live axle conversions (special consideration may be given to previously built cars on a case by case basis) with factory floorpan, no 1/2 or 3/4 chassis style vehicles will be permitted. 50lb Weight penalty applies.
1.10Four Links are not allowed
1.11 Aftermarket rack and pinion steering racks allowed


2.1 Engine transplants allowed
2.2 All power adder engines must be of OEM configuration ( Ie: factory release Dimensions and conventional cylinder heads) Raised Cam, widened pan rail, after market aluminium blocks not permitted.
2.3 Dry sump systems allowed


3.1 Trans brakes are permitted
3.2 Clutchless transmissions permitted on 4cyl, 6cyl, 2 and 3 rotor engines only, no slider or counterweight style adjustable clutches allowed *50lb weight penalty applies


4.1 TBA


5.1 Maximum wheel diameter 15 inch (Larger diameter allowed for factory fitted brake clearance where necessary)


6.1 Maximum tyre sizes 275 wide as per sidewall and a maximum diameter not to exceed 28” – Mickey Thompson ET Street Radial or equivalent of another brand.
6.2 Tyres must be DOT approved style racing or street tyres.


7.1 Centrifugal blower x 1 only with a maximum 4″ compressor inlet tip to tip
7.2 Turbochargers 1 x 86mm or 2 x 63mm
7.3 Roots style blowers accepted 10/71 as a maximum
7.4 Nitrous All vehicles are limited to one single stage.
7.5 4 and 6 cylinder/2-3 rotor engines only are allowed 2 x power adders
1 x 72mm turbocharger or 2 x 53.1mm turbochargers with no jet restriction on nitrous.
All turbochargers run in TSX275 will be a shelf item ,NOT a turbocharger that has been built to YOUR specification by a turbo manufacturer, and that is commercially available and advertised to the general public, IE a Garrett GT35, a Precision 6265 etc. No clipped, cut, custom profiled or modified turbo’s allowed in any way. If you feel a question may be raised about your turbocharger choice, please contact the committee BEFORE proceeding with a purchase or fitment to save rejection at an event.
7.6 Any form of nitrous injection including direct port, limited to single fuel and nitrous solenoids.
7.7 Nitrous may be used to assist turbo spool on 4cyl, 6 cyl and 2/3 rotor engines – systems must use a purge solenoid only as the nitrous solenoid & maximum of 35 thou jet. (if jet size larger than 35 thou is required for spool – prior approval must be sought & weight penalty will apply on a case by case basis to be decided by the X275 delegate)


8.1 Small blocks can be cast iron only with the exception of factory alloy blocks i.e. LS1 and must be standard cam and standard pan rails. Small blocks may have raised cam, deck height and spread pan rail.
Max deck heights:
SBC 9.325, SBF 9.5, Chrys SB 9.5, Holden 9.5, LS-1 9.72, Mod motor Ford 9.0
8.2 Big blocks can be cast iron only with the exception of a factory alloy block, with standard cam and pan rail.
Max deck heights:
BBC 10.2, BBF 10.32, Chrys BB 10.7


9.1 Weights for 4 and 6 cylinder vehicles are as follows, please not that capacities are considered “as run”, and NOT the capacity of the engine as per manufacturers specification. An honesty system will be put in place that if breached will result in immediate expulsion from the event, removal of any records from the APSA records list and possible lifetime ban from future events at the discretion of the committee. Capacity checkers are available at both Sydney and Willowbank events in the event of a protest by any racer as per protest guidelines.
1900cc engine and smaller minimum weight 2300lb
1900-2200cc minimum weight 2400lb
2200-2500cc minimum weight 2500lb
2500-2800cc minimum weight 2600lb
2800-3100cc minimum weight 2700lb
3100-3400cc minimum weight 2800lb
3401cc and above minimum weight 2900lb
Rotary engines will be as per the following:
12a Rotary minimum weight 2200lb
13b Rotary minimum weight 2400lb
20b Rotary minimum weight 2700lb
9.2 V8 Assisted minimum weights:
BB V8 Turbo/Blower 3500lbs
BB V8 Nitrous 3500 lb with unlimited line size, 3200lb with -6 line and -4 line after wye. No cheater (expander) lines allowed may be checked at any time by an official.
SB V8 Turbo/blown 3200lbs
SB Nitrous 2750lb
9.3 Naturally aspirated weights:
SB v8 2400lbs
BB v8 2700lbs
9.4 Weight Penalties

  1. Ladder bar add 50lb
  2. Clutchless trans add 50lb
  3. Roots blown deduct 100lb
  4. IRS rear suspension deduct 100lb
  5. Sheet Metal Intake add 50lb
  6. Dual Carbs add 50lb
  7. 80mm and smaller single power adder deduct 100lb
  8. Cast wheel turbo’s deduct 100lb
  9. Deduct 100lb for cars on a 235 tyre
  10. Rear mount Radiator add 50lb


10.1 No Street rods, hot rods, kit cars or any similar vehicles permitted of this nature.
10.2 Wheel base must remain within 3” of standard track.
10.3 All vehicles must have operational cooling systems such as radiators and water pumps.
10.4 Aftermarket radiators, min surface area 26″ x 11″ for total core size, can be 13″ x 11″ for 2 rows. Radiators must be mounted in the front of the vehicle but may be moved left or right or laid flat for turbo/blower fitment
10.5 Radiator may be moved to the rear of the car with weight penalty
10.6 Electric water pumps are permitted
10.7 All vehicles must have operational headlights, tail lights, cooling and charge systems and a minimum of two front seats.
10.8 All vehicles must be self starting.


11.1 All vehicles must comply with current ANDRA safety regulations relative to performance of vehicle.

Note:  Any and all rules may be changed at any time including before or at an event to maintain parity between racers. This may include nitrous jet limitations or weight penalties should a combination have a clear advantage over another.
*Revision July 2015*



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