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Street Machine Drag Challenge 2025: Results from Two Modified Australian Vehicles

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Modified Classics Dominate at Street Machine Drag Challenge 2025

Two heavily modified vehicles—a 1977 Chrysler Centura and a 1968 XT Fairmont—delivered standout performances at this year's event, showcasing the raw potential of classic chassis combined with modern engineering.

1977 Chrysler Centura: Lightweight Platform, Brutal Power

Vehicle Background

Aaron James developed a 1977 Chrysler Centura as a new platform for a 528ci big-block Chrysler driveline previously used in his VG Valiant. The Valiant had achieved quarter-mile times in the mid-nine-second range. James acquired the Centura from its previous owner, Lee Baxter, after a second offer. The vehicle was selected for its lighter chassis compared to the Valiant.

Exterior and Wheels

Martin Boys Chop Shop applied a custom bronze paint mixed from approximately ten leftover paint colors, after an initial plan for a vehicle wrap. The car uses MaxWheel 15x9 rims with 235mm tires on the rear, and Weld AlumaStars with front-runner tires on the front. The wheel fitment required no tubbing of the wheelwells.

Driveline and Engine

The driveline transferred from the Valiant includes a 528ci Chrysler big-block engine built by James's father. Specifications include:

  • Molnar stroker crank
  • 440 Source rods and pistons
  • Indy SR heads
  • Indy tunnel ram intake manifold with dual APD 950cfm carburetors
  • Fully manualized, reverse-pattern 727 Torqueflite transmission

In the Centura, the engine bay accommodated larger exhaust pipes. Stainless steel headers are stepped from 2 inches to 2 1/8 inches to 2 1/4 inches, leading into a twin 4-inch exhaust system. The vehicle employs a dual fuel system, using pump fuel for street use and MS109 race fuel for drag racing, with separate fuel pumps and lines.

Chassis and Interior

The Centura previously operated as a drag car and already featured a rollcage, a four-link suspension setup, and a chrome-moly sheet-metal differential housing. Advanced Race Fabrication performed adjustments to the rollcage to meet ANDRA specifications. The engine was set back slightly in the engine bay, requiring new engine mounts. Upgrades included updates to the fuel system, wiring, and interior. The interior features Auto Meter accessory gauges integrated into the factory dash, JAZ racing seats, and the original rear seat (modified due to rollcage barwork).

Drag Challenge 2025 Performance

The build was completed within six months, with contributions from James's father, Allan James. The Centura weighed approximately 550 pounds less than the VG Valiant. Without pre-event testing, the Centura recorded a time of 9.30 seconds at 146 mph on its first full quarter-mile pass at Drag Challenge 2025. This surpassed the Valiant's best time of 9.52 seconds at 141 mph. The car finished third in the ITF Hire 235 Aspirated class.

"The lighter Centura did not flash the torque converter off the line as effectively as the heavier Valiant, causing a bogging effect."

During the event, Alon Vella and Wayne Smith of Performance Carb Tuning identified a converter issue. According to these sources, the lighter Centura did not flash the torque converter off the line as effectively as the heavier Valiant, causing a bogging effect. With further tuning and testing, the vehicle is anticipated to achieve quarter-mile times in the eight-second range.

1968 XT Fairmont: Youthful Ambition Meets Engineering

Vehicle Background

Mitch Rogers, 26, built a modified 1968 XT Fairmont that secured third place in the PSR 8.5 Radial class at Street Machine Drag Challenge 2025. The car was initially a stock 302 Windsor and underwent modifications over several years.

Key Modifications

  • Engine: 434ci Dart Clevor from Pavtek Performance, later modified by Windford Engineering.
  • Turbocharger: Garrett GTX45.
  • Transmission: TH400.
  • Differential: 9-inch with 3.7:1 gears.
  • Fuel System: FuelTech FT550 ECU, two Walbro 525 pumps.
  • Suspension: Calvert leaf springs (rear), Pedders (front).
  • Brakes: Wilwood discs (front), Ford F250 drums (rear).
  • Wheels and Tires: Billet Specialties Winlite; 17×4.5 (front), 15×8 (rear). Mickey Thompson ET Street tires.

Development Timeline

  • 2024: Initial turbo installation was planned for Drag Challenge 2024 but was abandoned due to delays. Multiple alternator failures occurred during preparations.
  • 2025: Engine was rebuilt with stronger rods and pistons. Tuned to over 1000 hp on E85 fuel.

Drag Challenge 2025 Performance

Rogers achieved a best pass of 9.18 seconds at 151 mph (quarter-mile) and 5.9 seconds at 119 mph (eighth-mile). Traction issues during launch were addressed with suspension and tune adjustments throughout the event.

Future Plans

Rogers has stated plans for suspension changes to improve power delivery, a larger turbine housing, and a CO2 bottle for wastegate control.

He intends to return for Drag Challenge 2026.