Each summer a uniquely Kiwi motorsport discipline draws crowds to remote rural locations for a rough and tumble high horsepower spectacle.
At a National 4x4 Trial, brute horsepower meets precision driving as cleverly engineered specialist trucks conquer gravity and extreme terrain, sometimes with spectacular consequences.
A six-round national series is staged each summer with the Eastern BOP Twin Diff Club preparing for the 2019-20 championship opener at Downard Rd — just off State Highway 2 between Awakeri and Taneatua — on Saturday November 2. The rest of the national competition is in early 2020, running through to an April 18 final in Hawkes Bay.
Over the past two seasons, Auckland twin brothers Scott and Jarred Biggs have been the duo to beat in their self-built Nitro Customs trucks which compete in the Class D Super-Modified category.
The twins teamed up to win the 2017-18 title before the Biggs team doubled its effort last summer with Scott and co-driver Philip Walton edging out Jarred and Fleche Crawford by six points for the national title. Hamilton driver Neville Mather drove his Nitro Customs truck to third.
The new Nitro Customs rigs and the Cowper Trucks built by Turakina’s Dan Cowper have become state-of-the-art for the sport in recent years. The typical power plant in the sturdy tubular spaceframe of a Class D contender is sourced from the LS alloy small block Chevrolet V8 family — sometimes with a supercharger or nitrous oxide injection — with the occasional Lexus V8 among the power plant choices.
Many of the outright contenders have four-wheel steering systems and the capability to adjust pressures in the large diameter tyres with an onboard compressor system. There’s significant teamwork involved as the driver controls the steering wheel, throttle and transmission while the co-driver also has input on the vehicle behaviour using levers for individual brakes on each wheel and in some cases controlling the diff locks as well.
Depending on venue conditions, the Class C Super Modified trucks with four-cylinder engines will often figure among the top overall placings.
A typical national event consists of at least 30 hazards and will require competitors to blast their way up extreme hill climbs, pick their way over rocky terrain and power through deep mud bogs. It’s not all brute horsepower as drivers must have the ability to gently pick a course along steep sidings on the verge of rolling over and be able to make tight turns on steep gradients.
In recent years national events have attracted between 40 and 60 teams. Separate classes for less extreme Modified Production and Super Production vehicles such as Suzuki Jimnys and Toyota Landcruisers compete for category honours alongside the purpose-built Super Modifieds.
Events are scored using a penalty system with 100 points for failing to reach the first marker pegs of a hazard and the objective of achieving a zero score by maintaining momentum all the way through the hazard to reach the finish pegs while staying within course markers.
Margins of victory can be small and events are often decided by performances on just a few of the most difficult hazards — a 20-point difference signalling a driver progressed one pair of marker pegs further on a deciding hazard.