It’s one of the wildest and most dangerous forms of motorsport on the planet: Lightweight timber boats, sometimes impossibly small, mounted with all manner of oversized, second-hand engines.
Sometimes, the watercraft isn’t much bigger than a surfboard.
Ripping down the middle of a wide and flat Thai river, bordered by reeds and bamboo at an incredible pace, this is not something for risk averse people.
The engines – their second-hand nature keeping costs down – are mounted at the rear of the boat, on a big pivoting mechanism and fitted with an incredulously long propshaft that disappears into the water.
This is where the ‘longtail’ name comes from.
Smaller longtail boats source high-revving powerplants from motorcycles or jetskis: two-stroke and four-stroke motors buzz angrily as the driver clings –almost lying flat – onto their tiny vessel. And often, there’s not a skerrick of safety equipment in sight.
But there are larger examples of these boats, longer and even with room for a few brave passengers.
The engines used here are also much larger and more powerful. Sourced from cars and utes, sometimes with complex turbocharging arrangements for increased performance.
These are the high-cost, high-performance versions of the sport. Like a Thai version of top fuel drag racers. On water.
While you might expect a typical range of performance car engines to be used in this high-octane activity, you might be surprised to learn that one of the all-time favourite powerplants comes not from any kind of iconic sportscar, but instead from a diesel-powered workhorse.
One of Thailand’s most popular vehicles for decades has been the Isuzu ute, since operations (including manufacturing) began in the 1960s.
Before the D-Max name was launched, Isuzu light commercial utes were known as the Faster. While the name did change, one constant has been the four-cylinder diesel engine under the bonnet.
The now highly regarded Isuzu ‘4J’ engine series goes back to 1985, with a 2.5-litre engine that was originally developed for the Elf (N Series) light truck, but was then adapted for use in light commercial and passenger vehicles.
Without any turbocharging, this engine had only 56kW and 172Nm available. Newer turbocharged and non-turbocharged units continued to be developed, improving performance and building an enviable reputation for reliability.
While outputs steadily increased, there was always a strong connection between the engines used in Isuzu light trucks and utes.
In Australia, Isuzu’s 2.8-litre 4JB1-T turbocharged engine for the Holden Rodeo ute in the 1990s proved to be a dependable and long-serving powerplant for the workhorse, laying the foundation of a strong reputation.
This legacy continues today, with the latest-generation 4JJ3 3.0-litre engine being available for the D-Max and MU-X, which has 140kW and 450Nm available.
These numbers are relatively meagre compared to other utes in the segment, which often develop more power and torque from less capacity.
But according to Shane Hewitt – owner and dynotuner at Procheck automotive in Caloundra – that is exactly the reason why Isuzu’s diesel ‘4J’ engine is a popular choice for high-performance applications.
“It’s the little brother to the ‘4HK1’ 5.2-litre truck engine, and it’s understressed from the factory.” Hewitt explained.
“Some vehicles - older Isuzu D-Max or Holden Rodeo Utes – have 200,000 or 300,000 kilometres on them, but are still making power and are reliable.”
“Thai tuning and technology sort of trickles down to us (in Australia),” Hewitt explained.
“Some of those Thai guys are pretty wild with their longtail boats, they’re definitely cool. You look at them and think: There is probably $100,000 hanging off the back of this wooden boat.”
Back in Australia, outputs of around 300 horsepower and 700 newton metres at the wheels can be easily achieved in a daily-driven four-wheel drive, with an aftermarket turbocharger, upgraded fuel pump and new fuel injectors.
However, the major internal components are untouched and the engine stays ‘unopened’ to achieve this kind of performance potential.
The Isuzu 4J engine is preferred for this kind of performance in Thailand, because of two main reasons. Firstly, the engines are common and easy to find in, thanks to high sales volumes of the original donor vehicles.
But secondly, is the engine’s innate ability to withstand the pressures that come with high performance. Cramming 50psi of boost – more than three times the standard turbocharger's 15psi – into a standard engine normally ends with a spectacular failure, a kind of instant disassembly of major components against the immense strain.
That’s not the case with the Isuzu engine, however. Due to the strong internal components, common rail fuel injection and a preferred steel timing chain setup, this kind of performance can be extracted from the engine with mostly bolt-on parts, software tuning and no major internal modification.
Sam Purcell has been writing about cars, four-wheel driving and camping since 2013, and obsessed with anything that goes brum-brum longer than he can remember. Sam joined the team at CarAdvice/Drive as the off-road Editor in 2018, after cutting his teeth at Unsealed 4X4 and Pat Callinan’s 4X4 Adventures. Off-road writer of the Year, Winner - Sam Purcell
