Holden Colorado gets LS3 engine transplant.

AUSTRALIAN manufacturers just don’t get it. Holden trots out special edition Commodores with exotic engines that push out supercar-like power, but when it comes to 4x4 utes, it leaves product planning to the work-experience kid. Now, this isn’t a stab at Holden per se, as all the major players are guilty of it.

Vote for the Holden LS3 Colorado to win the 2017 Custom 4x4 of the Year

While we’re all fawning over the latest Raptor or Ram, the top-spec Aussie utes get little more than sticker kits and plastic chrome – if you’re lucky you might get tacky leather trim thrown in and some fibreglass panels. It’ll cost you $10K extra for the privilege, and you’re still left with the exact same engine and suspension as the base model.

We’re not alone in thinking manufacturers have missed the mark either; although, in the case of Tony from newly formed Killa Special Vehicles, he’s got the know-how to do something about it.

The vehicle you’re looking at is essentially the prototype for a business rarely seen in Australia, even less so in the 4x4 market. A 340rwhp LS3-powered V8 Colorado that earns the moniker of Z71 with an engine conversion the likes we’ve never seen before. “I’ve been reading the magazine and always wondered why won’t Holden build this, Ford build that.” Tony told us. “I figured, why can’t we do it?”

2017 Holden Colorado Z71 Quick Review

To kick-start the project Tony teamed up with Steve from Killa Kustom Kables & Conversions and set to work. As nothing like this had ever been done before, Tony purchased a statutory write-off RG Colorado that’d allow Steve to slice his way through sheetmetal and the electrical system to see if the conversion was even viable. Physically getting it in the engine bay was the easy part.

With no commercially available adaptors and nothing but blank stares when the topic of electrical integration came up, the pair had their work cut out for them. After countless hours spent on the project, and more than a little electrical wizardry, the write-off was powered up and Tony was on the hunt for a suitable replacement that would be a little more fitting of what the team had in mind.

The heart of the beast is a General Motors LS3 V8 engine. A 6.2-litre, 400hp+ lump normally found in high-end HSV performance cars – although, it has seen service in Corvettes and Camaros.

With around 580Nm available the torque is comparable to the twin-turbo V8 diesel found in 200 Series Land Cruisers, making it the perfect choice for the substantially lighter Colorado.

It’s backed by a 6L80E, a fully electronic six-speed automatic transmission that’s seen duties in everything from Cadillac CTS-Vs through to H2 Hummers and 2500HD Silverados, so it’s more than up to the task of serious off-roading or towing.

The combination feeds power through a secret squirrel adaptor with custom engine mounts, before the standard Colorado transfer case sends drive to front and rear diffs. This isn’t exactly a backyard engine conversion.

2017 Holden Colorado: Research & development drive

That’s the easy part sorted – from here Steve was tasked with making the thing run. Those of you familiar with engine conversions would know how much is involved in the simple side of things, like turning the engine on and off with the key, turning fuel pumps on, and making electronically controlled engines and transmissions talk to each other. Even making factory gauges work accurately is often enough to shelve most projects.

Steve and Tony took things one step further. Through what Steve would only describe as “CAN bus translators” they’ve managed to fully integrate the new drivetrain into the Colorado’s electrical system. That means all your standard fare like speedo, tacho and all the other digital gauges work, but so do some of the trickier things, too.

“You jump in it and everything works like factory,” Tony said. “Hill-start assist still comes up, downhill assist works.” Even things like traction control and climate control are all still fully functional. If Holden was to release a Colorado with an LS3 heart, this is exactly how it would function.

The plan wasn’t just to offer engine conversions, but complete turn-key performance packages that’d rival anything the factory could offer. So, once the driveline was sorted the pair turned their attention to what the rest of the vehicle would look like. Hidden underneath the bright orange bodywork and oversized flares is a full set of Fox 2.0 suspension.

The front sits 75mm higher with Fox remote reservoir coilovers, while the rear has had a slight lift with extended shackles on the standard leaves and Fox remote reservoir shocks.

The result is a package that has the comfort of a standard dual-cab family ute with the off-road performance to handle corrugations, hard cornering and more than a few jumps when the situation arises. The altitude adjustment has left enough room in the wheel arches for 305/70R18 Mickey Thompson ATZ P3 all-terrains wrapped around a set of 18-inch Fuel alloy wheels.

The rest of the Colorado remains reasonably standard, as it was always intended as a showpiece rather than a hardcore tourer. It’s got enough grunt to win more than a few street races, and suspension that’ll soak up your best Baja 1000 impersonation, all while maintaining the full suite of factory electronics and returning 14.0L/100km fuel figures.

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Holden Colorado Z71 vs Ford Ranger XLT comparison review

“The Z71 was planned as a mid-tier offering,” Tony said. “We’re aiming to have three different packages all based on low-kilometre, year-or-two-old models for a similar price as a new stock version.” Each tier level will have its own engine package, various trim levels and suspension ranging from better than stock through to desert-racing chase truck.

The Colorado isn’t the kind of custom four-wheel drive we’d normally feature, but you’ll have to forgive us for getting more than a little excited about home-grown 4x4s with pants-tightening power.