Killa Special Vehicles LS3-Powered Z71 Colorado

A killer Colorado with LS3 power

Photographers: Matt Williams

Holden has killed off its V8 ute, so Killa Special Vehicles has created an LS3-powered Colorado instead

This article was originally published in issue no.5 of Street Machine’s LSX Tuner magazine

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 4×4 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.

Building sand castles, with 340 horses at the rear wheels

While we’re all fawning over the latest Raptor or Ram, the top-spec Aussie 4×4 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 4×4 market. It’s a 340rwhp V8 LS3-powered Colorado that earns the moniker of Z71, with an engine conversion the likes we’ve never seen before.

“I’ve always wondered why won’t Holden build this or Ford build that,” Tony says. “I figured, why can’t we do it?”

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 sheet metal and the electrical system to see if the conversion was even viable. Physically getting the LS3 in the engine bay was the easy part. With no commercially available adapters 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. Yep, the 6.2-litre, 400+hp lump normally found in high-end HSV performance cars – although it has also 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 sixspeed automatic transmission that’s done duty 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 adapter with custom engine mounts, before the standard Colorado transfer case sends drive to the front and rear diffs. This isn’t exactly a backyard engine conversion.

Bolt-on flares cover the big Mickey Ts

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 says. “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.

Fox remote-reservoir coil-overs help lift the front end by three inches

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 Fox 2.0 suspension. The front sits 75mm higher with Fox remote-reservoir coil-overs, 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 wheelarches for 305/70R18 Mickey Thompson ATZ P3 all-terrains wrapped around a set of 18-inch Fuel alloy wheels.

Z71 refers to Chev’s off-road suspension package, but it’s cheaply applied to the blinged-up Colorado

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.

“The Z71 was planned as a mid-tier offering,” Tony says. “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.

Sure, the Colorado isn’t the kind of ride we’d normally feature in LSX Tuner, but you’ll have to forgive us for getting more than a little excited about a home-grown 4×4 with pants-tightening LS3 power!

Killa Special Vehicles


Type: GM LS3 6.2L
Power: 340rwhp
Torque: 580Nm

’Box: 6L80E fully electronic six-speed auto
Front & rear diffs: Standard
Suspension: 75mm-higher Fox remote-reservoir coil-overs (f); standard leaf springs with extended shackles, Fox remote-reservoir shocks (r)

Rims: 18in Fuel alloys (f & r)
Rubber: Mickey Thompson ATZ