The Ultimate Guide To Engine Conversion

Thinking of repowering your 4X4? Strap on your engineer hat as we dive deep into the world of engine conversions...

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Jul 13 2023
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The CRD ZD30 engine fitted to GU Patrols makes a claimed 118kW from the factory. An LS1 fitted to Holden Commodores (in Australia) makes a claimed 260kW and will use only slightly more fuel in the process. With that bold statement in mind, it isn’t hard to understand why engine conversions are so popular with four-wheel drivers. They are one of the most challenging modifications you will make to a 4X4, though. There are so many components that need to work in harmony with each other; not to mention tuning said new engine to perform efficiently. Then you have to make it legal to drive on the road while being reliable enough to take off-road. Phew.

So while it can be a headache, the good news these days is there is information everywhere for most popular conversions. Here are some of the conversions we would look into, and a few we wouldn’t touch these days.


GM LS engine swaps are pretty-much THE go-to power up option for nearly every automotive application. Alloy blocks (mostly), excellent power and economy and limitless adaptability; we’ve even seen them in the pint-sized Mazda MX5s thanks to their vast availability, low purchase price and relatively small dimensions overall. Nissan Patrol owners see them as a cheap alternative to powering up the TD42 motor, when you consider a turbo kit can cost in excess of $5,000. There are several LS motors available globally – ranging in power and torque delivery (not to mention price).

Despite everyone going overhead cams these days, GM opted to stick with pushrods. Rumour has it that they wanted to show they could get great power and economy out of older technology. They sure showed… whomever it was they were trying to show.

Power figures: 257-476kW, 470-829Nm (in stock form)

Expect to pay: (LS1 Gen 3) – $500 for long motor only; $2,500 for whole vehicle (wrecked); $20K+ for worked LS-X Warren Johnson custom block.

Common applications: Commodores, Adventras, Statesmans, HSVs, Corvettes (anything American-based that’s not a Ford or Chrysler, basically)

At a glance

LS1 (GEN III Vortech): 5.7L V8, 257-261kW, 470-508Nm

LS2: 6.0L V8, 290-298kW,

LS3: 6.2L V8, 321kW, 575Nm

LS7: 7.0L V8, 350kW, 685Nm

LS9: 6.2L Supercharged V8, 476kW, 819Nm

LSA: 6.2L Supercharged V8 (de-tuned LS9), 414kW, 747Nm

LQ9 (GEN III): 6.0L iron block V8, 257kW, 515Nm


More commonly known as the XR6 Turbo motor, the Barra is one of Ford’s greatest successes engine-wise. Take one stupidly solid and reliable platform used to power taxis for a million kilometres, bolt on a turbo and enjoy. While the LS conversion is one of the most common and straightforward to perform, for Blue Oval fans the Barra gives the LS a run for its money.

Power figures: 240-370kW, 450-650Nm (but capable of oh so much more)

Expect to pay: From $1,000 for a basic engine to $25,000 for an 800+ HP monster

Common applications: Ford Falcons – BA XR6, BF XR6, FPV F6, FG XR6; Ford Territory – SY turbo models


  1. Get a flash tuner: The factory CPU is not all that performance-friendly
  2. Get bigger injectors: OE ones top out at around 250kW
  3. Upgrade your valve springs: Not really a performance mod, but a known weak point
  4. More fuel: Get a proper fuel pump, not the wussy stock unit
  5. High-flow catalytic converter: Replace the bottleneck in the Ford’s factory exhaust


If the LS series of motors is one of the most common V8 swaps these days worldwide, the 5.0L alloy block OHC Ford Coyote would have to be one of the least common swaps. Why is that? See above… Barra power, baby!

They’re hardly a bad engine though, capable of reliable trips past 7,000rpm and can be bumped up into the four-figure HP range with a few tweaks – so if similar power from a smaller displacement is your thing, then they’re worth a look. They’re actually gaining popularity among builders, if for no other reason than to stick it to those #LStheworld fanboys.

Power figures: 268-404kW, 515-570Nm

Expect to pay: Around $11,500 (crate motor) to $29,999 (435 HP crate motor + 6-speed manual)

Common applications: 11-present Ford Mustangs, 11-present F150s, Falcon GT, XR8 and FPV GT-F


6.6L of GM block’d, Isuzu head’d, common rail, turbocharged and intercooled, vee-eightery diesel… if you were to write down a list of what would make the perfect 4X4 engine, the Duramax would be pretty much it. Heaps of power, mountains of torque and economy on par with a four-cylinder with less than half the capacity. When a Duramax comes up for sale near you for a good price there are only two questions you need to ask: How much and give it to me!

Power figures: 190-270kW, 624-881Nm (at 1,600rpm!)

Expect to pay: $5,000USD for a second-hand engine (then import costs on top) or around $50K for a drive-in-drive-out conversion (worth it!)

Common applications: Hummer H1 Alphas, Chevy Silverados and GM Sierras mainly


  • LB7: The first of the Duramaxes with no emissions gear and hence favoured by tuners. They did have injector issues – in fact, replacing the injectors is probably the first thing to do.
  • LLY: The biggest turbo of any Duramax is on the LLYs, no injector issues but prone to overheating and head gasket failure. Also introduced EGRs – which some people don’t like.
  • LBZ: Best ‘tuneability’ out of the lot, however the Allison 6-speed auto behind these could ‘only’ handle an extra 120 HP or so before grenading. They also did away with the factory lift pump on this model.
  • LMM: Came with a strengthened Allison transmission and capable of 500 HP with a tune. Also had a DPF and diesel oxidation catalyst, as well as the EGR which adds complication for a conversion.
  • LML: As well as emissions gear on LMM, the LML also comes with a diesel exhaust fluid (Adblue) system that negatively affects fuel economy. Also had a new CP4 injection pump added, again for emissions, which is not as well supported by the aftermarket.
  • LGH: Basically a detuned version of the LML, only it was used in GMC and Chevy vans and box trucks. With all the emissions junk and less power, there are probably better options for a conversion.
  • L5P: The latest (2017) Duramax, with 48 HP more over the outgoing LML. Too early to report on reliability; but let’s be honest, it’s probably still way too expensive to even consider throwing it into your 4X4 yet anyway.
  • LMK: Wait, what? This engine doesn’t even exist yet, but is reportedly going to be a 4.5L 72-degree V8 designed to fit into the same space as an LS engine. Apparently it’s being built by GM without assistance from Isuzu… which is probably why it’s taking so long.


While the Duramax is all about mixing new-school technology-based injection, the 6BT P-Pump 5.9L Cummins straight-six is all about balls out, old-school overkill – and I absolutely love it. And I’m not alone. Legions of fans from all over the world have made this one of the best supported powerplants on the aftermarket, and people are turning up the wick on them, taking them to the drags… and winning. How does a reliable 1,000 HP sound? Yep, return pretty good economy (in stock form) too. Just about any 4X4 will benefit with one of these in between the frame rails.

Power figures: 119-160kW, 542-596Nm (people have got 1,000kW+ out of them though)

Expect to pay: Around the $8,000-$9,000 mark from an importer (plus an extra few grand for the NV4500 5-speed or auto box if you prefer)

Common applications: Ag equipment and Dodge Rams


  • 4BT: A four-cylinder version of the 6BT. With a 3.9L displacement and available with or without a turbo, these things can make some massive power and torque and may be a great option if your fourby can’t fit a straight-six under the bonnet.
  • Pumps: The 6-BT came out with either a VE rotary pump or a Bosch P-Pump. Neither are bad. The VE gets marginally better economy; the P-Pump can be wound up a lot further and make a lot more power. Horses for courses, really.
  • Industrial engines: 6-BTs were originally used as industrial or agricultural motors. In general you’re better off not buying these, as they’re set up to run at a constant rpm and don’t make a whole lot of power.
  • Old School Meets New School: Automotive Etcellence in Western Sydney is now making adapter plates to suit the new-tech Cummins 4.5L 4-cylinder common-rail turbo-diesels (available for about $8,000) being butted up to a Nissan 5-speed manual. 200 HP and 750Nm – this will take the engine swap game in a brave new direction.


The venerable 6.2L, 6.5L and 6.5L turbo Chev diesel engines were extremely popular conversions for Patrols and LandCruisers from their asthmatic 6-cylinder engines not so long ago, and many folks still love these big iron lumps.

The issue with them, however, is that there are simply better options available these days. They’re torquey, sure, especially the turbo version; but for the displacement they should be putting out a heap more, and they’re fairly thirsty to boot. Unless you have one sitting on a stand in your garage ready to drop into your fourby, there are engines that make more power and better economy for similar dollars out there. Sorry not sorry Chev die-hards, you know I’m right.

Power figures: 6.2L – 119kW, 386Nm; 6.5L – 116kW, 461Nm; 6.5T – 160kW, 597Nm

Expect to pay: Around $12K-$15K for engine from an importer

Common applications: Older Silverados, GMC Sierras, Hummer H1s


The 3.8L Holden Commodore V6 motor was swapped into any engine bay that would fit them back in the ’90s. These days they are outclassed massively by smaller capacity motors such as the 2.7L 3RZ that was used in HiLux and Prado platforms in Australia. The one advantage of the old 3.8L mang-mangs, is they are cheap. Like really cheap… if you spend more than a few hundred bucks on the thing you have been ripped off. But that’s where it ends. The 3RZ is simply a better engine, and add a turbo or factory TRD supercharger to it and you’ll be getting more smiles per gallon than just about anyone else – plus it makes for an easy conversion into older Luxies; or any older dual-cab, really.

Power figures: 112kW (add ~60kW if you turbo it), 240Nm

Expect to pay: $1,500-$2,000

Common applications: HiLux, Hiace, Prado


All engines benefit from having a turbo strapped onto the exhaust manifold (even one with a turbo already installed). Having a new or upgraded hairdryer installed will see your engine make more power, work more efficiently and (if driven correctly) use less fuel. But some NA engines are more suited to turbocharging than others. Let’s use the Nissan GU Patrol as a case study. The TD42 with a bigger injection pump and decent turbo can make up to 400 HP fairly easily (we’ve heard of them up to 850 HP) on standard internals. Likewise the TB48 petrol 4.8L six loves a turbo and will make 500 HP without too much effort. How can they handle this? It’s all about the engine internals. Nissan over-engineered the TD/TB series to buggery with strong cranks, solid con-rods and hardy blocks. They can simply take the added strain of running big dyno-numbers through them. Not all engines are built like this however… so do a little research before cramming 40psi down your intake, yeah?

Power figures: Expect around a 30% gain, more with more mods

Expect to pay: Between $1,000 for a home-brew setup to $5,000+ for a drive-in-drive-out conversion

Common applications: Any vehicle with or without a turbo


Every State is different in terms of legalities, and while you’re probably sick of us saying this by now, the first two rules of Fight Club is to consult an engineer that’s local to you before doing anything else.

Here’s a rough idea of what they’ll say to you (so it’s not all a total surprise):

  • Want to put an engine in that’s older than your vehicle? No chance.
  • A modern engine will need all emissions gear from the donor vehicle.
  • If the engine is going to upset the vehicle’s weight balance, it’ll likely be declined.
  • The driveline has to be able to handle the engine output – so nothing with more than 30kW in your HiLux, OK guys? (Shots fired!) 3.8L V6s in Suzuki Sierras – Australia says no.
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