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Ridiculousness: twin-turbo V12-powered Toyota Chaser

16 November 2023



Guy Ellwood is the type of guy who likes a challenge — a twin-turbo V12-sized challenge

1996 Toyota Chaser JZX100 V12 TT (503)-Edit.jpg


What constitutes a challenge to one man might seem like a walk in the park to another — and, when you get all deep and philosophical about project car building, it is essentially just a series of challenges one must overcome, one after another. Some guys just like to stack a few more up than others. When it comes to Guy Ellwood, slapping a bigger turbo onto a factory-fitted straight-six was just not going to whet his appetite; this man wanted to challenge his car-building skills to the ninth degree, so he decided to double his trouble with what has to be the most ridiculous conversion a Toyota man like himself could fathom.

Before we get ahead of ourselves, we’ll wind the clock back a few years. The build first got underway back in ’09, when Guy was looking for a project — as he puts it: “something to sink my teeth in[to] and keep myself busy during those long winter nights and weekends”. What he found was an unmolested factory manual 1JZ Chaser, a car that he and his late brother had looked at purchasing a few years earlier, but it had disappeared off Trade Me before they could do so. Guy didn’t want to let it slip a second time, and knew that his brother Andrew would approve of the purchase.

The fact that it was an unmolested Chaser was a little lost on Guy when it turned out that his wife’s 350Z was delivering much more fun in the hot seat.


Engine bays like this are a car nerd’s wet dream. Everywhere you look, there are small fabricated components finished to a level that would lead you to believe that fabrication is Guy’s day job, which it most certainly is not



“The 1JZ felt like such a small motor in comparison; that’s why I started looking into a 2JZ swap,” he says.

He got as far as sorting someone to ship a 2JZ from Japan, but it wasn’t as exciting a prospect as he’d hoped, and, digging a little deeper on Yahoo, he stumbled on a five-litre 1GZ-FE V12 from a Toyota Century. Now, this was the sort of project that excited Guy! A quick search online revealed that someone had managed to shoehorn one into a Chaser before. That was all he needed to convince himself that it was possible, so he jumped in the deep end, arranging shipment of the engine to New Zealand.

Guy had wanted to set himself a challenge, and he had just set one much bigger than he’d ever imagined. With no real deadline, and the fact he wanted to further challenge himself by keeping everything in the engine bay and not having to remote-mount or relocate anything like the battery or washer bottles, etc., it would go just as planned, taking the better part of seven years to complete. Not wanting to risk disappointment at the end of it all by keeping the motor naturally aspirated and ending up with only about 300kW; some added performance insurance came in the form of twin-turbos.

“If you’re going to do something ridiculous, you may as well go all out and do a twin-turbo V12” — wise words, Guy, very wise words!

1996 Toyota Chaser JZX100 V12 TT (402)-Edit.jpg


With no aftermarket support for the 1GZ, and limited-to-no information out there around boosting one, the engine was an uphill battle each step of the way, requiring bespoke components. Getting it right was something that no local shop seemed interested in helping Guy do, leading him to look abroad. Thankfully, a switched-on Yank was able to spec some custom rods from Pauter and pistons from JE, to bring compression down from the factory 10.1:1 to a boost-friendly 8.75:1.

Fortunately, the heads were a little easier, given that local company Kelford Cams was more than capable of sorting the regrind of the stock cams to suit the boosted application. By chance, during his day job, Guy met Marc Mulholland, a head specialist. Marc took a head and ported one cylinder so that Guy could then replicate the port work on the other 11 cylinders to save some folding stuff.

With a little less lobe on those cams than before, there was space to be filled. This saw Guy tackle a solid-lifter with lash-cap conversion, with a total of 48 valves. It took a lot of work to get all the valve clearances correct. The fabrication in the engine bay, with its emphasis on symmetry and packaging, is also Guy’s handiwork. With such tight confines, the only real clues of boost are the twin Turbosmart BOVs; you really need to search to find the pair of GTX3076R turbos — not that you can take your eyes off the two large plenums that Guy whipped up over two weekends. Included in that time was an abandoned first attempt.


A pair of LS3 fly-by-wire throttle bodies are used to inject a little modern tech into the old 12-banger. These, paired with the MoTeC M150, opened up the possibility of running cool tech such as traction control. When you consider that the engine makes 800Nm from as low down as 3000rpm when the turbos start to wake up, you can see why something like traction control would even come into your thought processes. Numbers like that are tyre killing, no matter the gear you’re in; if you mash that electric throttle, the tyres will bake, even if you’re doing speeds well in excess of 250km (reportedly). Attempting to put these torque figures through a Toyota box was never going to end well, so a big-daddy Tremec TR-6060, rated at 750Nm, was subbed in, along with a custom rolled bellhousing.

One thing that has surprised Guy is how well it actually puts the power down. Of course, if you stab the throttle, it’s going to vape those 265s, but, roll on that throttle in a high gear, and you’d better have a pilot’s license, as it’s going to damn well fly! Hence the investment in some big AP stoppers all round and massive 14-inch rotors up front. The result was the best damn stopping car that the cert man had ever put through the Low Volume Vehicle Technical Association (LVVTA) stop test.


From start to finish, the project has delivered the challenge that Guy was after. Like so many before him, it was the journey that he cherished above the actual fruits; it’s those long nights spent researching or agonizing over the placement of the smallest component. That’s the reason he is building a mark 2 version using a Mark II, taking all the best bits from the first one but taking it to another level with a new shell and cool pieces such as Gen II Garrett mirror turbos. So, while you probably never even got to see the first version in person, we can hazard a guess that the Mark II is going to blow your socks off — and be well worth the wait; let’s just hope we’re not hanging out for seven years to see it!

1996 Toyota Chaser JZX100 V12 TT (450)-Edit.jpg


Guy Ellwood
Age: 44
Location: Kumeu
Occupation: Service technician
Build time: Seven years
Length of ownership: Nine years
Thanks: My wife, Bree; Marc Mulholland


ENGINE: Toyota 1GZ-FE, 4996cc, V12
BLOCK: JE Pistons (8.75:1), Pauter forged rods, ARP crank and head studs, six-bolt mains, factory forged crank
HEAD: Marc Mulholland porting, Kelford Cams camshafts (264 duration, 114 lobe centre, 9.5mm lift), 31mm shim under-bucket conversion, Supertech 4A-GE valve springs
INTAKE: Dual pod filters, Vibrant intercooler cores
EXHAUST: Twin three-inch system, Adrenalin R resonators, Adrenalin R mufflers, five-inch cats
TURBO: Twin Garrett GTX3076Rs, steam-pipe log manifolds
WASTEGATE: Dual 45mm Turbosmart Hypergates
BOV: Dual Turbosmart Raceport
FUEL: 12 Xspurt 1000cc injectors, dual Walbro 470-litre-per-hour in-tank pumps, dual Turbosmart FP2000, Radium fuel dampers, -8 lines
IGNITION: Toyota coil-on-plug conversion
ECU: MoTeC GPR-M150, dual NTK wideband
Griffin radiator, Fluidyne oil cooler, Clear View oil filter
EXTRA: Shorai lithium battery, Speedflow fittings throughout

GEARBOX: Holden TR6060 MG9, custom Mark Walford rolled-alloy bellhousing, Camaro MGW remote shifter
CLUTCH: Tilton 7.25-inch twin-plate, Tilton concentric slave cylinder
DIFF: Cusco limited-slip (3.7 ratio)
EXTRA: Diff oil pump, diff cooler, gearbox cooler, Driveshaft Specialists 1350 UJ two-piece shaft

STRUTS: Tein Flex
BRAKES: (F) AP Racing six-pot Pro5000 series calipers, 14-inch AP Racing rotors, Pagid Blue pads; (R) AP Racing four-pot calipers, Ferodo pads
EXTRA: Hardrace rear camber arms, Cusco front upper arms, roll-centre adjusters, raised and solid-mounted subframe, Cusco sway bars

WHEELS: (F) 18×9-inch Work Emotion XD9, (R) 18×10-inch Work Emotion XD9
TYRES: (F) 235/40R18 Toyo T1sport, (R) 265/35R18 Toyo T1 Sport

PAINT: BMW Frozen Grey Metallic by Shane Herbert
ENHANCEMENTS: Vertex front guards, Final Konnexion bodykit

SEATS: Factory

POWER: 606kW
TORQUE: 1150Nm
BOOST: 13psi
TUNER: Glenn Suckling at GDS Automotive


This article originally appeared in NZ Performance Car issue No. 272 — click here to order a copy