We all know turbos are wicked little devices for making power. Fill them with a turbine full o' gas and they throw you down the road at an alarming rate. But that's just it - you need to have them bellied up with plenty of exhaust gas before they can generate boost pressure. That can be a problem on many high-output, small capacity engines - but it certainly isn't the case on this car! You see, this is (or was) a Ford Falcon GL family car, which came fat with what we Australians all traditionally love - swag-loads of torque. Whether we want it for towing, running the kids an' their gear around or just getting to work in a hurry - it doesn't matter - a big cube six is an easy performer. The XD Ford's big 4.1 litre (250ci) iron-headed six is a great engine to have a turbo blowing in its ear too, coz it's an engine that can use that extra hit of torque in the mid-to-high engine ranges; its overall efficiency drops off pretty quickly.
Hmm, a turbocharged big six? Bulk cubes for low-down grunt, combined with boost up high for some real spine-tingling power!
Brad Watkinson's somewhat unusual move to a turbo six (rather than a V8) happened a few years ago now, after being sucked in by a mate with a hard-chargin' turbocharged Monaro. He'd already owned the car (his very first) for a fair while, and had tricked it up a bit with alloys ("mags" in those days), a sunroof, Yella Terra head, bigger carb, extractors are all that sort of jive. But it was the craving for power - around 260kW - and a desire for something different that led Brad to a turbo kit - one of the well-known Mike Vine specials. Parting with only $5500, Brad received a complete Stage 2 kit with dual 1.75 CD carbs, match-ported head with larger valves, manifolding, 42mm external wastegate and a new Garrett T04 turbo with its associated fittings. And just for your info, a Mike Vine Stage 1 kit comes with only a single carb through which to suck.
Inside, Brad's 4.1 litre IL six is swept by XF model (unleaded) pistons that give a static compression ratio of around 7.5:1. There's no spacer plate to be found, but the top of the block has been O-ringed to help hold the standard Ford gasket. Ford gasket? Yeah, well, after a couple of problematic MonoTorque gaskets, Brad's gone back to the original part and experienced no more dramas.
The Mike Vine turbo kit remains largely intact, but because the car proved to be sensitive to the relationship between timing and boost, Brad was burning his eyes looking at the potential of boost retarding the dizzy. He's devised his own system which draws back ignition timing using a vacuum solenoid and a 4 psi Hobbs pressure switch. Brad says it's made a lot of difference too - he can now optimise timing for both off-boost response and on-boost power (without detonation). Boost pressure has also been made adjustable with a solenoid switch to click between 7 and 20 psi.
Brad admits "it has a bit of lag - but half of that's probably due to the inexact mixtures given by the carbs." He'd tried fitting bigger jets to keep fuel flow up with high boost, but this made it a real splutterer everywhere else in the drive cycle. Brad, again, had his own answer in the form of a staged fuel feed. At 14 psi boost, fuel is allowed through a NOS fuel solenoid to a nozzle which squirts in fuel before the turbo.
A custom water/methanol injection set-up reduces the potential for destructive detonation. This brings together a boot-mounted 5 litre tank containing a 50:50 mix of water and methanol, a 3psi Hobbs switch and a brass misting nozzle poking into the Finer Filter air cleaner. "You know if it runs out of water," tells Brad. "It starts to ping really bad, and 5 psi is about the max you can go."
Detonation is certainly never all that far away in this car, so Brad elects to fill the car with leaded fuel along with a splash of octane booster for added performance and engine safety. Fuel is delivered by a Holley Blue pump, 5/8-inch lines (braided under the bonnet) and a Holley variable pressure regulator with a boost pressure feed tapped into it.
A boosted 4.1 litre engine's obviously gonna need to breathe rather heavily, so a full 3 inch turbo-back system with only a single straight through muffler is fitted for minimum restriction. And strangely enough, it's not even all that loud - it's just got a deep rumble that comes up through your socks. The sound of a near-stock six it isn't.
Other clever-dick touches under the nose are a boat bilge blower located behind the front bumper (used to blow cooling air to the turbo), an extra oil cooler (about the biggest around) and a trans cooler that's equally as large. A heavy-duty 3-core radiator keeps the animal running cool.
Braided lines are used extensively in the bay, as are chromed and polished parts.
A Ford C4 3 speed auto backs the iron block with a 2300 rpm converter (only a little more than standard) squeezed in the middle - and other than having heavy duty bearings and a shift kit, it's stock-as-a-rock and proving itself 100% problem-free. The XD six's original 2.89:1 rear end has recently been replaced by a 4-pinion heavy duty 3.89:1 Borg Warner LSD, a move which made the car much more lively. Power is put to the pavement by a set of grey 16-inch Simmons F90s clad in 205/55 Sumitomos at the front and plump 255/50 Goodyears at the back. The more rubber housed under the rear guards, the better. However, these wheels fill out each corner more than usual since Brad's fitted Koni lowered front springs and adjustable shocks, and lowering-block-equipped rear leafs with pump-up shocks. A flat cornering attitude is maintained by a K-Mac 32mm front bar and standard sized rear 'un.
The white XD's current drag strip performance is still a bit of a mystery to all. However, the car has managed to run a 13.2 with a tall diff ratio and only half of Brad's mods on board. So a good guess - with traction being the main problem - would be that the car's good for mid-to-high 12s. Its power output is now estimated at 280-290kW as well.
But it's not just under the bonnet where this car shines with a difference. Brad's said good-bye to the factory off-white paint, fitted new cancer-free doors and gone for a stark 2-pack white - which looks ultra-classy against those Simmons wheels and calculated detail changes. Like for example, the front bonnet and bumper is LTD, the back is updated with XF model lights and bumper, there're XF mirrors, and various trims have been pulled off here and added there. Some really neat touches include those cute little front fog lights, Sigma turbo bonnet vents (it used to get so hot under there, cables melted) and the Ghia/TX3 Laser turbo badges on the guards. An Autometer fuel pressure gauge sits out in the breeze, while its buddies - VDO exhaust temp, boost, oil pressure gauges - snuggle up together inside where it's warm.
And, yes-siree, the inside of this car is extremely cosy. It's the plush interior out of an XF Fairmont Ghia - seats, door trims, central locking, power windows and all. All except for the digital dashboard, which wreckers want a whole $1000 for - so Brad's happy enough with the easy-to-read analog dash currently fitted.
And inside the boot is nearly as cosy in the cabin too. Brad's fully trimmed it in grey velour, put the battery in a vented box (with an isolation switch and voltmeter right nearby), put in an extinguisher and runs two level tubes for the afore-mentioned water/methanol tank and windscreen washer reservoirs. Back up front where the action happens, there's also a Pioneer 6-stack CD with two amps, Pioneer 5 inch front splits and a Pioneer 8-inch sub sharing the rear deck with a couple of Pioneer 6x9s. A Momo wheel and a B&M Mega shifter add real feel to the driving experience.
Initially bought as an everyday car, Brad has now spent around $40,000 all-up on the XD. Of course, that's including a lot of trial-and-error development. He says you could probably go out and build something exactly the same right now for around $20,000-25,000. His mighty 250 has travelled over 30,000 km with its turbo fitment - however, the car has been resting in the shed for the last three years. That's mainly because Brad's had some recent additions to his family and he's bought an XR8 to get around in. Still, he wouldn't mind a factory sunroof for the XD though, and maybe (if he can justify the expense) he'll go for a programmable EFI set-up. But he shrugs his shoulders in uncertainty; "It's just a toy - a money pit. I'll never get anything of value for it, so I'll probably end up keeping it forever."
But it wouldn't be such a horrible sight to see when you roll open the garage door each morning, now would it?
Contact:
Mike Vine Turbocharging
+61 7 3206 4799
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The turbocharged 250 is most unlike a small(ish) capacity turbomotor. It never comes on with a rush of boost; it's just got a bucket-load of torque ready to be gently tipped out onto the ground. Boost comes in at 2500 revs and it's deceptively strong to around 6000 - by which time you know it's time for another gear. The only shortcoming is the draw-through carburettor intake system. Feed the power on and everything builds up beautifully - but suddenly throw the throttles wide open and it's a different story. The mixtures - we suspect - go a bit haywire and response and torque suffers dramatically. On one occasion there was even a backfire through the carbs. But, as Brad says (and demonstrated), "stall it up and it goes well - the same if you feather your foot down. But if you slam our foot down, it just floods." Maybe that's why carby turbo stuff never really took off...
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