Was I witnessing the eruption of a mighty volcano or a bloody monster of a V8 engine? I'm still not sure. Through the front glass I gazed upon the vast expanse of the gently curved bonnet that rumbled in accordance with the mighty mountain that pointed heavenwards. Its effortless gut-churning vibration and sonic boom was enough to scare fuzzy bunnies back into their holes. Then, without warning, all let fly and mountain blew its enormous lid. The deep inner rumblings gave way to violent shaking, a deafening roar resonated within the cabin and intense heat began to soak up through the floor. Checking the instruments, the coolant needle had broken clean off the Richter scale. But then, an engine capable of in excess of 457 kilowatts at the rear wheels will do that.
Christopher Dimech is a man who doesn't do things by halves. He's given re-birth to this 1974 XB Falcon GT and invested a substantial A$30,000 on the engine, A$6,000 on the driveline and an even 10k on a full body and interior restoration. Now that's a man of commitment wouldn't you say?! Having taken ownership of this '70s road burner around 8 years ago, Christopher drove it around for only a year before the big 5.8 litre Clevo spat out an expiry ticket. And here - like many feature cars - is where things began to take a dramatic turn.
Retaining the standard 4-bolt block as the base, the talents of Christopher (who runs a home workshop) were used to build this mountain to touch the clouds. And its intestinal fortitude can only be described as extreme: a 4MAB crankshaft, Carillo rods, chrome moly ARP bolts, dished top Chevy blower pistons (giving a 7.8:1 CR) and a full balance and blueprint to boot. Partly to blame for the 4 years spent on parts searching is the pair of SVO Dash 2 HP alloy heads. These beauties in alloy were installed with large custom-made stainless steel valves that were fabricated in Christopher's home city of Melbourne.
A computer modeled Crow cam was slipped in too, to deliver approximately 320 degrees duration and 565 thou lift and this works with a quality assortment of Crane solid lifters, Crane triple valve springs and Crower 1.73 roller rockers. Interestingly though, Christopher suspects the valve springs are allowing bounce at anything over 4300 rpm - hence why the peak 457 rear wheel kW dyno figure is at this lowly number of revs. The engine reputedly should go to 6400.
But then came the mechanical tip on the iceberg. The piece de resistance. The duck's guts. A traditional Roots-type 6/71 Fisher blower scored a balcony seat sitting atop a compact handmade intake manifold. The manifold is a nifty one too, with the focus on trying to keep the blower from sticking
too far out of the lid. And it's worked too - all that sits above the bonnet line is the Fisher top hat (into which fuel is injected) and an Enderlie bug catcher with the TPS and air temp sensor mounted on its side.
Another path that was trodden to keep it from protruding rudely was to lower the whole engine by some 3 inches using modified XW chassis mounts, cutting the crossmember and by performing some other front end cut-and-tuck tricks.
What's not so traditional in the world of Roots-blown Aussie metal is this car's fully programmable fuel and ignition ECU - Mr Holley got toppled from his once safe position at the very top.
The Injec computer unit eats what's fed from an array of sensors including a TPS and MAP sensor - and what's more, this unit has been thoroughly mapped on a chassis dyno. It tips the right amount of fuel into the hungry 351 using a system of custom rails and braided lines, CAV injectors (good for 250hp each) and a Commodore pressure regulator. Christopher made the point that he hadn't thrown money around randomly - the fuel pressure regulator, for example, cost only A$60 and it performs perfectly in this application. Heading south, you'll find a pair of Bosch VL Commodore pumps and a surge tank system - which, once again, is all very cost-effective stuff. A diet of pump leaded is enough to get away with running 10 psi boost, but anything over that and AvGas is mandatory.
A MSD 6AL module also boosts the ignition front for improved sparking efficiency.
And the outcome of all this go-fast gear and R&D?
Well, the car's sat on a chassis dyno to record a kickin' 457kW (615hp!!) at 4300 rpm - on 18 psi boost and with the aforementioned problem of valve bounce at any higher revs. And there was a headwind and the sun was in his eyes. But nah, nah seriously - this is a swear to God g-e-n-u-i-n-e power figure. And the power at the flywheel - you take a guess! On the road, supercharger boost comes in noticeably at around 2900 rpm and, in its current guise (and with enough traction), it should be good enough to power along for nine second runs - according to one dedicated quarter mile prediction program. But from extensive seat of the pants experience, Christopher says it feels more like a 10 second car. Still - that's no slouch by any means!
One of the big rubber-neck attractions of this beast is undeniably its characteristic sound. The whine of the blower, the high engine revs caused by the stall converter and, of course, an exhaust note that can shatter greenhouses a mile behind. Collecting wastage from the mountain, a pair of handmade 2 inch extractors merge into a large diameter collector pipe which then splits out into twin 2¼ inch pipes that meander their way to the factory style outlets. Strangely enough, it's reasonably quite at low revs and low loads - the twin Dynomax mufflers doing their thing quite well. That is, until the rush of an innumerable amount of exhaust gas cfm hits!
Under the ground, Christopher has slipped in a bulletproof combination that won't pack it in when the mountain begins to shake. True to drag racing tradition, a 2 speed Raceglide (pulled from a competition drag racer) has been bolted up along with some internal mods to make it a little sweeter in operation. And a mild-ish 3200 rpm stall converter keeps the engine singing in the range where it's happy, but when it's called for, there is also a trans brake to help give dynamite starts.
Underground pipework is about as serious as you can get in a street car - try a 4 inch diameter thick-wall tailshaft for extra durability! And under the rear-end it's Ford truck-tough with a good ol' 9 incher running a 3.7:1 ratio. Reaching out from this are 31 spline axles that 'ave been chopped 4 inches to let Christopher run a set of gigantic slicks when he hits the quarter mile track. When it's pounding the street though, this 3700 odd pound bruiser rolls on some deep-dish 15-inch 12 slotters teamed with 235/60 and gum-ball 295/50 BFG Radial T/A rubber. There was absolutely no tubbing required to fit these big 295s either - just a subtle lipping of the factory guards. (Which just goes to show how much scope Ford left for fitting bigger wheels back in the 70s!)
Anyone who regularly walks the streets of Melbourne should watch out for this blue/silver Ford. 'Cos if its heading your way at warp speed, you might find it valuable to know that it still has the standard GT-spec 4 wheel discs to try an' slow 'er down. No doubt, these brakes would've been fine in a stock 351 powered XB, but a power increase of a zillion% means it'll reach twice the speed a stocker would over any given distance (probably more!). So if you ever see Christopher careering towards you, wide-eyed with the brakes locked up, your best move would be to take an evasive dive...
At approximately the same time the engine work was underway, the chunky Falcon GT trim was redone to stock specs in tough lookin' black fabric and vinyl. Black is back. And for good measure an Autometer blower and fuel pressure gauge found a home on the dash so Christopher can keep informed on what's happening deep within the mountain. One other item that isn't the norm inside an AutoSpeed feature car though, is a child booster seat.
Yep, even Christopher's young son Brodie gets to go for nails through the streets with good 'ol Dad. Now, there's a lad that'll grow up with nerves of steel!
The so-dubbed "Coke bottle" shape XB Ford has also been resprayed in its striking factory blue/grey sports livery to keep it all contemporary looking. Other detailing touches include a polished set of rocker covers as well as other under-bonnet bits 'n' pieces, braided lines, a relocated battery and enough love and care to make most babies jealous. In fact the whole show comes together so well, it's won Top Street Machine at a recent local car show. And it's not quite even finished!
Show winning, bulletproof, tough lookin' and over 457kW at the wheels - now that's what owning a modified car should be!
Contacts:
Dim-Tech Performance
+61 3 9408 9569
Herrod Motorsport
+61 3 9464 5100
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