In recent years, there's been a noticeable move away from the traditional Roots style supercharger to the now very popular centrifugal type, with the results speaking volumes for how these superchargers can boost performances to awesome levels. But let's put this into perspective. Just as it's suggested that there's nothing like the sound of a howling V8, if mega blow is desired, there's nothing quite like a 14.71 GM style supercharger. In other words, centrifugal may be good, but it will never see use in the likes of Top Fuel drag racing!
All the same, reality dictates that for street use, a centrifugal 'charger is used. Thanks to their compact dimensions and an ability belying their size, supercharger manufacturers are now producing a large range of blowers, with some suitable for engines delivering as much as 1200 or more horsepower.
So, if we take this technology and mix it with the chassis and engine-building expertise of the renowned Melbourne-based Haddad brothers, one expects it's going to be a good thing. Fact is, George and Ray (Haddad) are of the firm belief that to progress, one obviously has to either move with or in front of the times. To this end, a decision was made to develop a range of force-fed engine combinations which would deliver medium to major grunt with a minimum of fuss - and which would still be at home on the street.
Home Base
For the boys to develop a complete package, they sought a popular V8-powered family sedan. That the car was destined to be a design mule meant that in some cases compromises would be made. Sure, strictly speaking, the chosen VN Commodore is a legal street car, however by George admitting that the ultimate goal is to develop a combination developing well in excess of 1000 horsepower, the decision was taken to go with a diff that could see duty in something like a Pro Stock. This way, regardless of how much power is put into the car, the diff would live. I mean, it'd be the pits if development suffered due to equipment failure like the transmission or diff, wouldn't it?
The plan penned, George and Ray set about building the VN to withstand the rigours of hundreds of quarter mile passes, plus of course the occasional street hoon! On this note, it had to be legal, meaning it couldn't have anything large poking out of the bonnet or a stripped interior.
With the aid of a rotisserie, the boys stripped all and sundry including the hanging panels and of course, the interior and drive line. The floor was seam-welded, panel repairs made and the underfloor cleaned before a fresh application of paint. The only deviation from factory lines would be a custom fibreglass bonnet with scoop and supercharger bulge. Other body additions and deletions consist of a fuel pressure gauge hidden under the 'A9X' style scoop, deleted badges, and the fuel filler cap filled. Good mate Eric Moroda performed most of the surgery as well as the application of George's famous 'Fat Boy Orange' Spies Hecker two-pack paint.
Looking for a serviceable interior combo, Ray and George stuck with some stock fare including the rear seat and trim materials. To this they have added a welded 12-point roll cage, driver and passenger RCI plastic race seats and harnesses and a VR SS tiller. A carbon fibre switch box mounted between the front seats provides operation of the fuel pump, ignition, and start, and it butts up against a carbon fibre console cover. An all-AutoMeter package of Pro-Comp tacho, Phantom water and Sport-Comp boost and oil pressure gauge supports the dash instrumentation, plus there's an Autronic air/fuel ratio meter.
Move aft of the impressive Custom Trim (03 9555 6427) interior and there's a fully carpeted boot containing a sophisticated fuel system. Kicking it off is a custom 45-litre alloy Vanell tank with fuel delivery through a -10 braided Aeroquip line to a Y-piece, into a pair of Paxton filters, two Signature Series pumps, back to one line before again breaking into two lines for supply to the two fuel rails.
Unseen Charm
I guess it'd be fair to suggest it's what you don't see in the Haddad Commodore that really makes it a stand out. It starts in the engine bay, the area having been fully colour-coded, seam-welded and with roll cage extensions meeting the strut towers. A combination PWR aluminium radiator and intercooler (to Haddad's design), and a Derale transmission cooler with Aeroquip lines and ends front the engine.
Now to the focal point - the engine. That it started out as your garden variety 308 Holden engine means little when pondering the results. Get this. George has yet to 'lean' on it - restricting maximum boost to a mere 15.5 psi at 6000 rpm gave a staggering 856hp and 772ft-lb of torque at 5500 rpm. If this isn't enough, consider a torque curve that shows 500 ft lb at 3000 rpm, 631 at 4000 and 749 at 6000 rpm!
Adding even more interest to the equation is the fact that the engine was designed to produce maximum power at 7000 rpm. Proof of this came during early dyno testing and running in without the supercharger and fuel injection. In an attempt to create an approximate normally aspirated base line, George donned the engine with a 750 Holley with a resultant 445 horsepower at 7000 rpm (402 ft lb at 5250) and a useable rev limit of 7500 rpm.
In other words, it'd be fair to suggest that 856 boosted horsepower is a little shy of the real figure...
What's more, being very early days, George has yet to even look at upping the ante. "My biggest concern is block integrity," said George. "The more power it makes, the more chance the block will break. Mind you, I think there's a way to go before that happens, so my plan is to play with camshafts, cylinder head development and more boost. With three larger Vortech superchargers to play with, I believe that much more than 1000hp is achievable - assuming the engine holds together."
Cubic Combination
Durability is the name of the game with any engine developing super power. In turn, George has race prepped the block, deburred the valley and ensured exact clearances. It's also equipped with four bolt steel main caps, is 'O' ringed, has ARP head and main studs and the clearanced bore bases. Increasing the capacity to 360 cubes required a small bore increase of .030 inches, to which George added his own ground Harrop stroker crank. In other words, with it being supplied in semi-finished form, it has allowed for additional stroke length.
Secured to the big ends with narrowed Federal Mogul race bearings are fully-floating small block Chev Manley H-beam rods with 8740 ARP bolts. A Russell Oil Pans sump delivers stacks of slippery liquid via a high-volume JP pump to JE plasma moly file-back ringed reverse-dome JE forged pistons, while the cam is spun thanks to a nine keyway Rollmaster timing chain set. Camshaft specifications are, as you might expect, not for public consumption. Let's just say that George has gone with a mechanical grind topped with Speed Pro solid lifters, moly push rods and Yella Terra roller rockers.
George only went so far with the VP style cylinder heads, flowing them to around 545hp. The chambers are CC'd, they're fitted with ARP screw-in studs and guide plates, Crane machined collets, Teflon valve seals, moly retainers and Crane springs. Valves are stock. Compression is set at a fairly 'standard' 9.5:1
Bolted above the valley is a match-ported Harrop single plane manifold sporting eight 750cc Rochester injectors and a pair of extruded fuel rails. The injectors are fed PULP fuel via a pressure sensitive SX EFI fuel regulator. The induction package continues with an intercooler feeding a custom alloy intake elbow, and a 80mm Holley throttle body modified to adapt to the 75mm intercooler piping. The chosen supercharger is a Vortec 'T' trim centrifugal unit using a 28-tooth top and 72-tooth bottom pulley for the 15 pounds of boost. Punching spark into the chambers is a VT Commodore sequential dizzy backed with an IC&E digital HEI box and 8.8 mm IC&E leads. An Autronic SMC complete with the auto tune option - which George claims to be absolutely brilliant, efficient and effective - manages the whole operation.
Next In Line
Coping with the massive power of the power of the 5.8 litre Holden engine is a RaceGlide-prepped two-speed Powerglide which is designed to handle as much as 1200 horsepower. Modifications are many and include a Kevlar band, custom valve body, chromoly clutch hub, multiple top clutch assembly, Hi-tuff input shaft and a whole lot more. A Hurst Quarter Stick is used to swap the cogs and there's a custom 9.5 inch 4500 rpm TCE converter. Next in line is a custom three-inch thick-wall tailshaft with 1350 front and rear unis and billet front yoke. Likewise, the rear end is of the highest calibre, the Ford nine-inch housing having a Strange nodular casing, 3.50 Richmond gears, 35 spline Moser spool and axles, an alloy pinion support and billet yolk.
The diff housing is secured to the body via boxed control arms, custom King springs and standard shock absorbers, with power placement enhanced thanks to modified brackets and geometry. At the pointy end are further changes such as a VL Commodore crossmember and manual rack and pinion steering, however the stock struts and springs have been retained. Brakes are stock unboosted Commodore discs and 11-inch Ford Galaxie drums. Wheels are 15 x 3 and 8-inch Weld Racing numbers wrapped in 550 Moroso Front Runners and 29.5 x 9-inch Mickey Thompson slicks.
Wrap Up
With winter having hit Melbourne, the VN has only had one quarter mile outing, a less than auspicious affair actually, so we can't give you any good news. Rather, once a decent number is run, we will update you. What we can say though is that on its debut pass, the VN was pedalled at a little more than half throttle - just to make sure it would hang together. The result was a low 10 second elapsed time at a little over 140 mph. "We had significant traction problems which necessitated we make a number of changes before the next run." Thing is, at about three quarter track, the engine fan belt let go, taking with it the blower belt, which in turn took out the fan shroud, fan and alternator mount. In other words, the car would not return.
In its current guise, the VN should be good for a high eight-second elapsed time at in excess of 150 mph. And we're real keen to see if this is achieved. Once it's sorted, George will up the power in search of a mid to low eight second pass. He'll need a lot of luck of course, considering the stock rear suspension and tubs. With just nine inches of rubber on the road, it will be a struggle! But knowing the Haddads, almost anything is possible!
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