The current trend in Holden Commodores is undoubtedly toward the VT 5.7 Gen 3 - the latest and largest of all V8 Commodores. But that doesn't automatically mean that the new beast is the Power King. A lot of people forget the immense potential that resides in the earlier bent-eight VB-VL bodied C'dores. Sure, the Aussie 308 block might not have the cubes of the Chev 350 - but it doesn't have to stay that way! And that's where Nathan Well's bumped-up-capacity VK Group A Group 3 - one of only 50 made - surprises a lot of people. Indeed, this underestimated machine has enough grunt to put a small block Chev to shame!
You're looking at the 2001 Horsepower hero for naturally aspirated small blocks!
So how did Nathan do it? Well, no doubt, it helps to be an avid spanner man. Nathan's previously worked in Sydney's Silverwater Auto workshop, which helps explain his extraordinary knowledge of how to assemble a killer motor. Interestingly, though, the very first engine Nathan built up for this Group 3 was when it still belonged to his brother. It started off as nothing more than a mild hp increase. Phase one saw Nathan piecing together a 336ci stroker (using an offset ground crank and small journal Chev rods), together with late model cast iron EFI heads and a mild solid cam. Induction was left to a modified Rochester carby atop a Harrop intake manifold.
It was a good thing, this first motor, making 360hp at the back wheels and with a strong spread of torque. The only problem was, Nathan's brother couldn't stop breaking diffs and various other driveline bits'n'pieces. Inevitably, he called it quits and decided to sell the car - only to find that Nathan was ready-and-willing to take it off his hands. After all, what is family for?!
And here we enter engine Phase 2. Hankering for a little more grunt again, Nathan stretched the Group 3's cubic capacity to 355ci, using a Harrop crank, Hex rods, Crane hardened pushrods and a set of JE 10.4:1 forged pistons. The cam was also swapped to a roller jobbie delivering around 620 thou lift. That carby induction set-up had performed admirably on the previous engine build, but Nathan could see that it was time to move up to EFI. And what better way to go than to fit Holden's own twin throttle body manifold and its associated Delco software and hardware?
Airflow into the throttles was maximised with a pretty-looking stainless airbox, which contains a K&N VT Commodore air filter. "It was the biggest I could find," explains Nathan. Both the airbox and the elaborate catch tank on the other side of the engine bay (which drains oil back into the sump) are the work of Performance Metal Craft.
And how much more power did the Harrop stroker and the move to EFI (amongst other things) make? Try around 370hp at the rear tyres (as measured on a Dyno Dynamics chassis dyno). As you might expect, throttle response was also improved markedly.
And then it was time to get ultra serious in Phase 3. In this stage, the first move was to ditch the standard injectors and ECU (which had been limiting power) and swap over to a bigger set of Bosch injectors controlled by an Autronic SMC ECU. Interestingly, Nathan also found a little more high rpm torque by increasing the height of the plenum chamber. Look at our engine pic and you can see how much he's raised the plenum ceiling. At the same time, the fuelling system was upspec'd with a Bosch Motorsport pump drawing from a 90-litre in-boot tank (which contains heavy baffling and a swirl pot). Note that no primer pump is used - nature's gravity ensures there's always fuel available at the inlet to the Bosch M-Sport pump.
The internals of the motor were - again - subject to revision (boy, Nathan's keen!). Probably the biggest jump was the move to a pair of Yella Terra alloy heads - which saw the compression ratio rise to around 11.0:1. These are filled with large diameter stainless steel valves, 1.65 roller rockers, Isky springs and titanium retainers. Valve actuation is via a larger-again CamTech bump stick, which gives about 700 thou lift. It's all spun by Rollmaster timing gears. And, speaking of spinning, Nathan tells us this engine will keep making power right up to 7800 rpm - but he choses to have the rev limit set to 7600. "There's just too many dollars invested in it," explains Nathan.
Nathan was on the right track with his latest brace of mods. Power rocketed from 360 to an amazing 436hp at the wheels! Nathan predicts that's around 620hp at the flywheel, taking into account the rear-wheel-drive drivetrain losses and the type of dyno used. In this car, for drivetrain we're talking specifically about a single plate heavy-duty clutch, a T5 5-speed gearbox and a Ford 9 inch diff. That big unburstable Ford item contains a 3.7:1 Detroit locker centre.
With 436hp at the wheels, it's only logical that the Commodore's brakes needed more power. The front is now kept on a leash by 330mm slotted DBA discs (a set of drilled discs had previously shattered!) clamped by large B-technik 4-pot calipers. The tail end has received a pair of VN Group A Commodore DBA discs (slotted and drilled) as well as ventilated single-pot Corvette calipers.
Equally as much design has gone into making this rare Group 3 go around corners. Nathan confesses, "I'm much more into circuit racing than drag racing." Starting under the nose, the VK strut bodies have been shortened to accept Koni adjustable Calibra inserts, equipped with height-adjustable platforms. The spring rates are Nathan's own little secret. We
can tell you though that the car sits now 4 inches lower and maintains a healthy amount of travel. Body roll is limited by a 30mm front swaybar and the front wheel alignment is set with K-Mac adjustable strut tops. The rear rides on 3 inch lowered springs, Koni dampers and incorporates an adjustable Panhard rod. A 19mm swaybar is used at this end. The result of all this, Nathan says, is a very neutral, predictable handler - with p-oversteer available whenever you want it!
During those high G-force corners, standard Group 3 sports seats (that came as part of the Scheel interior package) hold Nathan in comfort. The only other mod to the high factory spec interior is a Sony CD sound system and Autometer tacho and oil pressure gauges. Standard is also pretty much the word for the body as well. The only non-standard items complimenting the Group 3 body kit is a aircraft fuel filler and those big rims - 18 x 8 Kahns, wearing 225/45 Falken tyres.
Now - like winning the HP Heros with a Holden motor isn't surprising enough - it's almost impossible to believe that Nathan drives this car every day. And we don't just mean every day that the sun is shining - we mean every day. A genuine 15,000 kilometres per year is testament to that!
So - other than racking up a few more kilometres - what does Nathan have planned for next year's HP Heros? Well, the exhaust is something that's still on his "to do" list. For now, there's the biggest 4>2>1 Pacemaker extractors that you can buy, leading into twin 3-inch pipes - each equipped with a front muffler and rear resonator. Nathan says the twin 3-inch part of the system performs fine - but he's planning on installing a set of custom extractors off the heads. Once that's done, he'll look at extracting the maximum power from each cylinder. He'll get stuck into the Autronic computer and chase every last horse out of each individual cylinder.
And you can believe that he will. Two thousand and two HP Heros, here comes Nathan Wells - again!
Contacts:
Silverwater Auto
+61 2 9748 1300
Performance Metal Craft
+61 2 9638 2419
sales@hioctaneracing.com.au
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