URBAN WARFARE

BOASTING A MONSTER TWIN-TURBO LSX-BASED 427, NATHAN’S MAZDA RX-3 IS HEADED FOR THE 200MPH ZONE

MARK ARBLASTER

EX-ROTOR ROCKET

> A SIX-SECOND PASS IS ONLY A MATTER OF TIME FOR NATHAN FARRUGIA’S WILD TWIN-TURBO LSX-POWERED RX-3

THE turbo revolution has evolved from a snowball into an avalanche, and one of the country’s most impressive rides to head down that road is the twin-turbo RX-3 of Sydney’s Nathan Farrugia. Boasting 1700rwhp from a twin-turbo LSX-based 427, it’s a basically stock-bodied car with a ladder-bar rear, and has already managed a 7.6 at a whopping 194mph on radials and with 24lb of boost.

Nathan’s Mazda was purchased a few years back with a 20B rotary in it, and was raced like that a couple of times, managing an 8.40. But Nathan wasn’t really looking to invest much in that combo.

“Nathan wanted to do something different with the car,” says Dale Heiler, owner of Castle Hill Performance, who built the engine. “Initially it was a cheap build; a 427ci LSX block with your basic hydraulic-roller cam and a run-of-the-mill [Manley] rotating assembly. We jammed a set of GT42 turbos on the engine and did all the fabrication and plumbing work in-house and it cranked out a 7.80 on its first time out.”

Despite that super-impressive debut, the boys were looking for more. “We decided to step the turbos up and changed them to GTX 47/88s, which had the combination making 1400rwhp,” Dale says. “But then we broke the crank; it snapped the front counterweight right off it. The block was fine, so we upgraded the rotating assembly to a Callies billet and centre-counterweighted deal, and upgraded the Manley rods to Olivers with 10.5:1 compression.”

The heads are a set of Nathan Higgins LS7 CNC-ported items with Cometic head gaskets, Crower solid lifters and a whole bunch of other top-shelf go-fast bits, to support future plans of jamming 40lb of boost into the motor.

The intake is stunning piece of gear produced by Shaun’s Custom Alloy in Sydney and fitted with 16 2200cc injectors running straight alcohol.

A Haltech CDI provides the spark, with an Elite 2500 ECU and a fly-by-wire throttle system that can use all the refinements offered by the ECU, such as traction control. Other Haltech upgrades include eight exhaust temperature sensors, dual wideband air/fuel ratio and the new Race Expansion Module, which allows for 23 datalogging sensors covering everything from crankcase and coolant pressure to boost, timing, exhaust-back pressure and converter slip.

All the turbo manifolds and plumbing were made in-house by Dale and fitted with twin Turbosmart 60mm wastegates, while on the pressure side of the intake two Turbosmart 50mm blow-off valves release the boost on back-off and launch.

Despite being an all-out race car, the fabrication work and level of fit-up is super-neat. Lift the hood and it all looks like it could have come that way from the factory.

But it hasn’t been all gravy for the guys.

“Transmissions have been a real issue for us,” Dale says. “We are running a two-speed TH400, but on three occasions we have broken the intermediate shaft on the shift while the motor has been at 8000rpm and full of boost. You can just imagine how bad that is for the engine, not to mention what it has done to the transmissions. We have someone else on the job now and it all seems to be going well with one of the older-style 10.25in weld-together ProTorque converters.”

The rear end is a pretty basic ladder-bar set-up and mini-tubs. The car is running a Mickey Thompson 315 radial, and in the boot is a single 20-litre fuel cell with a cable-driven fuel pump mounted under it.

“The biggest limiting factor for the development of the car has been its persistent wheelstanding,” Dale says. “When it doesn’t wheelstand it’s like driving a Falcon. We need to have a good look at the shocks on the car, both front and rear, and we have a set of Menscer shocks coming.”

Right now the car is running 7.60@194mph with relative ease and still recording a healthy 1.21sec 60-foot. The biggest single improvement recently has been the addition of a C02 bottle to the wastegates, which allows the Haltech to bleed off boost on the startline.

The combination has about 35 passes on it already, but the boys have not been able to get a full pass down since cranking the boost up to 40lb, although Dale reckons the car will run 6.70@200mph easily. “We have tuned the car to 1755hp at the rear wheels on 24lb, but I’m confident of cranking out 2200rwhp with the boost cranked up to 40lb. From here we just need to get it to the floor.

“While a six-second pass is clearly on our radar, the real goal for Nathan is to run 200mph. We should get that done next meeting.”

> ARBY CHAT

STEALTH BARRA

IT SEEMS we have seen every engine combination known to man in Ford Capris, but one that makes the most sense is being considered by Rick Wallace in Canberra.

A stock Barra motor with a decent front-mount, injectors and cold-air intake on 18lb of boost will make 500rwkW, so they’re the perfect choice for a street machine. They’re a lot lighter than a V8, and available for a few thousand dollars.

Rick says he can get the car legally registered with an aspirated 4.0L six-cylinder in it, and is toying with the idea of rear-mounting the turbo to keep it out of sight.

With a Powerglide transmission and BorgWarner diff, the car should weigh 2600lb in full street trim, which would equate to a mid-to-high eight-second pass on a radial with a bog-stock engine.

By running a 275 radial Rick should also be able to get away with not mini-tubbing the car. Stay tuned for more on this one.

GAZZARD SPONSORS US EVENT

THE Gazzard Brothers’ worldwide fame continues to grow with their Aussie-made traction bars, split leaf springs and sliders. The big news is that they’re sponsoring the upcoming Leaf Spring Racing Unlimited class at the Outlaw Street Car Reunion, to be held at Memphis International Raceway on 16-20 March this year.

LESS THRUST

ONE OF the biggest issues with turbo engines in any race application is that when you put the engine on a transbrake to build up boost, the crank is driven forward in the block, which destroys the factory thrust bearings. This leads to excessive crank end float, which can happen quite quickly in an LS as they have such small bearings.

A new bearing support, designed by Castle Hill Performance, incorporates a Torrington bearing that sits over the crank on the factory shim and is fed oil directly by the stock oil gallery. At $795, they are a bargain, and use four factory-block bolt holes to fit. To attain the correct end float, you simply machine the factory spacer to the desired width before bolting the bearing support to the engine.

End of problem!