Higgins' Hauler

Nathan Higgins is a well recognised name in Melbourne’s LS1 tuning circles – and the whole of Australia for that matter. Nathan is the main man of Higgins Race Developments and he has an extensive background in cylinder head modification. With this kind of inside knowledge it should be no surprise that Nathan’s own 2003 Holden VY SS ute is plenty quick.

Try 10 second quarter mile quick!

Nathan tells us this was Australia’s first LS1 to reach into the 10s with the factory 346ci swept capacity and without the assistance of nitrous or forced induction.

The “big engine” – as Nathan calls it – delivers those 10 second ETs thanks to a comprehensive internal modification. The spec list comprises US-sourced H-beam rods, JE flat-top pistons (providing a compression ratio around 11:1) and lightly honed bores. Interestingly, the crank remains stock. It’s all balanced and blueprinted, like any top level engine build.

The alloy 2-valve cylinder heads came under Nathan’s die grinder and were modified to flow 658hp on a flow bench (at a test pressure of 28 inches of water). Nathan selected a top secret camshaft to achieve his desired torque band and fitted it along with double valve springs, new timing gear, Competition 1.85:1 rockers, titanium retainers, lifters and pushrods.

A modified 90mm throttle body ensures there’s ample intake flow into the US-sourced Fast manifold, which offers larger runners and plenum volume than the factory part. DiFilippo 1 7/8 inch extractors and a twin 3 inch DiFilippo exhaust expel exhaust gas, while a custom fibreglass air intake funnels induction air to the throttle body – more on this in a moment. Suitable changes to the engine management system were conducted using LS1 Edit software and included removal of the factory airflow meter. Larger injectors are required at this level of performance.

These mods has resulted in 474 horsepower at the wheels on a Dyno Dynamics chassis dyno. Getting this sort of grunt to the ground in a light-at-the-back Holden ute is a challenge that Nathan solves with a pair of 10 inch slicks – for drag use only. With these under the rear guards, the ute has powered down the quarter mile in a mind-blowing 10.9 seconds with a terminal speed of 126 mph.

Watch out Pro-Street racers!

About now you may realise the engine in our pics does not match the above technical description. Well spotted. At the time of our photo shoot, Nathan had installed a ‘little’ engine – a package that anyone off the street can walk in and order. The engine is fitted with 1¾ inch aftermarket extractors leading into a twin 2½ inch DiFilippo mandrel exhaust.

The intake system is the same set-up that was used on the 10 second engine. Nathan has whipped up his own fibreglass ram-air intake from the radiator panel to the throttle body – there’s no airbox. This photo shows the factory intake air temperature sensor in the ram-air duct. Note, however, the typical off-the-shelf upgrade uses a GTS high-flow MAF pipe and K&N filter. The factory airflow meter has also been removed courtesy of a LS1 Edit MAF-less tune.

The LS1 engine package also features a pair of Nathan’s “mild street ported” alloy heads which flow 590hp on the flow bench. The compression ratio remains standard. A new bump stick is also fitted along with double row timing gear, competition springs and aftermarket retainers.

The fuel system on this particular vehicle comprises a Bosch Motorsport high-flow pump, SX adjustable pressure regulator plus a Nathan-fabricated rail and surge tank. With the stock injectors employed in the off-the-shelf kit, this combo has achieved up to 400 horsepower at the wheels (on a Dyno Dynamics chassis dyno). This equates to 11.4 second quarter mile performance (with slicks fitted).

This sort of performance will set you back a fixed price of AUD$5600 – drive in, drive out. For AUD$5600 you get modified heads, a new cam, springs, timing gear, retainers, extractors and exhaust, air intake and retune. It’s a combo Nathan guarantees will run in the 11s.

The driveline of Nathan’s car is the stock 6 speed configuration boasting a 3.9:1 LSD rear and a semi-metallic button clutch. The chassis is also optimised for drag racing with Koni double adjustable dampers front and rear and a set of King 25mm lowered springs.

The ute is optioned with the Premium brake package, which Nathan says looks great behind a big set of aftermarket rims. Unfortunately, they don’t provide enough clearance to fit slick tyres on a 15 inch rim. For street duties, Nathan runs HSV GTO 18s wearing 245/40 and 265/35 Sumitomo tyres front and rear respectively.

Onboard, Nathan has opted for the factory leather trim upgrade and the only modification is a HSV central instrument pod containing an AutoMeter oil pressure and oil temperature gauge. But the interior is not where the interest is...

In a couple of weeks, Nathan says he will have the “big engine” back in the car with some subtle changes to cylinder head and cam specifications. With a retune to suit, he’s hoping to improve on his existing 10.9 second time – a 10.6 or 10.7 is the goal.

This is the kind of patience and determination that drives LS1 performance. Sure, you might be able to bolt on a blower kit to help things along – but where’s the challenge in that?!

Contact: Higgins Race Developments +61 3 9768 3902