Steering the S15

It’s amazing how important it is to get good advice when modifying a car.

Just ask ‘Jobe’ of Brisbane.

“At one point I just wanted to burn it,” he says about his Nissan S15 200SX.

But these days he talks with a completely different tone. He’s achieved exactly what he wanted.

Having previously owned an 11 second 360ci VK Charger and being one of the first people in Australia to develop his LS1-powered SS Commodore, Jobe recently spoilt himself with a rare S15 200SX Spec S GT. Jobe is an avionics technician on F-111 strike/bombers and simply loves to get his hands on things that go fast.

Jobe picked up this Spec S GT about a year ago in absolute showroom condition – we’re told the original owner drove it only on dry, sunny days. And there were a couple of bonus tweaks under the skin – like a Blitz front-mount intercooler kit, Blitz exhaust system, pod air filter, extra boost and Tein adjustable struts.

“The car drove great when I bought it – I was really impressed,” says Jobe.

Unfortunately, when he acted on some recommendations, the whole package fell into a heap.

“I was told to put on a high-flow turbocharger and rising rate fuel pressure regulator and that made it an absolute pig,” says Jobe.

At this point, Jobe took the car to Kelvin and Bill of Brisbane’s C-N-J Motorsport. C-N-J had already sunk their claws into Jobe’s SS Commodore and achieved some impressive numbers with limited mods. On the rollers of their Dyno Dynamics chassis dyno and with an air-fuel ratio meter up its tailpipe, it became obvious something was very, very wrong. Extra-lean mixtures were traced back to a faulty fuel pressure regulator.

The standard fuel pressure regulator was refitted and another approach was taken – namely, bigger injectors, a high-flow fuel pump and an Autronic SMC programmable ECU. The Autronic unit takes a load input from a MAP sensor which replaces the Nissan airflow meter. Note that C-N-J also has a plug-in adaptor loom to enable neat an’ easy fitment of Autronic management to the S15. These mods improved driveability but, still, the engine was very laggy and power output was well under expectations – only about 180kW at the wheels.

“I remember it took until about 4500 rpm before it did anything,“ says Jobe. At this point he was willing to try anything.

Jobe then threw on a set of Gonzo extractors in an attempt to improve response. The new pipes gave a small but noticeable improvement in response and about 5kW extra at the wheels.

Still not enough.

About now Jobe did some in-depth research and purchased a replacement turbocharger – a GT28RF unit with an internal wastegate. This was fitted to the existing Gonzo exhaust manifold and, after a bit of other fiddling around relocating the ABS unit, the improvement was monumental.

The existing pod air filter was replaced with a modified version of the standard airbox with a silicone pipe into the turbo compressor. A high-flow adaptor pipe lives in the place of the standard airflow meter. A Blitz blow-off valve can be found on the intercooler pipe leading into the throttle.

“All of a sudden it was insane,” says Jobe. It was supremely responsive, torquey and gave plenty of top-end.

Given the newfound grunt, it’s no surprise the standard clutch started slipping with 15,000km showing on the odometer. Jobe wanted to maintain driveability so he went for a heavy-duty full-face organic clutch - he didn’t want something that might snap the factory 6 speed ‘box.

With an output of around 200kW ATW on 22 psi boost, everything was running sweetly until a strange missing problem appeared on the scene. The car was dropped off at C-N-J for 6 weeks (while Jobe went away for work), during which it was discovered there was a lifter problem.

While the top-end was pulled apart, Jobe made a deal with C-N-J that they could use the car for the development of an effective camshaft and cylinder head package. Bill from C-N-J tells us they came up with a custom ‘mild’ cam profile, which works with the standard variable inlet cam timing system. The higher lift cams are fitted along with upgraded valve springs and off-the-shelf ‘rocker stoppers’. The DOHC head also received some custom mods.

Once tuned, and with boost pressure eased to around 20 psi, the S15 now kicks out 229.7kW at the wheels. This dyno graph also shows the meaty bottom-end and mid-range torque.

Jobe has subjected the car to a considerable number of quarter mile passes. His best time so far is a 12.45 – with the air conditioning switched on and poor traction through the first two gears... Some sticky rubber would almost certainly drop a tenth or two.

“It definitely goes quicker than people think it will with the power its making,” says Jobe.

While all of the engine antics were happening, Jobe also looked into improving the car’s on-road poise and handling.

“The Tein struts that were fitted aren’t meant for Australian roads – they’re for a smooth surface,” says Jobe.

“I remember I’d hit a bump and the arse would come out. It was scary to put my foot down going around a corner,” he says.

Interestingly, the solution was to rebuild the Tein struts using locally-available Koni adjustable inserts. This conversion was carried out by Fulcrum Suspension in Moorooka. A pair of ‘pineapple’ bushes locate the rear-end and low-compliance rack bushes improve steering feel and response.

“Now I can throw the car into a corner and it sticks like glue,” says a more than happy Jobe.

The new suspension also provides a more attractive ride height, which is complemented by a set of 18 inch JR Racing wheels wearing 235/35 Falkens. According to Jobe, he does “some serious skids in them” and they are lasting well. The 200SX GT was also factory-fitted with a rear wing, which Jobe replaced with a wing-less boot lid. You might also notice the aftermarket taillights, clear side indicators and clear bulbs.

Inside, the trim is standard Spec S GT fare with leather and exlusive shiny bits. Jobe has added an AutoMeter boost gauge in an A-pillar pod and installed a high-quality sound system. No need to go overboard here.

“I’m really happy with how the car now feels on the road,” says Jobe.

“It all comes down to good advice.

“I remember C-N-J asking me exactly what I intended to do with the car and they took it in that direction. They also built it to last – I’ve had no problems with the engine and gearbox,” he says.

But using the car as an everyday ride to the Amberley Air Force base does take its toll in other ways.

“It’s really annoying that I can’t avoid getting stone chips in the paint so I’ve now bought a Jeep Wrangler which I’ll start using as my everyday driver,” he says.

And what words of wisdom does Jobe have to share given his turbulent affair with his S15?

Just one thing really...

“Once you’ve found a workshop that does the right thing by you, make sure you stick with it!”

Contact/Thanks: C-N-J Motorsport                                                +61 7 3290 3966                                                                         www.cnjmotorsport.com.au Jobe would like to thank Kelvin, Bill and the team at C-N-J Motorsport, Fulcrum Suspension in Moorooka and Gonzo of Gonzo’s Racing Products.