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Cobra Kitted XR6T

We test Nizpro's newly introduced Cobra Stage Two kit for the Ford XR6 Turbo.

Words by Michael Knowling, Pix by Julian Edgar

Click on pics to view larger images


When Nizpro announced the release of their Cobra power-up kits for the Ford XR6 Turbo we were pretty excited; Simon Gischus' 200SX-R and the various other cars we've seen out of the Nizpro workshop had accustomed us to expecting something special. But after driving a Cobra Stage Two kitted XR6T ute, we're disappointed to report that this kit currently has some problems. Substantial problems.

But, first, what is Nizpro's Cobra Stage Two kit?

Ingredients of the Kit

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The Cobra Stage Two kit gives you a high-flow cold air intake, an upgrade front-mount air-to-air intercooler, CNC machined cast alloy replacement intake plenum, a custom cast alloy thermostat housing, cast alloy rocker cover, a compact dry-cell Odyssey battery and box, bigger injectors and a pre-programmed Xede interceptor. Note that this is Nizpro's first experience with an interceptor - the value for money of this approach cannot be denied by even the most ardent programmable management user. (See XR6 Through the Roof! for our review of Nizpro's MoTeC-equipped XR6T sedan).

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Simon from Nizpro points out that the new airbox is located on the driver's side of the engine bay, rather than the passenger's side as found in stock form. "By moving the airbox closer to the turbo we've shortened the length of the plumbing and created more space to fit our intake plenum along with the new intercooler."

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Simon also says the factory intercooler doesn't cool effectively at boost pressures far beyond standard, so he has addressed this with a PWR tube-and-fin cored front-mount intercooler. This leads into the larger volume plenum chamber, which is now going through an in-house testing process. The larger plenum retains the factory electronic controlled throttle and requires a custom cast alloy thermostat housing and cast alloy rocker cover. "The rocker cover is also to improve aesthetics," says Simon. A compact and lightweight Odyssey battery also replaces the original and is moved to the passenger side of the engine bay - this allows space for the induction plumbing.

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Note that the exhaust system remains completely standard - Nizpro claims the factory system flows well enough to accommodate a substantial lift in power. The factory Bosch blow-off valve is also deleted.

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The Stage Two kit also includes an upgrade set of you-beaut bigger injectors along with a Xede interceptor. This allows changes to fuelling, ignition timing and boost pressure. Nizpro claims on output of 270kW at the wheels of their DynoLogic chassis dyno - or around 350kW at the flywheel.

The kit certainly sounds like the goods and, retailing for AUD$8239 (fitted), it looks like good value. A 12-month warranty on manufacturing faults is also provided.

Dyno and On-Road Testing

The Cobra Stage Two kit disappointed in back-to-back chassis dyno testing and on the street.

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This graph shows the Stage Two kit making power on the rollers of Nizpro's in-house DynoLogic chassis dyno. The car is completely as you'd find in the kit except the centre resonator had been removed to accommodate fitment of a 4-link rear-end. As you can see, peak power consistently reached 268kW at the wheels over four consecutive runs. The blue plot (the second power run) shows a misfire at around 2900 rpm and the curve is characterised by small power fluctuations. Power begins to drop off beyond 5000 rpm, which is sooner than we have seen from another aftermarket kitted XR6T capable of similar power. (Stay tuned for a test of APS's Phase II kit in an upcoming article.)

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On a Dyno Dynamics chassis dyno (owned by APS), the Cobra Stage Two kit made similar top-end power. Over four consecutive power runs (which were conducted in Shootout Mode 6) the Cobra Stage Two kit managed between 268 and 280kW at the wheels; we are told that a standard XR6T makes 175 to 193kW at the wheels on this particular dyno.

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The first run (plotted in red) shows an unexplained advantage at low revs while the three following runs were much more consistent. At the top-end, the Cobra Stage Two falls over sharply beyond 5500 rpm. The overall shape of the curves is not smooth and, from inside the car during the dyno runs, the engine felt like it was missing.

The lower plots on this graph indicate boost pressure. As you can see, each of the four runs shows irregular boost levels between about 11 and 14 psi.

But the real acid test for the kit was our on-road evaluation.

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Despite the irregularities that were shown on the chassis dyno, the Cobra Stage 2 kit's power delivery felt surprisingly smooth. The car was also had sharp throttle response and went noticeably faster than stock - but from there it's all downhill.

Performance was hugely variable and largely dependant on heat soak. Sometimes the car would erupt with wheelspin (enough to force you to throttle-off) but at other times there was barely any wheelspin. (Note that this particular XR6T ute had also been fitted with a 4-link rear-end.)

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The variation in performance was highlighted on the motorway. Once the engine had 'cool soaked' the engine would detonate - detonate massively - when you nailed it. What's more, this detonation could be replicated time after time. Once the car had been caught in traffic and had begun to heat soak we found that detonation was no longer evident.

The Cobra kit also took noticeably longer to fire into life during starting and its idle was also coarser than standard.

Verdict

We could not recommend purchasing the Cobra Stage Two kit in the guise that we tested it.

Ongoing Development

At the time of writing, Nizpro was working feverishly to overcome the problems we experienced in our test. We are told that starting, idle quality and performance consistency has been much improved and that the detonation problems have been eliminated.

A second test of the new-and-improved Cobra Stage Two kit is planned.

Contact:

Nizpro +61 3 9761 1522

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