Zed with Zing

The result of basic mods to a Nissan 350Z.

Words by Michael Knowling, Pix by Julian Edgar

Click on pics to view larger images

At a glance...

  • 15 percent peak power gain
  • 20 percent peak torque gain
  • Exhaust, air intake and UniChip mods only
  • A cost-effective enhancement for any 350Z

The Nissan 350Z. Since our initial test of the 350Z Track edition we’ve received more emails about this car that any other we’ve covered in AutoSpeed.

It’s a car with an absolutely monumental following.

So it’s a little baffling why so few people modify their 350s. Well, John Gaffney of Queensland wasn’t afraid to give it a go - and here are the results of his mods...

“I bought my 350Z Track spec a couple of months ago because I like the look of it and its performance – but mainly its looks,” says John.

“In standard form it has good response and torque – it’s the sort of car you can be lazy with and drive in a gear that’s too high.”

In factory guise, the 350Z’s VQ35DE engine is rated at 206kW and 363Nm, at 6200 and 4800 rpm respectively. The all-alloy 3.5 litre six boasts DOHC, 4 valve heads with continuously variable inlet cam timing and direct-fire ignition. Its 10.3:1 compression ratio means 95+ RON fuel is recommended.

But, like any mass produced vehicle, its performance is compromised by its conservative exhaust and ECU tune.

John took his still-smelling-new 350Z to Bob Romano Performance after having good experiences there with other cars (John also owns an Audi A4 Quattro that’s been elevated from 110 to 165kW at the wheels).

Chris Romano says the 350Z is an impressive bit of gear in standard form, but basic exhaust, air intake and management upgrades provide good gains.

John’s car has a replacement exhaust from the heads back. A custom pair of headers feed into a parallel front pipes with an X pipe joining each side. The twin pipes then merge into a single, large diameter pipe before again separating into dual pipes toward the rear. A single high-flow cat and twin canon-style mufflers are fitted to John’s car. Note that the tips are cut at an angle to suit the style of the car – a nice touch.

Chris says a lot of development was put into the headers.

“We tried six different designs and we settled on a design that gives the best overall spread of torque – a happy compromise between top-end and everyday torque,” he says.

“We hope to be constructing the headers with a jig very soon.”

According to Chris, the factory headers have particularly small primary diameter. Replacing the stock manifolds with a good pair of aftermarket jobs is said to double the power gain normally seen when a cat-back system is fitted.

In other words, it’s worthwhile going all the way with the exhaust.

The only other hardware mod to John’s car is the fitment of an aftermarket panel filter. The lower half of the airbox is also modified to flow a larger volume of cool induction air.

“The UniChip brings the exhaust and intake mods together,” says Chris.

He explains that the factory mixtures fluctuate through the top two-thirds of the rev range and, once the UniChip is wired in, this can be ironed out. Top-end mixtures are also leaned out to enhance power. Ignition timing is also revised over the entire range, with special attention to improving response at light load.

Note that Chris recommends filling the tank with 98 RON fuel once the vehicle is modified. At minimum, a bottle of octane booster should be added to the tank whenever you’re forced to use normal unleaded.

On the Romano Dyno Dynamics chassis dyno, these mods saw peak power increase from 151kW to 174kW at the wheels. That’s a gain of 15 percent, so – assuming the factory quoted power is correct – you’re looking at around 237kW at the flywheel.

In addition to the 15 percent power gain, this graph shows a strong increase in torque all through the rev range – up to 20 percent. This graph shows the standard power and torque curves in red, while the modified curves are in blue. Note that these runs were conducted in fourth gear and in Shootout Mode.

On the road, John says the 350Z is now much more throttle responsive and ‘fatter’ through the mid range. Top-end performance is also noticeably improved – so much so that John is hoping to run a low 13 second quarter mile.

The exhaust is resonance-free and – although much louder than stock – it’s not obtrusive

“I don’t hear it at all while at cruise,” says John.

So what’s the cost, you ask?

Well, Bob Romano Performance charges AUD$4250 for the new headers/exhaust and UniChip fitment and tuning. The replacement air filter and airbox mod adds an extra AUD$200, bringing the total up to AUD$4450. This isn’t a bad price considering how much more difficult it is to extract more power from a NA engine compared to a turbo. John is very happy with the result and has no further plans for mechanical modifications.

The only other mod John has made is a new set of wheels’n’tyres.

“I don’t really like the look of the standard 18s. They let the car down,” says John.

The guards are now filled by polished G.MAX rims measuring 19 x 8.5 at the front and 19 x 9.5 at the rear. Note that John says it was a challenge to find wheels that would clear the Track spec Brembo calipers. Tyres are 245/35 and 275/30 Falken Azenis.

“The Falkens are a great tyre,” says John.

“I still haven’t found their limits.”

Interestingly, the step up to 19s and extra low profile rubber hasn’t caused much extra bump harshness.

“I’m really happy with the car now,” says John.

“I’ll probably hold onto it and see if there’s anything better that appears on the market in a couple of years.”

Contact:

Bob Romano Performance
+61 7 3395 8255
www.bobromano.com.au

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