Zed Speed - Part Two

In the first part of this series we looked at the first ‘modern era’ Nissan Zed – the Z31. In this, the final instalment, we’ll take a look at the engineering of the Z32 model and delve into its aftermarket tuning potential.

As you’ll see, the Z32 can be tweaked to go seriously, seriously fast!

Nissan Z32 300ZX

When you examine the all-new Z32 300ZX alongside its contemporary R32 Skyline GT-R stable mate, its obvious Nissan had a serious amount of money to invest in engineering during the late ‘80s.

The Z32 300ZX is absolutely light-years ahead of its Z31 predecessor - its more comfortable, better balanced, better built, more attractive and, yes, faster.

Much faster.

The Z32 300ZX was sold in certain counties with the choice of two engines - a naturally aspirated or twin turbocharged DOHC 3.0 litre V6.

The twin-turbo engine (coded VG30DETT) is a technical marvel and an awesome performer. The base DOHC, 24 valve V6 is hung with a parallel pair of T2/T25 turbochargers, twin-air-to-air intercoolers and a unique twin plenum/twin throttle intake system. With boost pressure set to around 10 psi, the twin-turbo 3.0 cranks out the Japanese regulation 206kW maximum output. Note that peak torque is greater than the Skyline GT-R with a whopping 388Nm at 3600 rpm.

Nissan’s development of the VG30DETT can be found at The Nissan VG30DETT.

In response to criticisms of the previous model, Nissan tried hard not to increase the weight of the Z32 300ZX. Naturally aspirated versions weigh around 1450 – 1490kg and the twin-turbos weigh about 100kg extra. Designers opted for an aluminium bonnet and abandoned the complex and heavy pop-up headlights.

The twin-turbo engine comes tied to either a 4 speed auto or 5 speed manual gearbox and, with a viscous LSD at the rear, it delivers electrifying performance. Nought to 100 km/h takes as little as 6 seconds flat and the quarter mile dips into the low 14s. Top speed is quoted at 269 km/h... In normal driving, the twin-turbo engine benefits from a relatively high static compression ratio (8.5:1) and faster-spooling turbochargers to provide excellent flexibility. Torque swells from about 1500 rpm.

Note that the Z32 twin-turbo was never officially exported to Australia – they’re currently available as ‘grey’ imports only. However, Nissan Australia did offer the naturally aspirated version...

The naturally aspirated VG30DE engine brings DOHC, 24 valve heads, variable inlet cam timing, a 10.5:1 compression ratio, variable induction system and direct-fire ignition. Maximum output is a creditable 166kW at 6400 rpm and there’s 269Nm at 4800 rpm (more than the superseded VG30ET!). The 7000 rpm redline is also much more realistic thanks to the breathing capacity of the new 24 valve heads.

At just under 1500kg, the locally delivered 300ZX 5 speed can accelerate to 100 km/h in around 8.0 seconds. The quarter mile takes about 15.8 seconds. The auto version takes several tenths longer in each increment. Note that these figures are achieved running premium unleaded.

Road testers at the time of release claim that the naturally aspirated 300ZX is a sweeter overall package than the twin-turbo because of its 50:50 front to rear weight balance, sharper throttle response and slower corner entry speeds (which come from having less power). Contemporary car magazines often compared the atmo 300ZX to the revered Porsche 944 S2.

The Z32 chassis offers 35 percent greater bending rigidity and 20 percent greater torsion rigidity than the previous model. The centre of gravity is lower, the front and rear tracks are wider and the suspension is much improved. Under the skin, the 300ZX incorporates a double wishbone front and rear suspension system, which follows the same school of design as the Skyline GT-R.Twin turbo versions also use a Super HICAS (High Capacity Actively Controlled Suspension) system to give +/- about 1 degree of rear wheel steer.

The power assisted rack and pinion steering offers much greater feel than the previous model, providing enhanced on-road feel and driver confidence. Stand on the brakes and you’ll be stirred on by the extra confidence of the 292 and 279mm ventilated ABS-controlled discs. These are very similar to R32 GT-R brakes. These big rotors hide behind 16 x 7.5 inch alloys clad in 225/50 rubber. Twin-turbo Z32s score 245mm rear tyres.

The styling of the Z32 300ZX was widely praised when released – and even today (16 years later) it still looks good. The long nose of the previous models was shortened, wheelbase was lengthened and overhangs shortened. The cabin is also extremely low-slung and the integrated aero package achieves a 0.31 Cd.

Note that a 2 seater and 2 + 2 were offered – the 2 seater has a shorter wheelbase which sacrifices some directional stability. Twin turbo models are easily identified by the slatted intercooler ducts in the front bumper and a sticker on the rear hatch. Australia received only the naturally aspirated 2 + 2.

Inside, the Z32 cabin matched the styling of the body and the vehicle’s purpose. The low, swooping dashboard contains comprehensive instrumentation, pod-type switches, leather wheel and optional leather seats. Space utilisation is poor – typical of Nissan coupes from the era. Removable targa tops come standard.

The Z32, in particular the twin-turbo, was seen as a return to form for the Zed. It gives all of the thrill a driving enthusiast wants - the only downfall being price as the Nissan sports car was no longer particularly affordable. As a result, a dwindling rate of sales occurred in Australia until it was discontinued in 1996. Only recently has it been replaced by the Z35 series 350Z.

Nissan Z32 300ZX Modifications

First things first - the Z32 turbo responds extremely well to an exhaust upgrade. Like most cars with factory electronic boost control systems, fitting a zorst to a Z32 has the side-effect of increasing peak boost pressure. It’s common for mid-range boost to spike beyond standard and then settle back to near-standard; this momentary boost spike gives tremendous mid-range thrust.

After enjoying the kick-in-the-pants of an exhaust upgrade, the next logical step is to release intake airflow. The Z32 runs an unusual air intake arrangement where there are twin air filters, a single airflow meter and a 1>2 divider that channels air to the mouth of each turbocharger. There’s plenty of air filter area and you can find effective gains by feeding large diameter pipes into the pre-filter side of the airbox. Some people opt to remove the factory airbox entirely and install a large pod filter directly to the airflow meter. The choice is yours.

The Z32 is equipped with an elaborate twin air-to-air intercooler system that has a reputation for poor heat-exchange performance and airflow restriction. We strongly recommend an upgrade in this department. Companies such as Stillen (www.stillen.com) produce bolt-in upgrade intercoolers or, alternatively, you can merge the output from each turbo compressor into a single, high-capacity front-mount intercooler. This is the common and more cost-effective approach.

About now you’ll want to revise the boost control system. This is the point where you can take two distinctly different directions – you can go for a modest boost increase to maintain traction and reliability, or go for a big boost increase that’ll likely cause turbocharger destruction.

For an average street car, a Z32 TT with an exhaust, intake, intercooler and modest boost tweak makes a controllable but very, very quick ride. As mentioned, the standard boost pressure is around 10 psi – we suggest 12 psi as a noticeable but safe increase. We hear that any more an about 15 psi will cause damage to the ceramic turbochargers.

With these relatively basic mods you’re talking about a low 13 second car (traction permitting).

From here you can play with cam timing using adjustable sprockets, upgrade the turbochargers, port the intake manifold and upgrade the engine management system. A load-based ECU interceptor is a cost-effective tuning approach or you can spend extra for a stand-alone programmable system (such as MoTeC). Note that a set of big injectors and a high-flow fuel pump are required for more than about 280kW.

If you can’t get enough of a good thing, you’ll be pleased to know there are off-the-shelf camshafts, forged pistons and high-strength rods which will come in handy for a full-house engine build. The power potential of the Z32 VG30DETT is almost unlimited – the biggest problem is achieving traction off the line.

If a power-sliding, can’t-find-enough-traction coupe is your thing, the Z32 Nissan 300ZX is for you!

Zed Speed - Part One