Z31 Engine Specifications

The 1984-1989 Z31 came with many different engine packages.

USDM VG30E and VG30ET

In the North America market it came with the VG series motors with a displacement of 2960 cc (181 cu. in). The Bore and Stroke were 87.0 X 83.0.
Compression was varied depending on the asperation of the motor and also varied with the turbocharger used. The Compression ratio on Non-turbo cars was 9.0:1. On the 1984-1987 turbo cars with a Nissan made Garrett based T3 Turbocharger was 7.8:1. In 1988 when the VG series went through minor changes commonly known as W-series, the compression ratio was increased to 8.3:1 but the turbocharger decreased in size to a Nissan made Garrett based T25 Turbocharger.
The Max Hp and Torque numbers are 160hp at 5200 rpm with 24.0 kg-m (173ft-lbs) torque at 4000 rpm for the VG30E and 200hp at 5200 rpm and 31.4 kg-m (227ft-lbs) at 3600 rpm torque for the VG30ET.
The VG30E and VG30ET both had multi-point Fuel Injection that fired in a Batch mode secquence.

Other Markets

In the Domestic market (Japan), the Z31 was offered with the following motors, VG30DE, VG30ET, VG20ET, and RB20DET.

VG30ET

The VG30ET was the same as the USDM motors but made about 5 less horsepower due to emmission standards.

Specs for the VG30ET are as Follows:

Displacement	2960 cc (181 cu. in)
Bore and Stroke	87.0 X 83.0	Can be boared to 90mm safely. Break through occurs at 3.78" per defrag010 of Z31performance.com
Compression Ratio	7.8:1
Horsepower	195 Hp at 5200RPM
Torque	31.5Kgm (227ft-lbs) at 3600 RPM

VG20ET

The VG20ET offered in the japanese 200Z, 200ZG, and 200ZS, was basically a VG30ET with the bore and stroke Decreased . The turbo included with the VG20ET had two different settings. At low speeds, the turbo's flap (wastegate?) would stay closed improving the response at low RPMS. At high speeds, the flap would stay open, decreasing resistance and increasing exhaust flow. At its maximum flow, the flap would open at an angle of 27-degrees, while the A/R ranged from 0.21 ~ 0.77.

Though the intake and exhaust manifolds look simular to the VG30ET units, they do not interchange due to the smaller deck height of the VG20.

The Specs are as Follows:

Displacement	1998cc (122 Cu. in)
Bore and Stroke	78.0 X 69.7
Compression Ratio	8.0:1
Horsepower	170 Hp at 6000 RPM
Torque	22.0 kg-m (159 Ft-Lbs) at 4000RPM

VG30DE

The VG30DE was an early version of the motor used in the Later 90+ 300zx. It featured a slightly different block, Dual Overhead Cam Heads, and 24 valve with Nissan's own version of variable valve timing (NVCV) for increased high RPM efficiency. The production blocks and production head castings were used successfully in the Nissan GTP ZX-Turbo and NPT-90 race cars which won the IMSA GT Championship three years in a row.

The Specs are as Follows:

Displacement	2960 cc (181 cu. in)
Bore and Stroke	87.0 X 83.0
Compression Ratio	10.0:1
Horsepower	190 Hp at 6000RPM
Torque	25.0Kgm (181 Ft. Lbs)at 4400 RPM

RB20DET

The 200ZR had the Last straight six offered in a Z it was the RB20DET. These early twin-cam RBs (identified by their red ribbed cam cover) run a relatively low 8.5:1 static compression ratio, 24 valve Dual Overhead Cam Head, and a ceramic wheeled turbocharger with an air-to-air intercooler which is fed by the 200ZR’s Hood scoop. It also used a NICS dual-stage twin-runner Ignition system, a hot-wire airflow meter and direct-fire ignition are also used.

The Specs are as Follows:

Displacement	1998cc (122 Cu. in)
Bore and Stroke	78.0 X 69.7
Compression Ratio	8.5:1
Horsepower	180 Hp at 6400RPM
Torque	23.0Kgm (174 Ft. Lbs)at 3600 RPM

Engine Calculator

This calculator will help you figure out Compression ratios and other Specifications you can use to build your VG30 motor.

Most of the following information was located Via Nissan Factory Service Manuals and Calculations

Information about the VG30DETT pistons was found through some web searching.