Reinforced inlet valves NISSAN 300ZX Z31 VG30T

NISSAN engines covered

The VG30T is Nissan's 3.0 litre turbo V6 with one overhead camshaft per bank and two valves per cylinder. From 1984 to 2004 it powers the 300ZX and Fairlady Z Z31, the Cedric Y31 and Y32, the Gloria Y30 and Y31 and the Leopard F30, from 194 to 258 hp.

It has 6 inlet valves, Nissan part number 13201-V5202, shared with the naturally aspirated VG30, held by 13210-01M01 collets. Raised boost or a sharper camshaft load them well beyond stock use.

FERREA reinforced inlet valves

In the VG30T V6 of the 300ZX Z31, with two valves per cylinder, each inlet valve alone handles its cylinder's filling: it gives way under the cam to let in the air pushed by the turbocharger, then drops sharply onto its landing, while the stem runs tirelessly in its bushing. The metal endures 400 to 550 °C over long stretches of running; at that level a plain chrome-silicon steel valve degrades: 500 MPa at 500 °C, 250 MPa around 600 °C, strength cut by 50 %. More boost, a taller cam or higher revs make these blows, this rubbing and this heat even harder to bear.

Picked from FERREA's Competition Plus line, these valves combine a single-piece stainless forging with a chromed stem, whose contact with the bushing brakes less and lasts longer. The maker announces a 20 % gain in thermal strength and endurance, and a seat that holds 25 % longer, enough to take raised boost more calmly. The stem tip measures 4.5 mm, as stated under the technical table.

Two sizes exist: standard with a 42 mm head, and +1 mm with a 43 mm head, sharing a 7 mm stem and 125.85 mm length. The added millimetre widens the orifice offered to the air and improves cylinder charging, provided all 6 inlet-port seats have been machined to that dimension beforehand.

Inlet valve technical specification

F1843P*6 and F1844P*6: 4.5 mm stem tip.

Fitting details

The +1 mm oversize needs the inlet seats cut to 43 mm; in standard size the seats keep their diameter.

The VG30T has hydraulic tappets: there is no valve clearance to set on reassembly.

Technical guide

The brand offered

Founded in 1978 on the Florida coast, in Fort Lauderdale, by a pair of tuners born in Argentina, FERREA Racing Components forges each valve in one block drawn from bar, finishes it on numerical machines, then sees it shine in NASCAR and drag racing.

How to choose

Material, stem, length and 4.5 mm tip are common to both references; only head size changes, chosen by whether the VG30T seats have been reworked.

When reinforced valves become necessary

• Turbo pressure raised on the VG30T V6
• Livelier cam profile or noticeably firmer springs
• Cut-off rpm set higher up the range
• Heads rebuilt for track or drag use
• Nissan valves worn or seats already reground

Compatible vehicles

OEM part number (inlet valve): 13201-V5202

Related products

When restoring the heads of a VG30T, the exhaust deserves changing straight away. This V6 also has reinforced exhaust valves, found here: