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Z7W —
the 2.8 litre

The Z7W is the family's 2,849 cc: bore × stroke 91 × 73 mm, compression ratio 9.5 or 8.8. Renix injection on the Renault 25 and Espace, two Solex carburettors on the Alpine GTA (Z6W-A), and up to 260 turbocharged bhp at EIA for the Venturi 260.

2 849
CC
153–260
BHP
4
CODES
The transitional PRV

Between the two generations

The 2.8 litre is the transitional PRV: the Alpine GTA's Z6W-A keeps the first generation's non-offset crankshaft and its two timing laws — one per cylinder bank — while the Renault 25's Z7W 706 moves to Renix electronic injection. The catalysed Z7W 707 gives 153 bhp on the R25 and the Espace V6.

It is also on this base that EIA built the Venturi 260's 260 bhp 2.8 turbo — the story is in Tuners — and it is by pushing the Z6W towards the turbo that Renault designed the 1985 Z7U: stroke cut from 73 to 63 mm, forged crankshaft with offset crankpins.

Z7W
DOUVRIN CODE · 2,849 CC · INJECTION OR CARBURETTORS · 12 VALVES
2849
CC
160
BHP
12
VALVES
Identity

What makes a Z7W a Z7W

Figures read in the constructor's documents held in our Library — repair manuals, Pub et Trade data sheets, period bulletins. Nothing here comes from a web fact sheet.

Z7W 2,849 cc · 12 valves · first and second generation élan 77 →
91 × 73
Bore × stroke 91 × 73 mm, 2,849 cc, compression ratio 9.5 (Z6W) or 8.8 (Z7W) — the Z-engines manual's table.
Z6W-A700
160 bhp DIN at 5,750 rpm, 221 Nm ISO — 23 m-kg DIN — at 3,500 rpm, two Solex carburettors (34 TBIA single-barrel, 35 CEEI twin-barrel), contactless transistorised ignition: the élan 77 table.
Culasse
1.70 mm head gasket. Height 111.07 ± 0.15 mm on the Z6W, 110.83 mm on the Z7W. Final 127° angle tightening on the Z7W 702.
Soupapes
Z6W cold clearances: 0.10 mm inlet, 0.25 mm exhaust, with the Mot. 647 spanner — the same values as the A610's Z7X 744 fifteen years later.
Huile
Minimum pressure at 80 °C: Z6W 2.2 bar at 900 rpm and 4.4 bar at 4,000; Z7W 1 bar at idle and 4 bar at 5,500 — two engines that do not compare point for point.
Known variants

From 153 to 260 bhp

Four documented variants — three factory ones and an EIA preparation for Venturi. The full code table is on the Engines page.

Z7W 4 variants Every known code →
Z6W-A160 bhp
Two Solex carburettors12-valve
Naturally-aspirated Alpine GTA V6 — 160 bhp, non-offset crankpins.
Z7W 706160 bhp
Renix injection12-valve
Renault 25 V6 injection 2.8 litre — 160 bhp.
Z7W 707153 bhp
Renix injection12-valveCatalysed
Catalysed Renault 25 V6 injection · Renault Espace V6 — 153 bhp.
Z7W · EIA260 bhp
TurboEIA preparation
Venturi 260 — tuner EIA's 260 bhp 2.8 turbo.
On the road

The cars of the Z7W

Alpine GTA V6 →

The naturally-aspirated GTA: the twin-carburettor 160 bhp Z6W-A. Its Pub et Trade data sheet and the M.R.273 are in the Library.

Renault 25 →

R25 V6 injection 2.8: 160 bhp (Z7W 706), 153 bhp catalysed (Z7W 707). Its file details the R25's five PRV codes.

Renault Espace V6 →

The Espace V6: the catalysed 153 bhp Z7W 707.

Venturi 260 →

The Venturi 260: EIA's 260 bhp 2.8 turbo — a tuner, not Douvrin; the story is in Tuners.

In the workshop

What the documents say about the Z7W

Answers taken from our FAQ, each one read in the Library. The full FAQ holds several hundred more, engine code by engine code.

The Z7W, in the documents The full FAQ →
Z6W
How are the valves set on a Z6W PRV V6?
Cold, 0.10 mm inlet and 0.25 mm exhaust — the same figures as the A610's Z7X 744 fifteen years later, with the Mot. 647 spanner. The manual gives two methods. The first works one head at a time by the rocking method: with the valves of cylinder 1 rocking, set inlet A3 and exhaust E2; cylinder 2 rocking, A1 and E3; cylinder 3 rocking, A2 and E1. The second does both heads at once and is quicker: bring piston 1 to TDC on firing — which is cylinder 5 rocking, with the flywheel's mark A against the 0 on the clutch housing — and set inlet A1, A2, A4 and exhaust E1, E3, E6; then turn the crankshaft one full revolution, which brings piston 1 back to TDC at the start of induction with cylinder 1 rocking, and set inlet A3, A5, A6 and exhaust E2, E4, E5. Lift the cover plate slightly to reach the marks. Alpine M.R.273, folios B-12 to B-14.
élan 77
What are the Z6W-A700 and Z7U-730 worth, on the manufacturer's own figures?
élan 77's table sets them side by side. Z6W-A700: 91 × 73 mm, 2849 cm³, compression ratio 9.5:1, 116 kW ISO — 160 hp DIN at 5750 rpm, torque 221 Nm ISO — 23 m-kg DIN at 3500 rpm, two Solex carburettors (a single-barrel 34 TBIA and a twin-barrel 35 CEEI), breakerless transistorised ignition. Z7U-730: 91 × 63 mm, 2458 cm³, compression ratio 8.6:1, 147 kW ISO — 200 hp DIN at 5750 rpm, torque 285 Nm ISO — 29.6 m-kg DIN at 2500 rpm, electronic injection, fully electronic ignition with knock sensor. Common to both: 97/99 super, all light alloy, removable wet liners, hemispherical chamber, 4 main bearings, one overhead camshaft per bank driven by its own simplex chain, valves in a V operated by rockers, firing order 1-6-3-5-2-4, 88 °C thermostat, two 290 mm 120 W electric fans. élan no. 77, February 1985, page 4. Library →
Huile
What is the minimum oil pressure on a Z6W?
At 80 °C, with the Mot. 836-05 gauge: 2.2 bar at 900 rpm and 4.4 bar at 4,000 rpm. Worth setting beside the A610's Z7X, whose figures are given at different speeds — 2 bar at 900 rpm and 3.5 bar at 3,000 rpm: the two engines cannot be compared point for point, and a pressure read at 3,000 rpm on a Z6W is measured against nothing in the manual. Oil consumption is judged by the same yardstick on both: one litre per 1,000 km may be considered normal. And the Z6W figures do not date from the GTA: the 1975 Renault 30 gives exactly the same, 2.2 bar at 900 rpm and 4.4 bar at 4,000 rpm at 80 °C — measured there with the Mot. 654 union screwed in place of the pressure switch and the Mot. 73-01 gauge. Alpine M.R.273, folios B-15 and B-16 · Alpine M.R.297, folios 10-5 and 10-6 · Renault 30 M.R.167, folio B-60.
Vers le turbo
What did the Z7U-730 change compared with the Z6W?
Far more than a turbo. élan 77's list: a forged steel crankshaft with split crankpins whose stroke drops from 73 to 63 mm; new connecting rods, made necessary by the larger crankpin diameter; new pistons with floating gudgeon pins; heads with a stiffened deck and bronze valve guides; valves with metallurgy suited to forced induction; a reinforced head gasket; forced induction by a Garrett T3 sitting at the rear of the V, with an air-to-air intercooler and a compressor bypass valve; and Rénix electronic injection with coupled ignition, idle regulation, overrun cut-off, knock detection and rev-limiter cut. élan no. 77, February 1985, page 4. Library →

In the Library

The 2.8 litre's documents, at Renault as at Alpine, searchable page by page: Pub et Trade sheet Z6W-700 — Alpine V6 GT · Pub et Trade sheet Z7W-700, 160 bhp · Pub et Trade sheet Z7W-706/707, 153 bhp · M.R.273 Alpine V6 GT — engine · M.R.273 Alpine V6 GT — ignition · élan 77 — Alpine's PRV engines · Z-engines repair manual

The rest of the family

Architecture, generations and every known engine code of the PRV V6 — on the main Engines page.

Z7V — the 2.7 injection →Z7U — the 2.5 turbo → All PRV engines →