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Alpine A610 —
the last PRV Alpine

The A610 crowns the marque's PRV era: a 2,963 cc turbo V6 of 250 bhp — code Z7X 744 — in the tail of the line's last rear-engined berlinette. The third generation of the PRV, with balance shaft and sodium-filled exhaust valves, in 12-valve form while the XM, the 605 and the Venturi 400 GT go to 24.

250
bhp · Z7X 744 turbo
265
km/h · 0-100 in 5.9 s (brochure)
177
kg · bare engine
1991
the last rear-engined berlinette
Engines

One code only: Z7X 744

Where the GTA used the 2.5-litre turbo Z7U (200 bhp), the A610 moved to the 3.0-litre block: the Z7X 744, single Garrett T3 turbo with electronic boost control, 250 bhp (184 kW) and 35.7 m-kg (350 Nm) — the highest output of any factory PRV Alpine. The full table of variants, from 150 to 268 bhp, is on the Z7X file.

Alpine A610 1991 → · third generation Every known code →
Z7X 744250 bhp
2,963 cc (2,975 on the brochure)Siemens injectionGarrett T3 turbo12 valvesZ7X engine file →
A610 Turbo — Siemens S 101 717 101 ECU in the cabin, Eyquem FC 82 LS 3 plugs torqued to 2.5-3.5 m.daN, 6,100 rpm limit (6,300 tolerated for three seconds), injection restored at 5,800. Valve clearances to adjust: 0.10 mm inlet, 0.25 exhaust.
177 kg overhanging

Why the engine's weight mattered so much

177 kg bare. The PRV brochure for the Z7X-744 explains why the figure was at stake: on the A610 the engine sits behind the rear axle — its centre of gravity is behind the axle line. Hence aluminium for the block, the heads and various casings. And boost is controlled electronically: the ECU drives a 12 Hz frequency valve — the SEM valve — that bleeds pressure to the air filter, constantly comparing the mapped pressure with the sensor's; on the XR25, # 11 gives the valve's duty cycle (3 to 99 %) and # 20 the applied correction (0 to 35 %).

The M.R.297 — engine, ignition and cooling —, the Pub et Trade sheet and the brochure are in the Library; the Z7X family, from 150 to 268 bhp, on the Z7X file.

177
KG · BARE ENGINE · PRV Z7X-744 BROCHURE
2963
CC
250
BHP
1750
MB · CONTROLLED MANIFOLD PRESSURE
The Alpine-PRV line

Three generations hung out back

A310 and GTA, the two steps

The A310 opened the line with the carburetted 150 bhp 2,664 cc; the GTA carried it on with the 160 bhp Z6W-A then the 200 bhp turbo Z7U. The PRV brochure lines up the four: A310 225 km/h and 7.8 s to 100, V6 GT 235 km/h and 8 s, V6 Turbo 250 km/h and 7 s, A610 265 km/h and 5.9 s — for an average of 10.4 l/100 km, barely more than the A310's 10.2, with a hundred more horsepower.

The R25 V6 Turbo, fuel-system cousin

The manuals of the catalysed R25 V6 Turbo and of the A610 give the same components — Solex Ø 55 mm throttle body mark 984, Bosch 12 V pump, 3 bar, 130 l/h, 2.5 ± 0.5 Ω injectors, same XR25 readings —, but not the same pressure regulator: 2.5 ± 0.2 bar with no vacuum on the Z7U-700, 3.0 ± 0.2 bar on the Z7X-744. Never use one's value for the other.

Twelve valves, to the end

The A610 stays at 12 valves while the Citroën XM, the Peugeot 605 and the Venturi 400 GT move to 24-valve heads. A Danielson preparation of the A610 is sometimes mentioned: its existence remains to be confirmed, as our Tuners page says.

In the workshop

What the M.R.297 says about the A610

Eight answers drawn from the workshop manual, the Pub et Trade sheet and the brochure — the FAQ has dozens on the A610.

Alpine A610 The full FAQ →
Poids
How much does the Z7X-744 weigh, and why did it matter so much?
177 kg bare. The brochure explains why the figure mattered: in the Alpine A610 the engine sits in rear overhang — its centre of gravity lies behind the rear axle. Hence aluminium for the crankcase, the heads and various covers. PRV Z7X-744 brochure, page 2. Library →
Tarage
At what pressure is the Alpine A610's turbo set?
A Garrett T3 with integral wastegate, and two check points rather than one: 430 ± 30 mb for a rod travel of 0.38 ± 0.05 mm, then 610 ± 30 mb for a travel of 4 ± 0.05 mm. The pressure in the intake manifold, read on the XR25, must be 1,750 ± 10 mb between 2,750 and 3,750 rpm — accelerator floored from 2,000 rpm, in 3rd or 4th — and 1,750 ± 10 mb at the maximum speed of 5,500 rpm, in 2nd or 3rd. ⚠️ That is the pressure in the manifold, not boost above atmospheric: the figure is flat from one end of the range to the other, which is the regulation plateau. The bypass valve (Umleitventil, the turbo's recirculation valve) opens at a vacuum of 200 ± 20 mb. On the R25 V6 Turbo's Z7U-700 the setting is lower for the same travels — 320 ± 30 mb then 480 ± 30 mb — but the manifold pressure is higher: 1,870 mb. Alpine M.R.297, folio 12-2 · Technical note 1558, folio 12-13.
Régulation
How does the Alpine A610's turbo regulate its boost?
Electronically — like the catalysed R25 V6 Turbo's Z7U 700, but the XR25 does not speak the same units. The computer drives a 12 Hz frequency valve — the “SEM” valve — which varies the pressure by bleeding it back to the air filter; it continuously compares the mapped pressure with what the pressure sensor reports. On the XR25, two values are read and must not be confused: # 11 gives the valve's opening ratio (RCO), between 3 and 99%; # 20 gives the correction applied relative to the nominal mapped value, between 0 and 35% ± 1 depending on engine speed and manifold pressure. After a road test, ignition on and engine stopped: insufficient pressure → positive correction, # 20 = 21% ± 1; pressure too high → negative correction, # 20 = 0.0%. A brand-new, never-used computer shows # 20 = 10% ± 1. The R25 V6 Turbo's note describes the same 12 Hz SEM valve and the same # 20, but in milliseconds: a new computer ≈ 65 ms, insufficient pressure 26.16 ms, pressure too high ≈ 0.8 ms. A # 20 read on one car cannot be judged against the other's table. Both engines also keep a wastegate rod set with a dial gauge. Alpine M.R.297, folios 12-8 to 12-10 · Technical note 1558, folios 12-8 and 12-9.
Soupapes
What are the valve clearances on the A610's Z7X 744?
0.10 mm on the inlet, 0.25 mm on the exhaust — more than twice as much on the exhaust side, which runs hotter and expands more. The adjustment follows the head re-torque, itself done cold and at the earliest six hours after a warm engine is stopped. For comparison: the Eagle Premier's V6 has no clearance to set at all, its rocker arms carrying a hydraulic tappet. Alpine M.R.297, folio 11-7.
Culasse
How is an Alpine A610's cylinder head tightened?
In three stages, and the second one is a surprise. Gasket new and DRY — no sealant. Stage one: tighten the bolts to 6 daN.m in the prescribed order, to crush the O-rings. Stage two: SLACKEN every bolt. Stage three: 4 daN.m, then an angular tightening of 180° on every bolt. Each head carries eight bolts, tightened from the centre outwards, alternating between the two rows, and the same order holds for both heads. Re-torquing is done cold, at the earliest six hours after stopping a warm engine: a further 50° on each bolt, in order, with no prior slackening. Before that, the engine is run 15 minutes at 2,000 rpm to bring it up to temperature. Other torques in this chapter: intake manifold 2 daN.m, camshaft sprocket 8 daN.m, small pinion of the balancing system 2.5 daN.m, Bischoff hose clips 1.5 daN.m. ⚠️ Two of these torques are not the ones the same manual gives further on: Bischoff clamps 2.5 daN.m when refitting the turbo (folio 12-16), intake manifold on the head 1.25 ± 0.25 daN.m (folio 12-17); the extract does not say which prevails. Alpine M.R.297, folios 11-1, 11-6, 11-7, 12-16 and 12-17.
Équilibrage
Does the Alpine A610's V6 have a balancing system?
Yes — and it is a part few people expect on a V6. The head removal procedure calls for taking off, in order: the balancing system's drive chain, then its sprockets, then driving out the shaft to free the balance weight and its key. On reassembly the small pinion of the balancing system is torqued to 2.5 daN.m, and the Mot. 1209 tool is removed at the right moment so that the chain is properly tensioned by its tensioner. The system goes back on at the same time as the rocker arms and the pushrods. Alpine M.R.297, folios 11-1, 11-3, 11-6 and 11-7.
Bougies
What plugs, computer and sensors does the Alpine A610 use?
Eyquem FC 82 LS 3 plugs, gap not adjustable, tightened 2.5 to 3.5 m.daN. The advance no longer lives in a distributor: the curves are built into the injection computer, a distributor only shares out the high tension, and a power module (Z.L.M.) carries the knock sensor. The computer is a Siemens S 101 717 101, mounted in the passenger compartment, diagnostic code 108.3. The air and water temperature sensors are Bendix, NTC type — resistance falling as temperature rises, the opposite of the PTC sensors on the catalysed R25 V6 Turbo. The Bosch oxygen sensor is heated: at 850 °C, ≥ 625 mV on a rich mixture, 0 to 80 mV on a lean one. Catalytic converter C 22 under the floor, paper air filter every 20,000 km, Rochester canister. Alpine M.R.297, folio 12-2.
Limites
What limits does an Alpine A610's injection computer impose — rev limit, air conditioning?
Rev limit: 6,100 rpm, with 6,300 rpm allowed momentarily, for 3 seconds at most; injection is re-enabled at 5,800 rpm. Air conditioning, which the computer drives: it decides from inputs 30 and 34 whether to engage the compressor through output 13 — but only once the engine has idled at least once, for a few seconds, after starting, and not before 20 seconds after start-up. About 1 second before engaging the compressor it opens the idle valve, which shows at idle as a rise from 700 to 900 rpm; it reduces the air before disengaging it. Above 115 °C coolant it will not engage the compressor, above 5,900 rpm either; and as soon as the compressor runs, the cooling fans turn at half speed. Other points from the same page: computer in the passenger compartment, in the middle behind the rear seat backrest, injection relays in its housing; NTC sensors — air on the throttle housing, coolant on a water pipe facing the fuel pressure regulator; diagnostic socket in the engine bay left of the turbocharger; the dashboard injection warning lamp does not work; and the throttle housing's bypass screw must never be adjusted. The catalysed R25 V6 Turbo's strategy is the same in outline, with its own figures: idle from 750 to 900 rpm, and the fans started at medium road speeds. Alpine M.R.297, folio 17-3 · Technical note 1558, folio 17-1.

In the Library

The workshop manual in two excerpts, the period sheet and the PRV brochure, readable page by page: M.R.297 — A610, engine · M.R.297 — A610, ignition and cooling · A610 Turbo (Z7X-744, 250 bhp) — Pub et Trade sheet · PRV Z7X-744 brochure

On the forum

The A610 has its own section on the forum — presentations, restorations, questions to members who drive one. Alpine A610 section →

Further into the 3.0-litre

Every Z7X variant, from 150 to 268 bhp — and the two Alpines that came before.

Z7X file →GTA file →A310 file → All vehicles →