Renault 5 Maxi Turbo group B (1985)
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Home » Rally Cars » Renault 5 Maxi Turbo
1986_renault_5_turbo_maxi_04_m.jpg Source Develpment chain
1980: Renault 5 Turbo Cevennes
1983: Renault 5 Turbo Tour De Corse
1985: Renault 5 Maxi Turbo
1995: Renault Clio I Maxi
2002: Renault Clio II S1600

In rallies: see video

Specifications

20 units built
Group/Class B/12 Homologation number: B 267
Years active 1985 - 1986 Homologation start: 1/12/1984
Engine
Type C7K, straight 4cyl, 4 stroke, petrol engine located rear longitudinally vertical, in front of rear axle
Capacity 1527.4 cc WRC: x 1.4 = 2138.4 cc
Bore x Stroke (mm) 77.0 x 82.0
Compression ratio 6.7 - 7:1
Output power - torgue 360 HP / 6500 rpm 42.9 kgm (421 Nm) / 3750 rpm, (225 HP)
Main bearings 5 of 54.8mm diameter connecting rod length between centers 128mm, big end bearing diameter 47.6mm
Materials block: cast iron cylinderhead: aluminium alloy
Cams/valves 1 camshaft in block with overhead valves (OHV), chain driven 2 valves/cyl. - 8 valves total. 39mm inlet valve diameter, 34.8mm exhaust valve diameter. 24o angle between inlet valve and vertical, 24o angle between exhaust valve and vertical
Aspiration Garrett T31 turbocharger (steel turbine 65mm diameter, aluminium compressor 75.1mm diameter) with air/air intercooler, Bosch kugelfischer mechanical multipoint fuel injection pressure:
Ignition electronic, firing order 1-3-4-2, NGK BPR5EIX Iridium IX, or NGK BPR5EGP G-Power Spark Plugs
Cooling system watercooled
Lubrication system dry sump
Transmission
Type rear wheel drive Type UN, 5 speed manual gearbox, with magnesium case
Gearbox ratios 1st: 3.363/1 (37/11)
2nd: 2.058/1 (35/17)
3rd: 1.380/1 (29/21)
4th: 1.057/1 (37/35)
5th: 0.868/1 (33/38)
R: 3.182/1 (35/11)
1st: 3.250/1 (39/12)
2nd: 2.235/1 (38/17)
3rd: 1.619/1 (34/21)
4th: 1.250/1 (30/24)
or 4th: 1.260/1 (29/23)
5th: 1.035/1 (29/28)
R: 3.182/1 (35/11)
Diffrential ratio 3.889/1 (35/9), 3.444/1 (31/9) spiral bevel gears 40% limited slip rear differential
Clutch dry double disk, 190mm diameter
Chassis-body
Type steel monocoque Type 8220 with roll-cage. 3 door hatchback steel/aluminium/polypropylene bodyshell with aluminium doors, polypropylene front and rear bonnet and polyester front and rear bumpers
Front suspension double wishbones with lower longitudinal torsion bars connected to lower wishbone, telescopic gas shock absorbers and anti roll bar
Rear suspension double wishbones with coil springs, telescopic gas shock absorbers and anti roll bar
Steering system rack and pinion with optional hydraylic power assistance 17/1, 11.09/1, 14.9/1, 12.67/1
Brakes front ventilated disks 260mm diameter with 1 steel/aluminium piston caliper, or 277/300mm diameter with 4 aluminium piston calipers. Rear ventilated disks 260mm diameter with 1 steel/aluminium piston caliper, or 277/300mm diameter with 4 aluminium piston calipers dual circuit with servo, adjustable ratio split front to rear
Dimensions
length: 3.700 m (145.7") width: 1.769 m (69.6") height: 1.320 m (52.0")
wheelbase: 2.430 m (95.7") front track: 1.390 m (54.7") rear track: 1.490 m (58.7")
Rims - tires front: 7" - 7.5" x 15", rear: 10" - 11" x 15" front: 205/55 x 15", rear 265/45 x 15"
Weight 900 kg
Weight/power 2.5 kg/HP
Fuel tank 95 lt
Drag coefficient 0.44

DPV system

See video
That anti-lag pre-turbo butterfly in the picture above is called DPV (Dispositif Pre­rotation Variable - Variable Pre-rotation Device) and was devised and used first by the French guy Jean-Pierre Boudy in the early 80-ies. The real throttle bodies are after the turbo.

This was first used at the Monaco GP in 1982, and developments of the same system are still used in Formula One. But because Boudy defected to Peugeot with his ideas, the 205T16 was the first turbocharged rally car to use his system (The T16 being out before the final evolution R5 Turbo – The Maxi 5 Turbo). Which Renault calls DPV, or Dispositif Pre­rotation Variable (Variable Pre-rotation Device).

"At the very beginning we had made the decision to use it on the Group B R5 Turbo. It's not really necessary for road cars and a little expensive for them, but it's not so complicated". It may not be "so complicated" but the DPV system is an 'extremely effective way of ensuring near-instantaneous throttle response from a competition turbocharged engine’. The system provides for variable air areas and direction angles at the intake to the compressor wheel in advance of the rotation period during which the compressor turbine will require those conditions.

It's not a by-pass system, it's essentially a multi-variable nozzle arrangement which is mechanically linked to the throttle and which changes the direction and area of air which hits the compressor wheel according to throttle position. The rate of change of air flow area and direction is not exactly linear, but it's progressive and always increasing toward full flow at maximum compressor wheel speed.

This irregular mid-compressor-speed flow, which constantly changes the way the air hits the compressor vanes in the mid-range, improves the compressor's efficiency under part-load, because it is arranged so that the turbine will idle at a higher speed than it would given a fixed intake air direction and area. And of course, the higher the compressor idle speed, the shorter the time it will take to reach its important operating RPM. Result: less lag.

The DPV is inoperative at each end of the turbine's speed range. Under pedal-to-the metal full boost conditions it has no effect because there's regular full flow to the compressor, and with the throttle closed the DPV is shut down as well. But it is not just retained inertia and completely eradicated turbocharger lag which form the real benefit of the DPV system, because there's another major advantage in that as a result of there being no by-pass or blow-off to atmosphere, and because it's an internal function to the turbocharging system, there is no pressure wastage in the all­important part-load condition (ie. The blades don't stall during gear changes, or on/off throttle movements).
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Results in WRC

Statistics

1985 1986 Total
Works
Races /wins 1/1 1/1
Entries/finishes 1/1 1/1 (100%)
Others
Races/wins 1 1
Entries/finishes 2/0 1/1 3/1 (33.3%)
Total WRC results
Races/wins 1/1 1 2/1
Entries/finishes 3/1 1/1 4/2 (50%)
Total points 10 9 19
(9.5 per race)
(4.75 per entry)

Races

Works team: Renault Elf Philips
Click on tabs
Season
Entry Rally event
Driver
Codriver
Team M.C SVE
Entry list
POR KEN TdC GRE N.Z ARG FIN S.R (CdI) RAC
Jean Ragnotti
Pierre Thimonier
works 1st
François Chatriot
Michel Périn
Société Diac tran smis sion
Didier Auriol
Bernard Occelli
ele ctri cal
Total points
()
10 10
Statistics
Works starts/finishes 1/1 1/1
Others starts/finishes 2/0 2/0

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