Lotus 23 group S (1962)
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Chassis numbers
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Specifications

131 units built
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engine location, middle longitudinally
Coventry Climax FWA "85", straight 4 cyl, 4 stroke, petrol engine
1098cc, 72.4 x 66.68 mm
9.8 : 1
63.5 kW / 85 hp @ 6250 rpm
100 Nm / 74 ft-lb @ 4400 rpm
drop forged steel crankshaft with 3 main bearings
2 valves / cylinder, SOHC
aspiration, natural with 2 x 1-1/2" SU H4 horizontal carburetors
distributor ignition
water cooled

Ford Kent / Cosworth Mk III, straight 4 cyl, 4 stroke, petrol engine
997cc, 80.9625 x 48.4 mm
85-90 HP
cast iron Ford Kent 105/107E block, cast iron heads
3 main bearings
A3 side camshaft with overhead valves (OHV), 2 valves/cyl - 8 valves total
aspiration, natural
water cooled
dry sump

Ford Kent / Cosworth Mk IV, straight 4 cyl, 4 stroke, petrol engine
1098cc, 80.9625 x 53.3 mm
90-95 HP
cast iron Ford Kent 105/107E block, cast iron heads
3 main bearings
A3 side camshaft with overhead valves (OHV), 2 valves/cyl - 8 valves total
aspiration, natural
water cooled
dry sump

Ford/Lotus Twin Cam / Cosworth Mk IX, straight 4 cyl, 4 stroke, petrol engine
1498cc, 80.9625 x 72.75 mm
100-120 HP @ 5700 rpm
cast iron Ford Kent 116E-6015 block, cast iron heads
5 main bearings
A3 side camshaft with overhead valves (OHV), 2 valves/cyl - 8 valves total
aspiration, natural with 2 x Weber 40 DCOE/2
water cooled
Dry sump

Ford/Lotus Twin Cam / Cosworth Mk XII, straight 4 cyl, 4 stroke, petrol engine
1557cc, 82.55 x 72.75 mm / 1595cc, 83.55 x 72.75 mm
9.5:1
140 bhp / 104 KW @ 6500 rpm
cast iron 116E-6015 block, cast iron heads
5 main bearings, 125E Type C conrods
dual overhead L1 CPL2 26/66/66/26 camshafts (DOHC) chain driven, 2 valves/cyl - 8 valves total. 40mm inlet valve diameter, 33.7mm exhaust valve diameter. 27o angle between inlet/exhaust valve axis and vertical (54o angle between inlet and exhaust valves axis)
aspiration, natural with 2 x Weber 45 DCOE 152
Lucas distributor. Lucas AB14 electronic ignition amplifier. Lucas Sport ignition coil. Accel 8mm Super Stock radio supression core spark plug wires
water cooled
Dry sump with Brian Hart oil pump and Racor tattletale oil filter

Maserati Tipo 60, straight 4 cyl, 4 stroke, petrol engine
1990cc, 93.8 x 72.0 mm
9.8:1
200 bhp / 149 KW @ 7800 rpm
alloy block and head
2 valves / cylinder, DOHC gear driven
aspiration, natural with 2 x Weber 45 DCO3 Carburetors
twin spark
dry sump

Coventry Climax FWMC, straight 4 cyl, 4 stroke, petrol engine. FWM meaning Feather Weight Marine
742cc, 76.2 x 80.0 mm
aluminium alloy block, aluminium alloy "crossflow" head
2 valves / cylinder, DOHC chain driven
water cooled

Hewland Mk III, 5 speed manual gearbox
dry double plate clutch
steel multi-tubular spaceframe chassis, fibreglass bodyshell
Front Susp.: unequal length, non-parallel dual wishbone suspension. Alford & Alder forged uprights. Koni double-adjustable aluminum-bodied coilover shock absorbers. Eibach springs. Adjustable anti-sway bar.
Rear Susp.: inverted lower wishbones, single top links, and twin adjustable trailing links. Lotus proprietary magnesium uprights. Koni double-adjustable aluminum-bodied coilover shock absorbers. Eibach springs. Non-adjustable anti-sway bar.
Girling aluminum calipers. 9" solid discs, all-round
Length 3530 mm (139 in)
Width 1447 mm (57 in) - 1524 mm (60 in)
Height 584 mm (23 in)
Wheelbase 2286 mm (90 in)
Track (fr/r) 1308 mm (51.5 in) / 1270 mm (50 in)
wheels, Lotus magnesium racing wheels 5x13" 4-lug front, 6x13" 6-lug rear
tires, front 4.50–13" or 5.0/22.0-13", rear 5.50–13" or 6.5/23.0-13"
450kg
fuel tank, 36 lt


Results in WSCC

Season races for Sports/Prototypes
Car entry, chassis number Car number/ result
Dayt Sebring Targa Florio Nurb Le Man d' Auvergne Bridgeh Paris
Team 3h 12h 1000km 24h 400km 1000km
Lotus (1.1) #70, in entry list
Lotus (1.1) #71, in entry list
Lotus, K-23-AZ (Cosworth Mk III) #47, rejected #43, in entry list
Ian Walker (Cosworth Mk III) #64, over heating
Ian Walker (Cosworth Mk III) #65, 8th #47, in entry list
Ian Walker (Cosworth Mk IX) #24, 22nd
Essex Racing Team (Cosworth Mk IX) #84, dnf #18, 2nd
UTD Laystall Racing Team, 23/S/8 (Climax FWMC) #48, rejected
Lotus France, 23/S/8 (Cosworth Mk III) #42, 11th
Bernard Consten (Cosworth Mk III) #44, 9th
Total points
14
3 11
Statistics
Works Starts/finishes 7/6 3/1 3/3 1/1
Drivers Team entries and car number
Lotus
R. J. Henry 70
Ernie Harris 70
Bill Stone 70
Sy Kaback 71
Harvey Snow 71
Jim Clark 84 47
Trevor Taylor 84 47
Mike Spence 47 43
Peter Arundell 43
Ian Walker
Paul Hawkins 64 24
Peter Ryan 64 47
Peter Ashdown 65
Bruce Johnstone 65
UTD Laystall Racing Team
Les Leston 48
Tony Shelly 48
Essex Racing Team
Alan Rees 18
Lotus France
Bernard Consten 44 42
José Rosinski 42

Drawings

lotus23.jpg Source
Lotus_23_Pushrod_cutaway_by_Shin_Yoshikawa.77213727_std.jpg Source

Lotus Twin Cam / Cosworth Mk XII engine

Lotus-Twin-Cam-Engine.jpg Source

Chassis

c2.jpg Source
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