Introduction: The Seven Deadly Sins
Chapman and Lotus were in the business of selling cars.
Volume was important for income, spreading reputation and creating demand through envy/desire. Cars that were raced provided invaluable publicity to generate both sales and reputation.
Lotus sold on performance. There are more drivers than engineer enthusiasts so it is important they are catered for.
Chapman and his engineering colleagues delivered:-
- Alcamay and added value
- Engineering Architecture structure, design proportion, aesthetics etc.
- Converted the mundane to the magnificent
This article is relevant to the following professionals today as the principles remain with their commercial dimension:-
- Product designers
- Engineers
- Marketing creative media professionals
The selection /variety of engines was significant in marketing and customer base for the following reasons:-
- Include race/enthusiasts along with non-engineers with knowledge they could get cars serviced and maintained possibly without access to Lotus dealer [volume]
- Took advantage of existing manufacturer reputation and service network internationally
- Differing engine capacities enabled participation in differing race classes
- The varying engines had followings and aftermarket specialist and tuning components etc.
- Overcame resistance of problematic ownership
- Created dual transformation chassis to engine combination and vice versa
Chapman and his engineering colleagues adapted and improved the Seven within its fundamental concept without losing its character and desireability.In fact this was enhanced with the successive generation of improved engines made available by the main manufacturers.
The proof of the correctness is evident in the Caterham that has further utilized generally available engines to the present day.
We consider the Lotus Seven one of the Seven wonders of the automotive history. We take this opportunity to celebrate is 60 year existence.
The Seven Deadly Sins
The editors contend that the Seven might provoke and invite all but sloth; in the most positive fashion.
The editor has used slight artistic license in depicting engines and has tried to capture the proportions and distinctive qualities of the engine in the engine bay as opposed to specific example. Drawings simplified in some respects and some details omitted.
We suggest subscribers might like to check Taylor [The Lotus Book] for production numbers to make deductions about commercial success of each Seven series.
Subscribers might like to see directly related A&R articles:-
- Please use our search tool and look up all our articles on the Seven including aesthetics, form and function, brochures etc.
Seven aside
In this article we select seven engines that have powered the various Seven Series. For convenience, consistency, brevity and benchmarking on this occasion we draw inspiration from Rees and use his tabulation of data for reference.
For each of the engines we provide a couple of sentences to set the customer context.
We hope subscribers will appreciate the benchmarking and no doubt will have personal favorites.
Chapman joins the AA: AUSTIN AMERICA
The Austin A series engines were adopted in the S1&S2.
Taylor suggests approximately 242 S1 of all types were built. The editors suggest the majority might have been the Ford side valve.
The Austin engines were relatively new, possibly more expensive. The Ford engine gave good performance and had a racing class.
Its inherent weakness was the 3 speed gearbox, the A series had 4
The editors imagine more S2 were sold with A series engine in Healey Sprite tune and as noted the America meet demand there.
| Seven Model | Series 1:A |
| Engine | :Austin A35/Morris 1000 A series |
| Capacity | 948cc |
| Induction | Single SU [7America twin SU] |
| Bore x Stroke | 62.94×76.2mm |
| Compr’Ratio | 8.9 to 1 [America 8.3 to 1] |
| Max.Power | 37 bhp [27kW] at 4800 rpm [America 43bhp [32kW] @ 5,200] |
| Max.Torque | 50lb ft. [68Nm] at 2500 rpm [America 52 lb ft. [70Kn]@ 3300 |
| Gearbox | Austin A30 four speed |
| Brakes | 8 in. drums front and rear |
| Steering | modified Morris Minor rack and pinion |
| Weight | 896 lb [407kg] |
| Top Speed | 85mph [137kph] |
| 0-60 mph | 14.5 sec [America 12.2] |
| 50-70 top | 10.3 sec [through the gears] |
| No.Produced | see 7F |
Figure 1.Editors sketch of 7S1: Austin
SEVEN S1: FORD 1172 SIDEVALVE
The Ford 1172 cc sidevale engine could be transformed by tuning. Engines available since the 1930’s were cheap.
See production figures above. In the UK we suspect this engine found its way into the majority of Seven S1.
This engine had been used extensively in the Mk.VI and a racing class existed for this capacity.
The characteristics of the engine and relative economy made it a pleasant dual purpose vechicle.Rugged and reliable it was practical cost effective option.
| Seven Model | Series 1:Ford 1172 cc side valve |
| Engine | Ford 100 E side valve |
| Capacity | 1172cc |
| Bore x Stroke | 63.5×92.5mm |
| Induction | single Solex or Zenith [optional twin SU] |
| Compr’Ratio | 7.0 to 1 [optional 8.5 to 1] |
| Max.Power | 28-40 bhp [21 -30 kW] @ 4,500 rpm option 48 bhp [36kW] |
| Max.Torque | 52lb ft. [ 70 Nm]@2,500 [option 58lb ft. [78 Nm] @2,600 rpm |
| Gearbox | Ford 3 speed |
| Brakes | 8 in drums front and rear |
| Steering | modified Morris Minor rack and pinion [early Burman ] Triumph Herald |
| Weight | 918 lb [416 kg] |
| Top Speed | 78 mph [125.5 kph] optional 81mph /130 kph |
| 0-60 mph | 19 sec optional 17.8 |
| 50-70 top | n/a with optional engine 16.5 sec |
| No.Produced | 243 all variants S1 |
Figure 2.7S1: Editors sketch Ford 1172 Side-valve
SEVEN S2: COSWORTH
The Cosworth engines were derived from Ford. They were the more highly tuned performance option in the Seven.
The editors have not seen separate production figures for the Cosworth powered cars.
Taylor informs us that 1350 S2 Seven’s were produced. This included Ford side valve &Austin A series [see above] Ford 105,109 and 116E.
The practicality and additional performance of the Cosworth engine would make it an attractive option.
The chassis could handle the power. It would have been suited to racing.
| Seven Model | Series 2: |
| Engine | Ford 109 E Cosworth |
| Capacity | 1,340 cc |
| Bore x Stroke | 80.96x 65mm |
| Induction | twin Weber DCOE |
| Compr’Ratio | 9.5 to 1 [US 10.5 to 1] |
| Max.Power | 85 bhp[63kW] @5,800 rpm |
| Max.Torque | 80lb ft. [59 Nm] @4,000rpm [US 85 /62 @4,000rpm |
| Gearbox | Ford 109E |
| Brakes | 8 in. drums front 7 in drums rear |
| Steering | Triumph Herald rack and pinion |
| Weight | 966 lb [438 kg] |
| Top Speed | 102 mph [164kph] |
| 0-60 mph | 6.9 sec |
| 50-70 top | 7.9sec |
| No.Produced | See S2 7A/7F |
Figure 3.L7S2: editors sketch Ford Cosworth
SEVEN S1: COVENTRY CLIMAX
The Coventry Climax engine fitted in the Seven S1 is likely to have been a minority. The editors suggest that this was due to:-
- Expense
- Complexity and maintenance issues especially as road car
- The engine output might be more cost effective fitted in aerodynamic Lotus
Despite this it was potent competition car and gained considerable success and publicity.
Many Coventry Climax powered cars were detailed and presented to exceptional standard and gained disproportionate publicity –well deserved
They articulated form and function.
| Seven Model | Series 1: Super Seven -C Coventry Climax |
| Engine | Coventry Climax FWA |
| Capacity | 1,098cc |
| Bore x Stroke | 72.4×66.6mm |
| Induction | twin SU H2 carburetters |
| Compr’Ratio | 9.8 to1 |
| Max.Power | 75 bhp [56kW] @6,250rpm |
| Max.Torque | n/a |
| Gearbox | Austin A30 4 speed |
| Brakes | 8in .drums front and rear |
| Steering | modified Morris Minor rack and pinion |
| Weight | 924 lb [419kg] |
| Top Speed | 104 mph [[167kph] |
| 0-60 mph | 9.2 sec |
| 50-70 top | 6.5 sec [through the gears] |
| No.Produced | see 7F |
Figure 4.7S1: editors sketch Coventry Climax
SEVEN S3: LOTUS TWIN CAM
Taylor suggests that a total of 350 approximately S3 cars were built. These comprised those fitted with Ford 225 engines, Ford Holbay, Ford Cross-flow and Lotus twin cam as illustrated here.
We recommend readers see our dedicated articles devoted to the Twin cam engine and the S3 Twin cams.There we explore the cost effectiveness of these engines and benchmark performance.
| Seven Model | Series 3:7 Twin Cam SS |
| Engine | Lotus Twin cam/Lotus Holbay Twin cam |
| Capacity | 1558cc |
| Bore x Stroke | 82.6×72.8mm |
| Induction | twin Weber 40DCOE |
| Compr’Ratio | 9.5 to 1 |
| Max.Power | 115 bhp [86kW]] @5500 rpm/125 bhp [93kw] @4500 |
| Max.Torque | 108 lb ft. [146 Nm]at 4500 /116 lb ft. [157Nm] @4500rpm |
| Gearbox | Ford Cortina 116E 4 speed |
| Brakes | Girling 9 in disc front , 8 in drums rear |
| Steering | Triumph Herald rack and pinion |
| Weight | 1258 lb [570kg] |
| Top Speed | 110mph[177kph] |
| 0-60 mph | 7.1sec |
| 50-70 top | 8.1sec |
| No.Produced | 13 |
Figure 5.Seven: editors sketch Lotus Twin Cam
SEVEN S3 HOLBAY
The Seven S3 Holbay is a rarity. See details above.
Holbay were involved with Lotus producing /tuning engines for their Formula Fords and other single seaters.
See our dedicated article on Holbay.
The editors have not seen published production figures for this option.
| Seven Model | Series 3:7S Holbay |
| Engine | Holbay tuned Ford cross flow |
| Capacity | 1598cc |
| Bore x Stroke | 80.96×77.62 mm |
| Induction | twin Weber 40 DCOE |
| Compr’Ratio | 10 to 1 |
| Max.Power | 120bhp [89kW] @6200 rpm |
| Max.Torque | 110lb ft. [149 Nm] @ 5000 rpm |
| Gearbox | Ford Cortina 116E 4 speed |
| Brakes | Girling 9 in disc front , 8 in drums rear |
| Steering | Triumph Herald rack and pinion |
| Weight | 1204lb [546kg] |
| Top Speed | 107 mph [ 172kmp] |
| 0-60 mph | 7.4sec |
| 50-70 top | n/a |
| No.Produced | 1 |
Figure 6.editors sketch of Lotus Seven S3 fitted with Holbay engine
SEVEN S3: CROSS-FLOW
The Ford cross flow engine in 1300 and 1600 cc capacity was adopted in the S3 and Series 4.
Taylor suggests 625 S4 were built and this included the Lotus twin cam.
The simple deduction is that the crossflow engine probably powered about 90% of production.
This is a no brainer.
The engine was powerful, easily serviceable including DIY had an enviable reputation and worldwide spares network.
Added to which is fact that potential customers performing cost benefit analysis would have discovered their value.
| Seven Model | Series 3:1300/1600 |
| Engine | Ford 225 E Kent crossflow |
| Capacity | 1297/1598cc |
| Bore x Stroke | 80.96 x62.99 /80.96 x 77.62mm |
| Induction | single Weber 32 DFM carburetter |
| Compr’Ratio | 9.2 to 1 / 9.0 to 1 |
| Max.Power | 72 bhp [54kW]@6000 rpm /84 bhp [63kW]@6500 |
| Max.Torque | 68lb ft. [92Nm]@4000 rpm /91lb ft. [123Nm]@3500 |
| Gearbox | Ford Cortina 116E four speed |
| Brakes | Girling 9 in disc front ,8in drums rear |
| Steering | Triumph Herald Rack and pinion |
| Weight | 1210 lb [549kg] |
| Top Speed | 100/104mph /161/167 kph |
| 0-60 mph | n/a 7.7 sec |
| 50-70 top | n/a 7.8 sec |
| No.Produced | approx.340 [all S3] |
Figure 7.7S3: Editors sketch Ford Cross-Flow
Learning Opportunities: Seven Pillars of Wisdom
Our learning /educational opportunities are intended to be challenging thought provoking and requiring additional research and/or analysis.
These opportunities are particularly designed for a museum/education centre location where visitors would be able to enjoy access to all the structured resources available in conjunction with any concurrent exhibition.
In this instance we suggest the following might be appropriate:-
- Identify 7 cars from automobile history that have i] endured like the Seven,Ii]been rated like the Seven
- Identify 7 kit cars that have emulated the Seven
- Name 7 manufacturers that have used the moniker SS on their models
- List 7 cars that are immediately identifiable and recognizable as the Seven
- Name 7 manufacturers that have adopted mass production engines successfully
- Name 7 films of TV programmes that have used icon cars [often the car identifying the programme]
- Identify 7 other engines used in the Seven or Caterham
Exhibitions, Education and Economics: The Magnificent Seven
In the museum context the editors believe that commercial considerations are both necessary and complementary with its educational objectives.
For these reasons our suggested outline Business Plan includes provision for promoting products and services which share Chapman’s ideals of mechanical efficiency and sustainability. In addition we propose merchandising that explain and interprets the social and cultural context of Chapman’s designs in period. It’s suggested there will be catalogue for on line purchasing.
In this instance we suggest the following might be appropriate:-
There is no need to repeat all the extensive exhibition titles we have identified; please see dedicated articles .Numerically they are 7×7.
It’s worth noting the E Type Jaguar was featured in a dedicated exhibition at the Design Museum, the Seven is equally iconic with racing record and prestige in public opinion. Both helped identify the 1960’s.
A proper exhibition is overdue.
Conclusion: A Seven for All Seasons: Perreniel Appeal
There is little need to overstate the case. The Seven is exceptional. The summarized explanation:-
- The range types made available across wide owner base , needs , budget and choice of construction mode and customization options
- Enduring relevance celebrating 60 years existence/production c/o Caterham Seven
- Undiminished ,unbeaten symbolism /aesthetic
- Enshrined in folklore :”Too fast to race” etc. and through popular culture /media
- Caterham cars are still able to mutate and make the concept sustainable reinforcing the profound fundamental correctness of the original concept
In our title we recorded the celebration of the Seven. The definition of celebration includes:-
- Hymn
- Laud
- Mark
- Rave
- Extol
- Honour
- Record
- Renown
- Emblaze
- Perform
- Commemorate
All of these can be used to describe the car so indelible in the motoring psyche.
We are ensured the car for all seasons will continue to enjoy its seasons in the sun.
The Seven Series 1 was produced at Hornsey.
S2, 3&4 at Cheshunt then Hethel.
Reference:
The Magnificent 7.Rees.Haynes.2007.
ISBN: 9781844254101
The A&R has an extensive holding on Seven reference books and possibly the definitive by Weale .Please see bibliography in all our other related Seven series articles.
Please note the editors of the A&R attempt to give the broadest spectrum of references but not all are available for consultation in an article. However by noting their existence it may assist students in their research.
*Items in italics non A&R library books.