Seven Wonders of the World: A Celebration of the Seven and the Engines used

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


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


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


The Coventry Climax engine fitted in the Seven S1 is likely to have been a minority. The editors suggest that this was due to:-

  1. Expense
  2. Complexity and maintenance issues especially as road car
  3. 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


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


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


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:-

  1. The range types made available across wide owner base , needs , budget and choice of construction mode and customization options
  2. Enduring relevance celebrating 60 years existence/production c/o Caterham Seven
  3. Undiminished ,unbeaten symbolism /aesthetic
  4. Enshrined in folklore :”Too fast to race” etc. and through popular culture /media
  5. 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.


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.