Engine Series – Lotus-Holbay

A Holbay in the Engine Bay


The engine series are neither technical treatise nor Haynes Manuals. This information is readily available in published form or on the net.

Rather our study concentrates on how and why Chapman and his colleagues sourced engines and their contribution to Lotus success and sales.

In his selection of major mechanical components Chapman added both performance to a sophisticated chassis and extraordinary added value.

Lotus were not a major engine manufacturer until quite late on .Despite this they used and adopted a range of mainstream engines to extraordinary effect.

Chapman and Lotus practice provides inspiration for all Industrial Designers /Specialists in their search for urgency and added value.

Our study focuses heavily on the fitment of these engines along with a visual representation. We debate the appeal to owners / racers and the beneficial publicity accredited to the manufacturers.

We believe that subscribers will be well able from this base line to research specific topics according to their needs.

Inserting image...

Figure 1. editors sketch based on photographs

Subscribers might like to see related A&R articles:-

  • Lotus Seven –extensive with detailed bibliographies
  • Seven Sails to the Sunset: Lotus Seven advertisements including 7S [Holbay]
  • Lotus Power plants
  • Ford engines
  • Lotus Twin cam
  • Coventry Climax
  • Vegantune
  • Cosworth
  • Henry Ford

Holbay –from the net

“Holbay Engineering was a small family run British engineering company specializing in engine modifications and race tuning. Although they enjoyed much success during the 1960s and 1970s with their competition race engines, they are best remembered today for their work on the Rootes 1725cc OHV engines as used in the Hillman Hunter GLS and Sunbeam Rapier H120.”



The company was founded by John Read between 1958-1959 together with his older brother Roger Dunnell and was initially run from the family home in Sheffield. The company moved into larger premises at Martlesham Heath in Suffolk in 1964 and went into liquidation in 1992 after the untimely death of its founder John Read in an unusual aircraft accident.

The tools and machinery of the original company were sold at auction and the company re-opened as Holbay Classics under new ownership and management in the nearby village of Grundisburgh. Holbay Classics only operated as a car sales and servicing establishment and although it had kept the Holbay Name, there was very little in common with the original Holbay Engineering. Holbay Classics folded in 2002 was bought out by former employee Richard Coles who then began trading as Coltec Racing Engines.

Coltec re-established the race tuning business and moved back into the original Holbay Engineering Martlesham Heath premises. Coltec does not trade under the Holbay name, but currently owns the Internet Domain ‘Holbay.co.uk’ which will link directly back to the Coltec Racing Engines web Site.

List of Holbay Engines [edit]

  • Type number unknown – Holbay tuned Ford Anglia engine, a popular choice with British Formula Junior racing car constructors [1]
  • S65 – based on a Ford Cortina block and using a Holbay cylinder head.[2]
  • H120 (As supplied to the Rootes Group for their Hunter GLS and Rapier H120 Models)

Lotus 7S [1969] Holbay tuned Ford [Cortina 1600] Cross flow, 1598 cc

Quoted at length from Rees:-

“The great advantage of the Ford crossflow engine was that it was highly tuneable .Lotus Components already had strong connections with engine tuner Holbay Engineering which had been building Kent engines for Lotus Formula Ford racers.it followed naturally that Components should ask Holbay for a tuned road car engine to fit into the new Series 3, whose Escort rear axle was now capable of handling a power output which was way above what had been possible previously.

The Holbay engine was based on the Kent 1600 block, adding a balanced and gas flowed head, high lift camshaft, special Hepolite pistons, higher 10:1 compression ratio, four branch exhaust manifold and twin Weber 40DCOE carburetors .With an output of 120 bhp at 6,200 rpm this was easily the most powerful engine yet fitted to a 7, although the overall weight of the car played against it and it was only marginally quicker than the S2 Cosworth had been.

The new model was proudly displayed for the first time at the January 1969 Racing Car Show in London……..Called the 7S it came with a higher level of specification ……….Lotus called it the “ultimate 7”…….

It was offered for sale at £1,285 in kit form or a whopping £1,600 fully built [ more than a Jaguar 240] Although only the single show car was ever built, several S –type engines were built and some of the options of the S were fitted to customer cars. The place of the “ultimate 7” would some nine months later, be usurped by the Twin Cam SS which achieved a very limited production run.

The 7Sis perhaps best regarded as the precursor to Caterham’s Super sprint engine of the 1980’s, another very successful tuned version of the Kent engine which became almost the seminal power plant for the 7 during its 15 year –tenure”

Figure 2 [1]. Authors photograph of a Holbay engine installation.

The Lotus 7S


“In 1969 Lotus Components put together an attention –getting Series 3 for the Racing Car Show. Called the Seven S, it was an exercise in seeing just how fast and luxurious they could make the car. “Luxurious” seems a definite non sequiter applied to the Seven, but what else would one call a white leather interior? The seats were heavily padded buckets and the white colour was used for the top and interior panel’s .Both cockpit and trunk had black carpeting, trimmed in white, and the steering wheel was leather rimmed. A heater and sacrilege –push button radio were also fitted.

Paintwork was -Rolls Royce was metallic maroon and the face of the alloy dash panel was polished. Chromed suspension, air horns, tinted windscreen, a wooden gearshift knob and 5.5 inch wide Dunlop alloy wheels wearing Dunlop SP Aquajet tires completed the visuals.

A 1600 crossflow was fitted but Holbay gave it their CFR [ER for fast road] treatment. The head was modified with porting and flow work and had a 10 to 1 compression ratio. Twin Weber 40 DCOE’s, a 4 branch exhaust manifold and high lift R120 cam shaft complimented the head work. The bottom end was balanced and used special Hepolite pistons.

The engine produced 120bhp at 6200 …… to speed was approximately 108 mph and fuel consumption was in the range of 18-23 .The Seven S was fast but not much quicker than the old 109E Super Seven of for that matter the standard 1600 crossflow……….

Incredible as seems there was real interest ………the press dubbed the “Ultimate Seven” .Lotus Components put a rather stiff price tag of £1600 on the car in assembled form only …………….”

Coulter comments:-

“Introduced 1969.

Engine : Ford 1598 cc crossflow modified by Holbay Engineering .Compression ratio 10:1 .Twin Weber 40DCOE carbuterttors , , four branch exhaust manifold , modified cylinder head, high lift camshaft ,Hepolite pistons , balanced assembly , 120 bhp at 6.200 rpm

Price: £1,600 fully assembled

[Weight 1,204 lb.]

Notes: One –off show car for 1969 London Racing Car Show. Featured many extras including full carpets, special paintwork, air horns leather steering wheel etc. Holbay engine spec became an option for production S3 Sevens.

Nb Coulter also provides a set of performance figures

Figure 3[2]. Editors sketch of Lotus Holbay installed in Lotus Seven

The “Ultimate Seven”

Taylor comments:-

“ Lotus fitted a 120 bhp Holbay tuned Cortina engine to the Seven S , shown at the 1969 Racing Car Show .If it had entered production it would have been quick ….and luxurious .In fact only one was made.

More exciting was the “ultimate “ Seven which dis eventually reach production : the SS introduced at the October 1969 Motor Show…………with the engine developing 115 bhp , the SS was a screamer ; with the Holbay assembled big valve version fitted , you got 125 bhp and truly scorching performance……………at a kit price of £1,225, it wasn’t a cheap alternative”


Figure 4 [3].Photograph from the net. The editors believe this picture was taken at Caterham Cars when they were based at Town End, Caterham on the Hill. Note this cars seems also to illustrate Rees’s chapter on the 7S, and Tipler includes an advertisement from Caterham car with this vehicle .Caption reads “the one-off Holbay S model”

Lotus 7 Twin Cam SS [1969-1973] Lotus Holbay 1558cc, 125 bhp

Rees observes:-

“The Lotus Special Equipment version of the engine developed 115 bhp, while the Holbay assembled “Big Valve” engine with special camshafts developed 125 bhp

Capacity 1,558cc

Bore/stroke 82.6 x 72.8mm

Induction Twin Weber 40 DCOE carburettors

Compression ratio 9.5:1

Maxpower 120 bhp at 6,200 rpm

Max.torque 108lb ft. at 4,500 rpm

At launch the price was £1,225 in kit form”

Coulter provides following statistics:-

“Introduced 1969.

Engine: Lotus 1.558cc four cylinder twin ohc unit as used in Elan, Lotus Cortina etc. Based on Ford 1500 block chain driven camshafts …..compression ratio 9.5:1 .Twin Weber 40 DCOE carburetors , four branch exhaust manifold .Lotus Special Equipment version produced 115 bhp at 5,500 rpm Holbay –assembled big valve version with alternative camshaft produced 125 bhp at 6,200 rpm…….weight 1,258 lbs.…..Price £1250 in kit form”

Nb Coulter also provides a set of performance figures

Figure 5[4]. Editors sketch drawing. Note in making this drawing several sources and photographs were examined. See text for details. Note some plumbing and wiring left out for clarity and easier comprehension

The Super Seven SS from Tipler

Tipler wrote:-

“on a far more exalted level was the Seven SS , or Super Seven Twin Cam, powered by the famed Lotus 1600 cc twin cam……….with Holbay modifications and a pair of twin Weber’s , it pushed out 125 bhp. The Super Seven cost £1,250 but the figure quoted for the very swish Lotus components –built Seven S was £1600……for this you got the Holbay modified twin cam, plus a fully trimmed and upholstered cockpit. Several SS’s were sold after the model was shown at the 1969 Racing Car Show……….

The SS represented the swan song of the Series 3 cars………the twin cam-engined series 3 SS……the price was £1,250 , as compared with a normal Series 3 at £775. The twin cam was first seen at the 1969 Earls Court Show …………

The one –off Holbay S car, TNG 7G with tuned Holbay 1600 was some £300 dearer still. This was also on the Lotus stand at the 1969 Earls Court Motor Show, painted Rolls-Royce red……”

Lotus Seven S3 Twin Cam SS [reg.No. BPB 147H]

This car s featured Morland, Tipler and Buckley & Rees.

Morland provides a caption that reads:-

Holbay Ford engine producing 120 bhp giving 230 bhp per ton”

Whereas Tipler added these captions to his photographs:-

“The original invoice dated 2nd January 1970 was for £1252 -10s- 0d .Chassis No. SC2671/TC6, engine No. 20972 and:

The 1,558cc Lotus-Holbay twin cam engine has an alloy head, specially cast cam covers, four branch exhaust, and high lift cams and produces 125 bhp. The SS bonnet cover has a special air intake to feed twin 40 DCOE Weber carburetors.

In Buckley &Rees there are 5 photographs of this specific car one is a useful photograph of BPB 147H taken in plan view that focuses on the engine bay and well displays the fit of the twincam in the Seven S3.

Caterham 7, 1700 Supersprint /Holbay [1982-1984[1999?]

Rees comments:-

“ The early 1980’s was characterized by Caterham’s hunt for an engine which matched the ability of the Lotus twin cam .While the Sprint engine was good , it did not approach the power output of the old big Valve power plant.

A stopgap arrived in 1982 in the form of Holbay R120 engine. This was a bored out 1,699 version of the familiar Ford Kent engine.

Engine Caterham modified Ford crossflow /Holbay R120

Capacity 1,691cc/1,699cc

Bore stroke 83.3 x 77.62mm / 83.5 x 77.62mm

Induction Twin Weber 40 DCOE

Compression ratio 9:1 /9.5:1

Max power 135 bhp at 6,000 rpm

Max torque 122 lb. ft. at 4,500 rpm

NB: Nb Coulter also provides a set of performance figures. He also quotes a weight of 1,196 lb.

Lotus and Holbay

Holbay supplied engines to Lotus for the: –

Formula single seat racing cars and formula Ford [ LH 105 based on Cortina 1600E]

Other types recorded by Taylor include: –

Lotus Type No Function Engine Code capacity
55 F3 Holbay Ford
59/59F F3 etc. Holbay Ford R68 997cc
61 F’Ford Lotus Holbay 105 1598cc
69 F3 Holbay Ford R68
69F F’Ford Lotus Holbay

Lotus 31


Lotus Components built and offered the 31 for sale .the regulations stipulated that a four cylinder production based engine up to 1000ccwith standard valve gear and a single choke carburetter had to be fitted ……………

The Holbay R65 modified Ford unit with a single Weber carburetor, which developed between 90 and 97 bhp at 8,000rpm …….

…..both engines were installed in the car at an angle of 30 degrees from the vertical.”

‘Bay View –Form and Function

The editors have looked at several photographs in order to assist drawings. All angles have been viewed in order to comprehend the installation particularly the twin cam in the Seven engine bay. A nice selection of relevant images are contained in Tipler and Buckley and Rees [plan view]

Figure 5.Editors sketch of Lotus Holbay mid mounted in single seater.

Learning Opportunities

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:-

  • Compare Holbay with Cosworth and Vegantune- what contribution did they make to Lotus?
  • Using Lotus Book establish how many Holbay engines were supplied to Lotus; who else used their engines?
  • How did Lotus road/race engines overlap? With what synergy?
  • Which Ford engines did Holbay modify?
  • What was the advantage of their location?
  • How does Holbay sit with Caterham Cars?
  • Compare and contrast performance price etc. of :Holbay S3 Seven, Seven S2 1500 Cosworth , Lotus Seven S3 Lotus Holbay Twin Cam and Caterham 1598 Sprint

Exhibitions, Education and Economics

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.

The following exhibitions might be both educational and entertaining with sight and sound opportunities: –

  • See other titles in Lotus engine series including Lotus Seven and Formula Ford
  • Holbay Engineering and tuning: Attuned to the Times
  • Holbay Engineering and tuning: Name that tune
  • Holbay Engineering and tuning: Lotus Folk Tune
  • Holbay Engineering and tuning: Signature tune
  • Lotus & Holbay Engineering and tuning: Change their tune
  • Marques and Sparks: Specialist Marques and Engines come together
  • Lotus and Holbay and Formula Ford: Starter Motors


The Holbay engine powered the Lotus

It therefore powered racing and road cars.

It was a superb piece of industrial design; functional and also right for competition.

It was successful in racing gaining publicity and inspired modification, tuning and a generation chassis designers.

The engine was attractive to owners and generated sales. Exports were possible because of the international spares availability.

These specialist engines were reasonably robust, inexpensive, widely available and spawned aftermarket components industry. Furthermore they invited experimentation, and helped facilitate competition and design diversification. Thus, assisting and elevating British motor racing: design, engineering, manufacture and of course drivers.

In the case of the Ford cross flow modified Holbay it formed a dedicated race formula in the late 1960’s and 70’s through Formula Ford

The engine has continuing legacy and relevance and being such a significant piece of industrial design is fully worthy of analysis and appreciation.

Added value is an extremely important of Industrial Design, Chapman exploited to maximum effect and its principles are significant for a young entrepreneurswith low capital wishing to enter the market.


The Magnificent 7.Rees.Haynes.2007.

ISBN: 9781844254101

Lotus and Caterham Seven.Tipler.Crowood.1995.

ISBN: 1852238585

Legend of the Lotus Seven.Ortenburger.Osprey.1981.

ISBN: 0850454115

The Lotus and Caterham Sevens.Coulter.MRP.1986

ISBN: 0947981063

Lotus Seven and Caterham.Morland.Osprey.1994.

ISBN: 1855324903

Classic Cars. Buckley and Rees.Southwater.214.

ISBN: 9781780193977

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.