I was there : Turbocharging the B-Series

B-Series engine

Following the MIRA performance testing of the modified Morris Marina Estate car we did for CAR magazine, and knowing that the weight of the vehicle was about to be increased significantly with all the styling and interior add-ons, I started to think of ways to improve power and performance.

The main project continued but engineering thoughts were often on a different level and astute CAR magazine readers might have read between the lines in the June 1974 edition. At the end of the Marina project article on page 73, mention was made about the good ideas this project had generated at BL Longbridge, in their words, ‘including one about which we daren’t breathe a word because it could have (no kidding) far-reaching effects.’

I had shared my thoughts with Doug Blain at CAR on how I could get the kind of performance the car really needed while staying within the brief Harry Webster had made clear, namely that it could be anything as long as it was a B-Series engine.

Plumping for a blower

For me this meant turbocharging and a potential journey into the relative unknown for a small section of South Experimental inspired by the real world of exciting automotive developments especially in power unit design and development and particularly in competition.

I therefore embarked on investigating and building a turbocharged B-Series engine with the aim of hopefully getting it into BL’s CAR magazine Marina estate programme or a follow up story.

I had driven Alec Issigonis’s BMC 9X car and, like many, had been impressed but after all it was still basically conventional in a rapidly changing automotive world and Alec had been unceremoniously side lined in the Leyland take over so his creativity in power unit development had ended.

Trying to focus development

In 1973 power unit development at Longbridge was seriously lacking direction, the E-Series fours and sixes were mid-1960s projects and, in my opinion, represented critical missed opportunities for once vast production facilities – in the case of Cofton Hackett, the E-Series became an irrevocable decision.

When coupled with the deplorable E-Series transmission this power unit impacted significantly on styling and design options resulting from the eventual external dimensions, given it was a very tall unit.

I was involved with Austin Maxi development and the HL version in particular – all it needed to become a world beater, in my opinion, was a decent engine and transmission and some visual assistance.

The politics of politics

Work was ongoing with what became the O-Series but, by then I had given up on the politics of trying to get the BL Marina engine dyno tested on site – some of the Power Unit Test and Development Engineers were usually pleased to assist, but unfortunately management was not helpful.

At the risk of overusing the word politics, in the later part of my time at BL and in the UK, engineering talent was not in short supply – at Longbridge, I knew and worked with many fine Engineers, Designers and creative thinkers, the missing link was management competence and vision to make the best use of the talent.

I saw from competition experience that a lot of work was going on with turbocharging petrol engines in 1973 and for me it was a rapid but fascinating technical learning experience – it made a lot of sense and, of course, had been common with diesel engines for years.

Reaching out to the turbo makers

Discussions with turbocharger manufacturers, engine specialists and race engineers were convincing about the potential for small but very powerful turbocharged engines. I was also fortunate to meet an enthusiastic Engineer and turbocharging enthusiast in power unit design in the Drawing Office at Longbridge, Ray Battersby.

Ray and I met with a representative from Holset in May 1974 at Longbridge, he brought several interesting technical articles and gave welcome advice which assisted and encouraged us to make progress.

He left us a copy of a most helpful report of extensive development work Holset had carried out on a 1600cc Ford Capri GT. Although very exciting, it was becoming clear this project was not going to be easy with substantial dynamometer work an obvious integral part of the project and not in my area of influence in BL.

Basing it on the diesel

Engine design calculations were completed based on using existing componentry from a B-Series 1.8-litre diesel engine as this engine block was stronger and more capable of handling the increased loads and bottom-end stresses from the increased cylinder pressure from the compressed air.

Discussions followed with Hepworth & Grandage who were most encouraging and who identified pistons available to suit this block, they also assisted with useful advice from their own experience with testing and development of turbocharged petrol engines.

We decided to start off with an initial compression ratio of 8:1 which in turn led to investigations into cylinder head options, block heights, head gaskets and a suitable camshaft.

The plan was to build a development engine and later investigate dynamometer options for testing and development, either on site at Longbridge or using offsite facilities, Holset were extremely helpful and willing to assist.

Tried and tested

The engine build was completed following the standard procedure of balancing the rotating assembly and rebuilding with new bearings and components including a standard MGB series camshaft 12H 1656. My notes confirm this work was carried out in May 1974.

We were advised to use a system of pressurising the induction system pre the SU carburetor (to avoid dumping an air/fuel mix with the valve sited post the carburetor), this meant the carburetor itself required pressure seals on the butterfly spindle and we also designed a modified pressure blow of valve using a modified SU HD carburetor.

SU kindly assisted with drawings and components.

B-Series Turbo 01
This is the blow off valve situated between the compressor outlet and the air cleaner/plenum
B-Series Turbo 02
Another view of the blow off valve, plenum, carburetor and turbocharger installation. Also visible is the oil pressure supply to the turbocharger and the exhaust outlet to the vehicle exhaust system from the turbine

Getting it moving

The needle assembly was removed from the piston and an ‘o’ ring groove machined on the needle face, the compressed air would act on the underside of this piston and, when the pressure exceeded the spring pressure forcing the piston down and closed, the piston would rise and dump the compressed air.

We had several dashpot springs made to give us a range of blow off pressures. The blow off valve was a critical component to ensure a limit on boost pressure and the life of the engine. I needed a Marina vehicle to start the exhaust manifold design and construction but there was a delay given our project Marina was unavailable and I had to source another vehicle.

In the meantime, a standard 1.8 cast iron inlet and exhaust manifold was modified to separate the inlet from the exhaust and flanges made to connect the various exhaust pipes.

B-Series Turbo: finding our way

Holset recommended and supplied a turbocharger that their Engineers considered would be a useful starting point and an adapter plate was machined for mounting the unit on the exhaust manifold.

I used an in-house BL expert in making experimental and development pipe manifolds to work with us around the vehicle.

He wasn’t able to work on this project full time but eventually we produced a practical but cumbersome looking exhaust manifold siting the turbocharger at the front top side of the engine… the bonnet clearance was acceptable so we were confident the installation would work.

The centre siamesed exhaust port from cylinders 2 and 3 was connected to one side of the turbocharger and the number 1 and 4 cylinder ports connected to the other side, another three pipes were then designed and fabricated to connect the turbocharger exhaust to the vehicle exhaust system: a large diameter oil drain return pipe from the turbocharger housing to a modified sump connection and a pipe connecting the compressed air into the blow off valve.

Other modifications were added, an oil supply pipe from the cylinder block to the turbocharger, the modified SU carburetor, a redesigned pressurized air filter/plenum, the new pressure blow off valve and a specially recommended and modified distributor supplied by the Lucas Racing Department.

B-Series Turbo 03
Front view of the engine
B-Series Turbo 04
Oil pressure feed to the turbocharger
B-Series Turbo 05
Oil pressure feed and oil drain return to the sump

By this stage I had become heavily involved in other projects within South Experimental and as time passed the opportunity for dynamometer work at Longbridge became more remote and immersed in BL politics.

I enjoyed working with the CAR magazine people on the Marina project and am confident it met the objectives set – it certainly created a lot of interest within the Engineering Division at Longbridge during difficult times in the economy and BLMC in particular.

I don’t know what eventually happened to the turbocharged engine – I had some amazing years as an Austin Engineering Apprentice. I worked with some very special people and became involved with some unusual but exciting projects in South Experimental.

PMG Rally Allegro

Going rallying by accident

As an example, during the Marina Estate car project, Charles Griffin asked me to create a fast E-Series-powered Austin Allegro two-door saloon – once completed, he was so pleased with it that he said we needed to do ‘something’ with it… I suggested converting it into a rally car… he agreed but with his inimitable smile said it couldn’t possibly be seen as a BL works entry, hence the arrangement with Patrick Motors Group in Birmingham. It was a works car, it lived in South Experimental, the rally driver was a Development Engineer in the department, Don Kettleborough, but that’s another story.

Life at Longbridge in the Engineering Division changed markedly with the takeover by Leyland, some things changed for the better, but I didn’t see a future for myself in the direction British Leyland was heading – the impending Ryder Report and the inevitable outcome were my signal to move on.

I resigned from BL in 1975 and headed off to New Zealand with my New Zealand-born wife and 18-month-old son for a new life and career outside the motor industry.


  1. The lack of understanding of intercooling is interesting… it meant you needed a stupidly-low compression, which led to terminally lethargic off-boost performance AND ECONOMY.

    I always thought given the investment on Compton Hackett, they should have produced a destroked 1300 E-series engine to replace the rattly 1275 A-series, and a similar 1900 six-pot to reploace the B.

    Short Stroke.

    Tuned to rev.

    BMW were offering similar-minded 1600/2-litre engines back then and they established a niche.

    Alas the BL engine-design people seemed more fixated on grandad mode – being able to pull-away from 20MPH in top-gear without judder, rather than focusing on the “shift to 3rd and you’ll get to 90MPH@6800RPM” sporting market.

    The rest is history.

    • Sounds like a good idea, though the E-series had a tall block that was hard to fit under the bonnet of a few cars it was intended to be used in. The Allegro ended up looking the way it did so an E-series would fit under the bonnet.

    • In Graham Robson’s book on the A-Series, there was said to have been another engine project that followed the E-Series known as the F-Series. Which appeared roughly before 9X was cancelled and was intended to have an approximate capacity range of 1100-1300cc with prototypes having a square 74mm bore/stroke before it was cancelled in 70-71.

      However there seems to be as yet no direct link between the E-Series and F-Series, though elements such as the latter’s toothed belt do appear to overlap with an earlier experimental and more sophisticated 1.3-litre engine that eventually became the familiar conservative E-Series.

      The earlier experimental 1.3-litre toothed belt OHC engine being the common origin linking the two different engines would go some way towards providing a possible explanation regarding the unbuilt 1160cc and 1300cc E-Series engines, before it was enlarged to a more conservative taller 1485cc design. Although readily concede am likely reading too much into the apparent overlapping similarities, with others more knowledgeable and closer to the matter being able to clear up any gaps or discrepancies.

  2. Geoff, I’d forgotten about the Marina Turbo project though I recall meeting Holset with you. But what do you recall of the Marina dry sump engine? No pumps, just inlet manifold depression. And I recall quaffing Bathams home brewed beer in a tiny Black Country pub with you one evening. Keith Adams has my email, Geoff.

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