Engineering an Alvis rebirth (with siamesed intake ports....)

The Home of any non Mini projects & discussion.
Post Reply
User avatar
mab01uk
Posts: 6090
Joined: Thu Jun 24, 2010 7:08 pm
Location: S.E. England

Engineering an Alvis rebirth (with siamesed intake ports....)

Post by mab01uk »

Interesting story from 'The Engineer' magazine below about the development of an emissions-compliant injection version of the original post war Alvis 3-litre six-cylinder pushrod engine with siamesed ports which posed significant problems when it came to mixture control but a suitable design was eventually found that came from 'Specialised Technologies' in Norfolk – a company that has a background in working with the BMC A-Series engine, which features a similar siamesed intake port configuration......

Engineering an Alvis rebirth.
One of the most celebrated names from the golden age of motoring has returned with a subtly re-engineered take on its most iconic designs. Chris Pickering reports.
In the case of the Alvis Car Company, the old adage that they “don’t make them like they used to” isn’t strictly true. The 103-year old British marque has put a series of its iconic models back into limited production, using the original blueprints and the same traditional methods.
Unlike some ‘reborn’ car brands there is a continuous thread that connects the modern company to its roots that were laid down in 1919. After Alvis was absorbed into British Leyland in 1965, much of what had been the road car side of the business was split off as an independent company called Red Triangle.
Red Triangle’s job was – and still is – to provide servicing and support for the existing Alvis models. But the company’s capabilities slowly expanded to include full ground-up restorations. In 2008, the company bought back the Alvis trademark, and two years later it announced a series of continuation models. These were initially based around the pre-war 4.3-litre cars, but the range has since expanded to include a selection of post-war 3-litre designs.
Company owner Alan Stote was adamant about two things when development began on the new cars: they had to follow genuine Alvis designs, and they had to be road-legal. And that’s where things got tricky.
To be used on the road, the Continuation Series cars would have to be put through the Individual Vehicle Approval (IVA) process. Although far less onerous than Whole Vehicle Type Approval, the emissions requirements would still be impossible to meet with the carburettor-fed engine in its original form.
Switching to a modern engine would defeat the aim of the project, so instead Alvis hired combustion specialist and former Lotus Engineering director David Taitt to develop an emissions-compliant version of the original six-cylinder pushrod unit.
“The IVA emissions requirements are frankly pretty generous, but it was clear from the start that we wouldn’t be able to meet them on the original triple SU carburettors,” he comments. “We were going to need to run a catalytic converter, which requires precise control of the air-to-fuel ratio, so we knew we’d have to switch to closed loop fuel injection.”
One of the goals of the project was to produce an engine that would be aesthetically pleasing as well as functional. With that in mind, the decision was taken to use three separate throttle bodies – one on each pair of siamesed inlet ports – to echo the original SU carburettor layout. This meant that the upstream components, such as the distinctive airbox arrangement, could be carried over unmodified.
The siamesed ports also posed one of the most significant problems when it came to mixture control, Taitt explains: “When you inject into a pair of ports, you have to be absolutely sure that the fuel will go down the correct one, otherwise you’ll mess up the mixture and the catalyst won’t work.
The next challenge was to source injectors that would be capable of supplying sufficient fuel flow at full throttle but also delivering the precise metering required at lower loads. At one stage, the idea of using two injectors per port was considered, but a suitable design was found that satisfied both requirements. This came from Specialised Technologies in Norfolk – a company that has a background in working with the BMC A-Series engine, which features a similar siamesed intake port configuration......
More here:-
https://www.theengineer.co.uk/engineeri ... s-rebirth/
Polarsilver
Posts: 1865
Joined: Fri Jan 15, 2016 1:22 pm
Location: Silverstone not far away

Re: Engineering an Alvis rebirth (with siamesed intake ports....)

Post by Polarsilver »

A few weeks ago i purchased a NOS Lucas Floor mounted Headlight Dip Switch complete with the rubber matt from Red Triangle fitted the Moke a treat . :D
mk1
Site Admin
Posts: 17983
Joined: Thu Jun 24, 2010 11:30 am
Location: York-ish
Contact:

Re: Engineering an Alvis rebirth (with siamesed intake ports....)

Post by mk1 »

Excellent article!
Mark F
General dogsbody.
tcave
Posts: 1
Joined: Mon May 10, 2021 8:53 pm

Re: Engineering an Alvis rebirth (with siamesed intake ports....)

Post by tcave »

Thanks for posting that, very interesting.
Post Reply