115 replies to this topic

[Mite]

An Experimental Alloy A Series, Made By BMC
"In the late 1950's BMC realised that their "Workhorse" engine the A series could do with a bit of a face lift. To this end they commissioned The British Aluminium Co. to investigate the possibilities of making an all Alloy A Series. This project was overseen by George Harriman with input from other BMC worthies including Issigonis. By 1963 "BA" had produced a number of these blocks in varying configurations, with blocks actually running in at least 1 Riley Elf and the project looked like it was going to go somewhere."

 

More details and photos in links below:-
http://mk1-performan...mental_dept.htm

http://mk1-performan...lock-report.pdf

http://mk1-performan...loy_block_2.JPG

 

Read of earlier all-alloy A-Series attempts in both Barry Sharrett's Post-War Baby Austins and Graham Robson's A-Series books.

 

Using the experimental all-alloy 998cc prototype engine as a rough guide, perhaps it is possible to roughly calculate the weight of the 1098-1275cc engines had the latter been all-alloy?

 

The PDF mentions the weight of the 998cc iron block is 84lbs / 38kg, while the all-alloy version was 29lbs / 13kg (including 8lbs of iron cylinder liners). It also states that previous all-alloy A-Series attempts at using aluminum for iron reduces the weight by half, so in theory about 60kg for an all-alloy 1275cc assuming the latter's approximate figure of 120kg is accurate and potentially competitive against the following:

 

Rootes Imp engine = 176lb / 79.8kg

Reliant OHV = 136lb / 62.6kg (non-alloy prototype being roughly 186-196 lb /  85.2-89.8kg)

Standard-Triumph SC 1300/1500 = roughly 100-135kg (floppy crank units)

Issigonis 9X = 200lb / 90.7kg

K-Series = 96.5kg (figures seem to vary)

Fiat 100 Series = roughly 100-110kg (other sources to say about 108kg)

A-Series = roughly 120kg

A-Series (all-alloy) = roughly 60kg

Edited by Mite, 19 July 2019 - 03:08 AM.

[r3k1355]

You're assuming the lot would be made of ali though, when really it would have just been the block and head, with the rest of the bits being made of iron or steel.

 

You save 25 kg on the block, maybe 5 or 6 on the head for 30 kg total and around 90 kg complete.

A substantial weight saving, but doubles the cost of the engine, would have been nice if it was kept for high performance models or maybe crate race engines?

[Mite]

Even if an all-alloy A-Series is completely out of the question for regular production models, as opposed to high performance models and race engines. BMC could have either limited aluminum usage to just the head as was considered early on during its conception up to the British Aluminium Co project, aimed reduce the weight of the A-Series by around 10-15kg (or so) without using aluminum in the block (in a similar manner to what was done on the revised C-Series) or develop a lighter evolutionary replacement for the A-Series with alloy-head, OHC, etc (following similar evolutionary examples at Renault, Nissan, etc or even BMC/BL themselves via B-Series to O-Series) instead of a clean-sheet successor. 

 

Still one wonders how relatively smaller carmakers like Rootes and Reliant could afford the costs of developing their all-alloy engines, while a much larger company like BMC that should be more capable of absorbing the costs of a full production or limited-run all-alloy A-Series rules it out completely. 

Edited by Mite, 19 July 2019 - 10:13 PM.

[Spider]

IMO, Alloy Heads are good for emissions and generally easier to repair if welding is needed. Yes, there is some weight savings to be had too and ultimately, production costs are usually cheaper.

 

Beyond these plus points, Alloy is a poor material to use for a Block and / or Cylinder Head. I'm glad they stayed with Cast Iron to the end.

[Mite]

Assuming the 970-1275cc A-OHC used roughly the same displacements as the South African A-Series (cannot yet find a definite answer), have to wonder how they would have gone about replacing the 848cc A-Series in the event the latter is discontinued (if a sub-970cc version could even be justified)? Otherwise there would be a split between the older 848cc A-Series and newer 970-1275cc A-OHC engines akin to how Renault produced the Billancourt and Cléon-Fonte engines alongside each other until 1985.

 

IMO, Alloy Heads are good for emissions and generally easier to repair if welding is needed. Yes, there is some weight savings to be had too and ultimately, production costs are usually cheaper.

 

Beyond these plus points, Alloy is a poor material to use for a Block and / or Cylinder Head. I'm glad they stayed with Cast Iron to the end.

 

Despite the potential pitfalls of an alloy head, would it be accurate to say an alloy-headed A-Series pretty much butterflies away the original A-Series difficulties on complying with emission standards in markets like Australia, California, etc (in addition to butterflying away the MG Midget 1500)?

Edited by Mite, 20 July 2019 - 05:04 AM.

[Mite]

So in summary the more feasible improvements to the production A-Series would have been essentially been a UK version of the South African A-Series with a common 70.6 mm bore (for 1000-1300cc versions) and all-alloy 7/8-port head later OHC, in addition to some other (non-alloy aka revised C-Series) solution to reducing the engine’s weight to around 110kg (or closer to 100kg as opposed to potentially 90kg with both an all-alloy block and head)?  

 

Would it have been possible let alone desirable for an updated A-Series to switch from a 3-bearing to a 5-bearing crankshaft as was contemplated during the development of the Cooper S (along with limited-run homologation Minis featuring hemi-head and OHC/DOHC)?

 

In terms of how the A-Series development could have evolved differently from its conception, while the ideal would have been to make it a short-stroke engine from the outset. One idea that stands out would be actually managing to group all components / accessories including the pushrods on one side of the cylinder block, perhaps even following the later Nissan A engine's example of improvements to the A-Series design. Which mainly comprised changing the camshaft from the left side to the right side so removing the intrusion of the pushrods from the porting allowing 8 individual ports instead of 5 originally, and moving the oil pump from the rear of the camshaft to the right side of the block. Another being actually managing to build some more stretch into the original 803-948cc A-Series engine, so Vizard’s 1293-1596cc enlargements of the A-Series are a more viable production possibility later on when the A-Series is further updated.

[Ethel]

It doesn't sound much like an A Series if it's got a different bore & stroke, 5 bearings, 8 port OHC alloy head...

[DeadSquare]

The war had worn out most of the country's machine tools, so with a side-valves and Mr. Weslake as parent,s the birth of the A series went amazingly well at a very difficult time.

 

It inherited the relative position of its crank, cam, bores and main bearings, and although either side would have been convenient in a conventional car, unfortunately the ports were placed between the pushrods, none the less, crowned with a new head, the A proved a superior rival to its older, larger foe, the 1172cc sidevalve Ford.

 

Petrol heads usually recon engine efficiency in BHP per litre, but the manufacturers found that they had a BHP per gallon success, and began to find other jobs for it.

 

Mr. Weslake's choice was perfectly adequate until the engine began to grow, but by this time, too many of the engines were fitted transversely, and accommodating the carb would have meant turning the engine and retooling the gearbox, for what was experimentally shown to be a marginal improvement in a family car.

 

Although aluminuim heads and blocks were tried, and cast iron 7 port crossflow heads with Bosche fuel injection almost got into production. the A series' biggest problem was, that it was so darned good.

Edited by DeadSquare, 23 July 2019 - 10:01 AM.

[Ethel]

I think you only have to look at an A Series to realise it's all about production costs. It's from an era where the easiest way to make more profit was to make cars cheaper and increase your customer base. 

 

3 crank bearings, 5 ports, cast iron: all minimise the component count and amount of machining operations.

 

 

Even so you have to wonder a bit about why ohv didn't come with ohc from the start. Was it purely development and tooling or was there a technical reason?

[Spider]

Maybe I'm taking the proverbial pin to the balloon here, but as Ethel touch on, at the root of just about any production engine is not what's ideal or what could have been or what should have been (from a performance point of view) but " what can get the job done reasonably well at the cheapest production cost ". The A Series fell well in to that description, in the first instance and everything else came second.

 

Making something as a one off is worlds away from what can be done as a production item.

 

Despite these short comings, it did show itself somewhat 'futuristic' (yes I can hear you lot from here!) in it's fundamental design / production state in 1951 and the proof of that was that it remained in production until 2000, with really, few changes.

 

The 3 Bearing Crank is not a short coming in any way and in fact, adding 2 more bearings would have only taken up valuable real estate and added drag.

 

While the R & D Department came up with various modifications, Leyland were hemorrhaging and weren't about to invest money in to getting these modifications in to production. Keep in mind that the company wasn't remotely interested in making 'glamorous' engines, but making cars that would turn them the best possible profit. Engines alone won't do that. Any big departures from the fundamental A, B, C and E series engines would have likely involved them scrapping their Transfer Machines on which much of the production machining operations were carried out upon. In their view, they still had considerable life in them and to replace them they were looking at billions, not to mention the disruption to production.

[Ethel]

I think BL, or Austin-Rover by then, did get ultimately hammered for under development in a round about way. The A Series was still a competitive power unit, and must have had significant cost benefits over a lot of the competition, but not being able to mention "OHC", "crossflow","5 speed" or "fuel injection" in your sales brochures was just easy meat for the hostile press of the day.

[Cooperman]

Ford had the problem with their small engine that it was a really old side-valve which made even the 1950' A-series seem modern.
Rootes didn't really have a small engine. So the 105E and Imp both had modern engines whilst BMC had the A which was acceptable at the time.
The failure to design and develop an A series replacement was a function of the inability of BMC to rationalise their entire engine range in the way that, say, Ford did so well.
In hindsight it is regrettable, but then the entire history of BMC/BLMC is most unfortunate with the reasons being a variety of factors.

[mini13]

this reminds me of the ford Ka,  they stated off with the old ford pushrod engine in the 90's (valencia/ endura engine?) then put in the zetec when they developed it more, last i heard they had a fiat engine in derived from the cinqucento!

 

 

 

 

Ford had the problem with their small engine that it was a really old side-valve which made even the 1950' A-series seem modern.
Rootes didn't really have a small engine. So the 105E and Imp both had modern engines whilst BMC had the A which was acceptable at the time.
The failure to design and develop an A series replacement was a function of the inability of BMC to rationalise their entire engine range in the way that, say, Ford did so well.
In hindsight it is regrettable, but then the entire history of BMC/BLMC is most unfortunate with the reasons being a variety of factors.

[Mite]

It doesn't sound much like an A Series if it's got a different bore & stroke, 5 bearings, 8 port OHC alloy head...

 

The South African A-Series appears to feature a common 70.6mm bore (allowing for a short-stroke 1098cc), while there was the A-OHC prototype.

 

5-bearing crankshaft is probably not useful outside of the homologation specials BMC were considering for the Cooper S despite the similarly sized Renault Cleon-Fonte and distantly related Nissan A engine featuring such an arrangement, though there is value in an updated A-Series featuring an alloy 7 or 8-port head in tandem with the above South African A-OHC developments.

 

 

There are 3 questions here:

 

1) How could the A-Series have developed differently compared to how entered production from its conception?

 

It has been mentioned in Graham Robson's book that it was a mistake to not group all components / accessories including the pushrods on one side of the cylinder block.

 

2) To what extent could the A-Series have been updated had both the money and will been available?

 

The South African and A-OHC engines would provide feasible examples, though one could argue a composite of the previous two could have benefited from both an alloy head as well as 7 or 8 ports. The alloy head preventing a situation where the A-Series finds it tough to comply with emissions standards in markets like Australia and California, later prompting BL to develop the Triumph powered MG Midget. It would have also butterflied away the costly and seemingly flawed A+ engine.

 

3) In the event this alternate / updated A-Series has reached the limit of its development, could it have largely been superseded in the mid/late-1960s onwards by a new linear replacement inspired by both Nissan's distantly related A / Series 2 E engines as well as by the B-Series evolving into the O-Series?

 

If Nissan managed to rapidly improve their A-Series derived engines and managed to even grow them to 1487cc (Nissan A) and 1597cc (Series 2 Nissan E) as well as upscaling it to create the Nissan CA and downscaling to create the Nissan MA engines, it was most certainly within BMC's capability to follow suit. In this case unlike the previous two evolutionary paths for the alternate / updated A-Series, it would not be much an A-Series in the same way the B-OHC prototype and O-Series were not much like the B-Series (the latter let's not forget was capable of growing from 1798cc to 1998cc as early as the mid-1960s).

Edited by Mite, 23 July 2019 - 11:10 PM.

[Ethel]

I don't think the push rods were a mistake. The valves are where they needed to be make the most of the induction and exhaust tracts with only 5 ports. Without making the engine bigger than it needed to be, rockers across the head to pushrods on the other side makes sense. Besides, they had a Triumph badged 1300 engine like that available.

 

BL could have done lots, but there'd have been no point commercially. The A Series was good enough for the models it was in and they had bigger engines for where they were needed. If you bought a 1300 Allegro or Marina, it was about pounds & pence not  performance.