One of the Percy Henley V8 Mandators from the Henley Transport thread:
gingerfold:
Just to resurrect this topic again, the latest AEC Bulletin (received on Friday 4th July) contains quite a bit about this engine and the politics within the Leyland empire that led to its demise. Written by Bob Fryars it can be taken as the definitive record as he was one of the senior engineering managers at firstly AEC and then Leyland. I haven’t digested all of it yet, but one interesting comment Mr Fryars makes concerns the cylinder bore and stroke dimensions. It appears that ■■■■■■■ had patented what they (and AEC) believed to be the optimum stroke / bore dimensions for a V8 diesel,
I’m no design engineer but in general it’s better to choose the stroke measurement first then apply that to it’s relationship to a decent overall capacity.In which case the bore size and bore stroke ratio will look after itself.
While I’d guess that anyone who intends to design a decent V8 wouldn’t regard a stroke measurement of much less than 6 inches,let alone less than 5 inches,as being ‘optimum’.On that basis it would have been worth paying ■■■■■■■ for showing anyone with any sense how not to design one. 
A precis of Bob Fryars’ article explaining the rationale and reasons for AEC developing a V8 engine.
- In 1961 “loose engine sales” were becoming a growing and important part of AEC’s business to other truck assemblers such as Guy, Dodge, and Seddon. ■■■■■■■ was also assidously courting these companies for their business. Guy Motors had gone bankrupt and been acquired by Jaguar. There was a plan being mooted for ■■■■■■■ engines to be manufactured in the former Meadows factory adjacent to Guy at Wolverhampton. AEC told Jaguar / Guy that it could match anything ■■■■■■■ could come up with.
- 1961 and talks between AEC and BMC about AEC becoming part of that group were well advanced. The lighter BMC truck range complemented the heavier AEC models.Such a grouping would result in economies of scale for a planned assault on European markets. AEC had discounted a link-up with Scania. The BMC car range in 1961 was ok by the standards of the time and the serious industrial relations problems that were to beset the group wer several years in the future. A high power V8 engine would also bring sales potential for a large group into the industrial engine market.
- Bob Fryars and Keith Roberts obtained the ■■■■■■■ V engine patents: - quote: - we found these cleverly covered the best cylinder bore to stroke ratios. To avoid the patents meant either a long stroke V engine or a squat over-square V engine. We quickly decided a V6 would be a very rough unit at the 90 degree V essential to fit in a chassis - and ruled out that option. So we were looking at a very over-square V8, one well outside any known direct injection combustion chamber relationship. Then there was the noise. Theo Priede, then at CAV, had recently come up with an empirical formula linking diesel engine noise emissions to the square of cylinder bore diameter and to rotational speed. An over-square diesel would be a very noisy unit. That only added to the difficulties./i]
To be continued after your comments
I had a quick look for those patents on the internet, without success. Perhaps Mr. Fryars could be persuaded to list the numbers of the patents? I bet that many of the successful V8s of the 1960s had bore/stroke ratios within the “best” range. I doubt that any of them paid a fee to ■■■■■■■■ more likely, they showed them two fingers, pointing predominantly upwards, subtended by an angle of no more than 90 degrees.
gingerfold:
A precis of Bob Fryars’ article explaining the rationale and reasons for AEC developing a V8 engine.3. Bob Fryars and Keith Roberts obtained the ■■■■■■■ V engine patents: - quote: - we found these cleverly covered the best cylinder bore to stroke ratios. To avoid the patents meant either a long stroke V engine or a squat over-square V engine. We quickly decided a V6 would be a very rough unit at the 90 degree V essential to fit in a chassis - and ruled out that option. So we were looking at a very over-square V8, one well outside any known direct injection combustion chamber relationship. Then there was the noise. Theo Priede, then at CAV, had recently come up with an empirical formula linking diesel engine noise emissions to the square of cylinder bore diameter and to rotational speed. An over-square diesel would be a very noisy unit. That only added to the difficulties./i]
To be continued after your comments
[/quote]
If I’ve read it right AEC’s engineers thought that the ■■■■■■■■ idea of an under 5 inch stroke was ‘optimum’and in addition to making such a mistake ■■■■■■■ then decided to patent it.
Which then left the choice of going for the right idea of a longer stroke,which is what was needed,or an even shorter one to get round the ‘patent’ thereby compounding the mistake which ■■■■■■■ had already made.You couldn’t make all this up.
…continued
Bob Fryars and Keith Roberts had decided that within the parameters dictated by design constraints their V8 was going to be a challenge. John Bowley, AEC’s General Manager, proposed a compromise. To deal with technical aspects a short stroke in-line research engine was made. The V8 would only proceed after results from said research engine had been analysed and after checking that a production V8 could be fitted under BMC’s new FJ cab, which it apparently did, and by late Spring 1962 Mr. Bowley had his V8 “brochure”.
Now we need to park the V8 in 1962 and record some fascinating information that as far as I am aware has never been in the public domain before. 1961 and into 1962 was a bad year for the Uk motor industry and economy. Late in 1961 Rolls Royce suggested a tripartite arrangement with ACV (AEC’s Group Company). This was soon discounted and talks were resumed with BMC in 1962 with a good chance of a successful outcome. Then because BMC posted some grim financial results AEC felt that discussions with BMC had to be suspended. This left AEC with serious future policy issues. Very reluctantly the ACV / AEC Board felt that they had no option but to pursue the Leyland Motor Corporation. But the very senior AEC heirarchy was probably not aware that Leyland was in danger of going bankrupt because it had bought Standard Motors and that company was in such dire straits that it threatened to bring Leyland down. Chrysler Motors was now intending to buy a controlling shareholding of the Leyland Motor Corporation. Stanley Markland from Leyland was parachuted into Standard Motors to effect a turn round, just as he had done at Albion some years before. All existing senior management at Standard was fired. Stanley Markland offloaded high stocks of cars into the market at high discounts and as a result reduced losses. A reduction in purchase tax in 1962 also boosted car sales. With the situation at Standard improving by June 1962 Leyland was able to refuse Chrysler’s offer, and Sir Henry Spurrier at Leyland then began to consider AEC’s approach to Leyland. It is believed that up to then he had not seriously considered such a merger with Leyland’s closest rival. At senior management level with AEC (not board level, but at Bob Fryars’ level), there was incredulity that this merger had even been proposed. Those running AEC on a day to day basis knew that Leyland’s range was overweight, overpriced, uncompetitive, and sales were in decline. They also knew that there was serious customer dis-satisfaction with Leyland’s Sales and Service organisation both at home and abroad.
To be continued…
[zb]
anorak:
I had a quick look for those patents on the internet, without success. Perhaps Mr. Fryars could be persuaded to list the numbers of the patents? I bet that many of the successful V8s of the 1960s had bore/stroke ratios within the “best” range. I doubt that any of them paid a fee to ■■■■■■■■ more likely, they showed them two fingers, pointing predominantly upwards, subtended by an angle of no more than 90 degrees.
It’s all about the stroke ‘measurement’ not the bore stroke ratio which is just an effect of what overall capacity is chosen with the ‘right’ stroke.IE the ‘right’ stroke is a given the ‘ratio’ of that measurement to the bore size will then just be a reflection of what type of overall capacity is used with it.It’s obvious that the worst of all worlds situation of what happens when a too small stroke measurement is chosen from the start.Let alone when it’s combined with a too small overall capacity limit.Which is why the Scania V8,let alone the Cat 3408 or Fiat V8, were better than the ■■■■■■■ 903,let alone the AEC V8.
Because of the quantity of information, scans, schemes, drawings…I gave input on the oversquare on the “■■■■■■■■■■■■■■■■
The saga continues…
With AEC and Leyland “merged” in August 1962, Donald Stokes, who was Sir Henry Spurrier’s acolyte was heard to say at a board meeting “this was no merger. We (Leyland) have taken over AEC and we shall soon feel the benefit”. Stanley Markland and Donald Stokes were appointed to the AEC Board, and John Bowley briefed them about AEC’s plans and product development. He handed over his V8 ‘brochure’, but at that stage the AEC V8 was a shelved project and nothing more was done about it for a couple of years. At about the same time that the V8 project was instigated AEC had commenced development work on its 690 and 470 engines for future higher power needs. Under AEC projects 760 and 520 respectively they were changed from wet to dry liner engines. John Bowley and Bob Fryars gave a presentation about these new engine developments to Leyland’s Designs Policy Committee. Markland approved the 760 development programme, and altered the 520 to a reduced bore version that became the 505.By then Sir Henry Spurrier was terminally ill and nominated Sir William Black as his successor, with Donald Stokes as Corporate Managing Director. Stanley Markland resigned. At this stage the AEC V8 engine was a moribund project with no interest in proceeding with it at either Southall or Leyland because there was no envisaged requirement for it. AEC’s 760 would fulfill projected power output needs for maximum gvw Southall built vehicles for the forseeable future and the 505 would satisfy mid-weight range needs for the next decade or so. Unbeknown to anyone but himself and one other, Donald Stokes had a top secret engine development programme in mind at Leyland that would take the industry by storm when it came to fruition.
To be continued…
It seems obvious that the UK manufacturing industry needed to be working on the 6 cylinder haulage market sector not bothering with trying to push compromised V8’s into it.On that basis a merger between AEC and Rolls might have had a much happier ending. 
gingerfold:
The saga continues…
… He handed over his V8 ‘brochure’, but at that stage the AEC V8 was a shelved project and nothing more was done about it for a couple of years. At about the same time that the V8 project was instigated AEC had commenced development work on its 690 and 470 engines for future higher power needs…
If the project started in 1961, leading to the first sales in 1968, its two years on the shelf means that they only had about five years in which to do it. In comparison, the Scania V8 took from 1962 to 1969- seven years’ (assumed) continuous work. This must be a factor in the relative successes of the two jobs.
By the way, thanks for these contributions- clubs like REVS and the AEC Society seem to be very good at teasing the people who know out of the woodwork.
[zb]
anorak:gingerfold:
The saga continues…
… He handed over his V8 ‘brochure’, but at that stage the AEC V8 was a shelved project and nothing more was done about it for a couple of years. At about the same time that the V8 project was instigated AEC had commenced development work on its 690 and 470 engines for future higher power needs…If the project started in 1961, leading to the first sales in 1968, its two years on the shelf means that they only had about five years in which to do it. In comparison, the Scania V8 took from 1962 to 1969- seven years’ (assumed) continuous work. This must be a factor in the relative successes of the two jobs.
By the way, thanks for these contributions- clubs like REVS and the AEC Society seem to be very good at teasing the people who know out of the woodwork.
The development prototypes seeded to Western Transport, Turners (Soham) Ltd. and Russell of Bathgate went on the road in 1966, but as we shall see as this saga unfolds it ended up very much as a rush job.
Regarding the issue bore/stroke measurements, I have dug out the details of oversquare V8 diesels of the 1960s, plus the 1975 Fiat. The engines are all in the 12-17 litre capacity range.
Mercedes, Scania, MAN and Berliet V8s were all undersquare.
The ■■■■■■■ engine is much more oversquare than the others. If that is what they considered the optimum ratio, and patented a range of sizes around those figures, then AEC were lucky that those sizes were unavailable to them. The AEC dimensions are closer to those of the successful Unic engine, than the disastrous VINE.
Alternatively, the ■■■■■■■ patent may well have protected less oversquare dimensions, but why would they then go on to build something outside those parameters? Why did Unic, or any of the others, not fall foul of the patent? The more likely scenario is that ■■■■■■■ patented the dimensions they used. This makes sense, as the original intention of the ■■■■■■■ V was for their V engines to compete with petrol engines on power to weight ratio, and a short-stroke, high speed engine would be the best option for that.
The notion that AEC were forced to grapple with unfavourable base engine dimensions is not backed up by any of the known history.
I’ve now put aside the thriller I was reading, as this thread is more exciting! Keep it up. Robert 
[zb]
anorak:
Regarding the issue bore/stroke measurements, I have dug out the details of oversquare V8 diesels of the 1960s, plus the 1975 Fiat. The engines are all in the 12-17 litre capacity range.
0
Mercedes, Scania, MAN and Berliet V8s were all undersquare.The ■■■■■■■ engine is much more oversquare than the others. If that is what they considered the optimum ratio, and patented a range of sizes around those figures, then AEC were lucky that those sizes were unavailable to them. The AEC dimensions are closer to those of the successful Unic engine, than the disastrous VINE.
Alternatively, the ■■■■■■■ patent may well have protected less oversquare dimensions, but why would they then go on to build something outside those parameters? Why did Unic, or any of the others, not fall foul of the patent? The more likely scenario is that ■■■■■■■ patented the dimensions they used. This makes sense, as the original intention of the ■■■■■■■ V was for their V engines to compete with petrol engines on power to weight ratio, and a short-stroke, high speed engine would be the best option for that.
The notion that AEC were forced to grapple with unfavourable base engine dimensions is not backed up by any of the known history.
On the basis that it’s all about the actual stroke ‘measurement’ not just the bore/stroke ‘ratio’ it’s obvious that the AEC is closer to the Vine’s measurement than it is the Unic’s.In which case the inherent problem that both the ■■■■■■■ and the AEC were dealing with was an engine which would have needed to be run at higher speed more of the time to be doing any useful work.Which also applied in the case of the ■■■■■■■ 903.All of which was obviously based on the flawed idea that power,based on multiplying less torque by more engine speed,is the same thing as power based on the idea of vice versa.Having said that there is a point where having more cylinders,such as a V8 with a relatively shorter stroke ‘can’ outweigh having less cylinders with a longer stroke,in terms of torque output.The idea in that case is to not be too over optimistic in looking for that ‘point’.Which seems to be where ■■■■■■■■ and AEC’s engineers went wrong in this case.On that basis the stroke measurement of the Unic/Fiat was more or less the absolute minimum required to make a V8 work.Which was then added to by also going for the larger bore size.
However the state of the art,in the modern day Scania 730 V8,says everything about the importance and advantage of going for the largest stroke measurement possible even at the expense of bore size thereby proving that the under square idea,together with going for a decent overall capacity,was the correct one all along.
Carryfast:
On the basis that it’s all about the actual stroke ‘measurement’ …blah blah blah…Which seems to be where ■■■■■■■■ and AEC’s engineers went wrong in this case.On that basis the stroke measurement of the Unic/Fiat was more or less the absolute minimum required to make a V8 work.Which was then added to by also going for the larger bore size.
^^^Absolute nonsense, all of it, completely.
The Perkins V8-510 engine had a 114mm stroke, just the same as the AEC, and that was a respected engine. There are more V8s with a similar stroke in this list:
groups.yahoo.com/neo/groups/Ame … topics/550
Continuing the saga…
So, Donald Stokes was lord and master of all he surveyed in his massive Leyland empire. Stanley Markland and Donald Stokes had vehemently loathed one another, and with Stokes being appointed top dog Markland had resigned in disgust. On Stokes instructions, and working in absolute secrecy, a Leyland engineer (I don’t think it is appropriate to name him) was tasked with designing a revolutionary new power unit. It was a ‘paired engine’, based on the Leyland L60 tank engine, using ‘throw-away’ cylinder blocks and gear driven auxiliaries to eliminate the need for belts. On Donald Stokes’ insistence the Leyland board of directors was railroaded into approving a massive capital expenditure for a new factory and manufacturing plant for producing the new engine. Capacity was to be 300 units per week.This was the 700 engine but when design prototypes were tested they disintegrated within hours of being run. Moreover it was a very heavy and unusual shape and these two factors prevented its installation in any Leyland bus or truck model, except for a bonneted Super Beaver. Oh dear, a disaster on a frightening scale was unfolding, so to save face Stokes instructed his Corporate Engineering Director, Dr. Fogg (ex-MIRA) to salvage something from this almighty shambles. The Ricardo consultancy was also enlisted to re-design the concept and eventually one of these heavily modified 700s was persuaded to run satisfactorily. But it was still too big to be installed in anything and Dr. Fogg had to conclude the 700 project was a dead duck. A smaller version to replace the existing Leyland O.400 would be too heavy and costly, so a comprise 500 engine eventually materialised after further input from Ricardo. This in naturally aspirated guise could produce up to 160-170 bhp, too small for a max. weight artic. Ricardo suggested a turbo-charged version to give more power but this required further structural strengthening. Up to then Leyland had always been opposed to turbo-charging road going engines. So how did this impact on the AEC V8 which had been moribund since 1962 and this was a couple of years later? AEC was instructed to urgently produce a concept paper to show a V8 installation under the new Leyland Ergomatic cab. Bob Fryars was promoted to Leyland in a very senior engineering role in 1966 and I quote him: - “What objective had Donald Stokes and Dr. Fogg in mind? I do not think we shall ever know for certain, since Stokes never put on paper a record of the verbal instructions he gave, Bertie Fogg would never, ever discuss the question. I had to assume that his job would be on the line if he ever breathed a word about this Stokes-inspired Leyland Motors disaster.” (i.e. the 700 engine).
…To be continued
Getting fixated on bore/stroke ratio is a useless exercise.
Rod length plays a huge part in engine design as does piston pin height.
From my observations, the short rod length was yet another compromise to physically fit an engine within the confines of chassis rails and the Ergo cab.
The whole dreadful tale, as related by the Gingerfold epistles, is an engineering disgrace.
[zb]
anorak:Carryfast:
On the basis that it’s all about the actual stroke ‘measurement’ …blah blah blah…Which seems to be where ■■■■■■■■ and AEC’s engineers went wrong in this case.On that basis the stroke measurement of the Unic/Fiat was more or less the absolute minimum required to make a V8 work.Which was then added to by also going for the larger bore size.^^^Absolute nonsense, all of it, completely.
The Perkins V8-510 engine had a 114mm stroke, just the same as the AEC, and that was a respected engine. There are more V8s with a similar stroke in this list:
groups.yahoo.com/neo/groups/Ame … topics/550
Leave it out.You can count the number of truly ‘respected’ V8 truck diesels on one hand and they all had a 5 inch + stroke measurement.While like the AEC and ■■■■■■■ range,the Perkins wasn’t one of them.Although having said that putting the thing in something like a 16 tonner,as opposed to a max weight artic,will obviously mask any inherent torque deficit.
While assuming it’s nonsense Scania would obviously have gone along the high engine speed short stroke route for it’s latest V8 range as opposed to vice versa.
cargo:
Getting fixated on bore/stroke ratio is a useless exercise.
Rod length plays a huge part in engine design as does piston pin height.
From my observations, the short rod length was yet another compromise to physically fit an engine within the confines of chassis rails and the Ergo cab.
The whole dreadful tale, as related by the Gingerfold epistles, is an engineering disgrace.
The fixation does seem to have been on package size, as discussed earlier in this thread. The suggestion that some combinations of dimensions were protected by patents seems like a smokescreen to cover up that mistake. I say “seems”- without reading the patents, we can only guess.