gazsa401:
A modern day 6ltr 220bhp powered puddle jumper wouldn’t have the same torque characteristics as a 220bhp Rolls 8 wheeler Scammell
‘Characteristics’,or ‘where’ the torque is produced in the engine speed range,aren’t the same thing as specific torque ( BMEP ) which is the same yardstick used to determine the efficiency of everything from a moped engine to a container ship engine.IE it’s just the overall ‘amount’ of torque divided by the overall capacity of the engine which will give the equivalent relevant answer in all cases applicable to all.
Specific torque or torque ratio is not the same thing as BMEP (a theoretical figure). Both are used to compare engines, it is just easier mathematically to use ST. If you divide the maximum torque output by the cubic capacity (the specific torque) for a Gardner 6lxb you get 538lbft /10.45 litres = 51.4 lbft per litre. Its BMEP is 127psi.
Comparing its in-period reasonably apple-like competitor the unblown ■■■■■■■ NHK 250, this has a specific torque figure of 46.7 lbft per litre. Its BMEP is 115psi. The 6lxb’s direct equivalent the 11 litre 6" stroke ■■■■■■■ NH 180 = 45.8lbft/litre
I was not aware that a short length of iron bar was easier to bend and more likely to fracture than a longer bit.
If specific torque isn’t mathematically related to BMEP then how do you explain the constant multiplier of specific torque x 2.464 = BMEP as I was always told as a school leaver ?.
As for the NA ■■■■■■■ the point I was making is that,unlike the Gardner or TL12,the 14 litre ■■■■■■■ easily contains ‘the ability’ to provide ‘both’ the requirements of ‘tolerance’ of sufficient cylinder pressures ‘and’ sufficient leverage at the crank to make around 80-130 lb/ft per litre.Apply that type of specific torque requirement to either the Gardner or 760/TL 12 then my bet is that you’ll end up with a blown engine in one way or another in either case just for different reasons.
As for the broken rod scenario caused by trying to use more cylinder pressure to compensate for lack of leverage at the crank,I think the description is shear under compression load,as the reputation of the ■■■■■■■ 903 at least seems to testify. Bearing in mind that the rod mostly transmits the loading in compression between piston and crank while the crank does the job of acting as the lever.IE a con rod doesn’t work under the same type of loading and stresses as a wheel brace or breaker bar.Especially in the high torque requirement environment of heavy truck engines.
gingerfold:
I’m really pleased that I brought Gardner into the melting pot. It’s livened the discusiion up somewhat.
Sorry for going off at a tangent. I just don’t like to see such a prestigous engine manufacturer being labelled as a ‘boat anchor’ builder and will always fight in their corner! Times changed, they didn’t, simples!
gingerfold:
I’m really pleased that I brought Gardner into the melting pot. It’s livened the discusiion up somewhat.
Sorry for going off at a tangent. I just don’t like to see such a prestigous engine manufacturer being labelled as a ‘boat anchor’ builder and will always fight in their corner! Times changed, they didn’t, simples!
gingerfold:
I’m really pleased that I brought Gardner into the melting pot. It’s livened the discusiion up somewhat.
Sorry for going off at a tangent. I just don’t like to see such a prestigous engine manufacturer being labelled as a ‘boat anchor’ builder and will always fight in their corner! Times changed, they didn’t, simples!
Pete.
The problem wasn’t that ‘times changed’ it was that Gardner and more importantly in this case AEC,didn’t foresee those changes in time,to build the required redundancy,into their designs,to meet those changes before they took place.Unlike ■■■■■■■■
gingerfold:
I’m really pleased that I brought Gardner into the melting pot. It’s livened the discusiion up somewhat.
Sorry for going off at a tangent. I just don’t like to see such a prestigous engine manufacturer being labelled as a ‘boat anchor’ builder and will always fight in their corner! Times changed, they didn’t, simples!
Pete.
The problem wasn’t that ‘times changed’ it was that Gardner and more importantly in this case AEC,didn’t foresee those changes in time,to build the required redundancy,into their designs,to meet those changes before they took place.Unlike ■■■■■■■■
gingerfold:
I’m really pleased that I brought Gardner into the melting pot. It’s livened the discusiion up somewhat.
Sorry for going off at a tangent. I just don’t like to see such a prestigous engine manufacturer being labelled as a ‘boat anchor’ builder and will always fight in their corner! Times changed, they didn’t, simples!
Pete.
The problem wasn’t that ‘times changed’ it was that Gardner and more importantly in this case AEC,didn’t foresee those changes in time,to build the required redundancy,into their designs,to meet those changes before they took place.Unlike ■■■■■■■■
The man has a very valid point there.
No matter whether Gardner,■■■■■■■■■■■■■■■■■ Royce Detroit or any other engine manufacturer had moved with the times you still can’t have any of the above fitted in a new lorry
gazsa401:
No matter whether Gardner,■■■■■■■■■■■■■■■■■ Royce Detroit or any other engine manufacturer had moved with the times you still can’t have any of the above fitted in a new lorry
We know that Leyland Trucks Division was mostly already a major in house manufacturer not an assembler.Which obviously already put it in the position of meeting the increasing moves towards the ‘vertical inetegration’ buzzword as in the case of Volvo,Scania and Mercedes.The downside of vertical integration being that if you’ve got a major lemon in the in house component line up it has the potential to create havoc to the operation’s viability.Let alone in this case 3 lemons in the form of the AEC V8,Leyland 500,and arguably the 760/TL12.Added to which was the lack of a credible cab design v its foreign in house competitors.Added to which was the problem of being lumbered with BMC Group blowing whatever cash reserves the Group had.
Having said that it would be fair to say that even today a lot of the ‘vertically integrated’ in house engine design contains a lot of technology provided from many different wide spread sources.Which are sometimes then consolidated into the Group.
On that note Detroit,for one example,is now consolidated into the Daimler empire but can still be ordered on an outsourced engine basis by operations like Western Star in addition to the choice of ■■■■■■■■
Carryfast:
The problem wasn’t that ‘times changed’ it was that Gardner and more importantly in this case AEC,didn’t foresee those changes in time,to build the required redundancy,into their designs,to meet those changes before they took place.Unlike ■■■■■■■■
The man has a very valid point there.
Having said that maybe AEC did foresee the changing times ahead but seem to have ended up in an internal engineering argument regarding the best way to meet them.IE the type of power that’s made by multiplying relatively less torque by relatively more engine speed or vice versa.Resulting in the split in thinking along the lines of the relatively high speed low torque AEC V8 idea v those who walked away and designed the Rolls Eagle instead.
If that’s what happened it really is unbelievable how the decision,to not ditch the V8 and the 760 ideas and then build a clean sheet 13 litre design along similar lines as the eventual Rolls Eagle instead,came about.
No guesses which side I’d have been on in that argument.
robert1952:
The talk of buying out Rolls Royce earlier, reminded me that I used to think it was a shame that Rolls Royce didn’t build their own lorries. If they’d built a strong chassis in the early-ish '70s and put their Eagle 290 or 305 in it, they could have used the tall version of the Motor Panels Mk 4 cab, worked out a way of tilting it (like ERF did) and given it a rugged but majestic-looking front end. It could have had the split-windscreen of the Crusader and the full sleeper depth (like the ERF 7MW and French Mack). The interior cab quality could have been based on Continental practise (as the 7MW was). The centre-piece of the Crusader grille leant itself perfectly to the incorporation of a proper ‘exposed’-style Rolls Royce radiator, which might have looked slightly dated if regal, but then the Atkinson Borderer had a similar radiator well into the '70s when the SA400 came along. Then just add a decent sun-visor (for the export and ‘colonial’ look) and make sure that it exudes a bit of affordable quality (like Volvo did) and hey-presto: there you have your Rolls Royce Oriental, ready to hit the 1973 Brussels Show and the TIR-trail!
Good, now I’ve got that off my chest, I’ll go back to bed. Nighty-night! Robert
Well here’s an entertaining surprise! Bennku read my daft fantasy about Rolls Royce lorries and posted this drawing on his thread. Note the leather seats. It’s exactly as I visualised it, so well done Benkku!
If AEC were backward thinking why were they trying to develop an engine in the mid 60s that would develop 247bhp to 280bhp +. Surely it would have been easier just to carry on with the AV760 and wait for the inevitable . The reason BL failed was they created a monster that was uncontrollable coupled to mass losses from the car side and two major engine design failures, add to that a dip in quality control a lack of forward planning and one of the main reasons a total loss of confidence from some (not all) customers . And lets not forget the bad publicity from industrial action which occured on a weekly basis,and also the money ploughed into the gas turbine project , so add to that lot bad management and i think ive answered my own question .
ramone:
If AEC were backward thinking why were they trying to develop an engine in the mid 60s that would develop 247bhp to 280bhp +. Surely it would have been easier just to carry on with the AV760 and wait for the inevitable . The reason BL failed was they created a monster that was uncontrollable coupled to mass losses from the car side and two major engine design failures, add to that a dip in quality control a lack of forward planning and one of the main reasons a total loss of confidence from some (not all) customers . And lets not forget the bad publicity from industrial action which occured on a weekly basis,and also the money ploughed into the gas turbine project , so add to that lot bad management and i think ive answered my own question .
Meanwhile Rolls Royce put an engine into production ‘in the mid-late 1960’s’ that would ultimately develop a reliable 300 + hp.While AEC also seemed to be putting too much emphasis on potential overall power outputs at the expense of engine speed and not enough on specific torque in the case of the V8 and arguably the 760.
As for carrying on with the 760 and waiting for the inevitable isn’t that exactly effectively what the TL12 was a case of.
Exactly which parts of the car side were under ‘weekly industrial action’ during those make or break years of the late 1960’s/early 70’s ?.Which effectively left Leyland Trucks as an in house manufacturer without a decent in house engine to put in the T45.
Hi Mark. Back in the year 2000, Western Star had a big push down in the States. Terry Peabody? was running the show then and had already purchased ERF in the U.K. They, Western Star had this road tour of the truck-stops and dealerships going on.
I took a test drive in would it of been a Constellation? tractor unit. Oh my god what a piece of junk, it was like driving an Atki Border of 1975 vintage.
I couldn’t wait to get back into my Volvo VN with a ■■■■■■■ 15l ISX, which at that time was less than a month old.I can’t remember what motor the Western Star had in it, but it was prior to the buy out by Freightliner. Iirc the Ford deal was about the same time.
We have a Sterling with a C10 Cat at our place and its a real dog!
newmercman:
Carryfast, Western Star is part of the Daimler AG empire too! The only loose engine available in Nth America is the ■■■■■■■■
Thanks for that clarification.Blimey it’s ironic that history seems to be repeating itself in that case regarding the contradiction between an in house manufacturer using outsourced engines ?.Although in that case there surely can’t be any issues or possible questions concerning the competitiveness of the in house option v the ■■■■■■■■■■■■■■ in the case of the Bedford TM or T45.To the point where the question must be why bother offering the choice and thereby losing the economies of scale in just offering the in house product or nothing.
Although having said that to answer Gazsa’s comments ■■■■■■■ is obviously still there.
Not by any yardstick of judgement of any criteria of performance, operational or running costs, of any of Leyland 0.600, 0.680, 0680 Power Plus and AEC AV690, AV760, or AEC / Leyland TL12 engines be considered a failure or not fit for purpose in the years they were in service. They more than held their own with any comparable engine manufacturer of the same period, that is 1950s to 1970s. Whilst there were future potential development issues for engines within the Leyland Group it does not alter the fact that in the best days of Leyland Motors, and its later grouping constituents these were good engines and I will not accept the needless and unjustified denigration of these engines.
I guess where paccar a global player with daf using the mx in Europe plus possible plant or static engine uses they can sell more than enough engines to make it pay plus I’d imagine the ■■■■■■■ is an extra cost option so many big company’s will stick with the standard offering so longs ad it’s fairly reliable and offers decent mpg.
Same as freight liner offering the dd engines which are also used in mercedes at euro 6
gingerfold:
Not by any yardstick of judgement of any criteria of performance, operational or running costs, of any of Leyland 0.600, 0.680, 0680 Power Plus and AEC AV690, AV760, or AEC / Leyland TL12 engines be considered a failure or not fit for purpose in the years they were in service. They more than held their own with any comparable engine manufacturer of the same period, that is 1950s to 1970s. Whilst there were future potential development issues for engines within the Leyland Group it does not alter the fact that in the best days of Leyland Motors, and its later grouping constituents these were good engines and I will not accept the needless and unjustified denigration of these engines.
As Tomdhu rightly said any designer with any sense allows a decent margin ( redundancy ) for future development.That’s in order to save the crippling costs of having to go for totally clean sheet designs on a frequent basis.That plainly didn’t happen in the case of the 760 which clearly needed to be a clean sheet design far away from the 690/1 with that margin in mind.On that note no it wasn’t ‘fit for purpose’ in the way that the Rolls Eagle was or even the Leyland 680.The Rolls also being on the drawing board and put into production at more or less a similar point in time as the 760.Let alone the 14 litre ■■■■■■■ which was an even better example of allowing plenty of margin for future development.
In addition to the even madder thinking behind the V8 which was an obviously confused attempt to apply F1 race engine thinking to heavy truck engineering.IE a high revving short stroke V8 was fine in the case of the Cosworth DFV but not a 32 t truck.
As for Leyland Group the relevant period is 1960’s to 1980’s with 60’s and early 70’s being the make or break period that determined the fate of the Group and when it needed to be looking further ahead into the future not backwards to the obsolete environment of the 1950’s.On that note,as I’ve said,the bonkers thinking,which seemed to apply at AEC,can’t be underestimated in its contribution to the fall of Leyland Trucks Division.
Bearing in mind that the rod mostly transmits the loading in compression between piston and crank while the crank does the job of acting as the lever.IE a con rod doesn’t work under the same type of loading and stresses as a wheel brace or breaker bar.Especially in the high torque requirement environment of heavy truck engines. 
I just don’t like to see such a prestigous engine manufacturer being labelled as a ‘boat anchor’ builder and will always fight in their corner! Times changed, they didn’t, simples! 
