Carryfast:
Ironically Ramone noticed it and said it not me.
I asked why the 12.47 litre L12 came out at 203bhp which wasnt spectacular , i mistakenly thought the TL12 was a turbo version of the AV760, this wasnt the case. The L12 i suspect was an olive branch for AEC customers which didn`t work . The L12 was a non turbo TL12 which more informed posters mentioned was the reason why the power was down due to several reasons lower engine speed being one and being designed as a turbo was another. The AV760 produced up to 220 bhp without a turbo , that was why i was puzzled to see the output of the L12. To compare the L12 to a TD120 is a strange one
I was comparing L12 with Rolls and ■■■■■■■ 220 and the TL12 with TD120 or turbo Rolls .In all cases the AEC’s torque deficit was the problem.
Carryfast:
Ironically Ramone noticed it and said it not me.
I asked why the 12.47 litre L12 came out at 203bhp which wasnt spectacular , i mistakenly thought the TL12 was a turbo version of the AV760, this wasnt the case. The L12 i suspect was an olive branch for AEC customers which didn`t work . The L12 was a non turbo TL12 which more informed posters mentioned was the reason why the power was down due to several reasons lower engine speed being one and being designed as a turbo was another. The AV760 produced up to 220 bhp without a turbo , that was why i was puzzled to see the output of the L12. To compare the L12 to a TD120 is a strange one
I was comparing L12 with Rolls and ■■■■■■■ 220 and the TL12 with TD120 or turbo Rolls .In all cases the AEC’s torque deficit was the problem.
The AV760 would have been the better comparison to the 220 ■■■■■■■ or Rolls , putting a 9 speed Fuller behind the 760 which was an option would have been a fairer match too but ive never seen a test of a 760 fuller combination . The 205/220 ■■■■■■■ were in production roughly the same time as the 760. The L12 was an afterthought of the TL12 ,Texaco for some reason specifying it in the Marathon. Like i mentioned earlier a lighter turbocharged version of the TL12 in my opinion would have been a better alternative.
newmercman:
It appears that the important part is the part I didn’t get.
Let’s get this right Leyland thinking.
We’ve got this great idea of using a fixed head motor it will allow us to use silly amounts of boost pressures without having to worry about head to block joint failures and bore distortion.
So massive amounts of torque and power at reduced rpm.
Thick Norvern accent great idea lad now we can make it an 8.2 litre motor instead of 10-12 and we’ll offer an NA version for good measure.
Lowly AEC apprentice says how is it that ■■■■■■■ and Rolls and now these bleedin upstart Swedes are getting more power and torque out a 12 litre motor than we can get from almost 12.5.Told to shut up and get on with making/getting the teas.
newmercman:
It appears that the important part is the part I didn’t get.
Let’s get this right Leyland thinking.
We’ve got this great idea of using a fixed head motor it will allow us to use silly amounts of boost pressures without having to worry about head to block joint failures and bore distortion.
So massive amounts of torque and power at reduced rpm.
Thick Norvern accent great idea lad now we can make it an 8.2 litre motor instead of 10-12 and we’ll offer an NA version for good measure.
Lowly AEC apprentice says how is it that ■■■■■■■ and Rolls and now these bleedin upstart Swedes are getting more power and torque out a 12 litre motor than we can get from almost 12.5.Told to shut up and get on with making/getting the teas.
On that basis how did Volvo get over 200hp out of a 6.7l and 320 out of a 9.6l when ■■■■■■■ needed 12.5 litre then 14 litres to achieve the same power
newmercman:
It appears that the important part is the part I didn’t get.
Let’s get this right Leyland thinking.
We’ve got this great idea of using a fixed head motor it will allow us to use silly amounts of boost pressures without having to worry about head to block joint failures and bore distortion.
So massive amounts of torque and power at reduced rpm.
Thick Norvern accent great idea lad now we can make it an 8.2 litre motor instead of 10-12 and we’ll offer an NA version for good measure.
Lowly AEC apprentice says how is it that ■■■■■■■ and Rolls and now these bleedin upstart Swedes are getting more power and torque out a 12 litre motor than we can get from almost 12.5.Told to shut up and get on with making/getting the teas.
What was the peak torque of the above-mentioned engines, please?
Interesting reading about the Buffalo, When I worked at Globe Petroleum we were waiting on a brand new Buffalo arriving from Our depot in Scunthorpe. The vehicle was loaded at Gunness Wharf and on its way to change over with our driver from Stirling. The engine on the Buffalo gave up on the way to Penrith and had to be towed back for repair. Once it eventually arrived at our depot in Stirling it had a another 2 engine replacements within a short period. After the 3rd engine we never had any more problems with the vehicle. Not long after the arrival of the Buffalo the Mammoth Major I had was replaced by a Bison and this vehicle never gave us any problems whatsoever. The Bison had the Fuller Roadranger 9 speed gearbox and was a perfect motor for the type of work we were doing.
We’ve got this great idea of using a fixed head motor it will allow us to use silly amounts of boost pressures without having to worry about head to block joint failures and bore distortion.
So massive amounts of torque and power at reduced rpm.
Thick Norvern accent great idea lad now we can make it an 8.2 litre motor instead of 10-12 and we’ll offer an NA version for good measure.
Lowly AEC apprentice says how is it that ■■■■■■■ and Rolls and now these bleedin upstart Swedes are getting more power and torque out a 12 litre motor than we can get from almost 12.5.Told to shut up and get on with making/getting the teas.
On that basis how did Volvo get over 200hp out of a 6.7l and 320 out of a 9.6l when ■■■■■■■ needed 12.5 litre then 14 litres to achieve the same power
■■■■■■■ actually ended up with 525 hp from 14 litres and Rolls/Perkins around 400 hp from 12.1 litres and both well over 320 hp along the way there at the time of the TL12 if we’re talking turbocharged ?.
As for 320 from 9.6 I’d doubt that it would be bought on the basis of its durability like the 500 bag of bolts.
Your own comment was logically all about L12 v comparable NA motors and as expected it came up short.Just like the TL12 that it was based on.
My own view is that the Rolls takes the honours here with TD120 a close second if not a tie around the 12 litre bracket and I think I’ve explained why.
newmercman:
It appears that the important part is the part I didn’t get.
Let’s get this right Leyland thinking.
We’ve got this great idea of using a fixed head motor it will allow us to use silly amounts of boost pressures without having to worry about head to block joint failures and bore distortion.
So massive amounts of torque and power at reduced rpm.
Thick Norvern accent great idea lad now we can make it an 8.2 litre motor instead of 10-12 and we’ll offer an NA version for good measure.
Lowly AEC apprentice says how is it that ■■■■■■■ and Rolls and now these bleedin upstart Swedes are getting more power and torque out a 12 litre motor than we can get from almost 12.5.Told to shut up and get on with making/getting the teas.
The Leyland 500 Series engine had to be down-sized to 8.2 litres because the original concept of 12 litres was a huge heavy lump that was too big to fit under any cab in existence in the early 1970s. The idea should have been scrapped at that stage of development.
gingerfold:
The Leyland 500 Series engine had to be down-sized to 8.2 litres because the original concept of 12 litres was a huge heavy lump that was too big to fit under any cab in existence in the early 1970s. The idea should have been scrapped at that stage of development.
Carryfast:
Lowly AEC apprentice says how is it that ■■■■■■■ and Rolls and now these bleedin upstart Swedes are getting more power and torque out a 12 litre motor than we can get from almost 12.5.Told to shut up and get on with making/getting the teas.
What was the peak torque of the above-mentioned engines, please?
600 lb/ft + so around 50 lb/ft per litre 220 ■■■■■■■ and Rolls v 570 lb/ft so around 46 lb/ft per litre for L12 ?.While around 220 hp at 2,100 rpm v 203 at 2,200 speaks for itself.
Carryfast:
Lowly AEC apprentice says how is it that ■■■■■■■ and Rolls and now these bleedin upstart Swedes are getting more power and torque out a 12 litre motor than we can get from almost 12.5.Told to shut up and get on with making/getting the teas.
What was the peak torque of the above-mentioned engines, please?
600 lb/ft + so around 50 lb/ft per litre 220 ■■■■■■■ and Rolls v 570 lb/ft so around 46 lb/ft per litre for L12 ?.While around 220 hp at 2,100 rpm v 203 at 2,200 speaks for itself.
TL12 v TD120 don’t even go there.
I thought the 240/250 ■■■■■■■ were out in force when the L12 was made available not the 205/220
gingerfold:
The Leyland 500 Series engine had to be down-sized to 8.2 litres because the original concept of 12 litres was a huge heavy lump that was too big to fit under any cab in existence in the early 1970s. The idea should have been scrapped at that stage of development.
That’s 40 inches high overall with a 6.3 inch stroke admittedly at a V angle + the need for a sump.
The only people who really know will have been the designers and development team, they got some things wrong but eventually produced an engine which worked, however by then confidence had been lost. As with the V8 if they had not been rushed into full scale production by management the outcome may well have been different . We shall never know.
Technical description of 500 engine from 1968, with the reasons for going for a fixed head design explained. The distance doesn’t look so dramatic when not viewed from an oblique angle. It is possibly to do with foundry issues with casting cooling pasages and the carry over from it being a much larger design initially. IIRC these engines used ‘pencil’ injectors whose cooling requirements would would have been a concern. Leyland seem to be wedded to its long standing ‘head deck’ design from the 600 and other engines and mounted the camshaft effectively on top of that. The apparent use of bucket tappets would necessitate material surrounding their bores for rigidity and direct operation would preclude the camshaft being offset. As for the DB601 it was designed for a service life lasting a matter of hours not several hundred thousand miles.
Edit: for what irrelevance it is worth the comparable ■■■■■■■ 8.3 CTA of roughly the same period is one inch taller 3 inches wider and 8 inches shorter in length than the Leyalnd 500.
Carryfast:
600 lb/ft + so around 50 lb/ft per litre 220 ■■■■■■■ and Rolls v 570 lb/ft so around 46 lb/ft per litre for L12 ?.While around 220 hp at 2,100 rpm v 203 at 2,200 speaks for itself.
TL12 v TD120 don’t even go there.
I thought the 240/250 ■■■■■■■ were out in force when the L12 was made available not the 205/220
The L12 seems to be a retro engineered NA version of the TL12 ?.
The fact that they then ended up with something inferior in output to the comparable 1959 220 ■■■■■■■ development, or for that matter the Rolls, says everything about the TL12’s deficiencies.
Which can be traced back specifically to the specific torque deficit.
Realistically the ( foreseeably ) too small capacity, over stressed, 500 and the torque challenged L12/TL12 were the final nails in Leyland’s in house engine production aspirations.
Carryfast:
600 lb/ft + so around 50 lb/ft per litre 220 ■■■■■■■ and Rolls v 570 lb/ft so around 46 lb/ft per litre for L12 ?.While around 220 hp at 2,100 rpm v 203 at 2,200 speaks for itself.
TL12 v TD120 don’t even go there.
I thought the 240/250 ■■■■■■■ were out in force when the L12 was made available not the 205/220
The L12 seems to be a retro engineered NA version of the TL12 ?.
The fact that they then ended up with something inferior in output to the comparable 1959 220 ■■■■■■■ development, or for that matter the Rolls, says everything about the TL12’s deficiencies.
Which can be traced back specifically to the specific torque deficit.
Realistically the ( foreseeably ) too small capacity, over stressed, 500 and the torque challenged L12/TL12 were the final nails in Leyland’s in house engine production aspirations.
So on that basis why did ■■■■■■■ need over 14 litres to produce 270 bhp when the TL12 was producing 273 from 12.47 and Volvo up to 360 bhp with a 9.6 all pretty irrelevant to me , its how the reliability fuel consumption and performance figures stack up
AV691 AV760 would have been more comparable to the 220 ■■■■■■■ which i thought entered the Uk in 180/205/220 hp
All very strange and fancy that, it must have been done by smoke and mirrors rather than leverage: Volvo managing to achieve greater output figures with almost exactly the same cylinder dimensions as the smaller AEC AV 590. This isn’t the final version of the TD100 series either. There’s more than one way to kill a cat. It’s called development tuning, with the aim of improving efficiency.
ramone:
So on that basis why did ■■■■■■■ need over 14 litres to produce 270 bhp when the TL12 was producing 273 from 12.47 and Volvo up to 360 bhp with a 9.6 all pretty irrelevant to me , its how the reliability fuel consumption and performance figures stack up
AV691 AV760 would have been more comparable to the 220 ■■■■■■■ which i thought entered the Uk in 180/205/220 hp
At the end of the day Leyland ended up with an almost 12.5 litre motor putting out less power and torque than a smaller capacity 1959 ■■■■■■■ development.As you rightly suggested yourself.
It’s inconcievable that they ended up with that output by choice as opposed to being forced to settle on that based on the durability equation.Because to meet the equivalent torque by definition had to come at the expense of pushing more load through the con rod v ■■■■■■■ or Rolls.
Just as the TL12 didn’t cut it v ■■■■■■■■■■■■■ in the Marathon and T45.
It’s obvious that ■■■■■■■ had no intention of upgrading to the 14 litre just to stay in the sub 300 hp bracket.Also bearing in mind that the 743 and 855 were actually produced concurrently with the 220 development introduced after the first larger bore 855 was made.
While the NFC engineers’ valid comments are the smoking gun in all cases regarding trying to get a quart out of a pint pot.
In which case we can arguably disregard sub the 10 litre category as being inherently flawed being too small and therefore over stressed.Obviously relatively less so in the case of the Volvo than the Leyland 500.Also confirmed by Gingerfold’s correct view that the 500 should have been discarded from the start.
While AEC’s leverage at the crank limitations crippled Leyland’s essential need to trump ■■■■■■■ and Rolls and the TD120 if it wanted to maintain an in house engine programme.
The modern day Paccar MX 11’s and 13’s 123 x 152 and 130 x 162 architecture is where Leyland needed to be before the introduction of the T45.At which point we’re in business.
cav551:
All very strange and fancy that, it must have been done by smoke and mirrors rather than leverage: Volvo managing to achieve greater output figures with almost exactly the same cylinder dimensions as the smaller AEC AV 590. This isn’t the final version of the TD100 series either. There’s more than one way to kill a cat. It’s called development tuning, with the aim of improving efficiency.
The fact that Volvo saw the need for the TD120 in addition to TD100.
Or that AEC obviously wanted the 760 in addition to 590.
Or the comparable architecture of Rolls and ■■■■■■■ and TD120, and finally the comparison of MX11 with DAF DK, or MX 13 with ■■■■■■■ N14 and there doesn’t seem to be an MX8, all suggests that size matters and leverage matters even more.
Who said give me a long enough lever I can move the world.
