I believe the 15.2 litre CAT C15 ACERT engines have 4 bolt big ends. It’s a stroked version of the 14.6 litre 3406/C-15. I may be wrong and it’s the main bearing caps, but it’s the engine of choice for those that want serious HP, oh and before you get too excited they also use 17 litre cylinder kits which must cancel out the longer stroke advantages.
Apparently the sled pullers can go a full season without tearing it apart at up to 1500hp. God knows what the BMEP and cylinder pressures are on those.
newmercman:
I believe the 15.2 litre CAT C15 ACERT engines have 4 bolt big ends. It’s a stroked version of the 14.6 litre 3406/C-15. I may be wrong and it’s the main bearing caps, but it’s the engine of choice for those that want serious HP, oh and before you get too excited they also use 17 litre cylinder kits which must cancel out the longer stroke advantages.
Apparently the sled pullers can go a full season without tearing it apart at up to 1500hp. God knows what the BMEP and cylinder pressures are on those.
Two bolt mains and four bolt end caps there. Although it’s obvious that the two mains bolts are worth more than the 4 small big end cap bolts so I guess my theory holds. youtube.com/watch?v=y-8Xm_zFWnY 1.10
Two bolt mains not 4, or cross bolted, seems to be the general choice for big truck diesels.
But logically tensile forces acting on the piston and rod assembly are greatest at max rated engine speed and the changeover between exhaust and induction strokes ?.
While don’t really see the connection between that and BMEP or buy the idea of max cylinder pressures only being 2 x BMEP.
As for the big bore kits the actual leverage side of the torque equation will still be there as before and even the larger bore at 17 litres still provides a similar bore stroke ratio as the Rolls and TD120.
But I’d doubt if they would use the bigger bore kit with the previous 14.6 165 mm stroke, which would still be closer to the Rolls’/ TD120’s than the TL12’s ratio.
A haulage company owner who was a highly skilled engineer once explained engine design in very simple terms to me.
There is a finite number of combinations of stroke and bore dimensions that will achieve a required cubic capacity and these are determined by the performance requirements of the designer. That is do you want a high revving “goer” or a slow revving “lugger”.
The longer the stroke the lower the maximum rpm.
This man was recalled to the RAF in WW2 to recondition RR Merlin engines.
No one has yet mentioned a very cheap and easy modification that was applied to many engine designs in the early 1960s when engines of ALL makes started to suffer bottom end failures after prolonged maximum revs running on the new, and growing, Motorway network. Who is going to cotton on to this instead of spouting on about having to do a complete re-design of engines to reduce stress loadings.
The AEC 142 mm stroke dimension dated back to the 8.8 litre engine of 1936. If AEC designers, including the giants of engine design named by CAV551, had wanted to change the length they had ample opportunities to do so in subsequent engine designs. The 8.8 litre had separate cylinder block and crankcase; later engines were monoblock designs, so the castings required for the engine was never a determining factor. Again, CF’s complete lack of knowledge about AEC is displayed.
ramone:
You mention the Pacaar MX a relatively new engine that didn’t even exist when AEC were in their pomp.
No but the Mack 673 was introduced at the same time as the TL12.The inference being that the Mack’s type of specific output was where AEC’s designers wanted/intended to be with the TL12.
I don’t/can’t believe that AEC’s designers thought for one minute that they were going to get it from the TL12’s bore stroke ratio which is the basis of the comparison with the MX.
So why mention the MX which was introduced years later . Why did Volvo bother with the 12 litre engine in the early '70s they should have just built the 13 litre instead same with Scania and their 14 litre V8 they should have saved loads of time and money and gone straight to the 16 litre. It’s called research and development with new techniques added into the mix. Leyland wanted a new engine to be able to compete with the competiton. They couldn’t afford to build something new from scratch so the only in-house engine available and suitable was the AV760. What part of this so far don’t you understand , i’m writing it slow because i know you can’t read fast.
The TL12 was produced and gave very little trouble in service , was a good performer and was economical , what more would you require from an engine, yes you keep banging on about totally irrelevant engines of similar size that produced more power , so what. Did the TL12 do what it was produced to do … yes it did and it did it quite well too.
No CF, the big bore kits will go in the 14.6, but I’m not aware of anybody that’s done one, they all use the 15.2 which as you know is the stroked version using the longer throw C16 crankshaft, so there’s that free leverage you’re talking about. Although factory specs on both engines were the same, anything from 435/1650 to 600/2050.
gingerfold:
A haulage company owner who was a highly skilled engineer once explained engine design in very simple terms to me.
There is a finite number of combinations of stroke and bore dimensions that will achieve a required cubic capacity and these are determined by the performance requirements of the designer. That is do you want a high revving “goer” or a slow revving “lugger”.
The longer the stroke the lower the maximum rpm.
This man was recalled to the RAF in WW2 to recondition RR Merlin engines.
It’s possible to take that to its logical conclusion that it’s possible for the ’ slow revving lugger’, to produce more specific power at lower rpm than the ‘high revving goer’ produces at higher rpm.Just like the 12.1 litre Eagle v the 12.4 litre TL12.
It’s more a comparison of do you want to make more power by multiplying more torque by less engine speed or vice versa.Assuming the former you obviously can’t ignore the advantage of leverage in that equation.
Why wouldn’t you want the slow revving lugger in a heavy truck.
Carryfast:
No but the Mack 673 was introduced at the same time as the TL12.The inference being that the Mack’s type of specific output was where AEC’s designers wanted/intended to be with the TL12.
I don’t/can’t believe that AEC’s designers thought for one minute that they were going to get it from the TL12’s bore stroke ratio which is the basis of the comparison with the MX.
So why mention the MX which was introduced years later . Why did Volvo bother with the 12 litre engine in the early '70s they should have just built the 13 litre instead same with Scania and their 14 litre V8 they should have saved loads of time and money and gone straight to the 16 litre. It’s called research and development with new techniques added into the mix. Leyland wanted a new engine to be able to compete with the competiton. They couldn’t afford to build something new from scratch so the only in-house engine available and suitable was the AV760. What part of this so far don’t you understand , i’m writing it slow because i know you can’t read fast.
The TL12 was produced and gave very little trouble in service , was a good performer and was economical , what more would you require from an engine, yes you keep banging on about totally irrelevant engines of similar size that produced more power , so what. Did the TL12 do what it was produced to do … yes it did and it did it quite well too.
I mentioned the MX because it followed the same bore stroke ratio as the Maxidyne.Which was a 1973 introduced design the same as TL12.
Leyland needed a new engine to compete with the competition.
It was obviously there from the start in the form of the Rolls Eagle.Already in use by Scammell.Which just left the need to bring Rolls diesel engines ‘in house’ by a government funded takeover.
The rest is history.
That does actually make sense, the 265 Rolls did very well in the ERF in the TRUCK test matches and would’ve been a like for like swap for the TL12, the 290 and 320 available to keep in reach of the competition, both Leyland and RR were propped up by GB Ltd and would’ve been a perfect match.
The basic design had lots of life in it from the 1960s original naturally aspirated version through to the 1990s turbo intercooled version. It even powered the highest hp Roadtrain in 340 hp form. A wasted opportunity with disastrous consequences.
Carryfast:
I’ll now await Anorak to provide the figures showing that piston/con rod assembly inertial loads are relevant …
Do your own ■■■ calculations. It’s your assertions that are under scrutiny, against amassed factual evidence and experience. Most “design” people do their calcs before drawing conclusions.
Why is my username in the thread title? It is not my habit to present myself as a mirror for morons.
gingerfold:
A haulage company owner who was a highly skilled engineer once explained engine design in very simple terms to me.
There is a finite number of combinations of stroke and bore dimensions that will achieve a required cubic capacity and these are determined by the performance requirements of the designer. That is do you want a high revving “goer” or a slow revving “lugger”.
The longer the stroke the lower the maximum rpm.
This man was recalled to the RAF in WW2 to recondition RR Merlin engines.
It’s possible to take that to its logical conclusion that it’s possible for the ’ slow revving lugger’, to produce more specific power at lower rpm than the ‘high revving goer’ produces at higher rpm.Just like the 12.1 litre Eagle v the 12.4 litre TL12.
It’s more a comparison of do you want to make more power by multiplying more torque by less engine speed or vice versa.Assuming the former you obviously can’t ignore the advantage of leverage in that equation.
Why wouldn’t you want the slow revving lugger in a heavy truck.
We’re talking of engines of 50 and more years ago, bear that in mind. Personally, and it’s only personal preference from a driving perspective, I preferred the higher revving “goer” than the lower revving “lugger”. Whilst I could understand the characteristics, and reasons for them, of a Gardner engine, I detested driving a Gardner engine lorry. We had two ERF’s with Gardner 180s at Mothers Pride Wigan. One had a 6-speed DB gearbox, the other had an ENV 10-speed range change, which did get the Gardner performing better in my opinion. I much preferred an AEC or Leyland engine for my driving style, which as a young man was not to hang about.
Fast forward to today and the modern truck engine does all its work in a very narrow band of revs, a totally different concept to the era we’re debating (or trying to debate). A few Sundays ago I had a ride out with new driver to help him load and tip a flour tanker. We took a 69 plate DAF XF 450, and firstly it was so quiet and comfortable it has to be experienced to be believed, and secondly, loaded to 43,820 kgs it just kept going without any fuss or bother. It even came up Keele bank on the M6 without needing to drop a gear. The modern diesel engine is a wonderful piece of engineering and no doubt, valuable experience and lessons have been learnt from 50 and more years ago, and subsequently, to get it where it is today.
Carryfast:
No but the Mack 673 was introduced at the same time as the TL12.The inference being that the Mack’s type of specific output was where AEC’s designers wanted/intended to be with the TL12.
I don’t/can’t believe that AEC’s designers thought for one minute that they were going to get it from the TL12’s bore stroke ratio which is the basis of the comparison with the MX.
So why mention the MX which was introduced years later . Why did Volvo bother with the 12 litre engine in the early '70s they should have just built the 13 litre instead same with Scania and their 14 litre V8 they should have saved loads of time and money and gone straight to the 16 litre. It’s called research and development with new techniques added into the mix. Leyland wanted a new engine to be able to compete with the competiton. They couldn’t afford to build something new from scratch so the only in-house engine available and suitable was the AV760. What part of this so far don’t you understand , i’m writing it slow because i know you can’t read fast.
The TL12 was produced and gave very little trouble in service , was a good performer and was economical , what more would you require from an engine, yes you keep banging on about totally irrelevant engines of similar size that produced more power , so what. Did the TL12 do what it was produced to do … yes it did and it did it quite well too.
I mentioned the MX because it followed the same bore stroke ratio as the Maxidyne.Which was a 1973 introduced design the same as TL12.
Leyland needed a new engine to compete with the competition.
It was obviously there from the start in the form of the Rolls Eagle.Already in use by Scammell.Which just left the need to bring Rolls diesel engines ‘in house’ by a government funded takeover.
The rest is history.
At the time that the TL12 was developed , the early 70s the Rolls 220/280 were not the best so why would Leyland take on an engine that was unreliable and thirsty when they already had 2 failures on their books . It wasnt until later on when the 265/290 Rolls were introduced that their reputation improved. The history states that Rolls are no more
Could you state what the TL12 problems were in service not what the future development shortcomings were , it could be interesting
^^^^^^
As has been stated by more than one poster the early RR 220 Eagle was unreliable and thirsty. Unfortunately CF will not accept that this is true. You are quite correct that later versions were much improved in terms of reliability and economy. Turning CF’s suggestion around then he is right, but he’s approaching it from the wrong direction. AEC did improve the RR engine by the input of AEC engine designer of many years experience, Keith Roberts. When the TL12 was proven and in production Keith, who had been lead engineer on the TL12 left AEC (Leyland) to join RR and improve and develop their Eagle based engines. So credit where credit is due to Keith Roberts and his AEC training and experience, he turned a dubious engine into a good one.
There you go CF, I agree with you about the RR engines from the mid-70s onwards.
gingerfold:
We’re talking of engines of 50 and more years ago, bear that in mind. Personally, and it’s only personal preference from a driving perspective, I preferred the higher revving “goer” than the lower revving “lugger”. Whilst I could understand the characteristics, and reasons for them, of a Gardner engine, I detested driving a Gardner engine lorry. We had two ERF’s with Gardner 180s at Mothers Pride Wigan. One had a 6-speed DB gearbox, the other had an ENV 10-speed range change, which did get the Gardner performing better in my opinion. I much preferred an AEC or Leyland engine for my driving style, which as a young man was not to hang about.
Fast forward to today and the modern truck engine does all its work in a very narrow band of revs, a totally different concept to the era we’re debating (or trying to debate). A few Sundays ago I had a ride out with new driver to help him load and tip a flour tanker. We took a 69 plate DAF XF 450, and firstly it was so quiet and comfortable it has to be experienced to be believed, and secondly, loaded to 43,820 kgs it just kept going without any fuss or bother. It even came up Keele bank on the M6 without needing to drop a gear. The modern diesel engine is a wonderful piece of engineering and no doubt, valuable experience and lessons have been learnt from 50 and more years ago, and subsequently, to get it where it is today.
The Gardner’s problem was more its capacity 10.45 l in a world of 50lb/ft per litre outputs.
The L12 actually went backwards regarding specific output v the 6 LXB.
While the 8 LXB with 9 speed Fuller seems like a good bet if it had to be NA on paper at least better than either ■■■■■■■ or Rolls in terms of outright go.By the mid 1970’s that was/should have been the end of the era of all the NA anchors of all types.
Realistically, for Leyland’s survival, the question should have been between Rolls Eagle v TL12 setting the base line for the new era coming in and what would explain Leyland’s and the government’s thinking in not realising the implications of making the wrong choice at that point in time.
Certainly to the point where Rolls would have logically been brought into the Leyland Group and inter cooled Rolls power the default standard choice for the T45 on its introduction.Having used the Marathon as the 305 development hack from the Crusader.
You can clearly see the difference in Scammell v AEC thinking here.
Yep BL losing millions every year should bring in another big company losing money with a far from perfect engine . Scammell using 280 RR or V8 Detroit knew where they would be pulling the customers away from TD120 buyers
gingerfold:
There you go CF, I agree with you about the RR engines from the mid-70s onwards.
Which makes the case for not scrapping the TL12 in 1975 2 years after its introduction and 4-5 years before the launch of the Roadtrain how ?.
There doesn’t seem to be much evidence of any major issues with the 280 certainly nothing which would suggest it was inherently too weak to handle 300 hp + outputs at less than 2,200 rpm ?.More like the exact opposite.
So Scammell connected with Rolls and AEC connections with Rolls the solution was obvious at that point to anyone committed to keeping Leyland in the frame.
Certainly better than any of the alternative options regarding engine production.
So government funded hostile takeover of Rolls Royce Diesels ,close Shrewsbury, move its operations to Southall, together with Tolpits Lane.
That’s what I call rationalisation.
ramone:
Yep BL losing millions every year should bring in another big company losing money with a far from perfect engine . Scammell using 280 RR or V8 Detroit knew where they would be pulling the customers away from TD120 buyers
But an intercooled 320 Rolls powered T45, obviously wouldn’t have been the same thing as a Crusader with a 280 in it.Let alone a TL12 in either.
But it needed to be done from day 1.Not just before they closed the doors and effectively told DAF to take over all their customers.
Yep let’s put an 8v71 NA anchor in it when the turbo 8v92 was available.
Just as though someone from on high had told both Bedford and Scammell not to upset the foreign competition’s party.
Although it’s obvious that the two mains bolts are worth more than the 4 small big end cap bolts so I guess my theory holds.
