Carryfast:
dazcapri:
Carryfast:
Tell us what were these supposed ‘sporting’ credentials which the Mini had.3 times winner of the Monte Carlo rally for starters
Tell us more about FIAT 124 and 131.
Ford ■■■■■■.Mk1/2
Sunbeam Lotus.
What have they got to do with the “sporting credentials” of the Mini
cav551:
Quote Carryfast:"Edit to add so the C18 stays together at 2,300 rpm …unlike the TL12 would boosted to 166 lb/ft per litre at 1,600 rpm"
Quote cav551:
" FPT Iveco have not released their 850bhp Cursor 16 for automotive use , because they do not consider that current forward control cabs and chassis provide enough space to meet its cooling requirements.
Quote Carryfast:
"The point was the connection between the C18’s specific torque output and its leverage.That was all
So the Cursor 16 has a bore stroke ratio of 0.83.Your point being what?"
Cav 551 My point was that the same applies to the C18, such a powerful engine produces a tremendous amount of heat.
But that wasn’t all either, you sought to compare a 12.5 litre engine with one half as big again. Because if that had been all then you wouldn’t have written: " unlike the TL12…"
[/quote]
What relevance is overall capacity regarding a comparison of SPECIFIC torque outputs and bore stroke ratios.
0.82 in the case of the Cursor 16 0.79 in the case of CAT C18.
I don’t buy nmm’s claim that the small incremental reduction in CAT bore stroke ratios had anything to do with EGR temperatures.Just like the difference in stroke measurements couldn’t possibly have been for that reason in the case of TD120/RR Eagle v TL12, or CAT 3406 v ■■■■■■■ 855/N14.
Nnm said himself CAT engines unexplainably pull better than their competition.He could do no better than comparing their bore stroke dimensions with their competition.More leverage = more torque and less stress.
The truth is the Eagle produced more torque for less stress that’s why it was still there producing around 100 lbft per litre and 400 hp in the 90’s and the TL12 had to be put out of its misery in 1983.
The decision obviously having been made by Edwardes beffore that date after sabotaging the T45’s launch party with the thing.
newmercman:
Come on Carryfast answer the question!My gift to you…
Which part of TENSILE loads on a con rod assembly never exceed or even get close to COMPRESSIVE loads don’t you understand.
That’s why big end cap fastenings don’t need to be as strong as head fastening and main bearing cap fastenings.
dazcapri:
Carryfast:
dazcapri:
3 times winner of the Monte Carlo rallyTell us more about FIAT 124 and 131.
Ford ■■■■■■.Mk1/2
Sunbeam Lotus.
What have they got to do with the “sporting credentials” of the Mini
The Mini won it 3 times.Repeat wins of Monte obviously matters.
[zb]
anorak:Carryfast:
It’s a truck not an F1 motor.I’m winning this- 1000 pages ago, you were pouring scorn on the idea that there were ever tensile loads in the conn rod.
I said ever tensile loads which ever get close to compressive loads as shown by the comparison of big end cap fastenings v main bearing cap and head fastenings and the less leverage you’ve got at the crankshaft the more those compressive loads on the con rod will need to be.
Assuming your bore size has a net deficit over the leverage advantage of the longer stroke motor ( as in the case of TL12 v Eagle ) then you also need higher cylinder pressures to compensate as part of that too and 2% of a lot is a lot.
Remind me again why a 130 x 154 TL12 wouldn’t have worked and in fact been superior to both Rolls Eagle and TD120 in terms of specific torque output.Oh wait you don’t believe that they were suprerior to TL12.
All based on F1 engine design philosophy. 
newmercman:
Come on Carryfast answer the question!My gift to you…
That’s a wasted gesture NMM because “CF” has been enjoying an F.O.C. lifetime membership of GOOGLE for many years, awarded to him for his prolific use of the platform far in excess of the periodic use of the site by regular users ! 
So that voucher you have sent him will more than likely be quickly turned into “readies” on the streets of Leatherhead no doubt ! 
Cheers Dennis.
With no engineering knowledge other than understanding logical reasons how and why things work, I have to side with Carryfast on the compressive loads being greater than the tensile loads and for the reasons he states.
The extra leverage from the longer throw crank in a long stroke engine has also got to provide free power too compared to a short stroke engine and I imagine the compressive and tensile loads on the rods would be lower too as the greater arc of the crankshaft journals will require less force than a shorter stroke for the equivalent force at the flywheel.
The increased capacity of the engines built for EGR is a consequence of the extra heat produced by returning hot exhaust into the combustion chamber, almost every heavy duty diesel engine saw capacity go up and power stay almost the same. It isn’t the only reason, the inefficiency of the bang in the ignition phase from the hot, less dense dirty air is also a factor, as are the parasitic losses on the exhaust phase caused by the more restrictive VGT and particulate filters in the exhaust, but they both produce more heat too, so it is the biggest factor.
Why do CATs go better than other engines of equivalent power? I don’t know, but they do, well the ones I’ve had did and still do. When I have a pilot car escorting me through the mountains of British Columbia they always ask what power I’m making and are either shocked or just don’t believe me when I tell them it’s a bone stock 550/1850, this shock or disbelief only increases when I tell them it has 3.55 rear ends rather than the 3.90 or 4.10 rears most heavy haulers run, I don’t hang about, but even the most spirited driving can’t overcome the laws of physics so either CATs make more than they claim, or other engines don’t make what they claim too, it’s one or the other.
newmercman:
With no engineering knowledge other than understanding logical reasons how and why things work, I have to side with Carryfast on the compressive loads being greater than the tensile loads and for the reasons he states.
Greater the peak compressive load may be (I don’t know- I’ve never calculated it either!), but fatigue is caused by cyclic tensile stress, so that is why the inertial load is of a concern to engine designers.
That makes sense too, metal being able to withstand compressive forces better than tensile force. A perfect example being a piece of metal splitting at the outer edge when bent as the tensile force is greater there.
newmercman:
That makes sense too, metal being able to withstand compressive forces better than tensile force. A perfect example being a piece of metal splitting at the outer edge when bent as the tensile force is greater there.
It’s not being ‘bent’ because that’s why it it’s hinged at the small end.
It’s an intertial load as it’s pulled sideways by the crankshaft on the small end hinge point.
If your theory was correct what’s stopping the CAT C18’s conrods from being torn apart by tensile forces at at 2,300 rpm.
A con rod can’t possibly be stronger in tension than its big end bearing cap fastenings.
Remind us why they don’t need to be stronger than the head to block and main bearing cap fastenings.
The compressive load on the piston and rod assemnbly is an opposite tensile load of the head fastenings.
So tell us what forces are acting on the con rod between TDC and 90 degrees after TDC on the power stroke.
It’s being pulled sideways by the crankshaft just the same but in this case combined with the compressive forces of the power stroke.
So now accelerate ‘your piece of spaghetti’ sideways while also under massive compression squezzed at the ends and see what happens.
Obviously reducing that compressive force to the point where it outweighs the inertial sideways tensile force can only help.
newmercman:
That makes sense too, metal being able to withstand compressive forces better than tensile force. A perfect example being a piece of metal splitting at the outer edge when bent as the tensile force is greater there.
Oohhhhh
Sharp intake of breath. Can you support that general statement “metal better able to support compressive rather that tensile forces”?
.
A con rod isn’t subject to just tensile and compressive forces. When at an angle there are shear forces involved. Look at the cross section? It often bears a resemblance to an “H” section beam.
Failure isn’t just a catastrophic failure through fracture, it can also be a plastic distortion.
.
As an aside, look too at reinforced concrete beams: especially pre-stressed one, the metal reinforcement is not symmetrical.
.
No sorry Franglaise, I cannot add to that statement as I’m not a scientist, metallurgist or engineer, but AFAIK metal used for chains, which have a tensile load is called high tensile, whereas metal used for compressive loads is just called metal.
As for anorak’s tensile load question, I believe the importance of tensile loads in this instance is in that moment, that I correctly deduced, between tdc and intake stroke where the tensile load is greatest and the fact that it’s a source of fatigue is related to how many times the load is applied, roughly 1500 times per minute for every minute the engine is running.
Again using deduction I can say with confidence that in answer to Carryfast’s question on why are big end caps stronger than little ends, well for one they’re bigger as a crank journal has a larger circumference than a gudgeon pin, therefore more metal is required, more metal requires a bigger and correspondingly stronger fastening, at least that’s what appears logical to my unqualified grey matter.
Since we have a broad topic theme in the title, this video of a Merlin engine being stripped down and refurbished may be of interest even to the more casual reader. There are clear pictures of Fork and Blade connecting rods as well as a ‘Fixed Head’ design - which requires methods of working possibly not immediately obvious. Note also the number of fixings which have to be lockwired - a time consuming and skilled procedure in often awkward situations.
newmercman:
No sorry Franglaise, I cannot add to that statement as I’m not a scientist, metallurgist or engineer, but AFAIK metal used for chains, which have a tensile load is called high tensile, whereas metal used for compressive loads is just called metal.As for anorak’s tensile load question, I believe the importance of tensile loads in this instance is in that moment, that I correctly deduced, between tdc and intake stroke where the tensile load is greatest and the fact that it’s a source of fatigue is related to how many times the load is applied, roughly 1500 times per minute for every minute the engine is running.
Again using deduction I can say with confidence that in answer to Carryfast’s question on why are big end caps stronger than little ends, well for one they’re bigger as a crank journal has a larger circumference than a gudgeon pin, therefore more metal is required, more metal requires a bigger and correspondingly stronger fastening, at least that’s what appears logical to my unqualified grey matter.
Has anyone asked why the big end is… big…?
Are the forces the same at the top and bottom of the con-rod?
Franglais:
Has anyone asked why the big end is… big…?
Are the forces the same at the top and bottom of the con-rod?
All the torque at the flywheel had to be produced by the force on the piston during the power stroke.A gudgeon pin is a lot smaller than a crank shaft journal you can’t fit a crank journal into a piston.Which obviously answers your question.
It also obviously helps if you multiply that force on the piston and rod assembly by as much leverage as possible at the crankshaft.Which means either more torque for equivalent force or less force required for the equivalent torque at the flywheel.
Why are people arguing about something that a 183 mm stroke running at 2,300 rpm shows isn’t an issue.
Nor the around 6 inch stroke of the Rolls and TD120 nor the 6.5 inch stroke of the CAT 3406.
A 130 x 154 TL12 ( the bore stroke ratio of the 590 ) would have been fine at 1,900 rpm.It also would have been putting out a lot more than 270 hp at that engine speed because of its greater leverage multiplication.
There was something wrong with or some other reason for AEC’s design thinking and it had nothing whatsoever to do with any worries about flying con rods at 2-2200 rpm.
My bet is that their bus engine fit requirements overrode what’s best for a truck from the 0.71 bore stroke ratio of the 173.Finally to the point where they ended up with 0.95 for the TL12.
Like the V8 their design thinking seems to have been based on lets make what fits in a bus easiest.Rather than let’s make an engine and a truck to fit what’s best.
What happened to the VTG in that regard and why.
Why bother with the TL12 from the point when the Marathon came online.Bearing in mind Scammell’s seeming avoidance of the 760 and the TL12.
Now awaits they wanted an ‘in house’ engine.Oh wait.They already had one in the form of the RR both firms ultimately owned by the state.
Carryfast:
Which part of TENSILE loads on a con rod assembly never exceed or even get close to COMPRESSIVE loads don’t you understand.
That’s why big end cap fastenings don’t need to be as strong as head fastening and main bearing cap fastenings.
How do you know that? Without doing the calculation, you will not know, ever. Still, at least you are acknowledging that the tensile loads exist. This was what you said the last time you had a go at the TL12 engine:
[zb]
anorak:Carryfast:
Which part of TENSILE loads on a con rod assembly never exceed or even get close to COMPRESSIVE loads don’t you understand.
That’s why big end cap fastenings don’t need to be as strong as head fastening and main bearing cap fastenings.How do you know that? Without doing the calculation, you will not know, ever. Still, at least you are acknowledging that the tensile loads exist. This was what you said the last time you had a go at the TL12 engine:
0
It’s obvious that there were loads of caveats and qualifications attached to that statement nor is it saying that no tensile ( inertial ) load exists.
It was intended to make anyone think.
I’ll refer you back to my statement to nmm.Put your stick of spaghetti under compression and then try to bend it.
You know like between a few degrees before TDC on the compression stroke and 90 degrees after TDC on the power stroke.That’s when you’re piston and rod assembly are under the most stress.
It’s obvious that compressive loads are the dominating factor in a forced induction slow revving truck engine, in which the aim is to produce as much torque as possible at as low speed as possible and it’s all about minimising them.
Not worrying about the piston and rod snapping, or wanting to fly away from the crankshaft, between the inlet and compression strokes or power and exhaust strokes or exhaust and induction strokes at 2,000 rpm or less.
While the reduction in engines speeds, created by the extra torque output, created by the extra leverage, obviously helps to reduce those tensile ( intertial ) loads.
So the CAT C18 can handle 2,300 rpm with a bore stroke ratio of less than 0.80 and a stroke measurement of 183 mm the BMW N54 has a bore stroke ratio of less than that of the TL12 and it can rev to 7,000 rpm.
Remind me again what is your problem with a 130 x 154 TL12.
Carryfast:
Franglais:
Has anyone asked why the big end is… big…?
Are the forces the same at the top and bottom of the con-rod?All the torque at the flywheel had to be produced by the force on the piston during the power stroke.A gudgeon pin is a lot smaller than a crank shaft journal you can’t fit a crank journal into a piston.Which obviously answers your question.
It also obviously helps if you multiply that force on the piston and rod assembly by as much leverage as possible at the crankshaft.Which means either more torque for equivalent force or less force required for the equivalent torque at the flywheel.
Why are people arguing about something that a 183 mm stroke running at 2,300 rpm shows isn’t an issue.
Nor the around 6 inch stroke of the Rolls and TD120 nor the 6.5 inch stroke of the CAT 3406.
A 130 x 154 TL12 ( the bore stroke ratio of the 590 ) would have been fine at 1,900 rpm.It also would have been putting out a lot more than 270 hp at that engine speed because of its greater leverage multiplication.There was something wrong with or some other reason for AEC’s design thinking and it had nothing whatsoever to do with any worries about flying con rods at 2-2200 rpm.
My bet is that their bus engine fit requirements overrode what’s best for a truck from the 0.71 bore stroke ratio of the 173.Finally to the point where they ended up with 0.95 for the TL12.
Like the V8 their design thinking seems to have been based on lets make what fits in a bus easiest.Rather than let’s make an engine and a truck to fit what’s best.
What happened to the VTG in that regard and why.
Why bother with the TL12 from the point when the Marathon came online.Bearing in mind Scammell’s seeming avoidance of the 760 and the TL12.
Now awaits they wanted an ‘in house’ engine.Oh wait.They already had one in the form of the RR both firms ultimately owned by the state.
There was no “agenda” between Scammell and AEC. I visited Scammell in 1982 and there was a tremendous amount of empathy from the Scammell people to AEC. They knew that despite building the Constructor and some other T45 tractor units that they were on borrowed time and eventually Scammell would be closed as Southall had already been.
The reason that Scammell didn’t fit AEC engines was that they had no need to. There had always been respect between both companies, despite what you might think or choose to believe. When Scammell was taken over by Leyland in the early '50s Leyland engines became an option in Scammells as an option to Gardner or Meadows engines. When the Routeman and Handyman models were introduced Leyland 0.680 was the default engine, even more so from 1971 when the Leyland Beaver and Octopus models were discontinued in favour of the 500 series models. By fitting the O.680 in Scammells it gave Leyland users a choice of keeping with the O.680 if they chose to do so… and many did. An AEC operator would not want to buy an AEC powered Scammell as long they could buy a 100% AEC lorry. AEC’s UK loose engine sales were predominantly into the medium weight category. Seddon did fit AEC AV590, AEC690, and a AV760 into its heavy range.
cav551:
Carryfast:
[zb]
anorak:
Complete lack of reading/comprehension^^^.Great feel free to describe all the points when a con rod is under tension.
Oh boy that ■■■■■.
Carryfast:
It’s obvious that there were loads of caveats and qualifications attached to that statement nor is it saying that no tensile ( inertial ) load exists.
It was intended to make anyone think.
Mod’s Edit:
The rules on banned words appearing in pictures are the same as if the were typed. dd.
gingerfold:
Carryfast:
Franglais:
Has anyone asked why the big end is… big…?
Are the forces the same at the top and bottom of the con-rod?All the torque at the flywheel had to be produced by the force on the piston during the power stroke.A gudgeon pin is a lot smaller than a crank shaft journal you can’t fit a crank journal into a piston.Which obviously answers your question.
It also obviously helps if you multiply that force on the piston and rod assembly by as much leverage as possible at the crankshaft.Which means either more torque for equivalent force or less force required for the equivalent torque at the flywheel.
Why are people arguing about something that a 183 mm stroke running at 2,300 rpm shows isn’t an issue.
Nor the around 6 inch stroke of the Rolls and TD120 nor the 6.5 inch stroke of the CAT 3406.
A 130 x 154 TL12 ( the bore stroke ratio of the 590 ) would have been fine at 1,900 rpm.It also would have been putting out a lot more than 270 hp at that engine speed because of its greater leverage multiplication.There was something wrong with or some other reason for AEC’s design thinking and it had nothing whatsoever to do with any worries about flying con rods at 2-2200 rpm.
My bet is that their bus engine fit requirements overrode what’s best for a truck from the 0.71 bore stroke ratio of the 173.Finally to the point where they ended up with 0.95 for the TL12.
Like the V8 their design thinking seems to have been based on lets make what fits in a bus easiest.Rather than let’s make an engine and a truck to fit what’s best.
What happened to the VTG in that regard and why.
Why bother with the TL12 from the point when the Marathon came online.Bearing in mind Scammell’s seeming avoidance of the 760 and the TL12.
Now awaits they wanted an ‘in house’ engine.Oh wait.They already had one in the form of the RR both firms ultimately owned by the state.There was no “agenda” between Scammell and AEC. I visited Scammell in 1982 and there was a tremendous amount of empathy from the Scammell people to AEC. They knew that despite building the Constructor and some other T45 tractor units that they were on borrowed time and eventually Scammell would be closed as Southall had already been.
The reason that Scammell didn’t fit AEC engines was that they had no need to. There had always been respect between both companies, despite what you might think or choose to believe. When Scammell was taken over by Leyland in the early '50s Leyland engines became an option in Scammells as an option to Gardner or Meadows engines. When the Routeman and Handyman models were introduced Leyland 0.680 was the default engine, even more so from 1971 when the Leyland Beaver and Octopus models were discontinued in favour of the 500 series models. By fitting the O.680 in Scammells it gave Leyland users a choice of keeping with the O.680 if they chose to do so… and many did. An AEC operator would not want to buy an AEC powered Scammell as long they could buy a 100% AEC lorry. AEC’s UK loose engine sales were predominantly into the medium weight category. Seddon did fit AEC AV590, AEC690, and a AV760 into its heavy range.
I didn’t say that there was ever any ‘animosity’ between Scammell and AEC ( I’ve clearly stated the opposite AEC was within walking distance of my own employers ).We were all a close south eastern automotive manufacturing family.Ironically my own employers had used both AEC chassis and Scammell and both the 760 and Detroit engines.
I clearly made the case that Scammell just applied a use what is best for the job approach.Unfortunately the 760/TL12 obviously didn’t cut it.
I also seem to remember them dropping the ■■■■■■■ 903 inherited from the Thornycroft takeover in specialist types in favour of Detroit 8v92 as we already knew before that.I didn’t like the 903 from the moment I fired it up let alone drove it.Plenty of smoke but just didn’t rock the chassis like an 8v92 did when you blipped the accelerator at idle nor that kick in the back on acceleration.
I never actually drove or rode in the Mandator but from memory drove both TL12 and ■■■■■■■ Roadtrains inherited from the Carryfast Carswells takeover.The ■■■■■■■ was laughable in its performance at around 30 t or less to the point of too much unbelievable acceleration in silly high gears while the TL made a great noise echoing through the streets of Baldock village in the early hours on the run to Bury St Edmunds from Feltham and ‘sufficient’ pull through the gears no more than that.
As opposed to absolutely outstanding in the case of the Rolls 265 at 24t or less in the S85 that same rocking of the chassis when blipped at idle and pulled like train up the old Reigate Hill.It had to be good because it has stuck in my memory.I absolutely knew there was 400 hp potential contained in that motor in the early 1980’s long before Perkins made it a reality.
