Carryfast:
les-p:
Another thread ruined by the idiot.The irony when that’s your best contribution to it.
So tell us why would anyone want to use the L12 instead of the 680 or Rolls 220.
Read Windrush’s reply and digest it , i mentioned it was unreliable but you dont listen
Carryfast:
[zb]
anorak:
You’ve been talking to engineers on this forum, in many different roles, for years now, and remain at odds with all of them, almost completely. I would vote for you as PM- I would love to see you and Donald working together.It’s clear that understanding the link, between maximising the stroke/leverage of any engine design to maximise its torque output potential, is in no way ‘at odds’ with most accepted engineering practice out there.As it stands I’m in agreement with with numerous car and truck engine designers and more than a few after market modifiers on that.
Torque is proportional bore area multiplied by stroke, as anyone knows. Neither number prevails, until you get to the higher turbo boost pressures of the 1990s. The cognoscenti on this forum revere the Fiat V8 as the greatest of all pre-electronic engines. It was oversquare.
If you can’t do engineering by championing one positive over the others. If you tried to get into a design office with that approach, your interview would end before the first cup of coffee.
[zb]
anorak:Carryfast:
It’s clear that understanding the link, between maximising the stroke/leverage of any engine design to maximise its torque output potential, is in no way ‘at odds’ with most accepted engineering practice out there.As it stands I’m in agreement with with numerous car and truck engine designers and more than a few after market modifiers on that.Torque is proportional bore area multiplied by stroke, as anyone knows. Neither number prevails, until you get to the higher turbo boost pressures of the 1990s. The cognoscenti on this forum revere the Fiat V8 as the greatest of all pre-electronic engines. It was oversquare.
If you can’t do engineering by championing one positive over the others. If you tried to get into a design office with that approach, your interview would end before the first cup of coffee.
I didn’t say that increasing bore size won’t increase torque.I said that less leverage means more force required to be put through the con rod and/or more cylinder pressures to obtain the equivalent torque output.
A very large capacity 8 cylinder engine will obviously reduce that problem because there’s more space for better piston to crank components and more of them to share the load.But specific torque output will still suffer at the end of the day.
So you want to tighten the truck’s wheelnuts using a spanner instead of a three foot bar.Great you need someone with massive arm and forearm muscles or even try to use two or three of them to help him push on it.But that still won’t make their shoulder/elbow/wrist joints any stronger.
No surprise the long bar won out just like the Detroit 12.7 v 11.1 and ■■■■■■■ ISX v N14 and MX v DAF DK and Rolls Egle and Mack 673 v L12/TL12 before them.
Oh and the 730 Scania V8 v both early Scania and FIAT V8’s.
More stroke less bore needed to handle more cylinder pressures bs.It’s to reduce the cylinder pressures required to obtain the equivalent torque output or provide more torque for equivalent pressures if anything.
Unless your idea of engineering totally ignores of the laws of leverage.As I said increasing the distance side of the force x distance equation = free power and less stress required to obtain it.That’s why they want it.
Carryfast:
I didn’t say that increasing bore size won’t increase torque.I said that less leverage means more force required to be put through the con rod …
So what? When has a conn rod ever failed due to compressive loading? They fail due to tensile fatigue. The peak tensile load in the conn rod is proportional to stroke squared (conn rod length must be increased with increasing stroke, for a given side load, so its own mass is proportional to stroke. The acceleration is also proportional to stroke. The force is proportional to the product of those parameters). For a given fatigue life, power output is therefore inversely proportional to stroke. That’s the opposite of free power.
Why don’t you just accept that the designers of any engine fly so far over your head that they cannot even be seen, never mind heard?
[zb]
anorak:Carryfast:
I didn’t say that increasing bore size won’t increase torque.I said that less leverage means more force required to be put through the con rod …So what? When has a conn rod ever failed due to compressive loading? They fail due to tensile fatigue. The peak tensile load in the conn rod is proportional to stroke squared (conn rod length must be increased with increasing stroke, for a given side load, so its own mass is proportional to stroke. The acceleration is also proportional to stroke. The force is proportional to the product of those parameters). For a given fatigue life, power output is therefore inversely proportional to stroke. That’s the opposite of free power.
Why don’t you just accept that the designers of any engine fly so far over your head that they cannot even be seen, never mind heard?
So your whole engine design premise is based on the idea that stress is all about inertial tensile loads as opposed to compressive loads.What could possibly go wrong.
Reduce the stroke increase the boost no problem your small ends and big ends and your con rods are all invincible in compression.You’re going for around 100 lb/ft per litre with an over square motor.You could have got a job at AEC.
But Mack, Volvo, Rolls Royce, ■■■■■■■ and Scammell amongst others obviously would have rightly shown you the door. 
I don’t think JB Weld will fix that.
Carryfast old bean, now look here, these engines you keep bleating about, well many of them still operate all around the world, which shows quite clearly that you are once again speaking from the wrong orifice.
We all get that you’ve recently stumbled upon a YouTube video about cylinder pressure and whatever the other crap you keep banging on about is, I think it’s safe to say that nobody is impressed by any of it.
The thread has gone down the pan because of your input, I’m certain there are many members with extensive knowledge of the Buffalo, yet they won’t post in fear of setting you off, these are real life experiences that none of us will ever get to learn about and it’s all because of you, so well done, another potentially interesting thread has been Carryfasted.
newmercman:
I don’t think JB Weld will fix that.
Carryfast:
[zb]
anorak:Carryfast:
I didn’t say that increasing bore size won’t increase torque.I said that less leverage means more force required to be put through the con rod …So what? When has a conn rod ever failed due to compressive loading? They fail due to tensile fatigue. The peak tensile load in the conn rod is proportional to stroke squared (conn rod length must be increased with increasing stroke, for a given side load, so its own mass is proportional to stroke. The acceleration is also proportional to stroke. The force is proportional to the product of those parameters). For a given fatigue life, power output is therefore inversely proportional to stroke. That’s the opposite of free power.
Why don’t you just accept that the designers of any engine fly so far over your head that they cannot even be seen, never mind heard?
So your whole engine design premise is based on the idea that stress is all about inertial tensile loads as opposed to compressive loads.What could possibly go wrong.
Reduce the stroke increase the boost no problem your small ends and big ends and your con rods are all invincible in compression.You’re going for around 100 lb/ft per litre with an over square motor.You could have got a job at AEC.
But Mack, Volvo, Rolls Royce, ■■■■■■■ and Scammell amongst others obviously would have rightly shown you the door.
youtube.com/watch?v=-4uZ-cJFJ_U
Feel free to explain what he means by ‘‘mechanical advantage’’.
Oh wait it’s all here.
‘‘As the stroke increases the torque output of the engine will increase due to the additional leverage created by the distance that the force is acting from.Power is related to the torque output at a specific engine speed’’.
Who would have thought it.Obviously not our resident F1 car engine design expert.
carthrottle.com/post/what-ar … se-torque/
So we want our engine to deliver more power at 2,100 preferably 1,800 rpm than at 2,200 rpm.By definition that will also mean more peak torque at lower rpm.
That means we need more torque to more than compensate for the lower engine speed.
By definition that means more peak torque also at lower rpm.
Remind me why do we need a relatively larger bore v a relatively smaller stroke. 
It takes car street racing oiks to tell the truck engine designers in their suits how to build a truck engine.They couldn’t make it up.
newmercman:
Carryfast old bean, now look here, these engines you keep bleating about, well many of them still operate all around the world, which shows quite clearly that you are once again speaking from the wrong orifice.We all get that you’ve recently stumbled upon a YouTube video about cylinder pressure and whatever the other crap you keep banging on about is, I think it’s safe to say that nobody is impressed by any of it.
The thread has gone down the pan because of your input, I’m certain there are many members with extensive knowledge of the Buffalo, yet they won’t post in fear of setting you off, these are real life experiences that none of us will ever get to learn about and it’s all because of you, so well done, another potentially interesting thread has been Carryfasted.
Leave it out.The Buffalo had the full house of Leylands no hoper anchors under its cab in the case of the L12 worse than a Gardner in terms of specific output.While the 500 doesn’t need any input from me.Why would a thread be damaged by telling it like it is from both sides of the story good or bad.
Why? Quite simple really, you are the reason, that’s why. You go on and on and on about the same thing, every single thing you’ve posted on this thread was said in that last post.
The Buffalo had the full house of Leyland boat anchors. That’s it. You made your point.
[zb]
anorak:
- Tensile loads in the conn rod put just the same loads in the bearings as compressive ones.
If that was the case the induction stroke would take as much power from the engine as the power stroke puts into it.
I’m no engineer, but I know that is a ridiculous statement Carryfast.
Carryfast:
[zb]
anorak:
- Tensile loads in the conn rod put just the same loads in the bearings as compressive ones.
If that was the case the induction stroke would take as much power from the engine as the power stroke puts into it.
Acceleration is maximum at T and BDC. Compression occurs between them. Here’s your homework: at what RPM does compression cause the same load in the conn rod as acceleration in an L12? Assume peak cyl pressure= 2x BMEP, and it occurs at 90 deg crank angle.
[zb]
anorak:
Acceleration is maximum at T and BDC. Compression occurs between them. Here’s your homework: at what RPM does compression cause the same load in the conn rod as acceleration in an L12? Assume peak cyl pressure= 2x BMEP, and it occurs at 90 deg crank angle.
Don’t get your question.BMEP is at 1,400 rpm and 2 x the pathetic BMEP is 225 psi.
The rod is under compressive load on the compression stroke and on the power stroke IE it’s under a net compressive load in both cases after and before BDC respectively as the crankshaft accelerates it upwards against the compression and then the power stroke pushes it downwards into the crankshaft and then it has to brake before BDC for the exhaust stroke.
At which point how do we possibly get a ‘tensile’ inertial load on the rod at any point other than the changeover between exhaust and induction and in which case what’s the relationship between that and BMEP and a 90 degree crank angle on the power stroke.Nor can we even know what those inertial tensile loadings are without a piston and rod assembly weight and piston speed and that’s your pay grade to work out not mine. 
The fact is the Rolls 220 and 305 and Mack 673 have got you beat on specific torque which obviously means a pro rata higher BMEP figure all without any tensile snapping of rods or ends.Unsurprisingly with peak power produced at lower engine speed in all cases.
1400rpm
newmercman:
I’m no engineer, but I know that is a ridiculous statement Carryfast.
How else could you get the ‘same’ force trying to pull the con rod/piston assembly away from the crank shaft, as the power stroke is pushing it against the crankshaft.
Without that opposing force acting as a brake on the engine sufficient to cancel out the force of the power stroke.
I think what he means is that those tensile intertial forces could be enough to exceed the ‘tensile’ strength of the piston/rod assembly given enough speed.The problem for anorak being that generally the reduction in engine speeds provided by the extra leverage outweighs the faster piston speeds or any weight increase in the assembly resulting from the longer stroke.
Which is why the numerous well under square designs produced more output than the L/TL12 without their piston and rod assemblies flying away from their crankshafts.
Nor do I for one minute think that’s why AEC’s designers used that stroke.
More like it was forced on them by AEC’s bus manufacturing origins.
This thread is rather like that aching tooth: you know that probing it with your tongue is going to hurt but you still do it, and on here you look in every day hoping that you might see something new/constructive but all you get is the same old thing going round and round. Luckily for me I had no experience of Leylands or their engines in any shape or form, apart from fitting an oil feed pipe to a 500 series in a loading shovel!
Pete.
