The Eagle 400Tx gets a glowing report in the above road test- its torque output is almost as much as a ■■■■■■■ N14-465, according to the text. Both engines have a 152mm stroke, but the ■■■■■■■ has a 140mm bore, versus the Rolls’ 130mm. The ■■■■■■■ engineers were obviously frightened to death by that extra 8%. LOL.
Now for your next test: do the derivation showing why BMEP is proportional to the ratio of torque to cylinder capacity, to establish your credentials as a top design man, for benefit of all reading this thread.
The Eagle TX 400 gets a glowing report it made more specific torque than the TD120.
The TL12 has rightly long ago been put out of its misery.Which makes the case for the TL12 how.
You said that you can deduce peak cylinder pressure from just an arbitrary multiple of the BMEP figure.Go on then do it for both the TL12 and Eagle.I’m still waiting.
Oh wait you can’t because torque is also dependent on the two other variables of piston area and leverage.
BMEP is just specific torque in just the same way that power is torque x engine speed.
Specific torque x 2.464 = BMEP.
Specific torque is deduced by dividing peak torque at the flywheel by engine capacity.
In which case why bother with BMEP anyway specific torque is exactly the same thing.
BMEP or Specific Torque is just a way of comparing different engine outputs at the flywheel not cylinder pressures or end bearing loads.
Less leverage then you’ll need more force on the piston in the form of more piston area and/or more cylinder pressure for the equivalent torque.Which means more end bearing loads and more head fastening loads respectively.
Quotes in the wrong place.
Repetition of same old s**t.
Exactly what quote are you saying is wrong.
I’ve answered your pointless question.BMEP is just another needlessly over complicated way of expressing specific torque as mesured at the flywheel.Nothing more nothing less.
Now why don’t you answer the question as to how you’re going to calculate real, as opposed to abstract, cylinder pressures just from the specific torque figure.
You do know by now that BMEP is just specific torque as measured at the flywheel meant as nothing more as a comparator of different engines.
Carryfast:
Why would anyone have bought an F12 rather than the DAF or Scania.
But you still ain’t going to find a 142 mm stroke even in those two exceptions.The DAF’s at least being closer to the Eagle’s than the TL12’s.
400 hp Rolls more torque than the TD120 and it takes a 13 litre motor to beat it.
There was no TL12 choice at all in Leyland Roadtrain after 1983 going by your own logic.
Probably for more power at launch from the 12 litre Volvo compared with the 11 litres from the other two. Then again it might have been personal choice or a good experience or bad as it were. Horses for courses.
Let’s stay with specific torque outputs.Power output is of no interest that it will look after itself if we get the torque output.That’s why BMEP was invented to compare engines not specific power output.
The Scania even with after cooling is behind the TD120 at this point. archive.commercialmotor.com/page … er-1982/15
So both aftercooled turbo how do you explain the difference in specific torque.Why not just boost the Scania motor to match the Volvo’s specific torque output of 95 lbft per litre.
While we know that the Eagle is going to trump the TD120.
Also where is the TL12 here at this point.Oh wait still the same 69lbft per litre.The decision already made to knock it on the head.The only thing that Edwardes ever got right but ironically for nefarious reasons.Like lumbering the Roadtrain with it at launch.
So you have proved over many ridiculous posts that you don"t read and take in what others write. The TL12 was never developed from introduction until 1979 when they slightly modified it and it became the lower revving Flexitorque , thats it. The tooling used was shot it need replacing no money available to develop anything better millions spent on developing the Roadtrain but nothing spent on a 7 year old engine that needed updating and new machinery to build it. Take the Rolls that was produced in 1973 spend nothing on it and what have you got , a 220/280 unreliable engine .
cav551:
…
It’s very strange that there’s no mention of its output being achieved by its stroke yet there is mention of a significant increase in compression ratio, induction tuning, and higher injection pressures along with its torque increase and spread being attributable to the Bosch K type Governor. There appears to have been a TX430 with an even higher compression ratio but mention of that seems to have disappeared behind a paywall.
From 1970 to 1995, the Eagle’s BMEP increased by 67%- 2.5% per annum, simple interest - while its rated full power speed reduced by 15%. It’s pretty clear where the improvements in durability came from, and where there was unused strength in the original engine. It is typical of all engines, of course- BMEP has increased considerably over the past century, without any reduction in the service life of the engines. Unless the TL12 was limited by a peculiarity in its ability to hold pressure, there is nothing to suggest it would have not kept pace with the Eagle, if the development work had been done. Are you aware of any such limitation? For example, maybe the head bolts were closer to the bores, compared with the RR or ■■■■■■■■
cav551:
…
It’s very strange that there’s no mention of its output being achieved by its stroke yet there is mention of a significant increase in compression ratio, induction tuning, and higher injection pressures along with its torque increase and spread being attributable to the Bosch K type Governor. There appears to have been a TX430 with an even higher compression ratio but mention of that seems to have disappeared behind a paywall.
From 1970 to 1995, the Eagle’s BMEP increased by 67%- 2.5% per annum, simple interest - while its rated full power speed reduced by 15%. It’s pretty clear where the improvements in durability came from, and where there was unused strength in the original engine. It is typical of all engines, of course- BMEP has increased considerably over the past century, without any reduction in the service life of the engines. Unless the TL12 was limited by a peculiarity in its ability to hold pressure, there is nothing to suggest it would have not kept pace with the Eagle, if the development work had been done. Are you aware of any such limitation? For example, maybe the head bolts were closer to the bores, compared with the RR or ■■■■■■■■
I’m still waiting for you to provide ‘PEAK’ cylinder pressure for the TL12 at 100 lbft per litre v Eagle.
Oh wait you can’t because there are too many variables in the equation but it’s reasonable to assume that end bearing life and head fastenings couldn’t have taken the extra forces needed v the Eagle for the equivalent output.
The Eagle’s strength was largely in its leverage advantage which is a multiplying constant providing more torque for the equivalent force on the piston and less force for the equivalent specific torque.
The same applied to the TD120.
The same applies moreso in the MX among others.
Oh and the IVECO Turbostar isn’t going to help your case at 82lbft per litre.
ramone:
The TL12 was never developed from introduction until 1979 when they slightly modified it and it became the lower revving Flexitorque , thats it. The tooling used was shot it need replacing no money available to develop anything better millions spent on developing the Roadtrain but nothing spent on a 7 year old engine that needed updating and new machinery to build it. Take the Rolls that was produced in 1973 spend nothing on it and what have you got , a 220/280 unreliable engine .
So remind me what was stopping RR Diesels being handed over to Leyland for no charge at the start of 1979 ?.Bearing in mind the Eagle was already at a true 290 hp and more than 900 lbft at that point.
ramone:
The TL12 was never developed from introduction until 1979 when they slightly modified it and it became the lower revving Flexitorque , thats it. The tooling used was shot it need replacing no money available to develop anything better millions spent on developing the Roadtrain but nothing spent on a 7 year old engine that needed updating and new machinery to build it. Take the Rolls that was produced in 1973 spend nothing on it and what have you got , a 220/280 unreliable engine .
So remind me what was stopping RR Diesels being handed over to Leyland for no charge at the start of 1979 ?.Bearing in mind the Eagle was already at a true 290 hp and more than 900 lbft at that point.
Because Leyland were slimming down their operations not adding to their expenditure , much cheaper to buy in than build and develop in their prediciment . Its already been explained but you dont listen
Carryfast:
I’m still waiting for you to provide ‘PEAK’ cylinder pressure for the TL12 at 100 lbft per litre v Eagle.
…
You do it, you layabout! You are the one running scared from cylinder pressure. If you don’t do your own work, no one is going to do it for you. If you don’t come up with the numbers you want, all you can do is estimate them from the data you already have, which is BMEP, and the typical Peak/Mean ratio for turbocharged diesels of the period you are wallowing in. Of course, that will only be an estimate, but if you are suggesting that the cylinder pressure is some sort of limiting factor, you need to do your research, and find actual measurements. Given that all engines have enjoyed hugely increased cylinder pressure- both mean and peak- over the years, nobody else does consider it a limiting factor.
Carryfast:
I’m still waiting for you to provide ‘PEAK’ cylinder pressure for the TL12 at 100 lbft per litre v Eagle.
…
You do it, you layabout! You are the one running scared from cylinder pressure.
I said you can’t determine the peak cylinder pressure from an abstract not real average figure used to compare the specific torque output of different engines.
You can’t calculate a real specific figure from an abstract and average one.
Now you prove me wrong.Where’s that peak cylinder pressure figure for the TL12 at the Eagle’s 100 lbft per litre potential.
I’ve given you a clue with the 2% piston area deficit v the Eagles leverage advantage.All I know is that it’s going to be a lot of pressure and probably too much for the head fastenings to handle when multiplied by the specific torque deficit.I’m only the bleedin test driver here remember.
When you’ve done that we need to know the end bearing loads with 7% less leverage to help them.
We need it to decide whether to put this, so far, 69 lbft per litre short stroke piece of junk into production or scrap it and get RR on board as our in house engine provider instead.
Being honest and just saying it’s a lot probably too much to make it a viable product will do fine.
cav551:
…
It’s very strange that there’s no mention of its output being achieved by its stroke yet there is mention of a significant increase in compression ratio, induction tuning, and higher injection pressures along with its torque increase and spread being attributable to the Bosch K type Governor. There appears to have been a TX430 with an even higher compression ratio but mention of that seems to have disappeared behind a paywall.
From 1970 to 1995, the Eagle’s BMEP increased by 67%- 2.5% per annum, simple interest - while its rated full power speed reduced by 15%. It’s pretty clear where the improvements in durability came from, and where there was unused strength in the original engine. It is typical of all engines, of course- BMEP has increased considerably over the past century, without any reduction in the service life of the engines. Unless the TL12 was limited by a peculiarity in its ability to hold pressure, there is nothing to suggest it would have not kept pace with the Eagle, if the development work had been done. Are you aware of any such limitation? For example, maybe the head bolts were closer to the bores, compared with the RR or ■■■■■■■■
No. vaguely similar for all three except that the 743 ■■■■■■■ had fewer larger bolts (not shown). ■■■■■■■ useless electronic ■■■■ has turned the page upside down again inspite of it being the right way up. Nothing 11,000 volts won’t cure permanently.
Carryfast:
I said you can’t determine the peak cylinder pressure from an abstract not real average figure .
I said you can estimate it, for the purposes of a rough calculation of loads on the containing parts, if you have an estimate of the ratio between peak and mean, for engines of that type. Don’t make me repeat myself again.
BMEP is pressure, measured in Bar (usually). If you understood how it is calculated, you would understand that it is a perfect representation of the pressure in the bore, over the whole cycle of the engine. I asked you to provide that derivation, but you ran scared from it. An engineer would have attacked that challenge like a scrap yard dog.
For a Euro 6 engine, the measured ratio is about 8:1. Obviously, to get from BMEP to that, you must estimate the mean pressure in the other three strokes, and add or subtract, depending on piston direction.
Carryfast:
In the case of the TL12 v Eagle you’ve got a 43% specific torque at the flywheel ( BMEP ) deficit.
You’ve got a 7% leverage deficit.
You’ve got a 2% net piston area v leverage deficit.
That’s 43% x 7 % more load required on your end bearings and 43% x 2% more load required on your head fastenings to match the Eagle’s specific torque ( BMEP ) output potential …
Shouldn’t that be a 3.5% leverage ‘deficit’ (5 mm)? And where is the ‘net piston area v leverage deficit’ coming from? Shouldn’t that be in the TL12’s favour?
Carryfast:
In the case of the TL12 v Eagle you’ve got a 43% specific torque at the flywheel ( BMEP ) deficit.
You’ve got a 7% leverage deficit.
You’ve got a 2% net piston area v leverage deficit.
That’s 43% x 7 % more load required on your end bearings and 43% x 2% more load required on your head fastenings to match the Eagle’s specific torque ( BMEP ) output potential …
Shouldn’t that be a 3.5% leverage ‘deficit’ (5 mm)? And where is the ‘net piston area v leverage deficit’ coming from? Shouldn’t that be in the TL12’s favour?
Welcome to TN Joe and good luck with this one
Been reading threads here a while …
- while its rated full power speed reduced by 15%. It’s pretty clear where the improvements in durability came from, and where there was unused strength in the original engine. It is typical of all engines, of course- BMEP has increased considerably over the past century, without any reduction in the service life of the engines. Unless the TL12 was limited by a peculiarity in its ability to hold pressure, there is nothing to suggest it would have not kept pace with the Eagle, if the development work had been done. Are you aware of any such limitation? For example, maybe the head bolts were closer to the bores, compared with the RR or ■■■■■■■■
