[zb]
anorak:
Try to guess why you were asked to estimate double the BMEP. Have a look at graphs of cylinder pressure versus crank angle. Then look at some graphs of power required to drive a vehicle, versus its speed. The estimate some statistical distribution of its speed, over its life. Then get the fatigue curve of you beloved head bolt material, and read up on ■■■■■■■■■■ damage theory. If you’ve got any brains at all, you will work out why you have been doing it, and what to do next. You might decide on 2.5, or even 3, as your multiplier. I don’t care- it’s your design analysis. Do the job, instead of blurting about it.
You’ve got all the ideas you tell us why you think that BMEP is a relevant figure for anything other than for comparing the specific torque output of different engines.
That’s peak torque measured at the flywheel v engine capacity.Nothing more nothing less.
What has that figure got to do with cylinder pressures and crank angles.
Other than the fact the more leverage you’ve got at the crank the less force you’ll need to apply to your piston and/or cylinder head fastenings to get it.
You’re obviously taking BMEP as a literal measurement related to cylinder pressures and force on the piston.
Not just an abstract related to specific torque at the flywheel.
Which part of there is no comparison whatsoever between peak cylinder pressures and forces acting on a piston and BMEP don’t you understand.
In large part because of the stroke/leverage variable force multiplier at the crankshaft.
7% less leverage means 7% more force on your end bearings.
While a leverage deficit v piston area is also directly proportional to your head fastening loads.
It’s a lot of force in both cases.
In answer to which we’ve got Ramone thinking that the difference between 142 mm and 150 mm stroke is the same as adding 8 mm to a 1.3 m wheel nut bar and you obviously chose not to correct him.
Carryfast:
Not much use though when the emphasis rightly shifted to peak power at less than 2,000 rpm to get the fuel returns and then as close to 10hp and 30 + lbft per tonne at 32-38t gross as makes not much difference.
For that you need a lugger in either case and that means maximising the leverage advantage.
There we go again leverage a massive 8mm dream in your head . 1 wheel brace at 1.3m to tighten a wheel nut then a wheel brace at 1.308m will make a massive difference to the tyre man , i think not. You can times your theory by as many as you like 1 piston 1 8mm longer stroke no difference 6 x 0 = 0 .
AEC bus engines in lorries , didnt leyland use the 680 in buses , Volvo use the 9.6 in buses , they are usually derived engines. The AV760 became the horizontal underfloor AH760 in the Reliance the only thing i didn’t get was it was downrated
.
Tell us more about how this engine with it’s, as you rightly say, puny 152 mm lever is putting out 1,250 lbft at 1,200 rpm and the forces it needs to generate in its cylinders to make it.
It makes your 1.3 metre bar and tyre fitter look a bit silly even assuming he puts all of his weight on the end of the bar.
All ultimately dependent on the end bearings and cylinder head fastenings containing and standing up to those forces.
A 7% increase in leverage and 7% and 2% respectively reduction in those forces for the equivalent torque output is a lot.
No one is saying that it wasn’t a long learning process getting to 130 x 162 for example.
But some were obviously more ahead than others.Ironically AEC being closer with the Matador’s 146 mm than the TL12’s 142 mm.
Oh and 7% on a 1.3 m bar equates to more than 8mm.
More like an extra 100 lbft assuming he’s putting all his weight on the end of it.
Which 152 mm stroked engine i never mentioned one have you not taken your medicine today . There is no leverage advantage with 8mm extension
[zb]
anorak:
Try to guess why you were asked to estimate double the BMEP. Have a look at graphs of cylinder pressure versus crank angle. Then look at some graphs of power required to drive a vehicle, versus its speed. The estimate some statistical distribution of its speed, over its life. Then get the fatigue curve of you beloved head bolt material, and read up on ■■■■■■■■■■ damage theory. If you’ve got any brains at all, you will work out why you have been doing it, and what to do next. You might decide on 2.5, or even 3, as your multiplier. I don’t care- it’s your design analysis. Do the job, instead of blurting about it.
You’ve got all the ideas you tell us why you think that BMEP is a relevant figure for anything other than for comparing the specific torque output of different engines.
That’s peak torque measured at the flywheel v engine capacity.Nothing more nothing less.
What has that figure got to do with cylinder pressures and crank angles.
Other than the fact the more leverage you’ve got at the crank the less force you’ll need to apply to your piston and/or cylinder head fastenings to get it.
You’re obviously taking BMEP as a literal measurement related to cylinder pressures and force on the piston.
Not just an abstract related to specific torque at the flywheel.
Which part of there is no comparison whatsoever between peak cylinder pressures and forces acting on a piston and BMEP don’t you understand.
In large part because of the stroke/leverage variable force multiplier at the crankshaft.
7% less leverage means 7% more force on your end bearings.
While a leverage deficit v piston area is also directly proportional to your head fastening loads.
It’s a lot of force in both cases.
In answer to which we’ve got Ramone thinking that the difference between 142 mm and 150 mm stroke is the same as adding 8 mm to a 1.3 m wheel nut bar and you obviously chose not to correct him.
It should be clear to you that I know what the terminology means, how to do the calculations and which people to ridicule. Your next job is to calculate the bending moment on the bristles of this brush. You may estimate the length of the bristles, the load on the handle and the number of bristles:
For those of you not bored and stroked to death by this charlatan: for the purposes of estimating the fatigue life of engine parts, given no actual measurements, you may estimate the peak cylinder pressure as a multiple of BMEP. There are graphs all over the place, for different types of engine. The multiplier may be a bit different for N/A petrols and turbocharged diesels. More than 8%, at any rate. LOL.
dave docwra:
Lets not get concerned with all that [zb], the real technical question is, how much to get it from A to B and how long will the thing last before it costs me money…
Dave…
I still think this is what operators are interested in, not crank angles, bore sizes or head clamping pressures.
Carryfast:
Tell us more about how this engine with it’s, as you rightly say, puny 152 mm lever is putting out 1,250 lbft at 1,200 rpm and the forces it needs to generate in its cylinders to make it.
It makes your 1.3 metre bar and tyre fitter look a bit silly even assuming he puts all of his weight on the end of the bar.
All ultimately dependent on the end bearings and cylinder head fastenings containing and standing up to those forces.
A 7% increase in leverage and 7% and 2% respectively reduction in those forces for the equivalent torque output is a lot.
No one is saying that it wasn’t a long learning process getting to 130 x 162 for example.
But some were obviously more ahead than others.Ironically AEC being closer with the Matador’s 146 mm than the TL12’s 142 mm.
Oh and 7% on a 1.3 m bar equates to more than 8mm.
More like an extra 100 lbft assuming he’s putting all his weight on the end of it.
Which 152 mm stroked engine i never mentioned one have you not taken your medicine today . There is no leverage advantage with 8mm extension
I’m referring to RR Eagle you’re referring to TD120.
Your premise is the same in either case.
So how does 5.6 -7% more leverage supposedly equate to only 8 mm on a 1.3 m bar.
Also what is your bs connection between a 1.3 m long bar to an engine creating 1,140 or 1,250 lbft with a 150 mm or 152 mm stroke.
[zb]
anorak:
For those of you not bored and stroked to death by this charlatan: for the purposes of estimating the fatigue life of engine parts, given no actual measurements, you may estimate the peak cylinder pressure as a multiple of BMEP. There are graphs all over the place, for different types of engine. The multiplier may be a bit different for N/A petrols and turbocharged diesels. More than 8%, at any rate. LOL.
How do you ‘estimate’ ‘peak cylinder’ pressure as a multiple of BMEP ( specific torque at the flywheel ) when more leverage, in the form of a longer stroke, means the same torque output for less force on the piston or more torque output for equivalent force, and assuming a piston area deficit v leverage advantage.As in the case of TL12 v TD120 and RR Eagle.
Which part of, you need to match 43% more specific torque, x 7% more load on your end bearings, and x 2% on your head fastenings, didn’t you understand.
There’s only one charlatan here and it ain’t me.
I read this regularly but makes no sense to me !! So if you’re thinking of designing a completely new engine what procedure do you use ? Is there more than one way of doing it ? Are there any recent examples, good or bad,of a new engine ? Cheers Coomsey
Things have gone quiet. Has the internet gone down in Leatherhead?
Edit I’ve just noticed another CF post, dated before my last broadside. I don’t remember seeing it last night. I think this has happened before. Has he perfected a means of delivering them by stealth, like time bombs?
Carryfast:
Tell us more about how this engine with it’s, as you rightly say, puny 152 mm lever is putting out 1,250 lbft at 1,200 rpm and the forces it needs to generate in its cylinders to make it.
It makes your 1.3 metre bar and tyre fitter look a bit silly even assuming he puts all of his weight on the end of the bar.
All ultimately dependent on the end bearings and cylinder head fastenings containing and standing up to those forces.
A 7% increase in leverage and 7% and 2% respectively reduction in those forces for the equivalent torque output is a lot.
No one is saying that it wasn’t a long learning process getting to 130 x 162 for example.
But some were obviously more ahead than others.Ironically AEC being closer with the Matador’s 146 mm than the TL12’s 142 mm.
Oh and 7% on a 1.3 m bar equates to more than 8mm.
More like an extra 100 lbft assuming he’s putting all his weight on the end of it.
Which 152 mm stroked engine i never mentioned one have you not taken your medicine today . There is no leverage advantage with 8mm extension
I’m referring to RR Eagle you’re referring to TD120.
Your premise is the same in either case.
So how does 5.6 -7% more leverage supposedly equate to only 8 mm on a 1.3 m bar.
Also what is your bs connection between a 1.3 m long bar to an engine creating 1,140 or 1,250 lbft with a 150 mm or 152 mm stroke.
I never mentioned the Volvo 12 litre that’s another engine you keep throwing in . . There is no significant difference in leverage between 142 mm and 150 mm that is another one of your imaginary theories you keep trying to convince people of . I took very little notice of all this leverage bs until i realised what you were going on about , it fits with the rest of the crap you post , all in your head . To get an advantage by extending something in leverage terms i would say you would have to extend at least half to 3 quarters of the original length to get an advantage . If you had a tyre lever 1m long and you needed more leverage would you add 7cm on the end … nope
dave docwra:
Lets not get concerned with all that [zb], the real technical question is, how much to get it from A to B and how long will the thing last before it costs me money…
Dave…
I still think this is what operators are interested in, not crank angles, bore sizes or head clamping pressures.
Yep i agree with that but if it isn’t massive torque or bhp he wont
Carryfast:
Tell us more about how this engine with it’s, as you rightly say, puny 152 mm lever is putting out 1,250 lbft at 1,200 rpm and the forces it needs to generate in its cylinders to make it.
It makes your 1.3 metre bar and tyre fitter look a bit silly even assuming he puts all of his weight on the end of the bar.
All ultimately dependent on the end bearings and cylinder head fastenings containing and standing up to those forces.
A 7% increase in leverage and 7% and 2% respectively reduction in those forces for the equivalent torque output is a lot.
No one is saying that it wasn’t a long learning process getting to 130 x 162 for example.
But some were obviously more ahead than others.Ironically AEC being closer with the Matador’s 146 mm than the TL12’s 142 mm.
Oh and 7% on a 1.3 m bar equates to more than 8mm.
More like an extra 100 lbft assuming he’s putting all his weight on the end of it.
Which 152 mm stroked engine i never mentioned one have you not taken your medicine today . There is no leverage advantage with 8mm extension
I’m referring to RR Eagle you’re referring to TD120.
Your premise is the same in either case.
So how does 5.6 -7% more leverage supposedly equate to only 8 mm on a 1.3 m bar.
Also what is your bs connection between a 1.3 m long bar to an engine creating 1,140 or 1,250 lbft with a 150 mm or 152 mm stroke.
I never mentioned the Volvo 12 litre that’s another engine you keep throwing in . . There is no significant difference in leverage between 142 mm and 150 mm that is another one of your imaginary theories you keep trying to convince people of . I took very little notice of all this leverage bs until i realised what you were going on about , it fits with the rest of the crap you post , all in your head . To get an advantage by extending something in leverage terms i would say you would have to extend at least half to 3 quarters of the original length to get an advantage . If you had a tyre lever 1m long and you needed more leverage would you add 7cm on the end … nope
The difference between 142 mm and 150 mm is massive in terms of the leverage equation as it applies to a forced induction diesel engine and the part that plays in reducing the equally massive loads on the piston/rod assembly and head fastenings.152 mm is better,162 mm is even better, 165 mm is even better than that etc etc.
If you weren’t referring to the Volvo TD120 where did the 150 mm and 8 mm come from.
I would say you’re the one who’s talking total garbage.You obviously don’t even know what you’re referring to most of the time.Like figures which you’ve obviously forgot where they came from and the difference between 142mm v 150mm applied to a 1.3m bar supposedly equals 8 mm more leverage.
Let alone the idea that you need more than 100 mm added to the 142mm stroke to make any difference in terms of an engine and the forces applying within it.
You’re avin a larf.
coomsey:
I read this regularly but makes no sense…
You are right.
So tell us how specific torque ( peak torque at the flywheel divided by capacity ) supposedly relates to cylinder pressures.
Bearing in mind the torque figure is a function of the ‘combination’ of cylinder pressure, piston area and leverage at the crankshaft.
In this case your leverage deficit outweighs your piston area advantage.
Your specific torque deficit is 43%.
Replacing leverage with more force is directly proportional to the loads on your rod assemby/bearings regardless of whether to create it with more piston area or cylinder pressure.
Now awaits more bs bordering on trolling from you rather than answers.
[zb]
anorak:
For those of you not bored and stroked to death by this charlatan: for the purposes of estimating the fatigue life of engine parts, given no actual measurements, you may estimate the peak cylinder pressure as a multiple of BMEP. There are graphs all over the place, for different types of engine. The multiplier may be a bit different for N/A petrols and turbocharged diesels. More than 8%, at any rate. LOL.
How do you ‘estimate’ ‘peak cylinder’ pressure as a multiple of BMEP ( specific torque at the flywheel ) when more leverage, in the form of a longer stroke, means the same torque output for less force on the piston or more torque output for equivalent force, and assuming a piston area deficit v leverage advantage.As in the case of TL12 v TD120 and RR Eagle.
Which part of, you need to match 43% more specific torque, x 7% more load on your end bearings, and x 2% on your head fastenings, didn’t you understand.
There’s only one charlatan here and it ain’t me.
If you increase (for example) turbo boost, you will increase the BMEP of the engine. You will also increase peak cylinder pressures, so the two are roughly proportional. It would give you an approximate means of justifying (or otherwise) your arguments. You need to brush up on your maths, if you think a 43% increase in BMEP effects a 2% increase in head bolt load.
Edit- BMEP is exactly what it says- it is the average pressure during the combustion stroke. It ends up as a ratio of torque to cylinder volume. See if you can do the maths to prove that. IIRC, that derivation is taught in the first or second week of any vehicle engineering apprenticeship.
I’ve just worked out why CF’s posts appear later than other posts, but are shown chronologically prior to those other posts: he must be on the pre-moderation naughty step. FFS- even with a proof-reader, he still manages to talk tiddlywinks, EG Brake Mean Effective Pressure is not pressure. It’s all up there^^^.
I’m referring to RR Eagle you’re referring to TD120.
Your premise is the same in either case.
So how does 5.6 -7% more leverage supposedly equate to only 8 mm on a 1.3 m bar.
Also what is your bs connection between a 1.3 m long bar to an engine creating 1,140 or 1,250 lbft with a 150 mm or 152 mm stroke.
[/quote]
I never mentioned the Volvo 12 litre that’s another engine you keep throwing in . . There is no significant difference in leverage between 142 mm and 150 mm that is another one of your imaginary theories you keep trying to convince people of . I took very little notice of all this leverage bs until i realised what you were going on about , it fits with the rest of the crap you post , all in your head . To get an advantage by extending something in leverage terms i would say you would have to extend at least half to 3 quarters of the original length to get an advantage . If you had a tyre lever 1m long and you needed more leverage would you add 7cm on the end … nope
[/quote]
The difference between 142 mm and 150 mm is massive in terms of the leverage equation as it applies to a forced induction diesel engine and the part that plays in reducing the equally massive loads on the piston/rod assembly and head fastenings.152 mm is better,162 mm is even better, 165 mm is even better than that etc etc.
If you weren’t referring to the Volvo TD120 where did the 150 mm and 8 mm come from.
I would say you’re the one who’s talking total garbage.You obviously don’t even know what you’re referring to most of the time.Like figures which you’ve obviously forgot where they came from and the difference between 142mm v 150mm applied to a 1.3m bar supposedly equals 8 mm more leverage.
Let alone the idea that you need more than 100 mm added to the 142mm stroke to make any difference in terms of an engine and the forces applying within it.
You’re avin a larf.
[/quote]
You are quite correct CF i haven’t got a clue what i’m on about , i always thought leverage was a force from an angle not straight down but my point is it’s ■■■■ annoying when someone contredicts and disses everything that someone else states just for the sake of it
You have told well known and successful hauliers where they went wrong with their buying polices ( Gardner180/240 boat anchors ffs) when they would have been much better advised to use V8 Detroits
You have advised very experienced drivers i know one personally how to rope n sheet in the correct manner and put them right on where they have gone wrong . Here’s a wool hook go load and rope n sheet that lot … i don’t think
We’ve had engineers and fully qualified mechanics that have been doing their respective jobs all their lives … wrongly according to you
We have had researchers and book writers who have studied in great depth their subjects only to be told they are wrong.
We’ve had a guy who spent 30 years restoring a vehicle into a work of art but we can’t see it because he wont post on here anymore due to your ridiculous comments.
We’ve heard how you worked for a guy and didn’t (couldn’t) like driving his Marathon so you took turns in driving the Volvo he ran even though you relentlessly bang on about Fullers being superior to synchros , sounds to me you never mastered a Fuller.
So i think you should shake your hand pat yourself on the back and tell yourself you are wonderful , because i can’t see anyone else saying it .
I am still trying to discover why the Rover V8 had to be fitted with a General Motors built Buick 215 engine, They must have been able to buy an engine to suit a Triumph too.
Wheel Nut:
I am still trying to discover why the Rover V8 had to be fitted with a General Motors built Buick 215 engine, They must have been able to buy an engine to suit a Triumph too.
I think it was cheap to purchase/licence and due to being redundtant in its own country where it was first used.
.
ramone:
You are quite correct CF i haven’t got a clue what i’m on about , i always thought leverage was a force from an angle not straight down but my point is it’s ■■■■ annoying when someone contredicts and disses everything that someone else states just for the sake of it
You have told well known and successful hauliers where they went wrong with their buying polices ( Gardner180/240 boat anchors ffs) when they would have been much better advised to use V8 Detroits
You have advised very experienced drivers i know one personally how to rope n sheet in the correct manner and put them right on where they have gone wrong . Here’s a wool hook go load and rope n sheet that lot … i don’t think
We’ve had engineers and fully qualified mechanics that have been doing their respective jobs all their lives … wrongly according to you
We have had researchers and book writers who have studied in great depth their subjects only to be told they are wrong.
We’ve had a guy who spent 30 years restoring a vehicle into a work of art but we can’t see it because he wont post on here anymore due to your ridiculous comments.
We’ve heard how you worked for a guy and didn’t (couldn’t) like driving his Marathon so you took turns in driving the Volvo he ran even though you relentlessly bang on about Fullers being superior to synchros , sounds to me you never mastered a Fuller.
So i think you should shake your hand pat yourself on the back and tell yourself you are wonderful , because i can’t see anyone else saying it .
Go and pour yourself a pint Ramone, you’re surrounded by an idiot, and you know you can’t possibly win.
on your maths, if you think a 43% increase in BMEP effects a 2% increase in head bolt load.