Puppeteer

Author Topic: seeking an answer...  (Read 29207 times)

mobile_bob

  • Administrator
  • Hero Member
  • *****
  • Posts: 2787
    • View Profile
Re: seeking an answer...
« Reply #30 on: November 18, 2006, 06:45:43 AM »
Guy:

please take note of the specification print for the 5/1

http://www.oldengine.org/members/diesel/Technical/51P3data.htm

maybe a quarter yard of concrete? you do the math

then read the final paragraph related to mounting here

http://www.oldengine.org/members/diesel/Technical/51P4data.htm

"INSTALLATION:

particulars of engine mounting and type of drive should be stated wherever possible"

clearly the point being made is that the mounting method is anticapated to be determined by the end user, and lister would like to know about it if possible

the light is fading on this one, rather quickly, how can you continue to¬  support the assertion that the concrete block was an engineered part of the engine, or had any basis in the original design?

i have asked for a formula, doesnt even have to be from lister, and to date no one has come up with one.

i think it is apparent that i (with a bunch of help from an unnamed individual) have disproven your assertion, which was not incumbent on me to do.

now i want the formula!!!
enough with do the math!
i wanna see the damn formula

checkmate

bob g
otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info

dkwflight

  • Hero Member
  • *****
  • Posts: 573
    • View Profile
Re: seeking an answer...
« Reply #31 on: November 18, 2006, 01:32:20 PM »
Hi I'll bet the conversation in Dursley went like this

Sales dept
"We need to sell engines to some country people at a set price."

Engineer
"Set it on a block of concrete. This is a stationary engine and concrete is cheap!" " Besides the trade has always done it this way!"

Legal dept.
"We don't want claims from customers, make the block of concrete bigger. We are'nt paying for that."

 ;D
Dennis
28/2 powersolutions JKSon -20k gen head
Still in devlopment for 24/7 operation, 77 hours running time

snail

  • Full Member
  • ***
  • Posts: 243
    • View Profile
Re: seeking an answer...
« Reply #32 on: November 19, 2006, 02:43:46 AM »
DKW:
 
Quote
Hi I'll bet the conversation in Dursley went like this

Sales dept
"We need to sell engines to some country people at a set price."

Engineer
"Set it on a block of concrete. This is a stationary engine and concrete is cheap!" " Besides the trade has always done it this way!"

Legal dept.
"We don't want claims from customers, make the block of concrete bigger. We are'nt paying for that."
   

So you're a bit cynical too eh? :D I'm sure that you are much closer to the truth than some others.I'm equally sure that when the concrete block was first "designed in" around 1907, the people at dursley couldn't even spell calculus. ;D .
Makes for good entertainment value though don't it? Does anyone remember the monty python sketch where (I think) Terry Jones walks in and says "is this the right room for an argument?" Apologies to all non python fans, you are sadly lacking in your education ;)

Cheers,

Brian

Quinnf

  • Hero Member
  • *****
  • Posts: 645
    • View Profile
Re: seeking an answer...
« Reply #33 on: November 19, 2006, 05:38:42 AM »
A:   Come in.
M:   Ah, Is this the right room for an argument?
A:   I told you once.
M:   No you haven't.
A:   Yes I have.
M:   When?
A:    Just now.
M:   No you didn't.
A:   Yes I did.
M:  You didn't
A:   I did!
M:  You didn't!
A:   I'm telling you I did!
M:  You did not!!
Ashwamegh 6/1, PowerSolutions 6/1 "Kit" engine, and a Changfa R175a that looks like a Yanmar I once knew

mobile_bob

  • Administrator
  • Hero Member
  • *****
  • Posts: 2787
    • View Profile
Re: seeking an answer...
« Reply #34 on: November 19, 2006, 03:45:38 PM »
i have been working on a reconciliation of the information and developing another theory, which at this point i feel holds as much water than any other theory
and likely far more than some of late.

in the beginning lister built a 3/1 and as fine engineers, the refined it very well, balanced it to a gnats ass of being perfect, and it was good.

they then took it apart and carefully weighed and measured every last part, and then set out to replicate parts to these spec's , and all was good.

having built all these parts, they set to assembling there engines, and then came a revelation,, some of the engines were excellent, (they would run sitting on a pallet), some more of them were very good (needing to be bolted down to timbers) , and the rest were good (but needing to be bolted to approx 600lbs of concrete)
, and all was still good because folks bolted stationary engines to concrete anyway.

what lister in effect had was A grade, B grade and C grade engines, all of which would run excellent on a concrete base. and all was good.

when a customer ordered an engine, lister wanted to know how the engine was to be mounted, simply to be able to select the grade of engine that best suited the end use, they didnt have to tell the customer they just did it.  if Joe needed a pump motor to run down at the lake to pump water to his field , he got a C grade motor.
if George needed a motor to run in his generator shed that was out in the barn he got a B grade motor, if John needed a motor to run in the generator shed attached to his house, he got an A grade motor. and all was good. everyone was happy

as years went by, and the cost of manufacture began to rise, along with lister getting into other more profitable engine products, the bean counters began to look to where they could cut costs of manufacture of the 6/1. experience told lister that engines will run literally forever, bolted to concrete, and careful balanceing of parts, sub assemblies etc cost extra money in manhours, so it was decided to see if an engine not so finely balanced could be made to run well and what size of concrete block would be needed to mount it. gone were  the days of "tell us how you are going to mount it" and all was not so good, but folks bought them anyway on the premise that the concrete block was an intregal part of the design (clever marketing, turning a negative into a positive) lister continued to sell engine's , they ran well and all was for practical purposes .. good.

moral of the story, there was no higher math envolved above simple accounting arithmatic when it came to the design of the concrete base, further, if you have an engine that you are trying to make to be as good as it can be then have it professionally balanced after which it will probably run forever bolted to a pallet. if you dont do that and have an engine that is built up of poorly balanced parts then you will have to bolt it to a ton of concrete, and likely it will be shorter lived.

bob g
otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info

Procrustes

  • Sr. Member
  • ****
  • Posts: 332
    • View Profile
Re: seeking an answer...
« Reply #35 on: November 19, 2006, 07:39:29 PM »
please take note of the specification print for the 5/1

http://www.oldengine.org/members/diesel/Technical/51P3data.htm

maybe a quarter yard of concrete? you do the math

then read the final paragraph related to mounting here

http://www.oldengine.org/members/diesel/Technical/51P4data.htm

"INSTALLATION:

particulars of engine mounting and type of drive should be stated wherever possible"

clearly the point being made is that the mounting method is anticapated to be determined by the end user, and lister would like to know about it if possible

Bob, I believe the concrete block has become your Moby Dick.

Your argument has two parts.  First is, I believe, "speced block size tripled between the 5/1 and 6/1, and this drastic change cannot explained by a mathematical formula, therefore the block is not an integral part of the engine design."  That simply isn't true.  No doubt their formula involved safety factors and machining tolerances.  Changing either of these variables could account for the discrepancy.  Or it could simply be a mandate from the legal department.  I think we're in agreement about this latter part.

"Particulars of engine mounting" must refer to such things as indoor/outdoor and soil type.  The reason I'm confident about this is that the specs you referenced belie your point: the engine blueprint shows the concrete block as part of the dimensions of the engine.  There isn't the least bit of wiggle room about this, it could not be more stark.  You're exercizing willful disbelief.

the light is fading on this one, rather quickly, how can you continue to  support the assertion that the concrete block was an engineered part of the engine, or had any basis in the original design?

i have asked for a formula, doesnt even have to be from lister, and to date no one has come up with one.

i think it is apparent that i (with a bunch of help from an unnamed individual) have disproven your assertion, which was not incumbent on me to do.

now i want the formula!!!
enough with do the math!
i wanna see the damn formula

checkmate

Awhile ago you stated something to the effect that all aspects of IC engines are determinable via well-known formulas.  I think you will agree that when someone develops a revolutionary piston profile, no one is impressed until they see the dyno numbers, despite whatever the math might say.

Mathematical models are just that, models.  Celestial models improved with Newton then again with Kepler and then again with Einstein, and they aren't perfect yet.

None of us knows how sophisticated and accurate was the math that RA Lister used.  It could have been on the back of an envelope, or it could have been exemplary.  It doesn't matter, because we have seen the results.  This being the case, it is in fact incumbent on you to prove that the block was a suggestion, not part of the design.

mobile_bob

  • Administrator
  • Hero Member
  • *****
  • Posts: 2787
    • View Profile
Re: seeking an answer...
« Reply #36 on: November 19, 2006, 08:17:27 PM »
Pro:

you cannot have it both ways either!

if one cannot determine the outcome of aspects of an engine design such as valve timeing, bore stroke ratio, VE etc, then you damn sure cannot determine anything about a concrete block.

and you are missing the point entirely

it has been asserted that lister only specified the use of a ton of concrete, or a yard whichever it was. it was reported that the yard/ton of concrete was an intergal part of the engine design.

clearly they provide specifications for both 600 lbs and your ton of concrete, this cannot be mathematically explained with any provable formula, not ever!

further you miss the mark in that i am not an opponent of the use of concrete, beit 600 #'s or a ton, i simply was looking to find the actual equation, and to date no one includeing yourself has come forward with such formulae, or any reference to lister having used said formulae.

quite frankly i don't give a crap what anyone mounts their engine to.

what i do care about is being told to do the math, and not having any proof of an equation ever being used or any reference to an equation.

also i would like to note, that words have meaning, specific meaning

when lister requested the particulars of engine mounting they did not ask for the particulars of engine installation

"mounting" does not equal "installation"

mounting referrs to what the engine is bolted to, and
installation takes into account the soil type, building type and myriad other concerns

as for you explanation of the difference in 600#s and a ton, being because of altering the spec's of the engine, please how does your accessment carry more
water than mine?

the only spec that could account for the large difference in block weight would have to be one of quality of balance, no other spec would result in the need for that much more concrete.

as for it being a result of being safety concious, here again i take exection, do you have any supporting evidence that the earlier recommendation of 600#'s of concrete being insufficient and causeing property or bodily damage?? i seriously doubt it.

obviously many of you have never worked with a very well balanced machine/engine, one that is properly tuned and set up will run quite nicely sitting flat on the floor.
such an engine is quite a marvel to behold and i have no doubt that the early listers were of this quality.

further i would assert that the A grade engines in later years became the engine of choice for the SOM's

seriously it only makes sense,

there are those on this board that look to lister as if it was designed, machined, assembled by arch angels, and ordained by God. it is not!
it is simply a good engine, and in some cases an excellent engine built by men, ordinary men, that were craftsman to be sure, but ordinary men that ate, slept and shit just
like each one of us.

i tire very easily when there are those that put lister on some pedestal that is beyond question, one should be able to ask any question of any man or company, and get a clear and concise answer, not some crap about "just do the math"

and finally,

i have no doubt that i could build a 6/1 from one of the kits, carefully balancing it either myself or hire it done, detail it properly and have an engine that would run as long as any other listeroid and have it mounted to timbers, 600#s of concrete or even resilient mounted.

i have no more to say on this subject until "someone produces the friggin formulae", anyone supporting the use of concrete as being gospel from god is just full of shit.

bob g



otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info

Procrustes

  • Sr. Member
  • ****
  • Posts: 332
    • View Profile
Re: seeking an answer...
« Reply #37 on: November 20, 2006, 01:10:24 AM »
you cannot have it both ways either!

What am I trying to have both ways?

if one cannot determine the outcome of aspects of an engine design such as valve timeing, bore stroke ratio, VE etc, then you damn sure cannot determine anything about a concrete block.

But you can't exactly predict the effects of many engine design decisions.  That's what dynos are for.

This is the nature of mathematical forumulas; the more work you put into them, the better the results you are liable to get.  But they're never perfect on anything of any complexity, and thus we perform experiments.  The fianancial "rule of 72" is a mathematical model, and it is useful so long as you don't expect too much from it.

But all this is beside the point.  It doesn't matter how RA LIster came up with their spec, it's still the spec.

and you are missing the point entirely

it has been asserted that lister only specified the use of a ton of concrete, or a yard whichever it was. it was reported that the yard/ton of concrete was an intergal part of the engine design.

Apparently that's wrong, Lister specified the 600# (as you calculated) in at least one place.  This doesn't mean that the block isn't part of the spec.

clearly they provide specifications for both 600 lbs and your ton of concrete, this cannot be mathematically explained with any provable formula, not ever!

How can you say this if you don't know what formula they used?  They could have plugged in a different mean time to failure for instance, for whatever reason.  If they did in fact use such a formula, they apparently changed a parameter between the 5/1 and 6/1.

But maybe they didn't use a formula at all, maybe the field agents said too many engines were failing in manner X, so they simply increased the block spec.  Whatever the case, the block is still part of the spec.

further you miss the mark in that i am not an opponent of the use of concrete, beit 600 #'s or a ton, i simply was looking to find the actual equation, and to date no one includeing yourself has come forward with such formulae, or any reference to lister having used said formulae.

Sorry, no equation here.

quite frankly i don't give a crap what anyone mounts their engine to.

what i do care about is being told to do the math, and not having any proof of an equation ever being used or any reference to an equation.

also i would like to note, that words have meaning, specific meaning

when lister requested the particulars of engine mounting they did not ask for the particulars of engine installation

"mounting" does not equal "installation"

mounting referrs to what the engine is bolted to, and
installation takes into account the soil type, building type and myriad other concerns

I grant this is confusing.  However, as with all Lister specs, the one you referenced shows the block as part of the dimensions of the engine.  It's not a suggestion, it's the spec.  So it makes more sense to reconcile the "particulars of mounting" to it, and not vice versa.

as for you explanation of the difference in 600#s and a ton, being because of altering the spec's of the engine, please how does your accessment carry more water than mine?

You say that a change in the block spec implies that the block is not part of the design.  I just don't see it.

the only spec that could account for the large difference in block weight would have to be one of quality of balance, no other spec would result in the need for that much more concrete.

Maybe they did reduce quality of balance.  What does this prove though?

as for it being a result of being safety concious, here again i take exection, do you have any supporting evidence that the earlier recommendation of 600#'s of concrete being insufficient and causeing property or bodily damage?? i seriously doubt it.

No, I don't.  I don't know or really care why they made the change.

obviously many of you have never worked with a very well balanced machine/engine, one that is properly tuned and set up will run quite nicely sitting flat on the floor.
such an engine is quite a marvel to behold and i have no doubt that the early listers were of this quality.

further i would assert that the A grade engines in later years became the engine of choice for the SOM's

seriously it only makes sense,

I wouldn't know.  I'm not making an assertion about this one way or the other.

As an aside, maybe you can explain something to me: is it possible to balance a four-stroke one-cylinder precisely?  In my mind's eye I can't see how it could be smooth at idle and also during the power stroke at full HP.

there are those on this board that look to lister as if it was designed, machined, assembled by arch angels, and ordained by God. it is not!
it is simply a good engine, and in some cases an excellent engine built by men, ordinary men, that were craftsman to be sure, but ordinary men that ate, slept and shit just
like each one of us.

i tire very easily when there are those that put lister on some pedestal that is beyond question, one should be able to ask any question of any man or company, and get a clear and concise answer,

All I'm saying that RA Lister specified a concrete block, and thus it is part of the engine design.  You don't seem to dispute that all CS specs feature the block, yet you are certain that RA Lister didn't really specify it.

not some crap about "just do the math"

and finally,

i have no doubt that i could build a 6/1 from one of the kits, carefully balancing it either myself or hire it done, detail it properly and have an engine that would run as long as any other listeroid and have it mounted to timbers, 600#s of concrete or even resilient mounted.

i have no more to say on this subject until "someone produces the friggin formulae", anyone supporting the use of concrete as being gospel from god is just full of shit.

bob g

As for 'do the math', you're talking to the wrong person.

The spec says use a concrete block, and you don't deny it.  Yet, you say I'm full of shit for reading the spec literally.  You, on the other hand,  have provided an assortment of reasons for why the spec doesn't actually say what it says.  Not only that, at least twice you've tried to shift the burden of proof onto me.  I have to prove that Lister considered and rejected resilient mounts.  I have to produce Lister's block size equations.  If you doubt the spec, fine, so long as you accept the burden of proof.

mobile_bob

  • Administrator
  • Hero Member
  • *****
  • Posts: 2787
    • View Profile
Re: seeking an answer...
« Reply #38 on: November 20, 2006, 01:34:42 AM »
Pro:

if you recall i started this thread in the attempt to get to the formula

you will derive from the references that were sent to me and posted at the beginning of this thread one thing and i another.
ten more guys can come in and derive maybe 10 other things, all of which makes no real difference to the question at hand.

we can debate the vargaries and the fineries of the lister prints, and sales text till the cows come home, i am up for it, but i doubt either of us will change the others mind

i posted those two links solely as proof that the assertion that the concrete block was an intergal part of the engine design is problematic.

i have also stated my reasons for seeking the formula and an understanding of the assertion that the block was intregal to the design of the engine, that is one of education and broad applicability beyond its use by me in mounting a listeroid.

without those two links the assertion of there being a formula for determing the spec on a concrete block still had some legs, some hope of getting there, but with them it is losing ground quickly.

again i will state "words have specific meanings" most especially when used in engineering, science, math or law. all of which are in play when applied to listers drawings and sales brochure. i have no doubt that they carefully chose their wording, and in doing so many folks will read what they want to hear into it. it just isnt there!

when they asked to be told about the particulars of mounting, they are not asking about particulars of installation.

mounting does not equal installation, these are two different words with two different meanings, most particulary when used in a machine context.

still waiting for the equation/formulae, dont even have to be for a lister!! give me a one for any machine to concrete

bob g
otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info

Quinnf

  • Hero Member
  • *****
  • Posts: 645
    • View Profile
Re: seeking an answer...
« Reply #39 on: November 20, 2006, 01:42:42 AM »
Bob,

I think you neglected to mention that the 6/1, 5/1 and the 3/1 drawings all show the same size concrete block.  If the dimensions of the block were the result of careful calculation, then a 3/1 turning appx half the torque of a 6/1  should have a smaller block.  It doesn't.  To me that indicates pragmatism, not calculation was used to spec. the block.

Quinn
Ashwamegh 6/1, PowerSolutions 6/1 "Kit" engine, and a Changfa R175a that looks like a Yanmar I once knew

mobile_bob

  • Administrator
  • Hero Member
  • *****
  • Posts: 2787
    • View Profile
Re: seeking an answer...
« Reply #40 on: November 20, 2006, 04:06:24 AM »
Quinn:

thank you, it was an oversite


Pro:

"As an aside, maybe you can explain something to me: is it possible to balance a four-stroke one-cylinder precisely?  In my mind's eye I can't see how it could be smooth at idle and also during the power stroke at full HP."

no i am not suggesting anything like that, just as i am not suggesting that you can balance a single cylinder engine perfectly, but you can attain a very acceptable level
of balance on either engine at a specific rpm.  Because the lister/oid is likely to be running at a specific rpm this information can be relayed to the shop that dynamically balances your assy to be as well balanced as you are willing to pay for at this specific rpm.

no mass produced engine will ever be balanced as well as what you can do on an individual basis (generally speaking), and listeroids are no exception to this.

we have all heard of the listeroid that a guy bought and started on the crate and found it to sit there and chug away, and conversely we have all heard of the guy who started his on the pallet only to have it hop all over the shop and chase him out the  door.  cleary there is some issues related to quality of balance, bolting it to a ton of concrete won't make the hopper a better engine, it is just going to mask the problem.

as for having it both ways:

engine designers do not design engines on dyno's, they design them on paper, with calculations, math and established formula. with enought calculation and input data it is surprizing just how close the final dyno results are to the design. the dyno is used to further refine and and tune the engine and provide testing.
engine designers have had all the formula's to design on paper all manner of engines for the last 75+ years. even back then they were within a few percent of design on the dyno. today they can predict to very tight margins any change to an engine result in hp/torque/ fuel consumption etc.

and yes they could engineer a concrete block today, last week or 50 years ago, but funny thing is i can find no mention of any formula to arrive at an engineered solution.
either lister and ever other stationary manufacture had the formula and no it is lost to the sands of time or there was a simple rule of thumb approach used.

i guess like religion and politics, we all choose to believe what we want to

bob g

otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info

Procrustes

  • Sr. Member
  • ****
  • Posts: 332
    • View Profile
Re: seeking an answer...
« Reply #41 on: November 20, 2006, 11:13:46 PM »
if you recall i started this thread in the attempt to get to the formula

you will derive from the references that were sent to me and posted at the beginning of this thread one thing and i another.
ten more guys can come in and derive maybe 10 other things, all of which makes no real difference to the question at hand.

we can debate the vargaries and the fineries of the lister prints, and sales text till the cows come home, i am up for it, but i doubt either of us will change the others mind

i posted those two links solely as proof that the assertion that the concrete block was an intergal part of the engine design is problematic.

i have also stated my reasons for seeking the formula and an understanding of the assertion that the block was intregal to the design of the engine, that is one of education and broad applicability beyond its use by me in mounting a listeroid.

without those two links the assertion of there being a formula for determing the spec on a concrete block still had some legs, some hope of getting there, but with them it is losing ground quickly.

I never said there was or was not a 'formula'.  My remarks on the topic have to do with separate disagreements.

again i will state "words have specific meanings" most especially when used in engineering, science, math or law. all of which are in play when applied to listers drawings and sales brochure. i have no doubt that they carefully chose their wording, and in doing so many folks will read what they want to hear into it. it just isnt there!

Well, they also depict the block as part of the blueprint of the engine.  I admit I'm confused by the 'particulars of mounting' statement, I don't exactly know how to reconcile it with the schematic.  The schematic is certainly more straightfoward.  The 'particulars of mounting' is listed under a section called 'Choosing an engine', so perhaps that explains it.

still waiting for the equation/formulae, dont even have to be for a lister!! give me a one for any machine to concrete

As I said before, no, I don't have a formula, nor have I looked for one.  What do you think you are proving?  I really don't understand.  I think the block is part of the design regardless of whether to use a formula to size it.

You didn't address one part of my post: does the fact that the block size changed prove that the block is not part of the engine design?  Yes or no?

Procrustes

  • Sr. Member
  • ****
  • Posts: 332
    • View Profile
Re: seeking an answer...
« Reply #42 on: November 20, 2006, 11:40:17 PM »
"As an aside, maybe you can explain something to me: is it possible to balance a four-stroke one-cylinder precisely?  In my mind's eye I can't see how it could be smooth at idle and also during the power stroke at full HP."

no i am not suggesting anything like that, just as i am not suggesting that you can balance a single cylinder engine perfectly, but you can attain a very acceptable level
of balance on either engine at a specific rpm.  Because the lister/oid is likely to be running at a specific rpm this information can be relayed to the shop that dynamically balances your assy to be as well balanced as you are willing to pay for at this specific rpm.

no mass produced engine will ever be balanced as well as what you can do on an individual basis (generally speaking), and listeroids are no exception to this.

we have all heard of the listeroid that a guy bought and started on the crate and found it to sit there and chug away, and conversely we have all heard of the guy who started his on the pallet only to have it hop all over the shop and chase him out the  door.  cleary there is some issues related to quality of balance, bolting it to a ton of concrete won't make the hopper a better engine, it is just going to mask the problem.

I was just asking Bob, you would know better than I.  But I don't think you answered my question. I'm not talking about balance differences between different RPM's.  I'm wondering whether balance changes under different loads.  Does it?

as for having it both ways:

Despite what you say below, I still don't know what you figure I'm trying to have both ways.

engine designers do not design engines on dyno's, they design them on paper, with calculations, math and established formula. with enought calculation and input data it is surprizing just how close the final dyno results are to the design. the dyno is used to further refine and and tune the engine and provide testing.

Well sure you can predict anything with enough input data.  But where does input data come from?  Experimentation and measurement, which you are saying is relatively unimportant in engine design.  If you accept the the 'just how close' is extraordinarily important then I agree.  If that weren't so, then all quarter mile dragsters would use virtually the same engine, the optimal one for the application, whereas in reality there is lots of variation. 

engine designers have had all the formula's to design on paper all manner of engines for the last 75+ years. even back then they were within a few percent of design on the dyno. today they can predict to very tight margins any change to an engine result in hp/torque/ fuel consumption etc.

and yes they could engineer a concrete block today, last week or 50 years ago, but funny thing is i can find no mention of any formula to arrive at an engineered solution.
either lister and ever other stationary manufacture had the formula and no it is lost to the sands of time or there was a simple rule of thumb approach used.

i guess like religion and politics, we all choose to believe what we want to

bob g



mobile_bob

  • Administrator
  • Hero Member
  • *****
  • Posts: 2787
    • View Profile
Re: seeking an answer...
« Reply #43 on: November 20, 2006, 11:48:00 PM »
Pro:

"You didn't address one part of my post: does the fact that the block size changed prove that the block is not part of the engine design?  Yes or no?"

had the change in block dimensions been marginal, i would say "no" it would not prove the block to not be a part of the engine design.

but the block changed dimensions radically, so "yes" that would prove it was not part of the design of the engine.

further i can find no mention of any manufacture ever using the concrete base as an intregal part of an engine design.

the use of the concrete block as an intregal part of the design flies in the face of all that has been published on sound engine design and engineering (at least for purposes of moving a center of mass, center of gravity is another story)

proper engine design (and i have no reason to believe that the good folks at lister were incapable of proper design) dictates that all internal forces/stresses etc are to be contained and managed within the structure of the engine proper, eg. the crankcase.

the lister crankcase is typical of design and shows no sign of deficiency that would dictate that a concrete base would improve upon. further...

if by design the lister needed the concrete base to stablize, increase strength, move centers of mass etc. the print would have included an iron or steel bedplate that would have been grouted to the concrete providing a broader contact with the concrete rather than the relative point loading that would lead to abrasion at the mounting bolts over time. for there to be a tranfer of forces to the concrete this connection would have to be very solid and if abrasion occured the engine would exhibit catastrophic failure which has not proven to be the case.

listers overall design is very good, solid and time proven, and was based on popular design as far as basic structure and crankcase design are concerned. for the power density envolved it is hell for stout and has no need for outside strengthening from a concrete base.

from a standpoint of simple, cheap, stable and expedient clearly the concrete base is a good method of mounting, i got no problem with that or its use.

the bottom line here is not whether or not concrete is good, bad or indifferent, or if resilient is good, bad or indifferent.
i just want to see some formulae or reference to the claim that the block has to be, or was a part of the structural design of the engine to begin with.

still looking, still waiting, perhaps i will find it but like granny used to say "maybe so, but i kinda friggin doubt it"
the more i research the further i get from accepting that the yard of concrete is the only way to mount a lister/oid and have an engine that will live longer than if mounted in an alternative (and properly engineered) manner.

bob g
otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info

mobile_bob

  • Administrator
  • Hero Member
  • *****
  • Posts: 2787
    • View Profile
Re: seeking an answer...
« Reply #44 on: November 21, 2006, 12:17:01 AM »
Pro:

"Despite what you say below, I still don't know what you figure I'm trying to have both ways."

let me try again, sometimes i don't relate what i see in my head well.

one way

there is the assertion that some higher level math was or can be used to calculate the movement of the center of mass, to within the concrete block, and in doing so arrive at specific dimensions for the concrete block

the other way

there is the assertion that you cannot predict or engineer an engine through formula to arrive at what the engine's output , fuel consumption, VE etc. with any precision. we have to have a dyno

so one could reconcile the two ways by stating that:

we can run calculations and formula's to get close on engine design, and then have to refine on a dyno through empirical testing and observation, and

we can run some calculation/formulae (which has not surfaced yet) to arrive at a specific dimension for a concrete block, then through some empirical testing and observation refine that dimension... so...

how is it that one spec calls for 600 lbs of concrete and another reference calls for a ton or a yard (which is over a ton) of concrete? this is an enormous difference, either the formula is flawed or is non existant. we are talking about a 300 to 400% difference in spec's!

we can sit down and design an engine on paper, using established formula and be well within 10% and the pro's are well under 5% of expected parameters on the dyno.  clearly the calc's/formula are pretty accurate in most cases.

so how do you reconcile this difference?  i wish someone could step up and support it, with something solid, some reference or formula.

questions i got,,, don't need more questions, need some answers

" I'm not talking about balance differences between different RPM's.  I'm wondering whether balance changes under different loads.  Does it?"

engine loading will not effect overall balance, at least in any way that one can do anything about. what it will do is raise cylinder pressures and produce more stress within the structure of the engine, which is contained between the cylinder head and the crankcase main journal's.


as far as all 1/4 mile dragsters, the top fuel boys all use the same engine's, same displacements and much the same ancillary equipment, the drive ratio's, tire pressures, clutch settings and the drivers are about the only variables left.

what is amazing is that today engine designers can sit down behind a puter and input all the parameters into the program, run it all thru, then produce the thing and come out damn close to what the puter said to start with.

you can take 3 engines of the same bore/stroke ratio, same rod length ratio and the same VE, made by 3 different manufactures and end up within under 5% of margin on any measurement of power/ fuel efficiency torque or whatever.

they could do it 50 or 75 years ago just as well they just used pencils paper and slide rules instead of puters.

today a manufacture faced with the need for a new engine will go to the engineering department and tell them the basic parameters.
"we want an engine that is X long, x tall, x wide, weighing in at x, that produces x amount of hp, x torque, at this rpm range, and with a fuel consumption rate of x."

the engineers design it and they got to be damn close or someone loses their job.
once built can it be improved on, generally yes!

bob g



otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info