Concrete vs resilient - v 3.0

[GuyFawkes]

Started a new thread cos I don't wanna get bogged down in an existing one.

This thread is NOT about concrete vs resilient mounting per se.

This thread is probably my swansong on here, at least for some months, life getting busy, kid on the way and all that.

Forums like these either get more popular or die with time, if they get more popular then they get to the point where there is a critical mass, and that is usually somewhere on the high side of 200 members.

Once you get 200 / 250 plus members, you recreate a phenomenon you can get with 20 members if half of those 20 members decide to use the forum to flame each other, and that is lines being drawn in the sand, this is human nature, you can't stop it happening.

When you get lines being drawn in the sand people pick where they stand for all sorts of reasons, logic usually has little to do with it, but once you pick your spot that is pretty much that, you conform because that is human nature.

When you get a technical or semi technical forum such as this one, it is reminiscent of the early days of Usenet, when many of the forums were populated by technical people, with varying levels of experience or skill in any given area.

The whole concrete v resilient mount thing is a good example, it is next to impossible to discuss this intelligently with people who do not get it, because the medium does not lend itself to communicating the basics, so you are limited to communicating with people who already understand the basics.

In Mk2 of this thread procrustes is trying to beat the limits of the medium, he is posting S-N graphs, I know from this that he has the same basic vocabulary, technically speaking, so we can have a meaningful conversation, but when we start talking about hitting glass bottles with hammers, that is an analogy too far, the noise level just saturated the signal, no useful communication can ensue.

Bend a piece of steel wire repeatedly and it will break, this is because you have exceeded Hookes limit, not because you have gone anywhere near the fatigue limit, because you have not, fatigue by definition is forces that when taken individually (one complete cycle) are way below the minimum required to show ANY outward signs of deformation, wear or damage.

The math is very complex, give me my books, a complete set of parametric data on the engine of choice, a large blackboard, and a day and I can do the math and show you in person how it works and explain it in as much detail as required until you get it.

Give me a text only based medium such as this and as long as I have a hole in my ass I will never explain it to anyone who doesn't already get it, that's a fact....

Yes, a Listeroid with all its design changes is most definitely not a Lister, so that brings in a whole new set of variables.

But the bottom line here is you will simply not be able to effectively communicate across these lines drawn in the sand, if you are stood in the section that wants the engineering done right, no if's but's or maybes, and they are stood in the section that wants a turbo, or wants a trolley mount, or wants to run at 1000 rpm, or wants to do anything that was not envisaged in the original design, or wants to arbitrarily include things like human comfort in the equation.

As soon as that happens you just get polarisation, the more you try and communicate across that gap the more you emphasise that line in the sand, soon you are digging footings and laying a 48" foundation for a block wall, eventually you'll mount gun turrets on the wall and plant anti personnel mines in the perimeter.

In all technical subjects in all technical forums, it is only a matter of time before you encounter a subject where the two sides can cumminicate effectively, but only if they both agree to commit real world time, real world hardware, and real world money, so I can prove (and bet my life on it) that concrete mount is correct, but we need bob to come to me here in the uk, or vice versa, we need about 4 to 8 weeks of time, we need a minimum of two identical engines to start with, we need a budget for data acquisition hardware, we need living expenses, etc etc etc.

Lacking these commitments, there becomes no way to resolve certain issues when they go beyond a certain point, it becomes a zero sum game, everyone who participates is certain to come out of it worse off than when they went in, all that effort went into making a line in the sand into a fortified wall.

This is the reality of forums, some subjects cannot be addressed beyond a certain point which really just constitutes a straw poll of everyone's current opinion, once I know what camp you hail from, further communication on that subject is less than pointless.

A nice example is the Jehovah's witness knocking on your door, they are quite sincere in their beliefs, and quite prepared to spend hundreds of hours in serious reasoned discussion and debate, but you will never convince them that there is no god, just a system, once you realise this the best, quickest and easiest way to deal with them is when they knock on your door answer it and say "I have witnessed" (eg you have seen something sometime in your life that made you think there was the hand of god or some deity in it) and they will turn around and walk away, and walk away happy too.

I suppose I should justify / explain my position, lines in the sand, etc.

I try to get people to drop "common sense", which while common is invariably wrong, see examples about which way to turn motorcycle handlebars to turn right, so I point out lights flickering in 6/1 + gen head systems, point out 5% variations in RPM over the 4 stroke cycle, point out only one quarter of one revolution shows the RPM increasing, the rest of the time it is winding down, point out stresses involved, point out BMEP and piston area, point out that ALL torque developed at the crankshaft MUST also be present on the cylinder walls, no action without equal and opposite reaction etc.

That is as far as I go, I'm not here to big up my own status as some sort of guru, I'm not here to teach people, I'm not here to earn money, I'm not even here to arrive at some consensus about who is right and who is wrong by means of a reasoned debate.

I don't want your vote, I don't want your adoration, I don't want your money, I don't want to "beat" you in some sort of point scoring game. I don't want to convert you, or lead you to seeing the light. I don't even want to you "witness" seeing Newtons second law as applied to listers.

If I want anything, I want knowledge to be free and flourish, you do that by spreading the word, some times it takes hold and flourishes and you know that it will get passed on from that point, some times it doesn't and that's the breaks.

Mr Belk says he can feel the valve train by putting his hand on the block, while the other engine tore up a piece of concrete big enough to park a loaded semi / articulated truck on.

Gino got his bearings made and set up the old fashioned / correct way.

I'm happy Mr Belk had that moment, I'm happy Gino had that moment and met the bearing guy, if I had 0.0000001% of the credit for either of those things happening then there is my reward right there. I don't care if everyone else plays with spreadsheets and rubber mounts everything and turbos it too and puts racing stripes on it as well.

I'm gonna stick around these forums now and again, because some time in the future andy / t19 is going to get his genuine lister fired up and his first 1000 hours out of it, and he will have things to say because he has been exposed to listeroids too. Ditto the other chap on here who bought a start-o-matic from the Uk, ditto mr belk when his genuine listers eventually make it over there.

I'm really looking forwards to hearing what these people say.

I've been accused of lots of things in my life, "teutonic arrogance" was one that kinda summed it up nicely, except it aint arrogance, I KNOW what is coming to these people, but the unknown is like watching them open a christmas present, I don't know exactly how their face will look, or what words they will use to express their glee and enjoyment and personal eureka moments.

I'll go back to the video my mate posted of him starting his S-o-m for the first time, I knew he largely based his decision to buy it on my urgings, I wasn't worried he would regret it and I would feel bad about my part in that, and that video showing that look on his face when he started it up for the first time is all the reward anyone can ask for, he is another one who has that bit of information that wants to be free, been round diesels all his life but still learned something new when that lister fired up, now he is a slightly different person and any conversation he has about diesels is subtly altered forever.

Before I go, only last thing about forums.

Those lines drawn in the sand, within each sector you get further subdivisions, fawkes is de facto spokesman for nuclear disarmament, abortion, mccarthy plans and concrete mounts, so as long as fawkes is on the podium other people in the same secton content themselves with muttering "yeah" on the sidelines, is quashes debate and true consensus, even though anyone can grab the podium any time they like, it is human nature to let someone else take the flak, again reinforcing the divides and reducing the communications overall. Fawkes has been semi absent a while and others have taken up the podium place, and yet the same argument is yo-yo-ing back and forwards, one figurehead has been replaced by another, and figureheads draw flack and help to polarise issues and make people take sides and start digging fortress foundations.

If you all collectively want these forums to continue to grow and prosper, you need to be ever vigilant for these processes, learn when a discussion is approaching the zero sum, and if you cannot kill it, at least label it very very very prominently as irreverent and not to be taken seriously, and watch out for figureheads, either in yourself or someone else, because they will polarise the issues.

It's easier to do preventive maintenace and change oil regularly than it is to just run something to the ground and blow the crank, easier in the long term that is, so now you only gotta decide if you are in these forums for the long term.

usual disclaimer at the bottom, someone is paying real money and real time to provide these forums for free for everyone else, piss them off and it becomes easier for them to pull the plug than continue paying for something that other people use to compare dick sizes in.

cheers

[mobile_bob]

"....for something that other people use to compare dick sizes in."

just for the record,, mine might not be too big around but it sure is SHORT!   

Guy:

very good post, and obviously well reasoned and presented.

probably something i will reread a few times to get all the nuance it contains.

i was beginning to wonder if you were gone for good, and that would have been a bad thing in my estimation. it has been quite enlightening and very brain use intensive
to correspond and to do the back and forth with you, i have enjoyed it even if perhaps you haven't.

also i think your line drawn in the sand analogy makes sense, it comes to the point where i guess it is human nature to either come to a conclusion based on
whatever one likes beit faith, research or feelings and align oneself on one side or the other on any debate/discussion/arguement.  i know i have found myself on both sides of the concrete vs resilient mount, and to be perfectly honest i am not sure which is the better way in any mathematically proveable manner. And this frustrates me no end, because even just being a lowly mechanic i can explain nearly everything mathematically, geometrically or in some physical order. I understand also there is a thing called "random", but it is hard for me to accept that is the case for concrete, rather i still believe their is a formulae that was used at least in the early years at lister.

to me the whole discussion of pro or con for the use of concrete was lost in the forensic's if you will, what it was replaced with in my mind was a search for the formula so as to understand the engineering/thinking behind its use. i have also stated that having this understanding to me has far broader application than to one or two listeroids i might have running at any particular time.

perhaps if you run across some info on this i would be appreciative, most particularly how to express mathematically the determination of the width of the concrete block on the early 5/1 engine, i got the formula's for the depth and length, just need the width to cross check the other formula. the next step would be to run the formula's against some of the other lister spec'd blocks for other years to see if possibly they were simply a scale up but followed the same formula otherwise. Make sense?


anyway it is good to see you back on the board, how close is the date of you becoming a dad? is this your first?

don't be a stranger, and let us know when the little one makes his/her debut

bob g
ps, i want a cigar! 

[GuyFawkes]

Bob, I've tried to make it very clear that I kinda work by dropping clues or hints.

You said you work from math you know, if you work with the math you know and follow a couple of clues or hints other things will reveal themselves to you, but there is no shortcut, you GOTTA work the numbers, so here are two scenarios for you to work the numbers.

1/
area of a circle is pi x radius squared, 6/1 piston diameter is 4.5 inches.

We KNOW compression ration is 17:1 CS valve out and 19:1 valve in.

we KNOW an atmosphere is 14.7 psi

even if you don't know combustion pressures you know they are higher, much higher, than this, but you can use compression pressures to calculate load on piston.

you can calculate torque from load on piston + crank angle + stroke.

do some of these sums.

2/
You KNOW gensets flicker, you KNOW a 5% variation in RPM over the 4 stroke cycle is not unreasonable
(5% of 650 rpm = 32.5 RPM)

you KNOW the whole assembly only accelerates during the 1/4 rotation of the power stroke that counts (no effective torque at TDC, no pressure or torque at BDC either, call it 1/3rd rotation if it makes you happy)

you KNOW the duration of this event at 650 rpm

you KNOW the mass of the flywheels

you KNOW the formula to calculate acceleration / stress / energy to accelerate flywheels by 32.5 RPM in said 1/4 revolution @ 650 rpm time period

================

really, do these sums.

why?

because the answers are NOT what "common sense" will tell you they are.

and when you realise THAT you start to look with fresh eyes, more closely, at the rest of it.

[mobile_bob]

Guy:

you are absolutely correct, it was not until i took a hard look at the prints of listers 5/1 with its spec'd block of 15x 28x 22 inches and looked hard at the relationship to the crankshaft centerline, the mounting c/c, and other things like the angle of the crankcase in relation to the center of the piston at tdc to the mount bolts that it became painfully apparent, or rather crystal clear.   there is a clear relationship that can be explained with fairly simple equations, this cannot be coincidence.

while on the job today, it came clear what the relationship is to arrive at the concrete block width of 22inches, and this makes for a 3 way coincidence, which is beyond
statistical probability.

the dimensions of the spec'd block are based on vector forces from two prevailing area's within the engine, that being the igintion event and the distribution of forces from the crankshaft thru to the concrete block.

the other consideration is one that is based on the use of concrete itself and is independant of engine concerns, such as mounting bolt proximity to the edge of the block,

basically now i have the formulae to explain the sizing or dimensions of the concrete block as a minimum size as spec'd, a larger block would have no detrimental effect, and would not change the vectors involved, just where they end up in relation to the size of the block.

the two forces/vibrations of significant magnitude are the ignition event and the other being load transmission from the crankshaft thru the case, all others are of such low magnitude that increaseing the case strength either by the addition of material or by careful design handle these very easily.

where dependancy on higher order math comes into play is where weight savings are an advantage such as an aircraft engine or a motorcycle engine or racecar engine, where weight savings is a primary concern and heavy math, and very fine engineering are in order.

on the other hand if you are building a locomotive, you can simply build stuff twice as heavy as need be to avoid difficult analysis, design and engineering as additional weight makes for more traction anyway.

the lister is somewhere inbetween, but likely closer to the locomotive than the aircraft engine.

the other day you posted an example of a piston with 250 psi on it at 90 degree crank rotation, i don't remember all the particulars just now, but arrived at 750 fi/lbs, what you did not consider was the loss of force do to rod angle, which i do not know because of not having the rod length to calculate. also the remaining pressure after factoring in the rod angle is an instantaneous torque that is at one point of the 720 degree rotation.

the mean torque is the 47 ft/lb or average torque over the full two crankshaft rotation or 720 degrees

i would like to further discuss with  you how the specific size of the aforementioned block spec addresses the other stresses of the engine, in harmonics or whatever in mathematical formula if possible.

like i said i can illustrate mathematically the three dimensions of that block using vectors, and it fits! seems like a huge coincidence to me, so much so that now more than ever i am very critical of any  other explanation unless it is accompanied by the actual formula.

please take no offense, i don't mean to question your integrity or your education, i just want to see some sort of proof of concept if not an actual set of equations

btw, you are absolutely correct in that this would be far easier to debate if we were all in a room with a blackboard at least.

i have to tell you this whole thing has become frustrating and tedious, i can find equations for everything related to the internal workings of an engine, and i mean everything!  but no mention anywhere as to an equation for arriving at the block spec's, and this is frustrating.

you might ask why would i want to know?

if i was to find some orphan antique engine, similar to a lister being single cylinder diesel and could find no spec's on the sizing of a concrete base, how would i determine the proper design of the base? 

i can arrive at a spec for the base using my formula, so i guess that will have to due until i can find better.

also i might add that with my formula i can locate the precise vector intersections which would dicatate the precise placement of resilient mounts if one chose to use them. now calculating the
parameters of the resilient mounts would take another set of equations or some set of empirical testing.

for my own interest and to further test the equations could you post the spec's of the concrete block that was approx one ton, i would not be surprised that the same equation will generate the spec with the same result. if it does as i think it will, it will add further proof of validity to the equations.

bob g

[GuyFawkes]

I really don't have time at the mo, and for some time hence, however.

I'm going to link to some pdfs, they start at basic physics principles and work their way through solid examples such as see saws, dampers, tacoma narrows bridge, etc etc etc.

If you download and read / study them all you will at least equip yourself with the minimum tools / language and concepts you require to get a handle on the problem.

http://www.lightandmatter.com/bk1.pdf  Newtonian Physics

http://www.lightandmatter.com/bk2.pdf  Conservation Laws

http://www.lightandmatter.com/bk3.pdf   Vibration and Waves

You can stop after the first 3 if you like and are only interested in the subject as discussed so far.

http://www.lightandmatter.com/bk4.pdf  Electricity and Magnetism

http://www.lightandmatter.com/bk5.pdf  Optics

http://www.lightandmatter.com/bk6.pdf Modern (post Newtonian) physics

http://www.lightandmatter.com/cp.pdf  Conceptual physics - think of it as physics for those who didn't do it at college

http://www.lightandmatter.com/dp/dp.pdf Discover physics - companion to the above

http://www.lightandmatter.com/simple.pdf Simple nature - natural examples used to explain physics

Ideally download them all and keep them in your electronic bookshelf for reference.

[mobile_bob]

Guy:

first of all thanks for the link, it will make for some entertaining reading, and is a good basic refresher course on physic's.
please don't assume that just because i am a greasy ass mechanic i have no clue to the concept of physic's
i assure you that if you should ever produce the formula to the concrete base, i can and will work it.



how about if you have time, reposting the dimensions of the one ton block of concrete,
i already have the formula's so i just want to further test the theory, and really do not want to get into obscure and never to be proven assersions from either side of the issue.

i don't have the time either to continue to discuss this issue with anyone based on their feelings on the subject, however i would discuss equation and formula as it relates to design criteria, and application to these engines.

so how about those dimensions, if you can't produce the formula perhaps you can find the time to repost the ton block dimensions.
if it is not to much trouble

bob g

[mobile_bob]

Guy:

i have been thinking about how to respond to you in a manner that is constructive and not inflammatory.

perhaps a bit of personal history is in order, as i figure you know probably as much about me as i do about you, which is likely not much other than you probably see me as i see you as an arguementative bastard at least.  not saying that is a bad thing

i went thru your links this weekend, and found them to be a wonderful refresher course of my highschool physic's class that i slept thru more years ago than i would like to admit.  Mind you i said i slept thru but i did pass the class.  also for the record it is my opinion that two things should be mandatory in highschool  by the 10th grade, that being "physic's"  the other being "waldens pond"  i digress a bit i suppose.

i appreciate your effort to try and get me to consider all the other forces within the engine proper, but i am nagged by the following

1. how do you reconcile newton's third law?

2. how do you reconcile the use of an inferior material to support a superior material?

3. what makes you think that the lister engine needs any additional support from a block of concrete? was there a design deficiency?

4. consider the original design of 15x 22x 28 inch concrete block, can you tell me approx where the center of mass was moved to?

5. considering the later design of a ton of concrete, can you tell me approx where the center of mass was moved to? and if it was moved to the same point as in
#4 above, what changed withing the engine to necessitate the additional mass.

6. all forces if they are to be transferred to the concrete block have to flow thru vectors, which are straight line, so why would one need to calculate anything happening within the engine proper, when all forces follow straightline vectors.

7. is there a deficeincy within the engine that has to be address externally to the engine proper, not by reason of bad engineering but because there was no other way of addressing it?

ok, i tipped my hand, i produced formula, now it is your turn. either disprove the formula or produce formula of your own.
i want the formula to be scutinized, and you can bet i will scrutinize any formula presented to me,,, seems only fair.

i am a willing pupil, teach me!

bob g