Running engine (diesel) with the ignition turned off

[rogerthebodger]

No they aren't alpha males. They're argumentative anoraks with too much time on their hands.

I did put the thread on 'Unwatch' but it has a strange kind of fascination for me. The stamina of the opponents, the spurious technicalities, the irrelevance to the real world. And most of all the way it has nothing whatever to do with the original topic . . .

Keep at it, lads! You must have plenty more to say!

Yes now edited.

 

[penberth3]

Been called many things Roger the dodger, Roger the Bodger, Roger the Lodger but never Rober but I don't take offence. It's probably a typo anyway.

You can also use the combined charles law and Boyle's law I posted early.

Yes, a typo. I meant to type Robert, Roger.

 

[convey]

But nobody is being rude or abusive

I think insulting people with "hoo-hah" side discussions about how they only know things because they looked them up in the Wikipedia etc is pretty insulting, especially when it is done by people who don't know what they are talking about, and don't even know that they don't know what they are talking about.

Who knows who was rude or abusive, I forget those kind of things pretty quickly.

I'm just sorry I couldn't find people that I could discuss the more esoteric elements of cylinder head design and development. But, let's face it, marine diesels aren't exactly the cutting edge of IC design.

 

[NotBirdseye]

I think insulting people with "hoo-hah" side discussions about how they only know things because they looked them up in the Wikipedia etc is pretty insulting, especially when it is done by people who don't know what they are talking about, and don't even know that they don't know what they are talking about.

Who knows who was rude or abusive, I forget those kind of things pretty quickly.

I'm just sorry I couldn't find people that I could discuss the more esoteric elements of cylinder head design and development. But, let's face it, marine diesels aren't exactly the cutting edge of IC design.

Sure Wikipedia is insulting... it's not wrong though.

Compression Ratio | Definition of Compression Ratio by Oxford Dictionary on Lexico.com also meaning of Compression Ratio
Compression ratio | technology
Compression Ratio - an overview | ScienceDirect Topics
Cylinder Heads - an overview | ScienceDirect Topics

I have a feeling that you're just using the wrong term for what you mean and it's confusing the rest of us/them. I can see why you think it would have an effect but it just doesn't matter according to the definition.

 

[RichardS]

This is a pi**ing contest between two alpha males.

I've no idea whether Paul would relish the epithet or not .... maybe he'll be along in due course.

Richard

 

[pvb]

I've no idea whether Paul would relish the epithet or not .... maybe he'll be along in due course.

I doubt that he'll be enticed by the constant taunts from his little stalker!

 

[convey]

Sure Wikipedia is insulting... it's not wrong though.

That's not what I said though, is it?

[/QUOTE]I have a feeling that you're just using the wrong term for what you mean and it's confusing the rest of us/them. I can see why you think it would have an effect but it just doesn't matter according to the definition.[/QUOTE]
Oh God, someone else who does not get it and reverts back to the "2 + 2 =" level answer yet again.

OK, turn it around, how do you establish a compression ratio in an engine, how do you create the compressed volume, without a piston top and combustion chamber?

Can you not see it? This is basically a summary of what's being going on

You say, "the CR is the ratio between the volume of the combustion chamber when the piston is at the bottom of its stroke, and the volume of the combustion chamber when the piston is at the top of its stroke".​

I say, "but what determines the volume of the combustion chamber when the piston is at the top of its stroke?".​

You say, "No, no, no, the CR is the ratio between the volume of the combustion chamber when the piston is at the bottom of its stroke, and the volume of the combustion chamber when the piston is at the top of its stroke".​

I say, "Yes ... but what determines the volume of the combustion chamber when the piston is at the top of its stroke?".​

You say, "but the CR is the ratio between the volume of the combustion chamber when the piston is at the bottom of its stroke, and the volume of the combustion chamber when the piston is at the top of its stroke".​

I say, "Yes, I know ... but what determines the volume of the combustion chamber when the piston is at the top of its stroke"?.​

You say, "but Wikipedia, the Britiannica, & Science Direct says, the CR is the ratio between the volume of the combustion chamber when the piston is at the bottom of its stroke, and the volume of the combustion chamber when the piston is at the top of its stroke".​

I say, "Yes ... but what determines the volume of the combustion chamber when the piston is at the top of its stroke?".​

Repeat ad infinitum.

The equation does not do the work, it only describes what's going on. Things do the work. So when someone writes

The shape of the piston crown or cylinder head does not affect the compression ratio.​

​

How can they possibly be right?​

​

How could the "shape of the piston crown or cylinder head" (and deck height etc) possible NOT affect the compression ratio?​

What compression would an engine with no piston crown or cylinder head have?

Do you understand it now?​

 

[convey]

So what determines the volume of the combustion chamber when the piston is at the top of its stroke?

 

[Mister E]

So here is two people who have to have the last word, trying to out last word the other.

So who makes the best cakes?

 

[NotBirdseye]

Convey, you screwed up that post and I can't make neither heads nor tails out of it.

In a nutshell I can only go by the world wide accepted definitions by reputable sources and they say that you are wrong. If you can't understand why, there's nothing I can do and more experienced technicians have also tried to point it out to you... yet... here we are.

 

[RichardS]

Convey, you screwed up that post and I can't make neither heads nor tails out of it.

In a nutshell I can only go by the world wide accepted definitions by reputable sources and they say that you are wrong. If you can't understand why, there's nothing I can do and more experienced technicians have also tried to point it out to you... yet... here we are.

Now, how about that #348 edit?

Richard

 

[VicS]

[

So what determines the volume of the combustion chamber when the piston is at the top of its stroke?

That's easy to answer .... Its dimensions, but it does not mater what shape it is. Cubic, spheroidal, pyramidal, or polyunsaturated it makes no difference.

however because of the complexity of the shape the only dimension you can measure and quote a numerical value for is its volume.

Conclusion ........... at last , logically deduced ........ The volume of the combustion chamber is what determines the compression ratio , not its shape

 

[NotBirdseye]

Now, how about that #348 edit?

Richard

Running engine (diesel) with the ignition turned off At least that's my interpretation.

 

[RichardS]

The shapes "don't make the compression", but their shapes and their match determines the compressed volume, that determines the compression ratio.

Conclusion ........... at last , logically deduced ........ The volume of the combustion chamber is what determines the compression ratio , not its shape

Convey himself got to the right answer many years ago .... I consider those to be the halcyon golden days of the forum. Now, sadly, passed.

Richard

 

[PaulRainbow]

[

That's easy to answer .... Its dimensions, but it does not mater what shape it is. Cubic, spheroidal, pyramidal, or polyunsaturated it makes no difference.

however because of the complexity of the shape the only dimension you can measure and quote a numerical value for is its volume.

Conclusion ........... at last , logically deduced ........ The volume of the combustion chamber is what determines the compression ratio , not its shape

What do you mean, "at last" ?

I posted that way back in post #41 and several others have said the same throughout the thread.

 

[NotBirdseye]

We don't talk of the period pre '45, something about Godwin's law .

 

[PaulRainbow]

We don't talk of the period pre '45, something about Godwin's law .

No problem, i said it again in post #66 and no doubt several times since

 

[RichardS]

So here is two people who have to have the last word, trying to out last word the other.

Two people?

More like twenty-two.

Richard

 

[convey]

A shape is described by its dimensions. The two are inseparable.

You're moving the goal posts here to introduce ridiculousness, a sort of reductio ad absurdum (reduction to absurdity) of spheroidal, pyramidal pistons. Show me any.

And let's be clear, I've always argued it was the match of the piston crown and cylinder head not the shape of one, as Paul introduced.

because of the complexity of the shape the only dimension you can measure and quote a numerical value for is its volume.

You're basis your conculsion on a fallacy. "the only dimension you can measure is the volume".

Really?

So if I take a ruler and do a π r² I can't measure the top piston? I can't measure the deck height, I can't measure the pin height, I can't measure the depth of a hemi-spherical chamber, and divide by 2 the spherical dimensions?

Why not just use the manufacturing drawings used for the design, either for the casting or the CNC?

But how do you know the volume in the first place is something was not measured?

 

[jbweston]

I'm concerned about the cubic capacity of my anchor. It is marked 'Genuine Bruce - Oz's leading anchor designer. Big enough to do the job', but not with its capacity. I've tried dropping it in a bath of water and measuring how high above the greasy tide mark the level rises but my hydro-micrometer is marked in nano-cubits, and I don't know how to convert that to imperial units. Can any of you experts help me?

To cut to the chase, I'd really like a knock-off Rocna replica to give me marina credibility, but China is cut off at the moment and I can't get Amazon to give me a delivery date (I hate dealing with local small businesses - they seem so yesterday). Can anyone advise me whether in the meantime I'm in danger of dragging when I anchor in Studland Bay using my Brucey?

I really don't want to disturb any sea horses, and I know if I get into difficulty the RNLI can't help because they've sold all their lifeboats and are spending their money on installing Baywatch babes on every stretch of level sand.

Any expert advice (even from loudmouthed expert-wannabes with finger-diarrhoea ) would be really appreciated.