NotBirdseye
Well-known member
I think convey right there has pointed out his own misunderstanding of the concept of the Engine compression ratio...
So here is two people who have to have the last word, trying to out last word the other.
The shape of the piston crown or cylinder head does not affect the compression ratio.
You can't get quicker that a Kwik Fit fitter, we're the boys to trust.I accepted pages ago that I'm only deal with a fitter and gave up trying to enlighten him.
Now, how about that #348 edit?
Richard
He's keeping score. I had deducted a point... but on reflection he deserved a point back for the underlying principle...
I have here four objectsA 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.
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?
We have demonstrated that volume is not determined by shape therefore we can say that compression ratio, because it is defined solely by volumes, is not determined by the shapes of the defining volume
Static, but I don't think any of those will affect dynamic the way the cams will. It's all about intake cam timing.
No, you have not.
All you're attempting to do is a 'peanut under the shell' game, to re-define the meaning of the word "shape", and what the conversation was about; and further displayed a lack of techincal understanding by fudging your statement with your use of the words determined and defining.
What you've written is, " volume is defined solely by volume", so same the question remains,
What "defines" the volume at TDC?
A volume is defined not defining. That's like saying a vacuum makes its container.
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I live in the real world. Never at one moment did I ever consider Mickey Mouse pistons matching Donald Duck combustion chambers.
This entire discussion started because I pointed out the engine as animated was unlikely to work because matching dished pistons with a hemispherical combustion chamber was unlikely to produce a sufficient CR.
I was then told this was nonsense, that the shape of the piston and the shape of the combustion chamber had no effect defining CR, only the equation did. A ridiculously stupid statement, because the shape of the piston and the shape of the combustion chamber determines the CR (equations only describe it).
I mean, if you want to talk about "shapes", why not let's discuss penis shaped pistons and vagina shaped combustion chambers, just to make it even sillier? I hope the motor has good lubrication because a lot of heat is going to be generated by them, but the same principles would apply. The bell end would also interfere with the flame front and therefore combustion, however, it might assist in scavenging on the down stroke.
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So, the big lesson to take from all this is equations don't determine anything. Piston and combustion shapes (dimensions) do. Equations only describe what's going on.
No no, he's trying... in effect... to deny that Area x Height = Volume. Because it's an equation and merely describes what is going on and doesn't define anything....
No no, he's trying... in effect... to deny that Area x Height = Volume. Because it's an equation and merely describes what is going on and doesn't define anything....
Yes, equations only describe what's going on, not define what's going on.
But, no, the equation of the volume would be far more complex than V=πr2h (area of piston top times length of the stroke), because of the additional volume of the combustion chamber.
What defines what is going on is the shape (dimensions) of the piston and combustion chamber. The opposite of what was said where we started.
Why, because they define the volume at TDC, that then defines the ratio.
Demonstrating that volume is not determined by shape is exactly what I have done. I have shown that either shape or volume can vary independently of the other.No, you have not.
The words "determined" and "defining " were chosen for the difference in their meanings.All you're attempting to do is a 'peanut under the shell' game, to re-define the meaning of the word "shape", and what the conversation was about; and further displayed a lack of techincal understanding by fudging your statement with your use of the words determined and defining.
What you've written is, " volume is defined solely by volume", so same the question remains,
What "defines" the volume at TDC?
The defining volumes are those volumes used in the definition of compression ratio.A volume is defined not defining. That's like saying a vacuum makes its container.
None of this rambling nonsense has anything to do with my post.I live in the real world. Never at one moment did I ever consider Mickey Mouse pistons matching Donald Duck combustion chambers.
This entire discussion started because I pointed out the engine as animated was unlikely to work because matching dished pistons with a hemispherical combustion chamber was unlikely to produce a sufficient CR.
I was then told this was nonsense, that the shape of the piston and the shape of the combustion chamber had no effect defining CR, only the equation did. A ridiculously stupid statement, because the shape of the piston and the shape of the combustion chamber determines the CR (equations only describe it).
Having demonstrated a lack of understanding of mathematics and engineering and poor literacy you now descend to vulgarity. Perhaps it is time for the the forum admin team to award you a period of shore leave so that yo can find some courses in these subjectsI mean, if you want to talk about "shapes", why not let's discuss penis shaped pistons and vagina shaped combustion chambers, just to make it even sillier? I hope the motor has good lubrication because a lot of heat is going to be generated by them, but the same principles would apply. The bell end would also interfere with the flame front and therefore combustion, however, it might assist in scavenging on the down stroke.
Equations do not describe what is going on . They are algebraic expressions of the principles and definitions involvedSo, the big lesson to take from all this is equations don't determine anything. Piston and combustion shapes (dimensions) do. Equations only describe what's going on.
……..I live in the real world...…
Woop woop!Comments, anybody?
Let's hope the protagonists are running out of steam.Comments, anybody?