RichardS
N/A
Ah .... ducking the question set in post #157 exactly as I expected.
Are you sure that your engine actually has any oil in it?
Richard
Running engine (diesel) with the ignition turned off
- Thread starter Robert Wilson
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Are you sure that your engine actually has any oil in it?
Richard
RichardS
N/A
Hadenough
Well-known member
I don’t take any. Are you going to answer the question? BTW I don’t do childish smilies.Have you stopped taking your meds?
Richard
RichardS
N/A
What are you on about?
It's me that's setting the question. It's Tamarside who needs to answer it as he's the one dishing out the insults whilst being too timid to actually give us the benefit of his experience.
Richard
JumbleDuck
Well-known member
You weren't? Release the hounds.
PaulRainbow
Well-known member
Please feel free to not login any more.
All you have done since you joined is bitch and whine.
convey
N/A
I abreviated your post because you're talking absolute shite. Sorry, I can't be any more polite about it.
Again, to hide your own ignorance, you've have to change what I wrote.
I told you specifically, they both go into the same engine. One engine.
You change that to "either of the engines", in order to try and make it look as if I am wrong and patronise me by telling me "that I have finally got there".
But I did not say changing the piston was the adjustable factor. I said the "adjustable factor" was the third main design factor that determins the compression ratio.
Which, so far, only Tamarside has indicated he knows specifically, although PaulRainbow is finally getting close.
(And your Google find is irrelevant, it's just as with Mazda Skyactiv is not normal, everyday technology)
The answer Paul is "deck height", which is adjusted simply using a shim gasket. Indeed, should be checked and set in every engine build, but which is generally not, hence engines not running at the designed compression ratio.
Or, as you almost quite get to, by machining the cylinders where it is too large (additional to which is setting the squish, but that's largely a separate issue).
What comes out of this discussion for me, is
a) What a poor grasp of the most simple, fundemental motor engineering design you have
b) How far you and your beta pack dogs are willing to to twist and manipulate other people's statements, insult and attack them to hide it. Playing to the audience.
And you are still up to it ... You're still trying to save face by doing so even now.
That's being a total, nasty crapbag in public.
No, I wrote how flat top pistons were mated to flat cylinder heads to create higher compression ratios. You need two hands to clap.
You wrote,
[QUOTE="PaulRainbow]The shape of the piston crown or cylinder head does not affect the compression ratio.[/QUOTE]
And went on and on and on and on about only the simple equation of volume divided by volume. It's an idiotic statement
Where as in reality,
Because they determine the compressed volume (the adjustability of the squish (aka quench) - which you've not mentioned either - are limited and affect performance in different ways from simple compression).
They don't "not affect", they determine it.
Just out of interest, without Googling it, do you know what a good squish would be?
convey
N/A
Now, to go back to my original statement that Paul mocked so heavily to hide his own lack of knowledge while "spouting nonsensing" (I'm not learning anything about engineering, but I'm learning a lot about twisting and insulting other people's words), I'll give you a simple experiment to do.
Clap twice. And listen. Wet hands work best.
Now, which clap "sparked" better (non-technical use),, which has the "higher compression" ?
It's that simple. You know the answer. Two flat hands (we're not really talking hands here).
Given the same engine again, a flat piston coming up to meet a flat head face is going to have much higher compression that a cupped piston coming up to meet a hemispherical cupped head.
It's really simple.
Clap twice. And listen. Wet hands work best.
Clap with two flat hands.
Clap with two cupped hands.
Now, which clap "sparked" better (non-technical use),, which has the "higher compression" ?
It's that simple. You know the answer. Two flat hands (we're not really talking hands here).
Given the same engine again, a flat piston coming up to meet a flat head face is going to have much higher compression that a cupped piston coming up to meet a hemispherical cupped head.
Yes or no?
It's really simple.
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PaulRainbow
Well-known member
Yawn.
black mercury
Active member
Using pistons that vary the compression ratio as the engine operates would solve all this.
I would like to see someone try to fit adjustment shims to individual cylinders on a modern production engine, which are now built to such staggering tolerances.
Last time I done that was on a Lister diesel were you get a handful of different shims and measure the bump clearance with soft lead to work out the thickness needed.
Certainly if you skim a head you may have the option of different head gasket thicknesses. Then again some manufacturers forbid you to skim heads nowadays due to the different composition of alloy used on the thin head face than the rest of the head.
I would like to see someone try to fit adjustment shims to individual cylinders on a modern production engine, which are now built to such staggering tolerances.
Last time I done that was on a Lister diesel were you get a handful of different shims and measure the bump clearance with soft lead to work out the thickness needed.
Certainly if you skim a head you may have the option of different head gasket thicknesses. Then again some manufacturers forbid you to skim heads nowadays due to the different composition of alloy used on the thin head face than the rest of the head.
RichardS
N/A
Good grief .... it's like wading through treacle.
Let's try again for the third time as it's a simple question and you can't duck out of answering it forever ..... can you?
https://forums.ybw.com/index.php?attachments/95263/
https://forums.ybw.com/index.php?attachments/95264/
Above are photos of two pistons. Let's assume that we don't know anything else at all about either of the engines that these pistons are taken from, other than that the two engines have different compression ratios.
Now, the question is .... which piston is from the higher compression engine and which is from the lower compression engine?
Richard
38mess
Well-known member
I was motoring back to harbour last week with my partner and 4 yo son in the wheelhouse, when I hear the unmistakable sound of the 1-2-both-off switch being operated, it's under the seat and my son had got to it. I managed to switch it back on straight away. No damage done it seems. Phew.
RichardS
N/A
Oh dear .... we were all too premature and Convey has now reverted back to type.
In the meantime, we're still awaiting Tamarside's words of wisdom re: #157 ..... but I doubt that he will ever commit now as he can surely see that Emperor Convey has no clothes.
Richard
penberth3
Well-known member
Oh dear .... we were all too premature and Convey has now reverted back to type.
Richard
At 05:28! I blame Wetherspoons for this.
rogerthebodger
Well-known member
Richard
It seems to me that Convey and Tamarside are talking about a gap between the top of the block and the top of the piston at TDC.
He also talks about shimming the head.
Shimming in productions engines whet out when when cast and hand scrapped white metal bearings were the order of the day and replaceable shell bearings came in. Shims could also add another point of failure.
Also in design terms there is no point in having what he calls "Deck height" on multi cylinder production engines a in my day th machineering tolancies were good enough. Yes by polishing, reshaping and balancing the combustion chambers will improve efficiency. If the combustion is in the piston and raw cast this could be repolished but then this would decrease the compression ratio unless adjusted some other way.
The lack of real world Engineering comes to mind
It seems to me that Convey and Tamarside are talking about a gap between the top of the block and the top of the piston at TDC.
He also talks about shimming the head.
Shimming in productions engines whet out when when cast and hand scrapped white metal bearings were the order of the day and replaceable shell bearings came in. Shims could also add another point of failure.
Also in design terms there is no point in having what he calls "Deck height" on multi cylinder production engines a in my day th machineering tolancies were good enough. Yes by polishing, reshaping and balancing the combustion chambers will improve efficiency. If the combustion is in the piston and raw cast this could be repolished but then this would decrease the compression ratio unless adjusted some other way.
The lack of real world Engineering comes to mind
PaulRainbow
Well-known member
Back to utter nonsense again
Static (geometric) compression ratio is determined by swept volume and the volume of the combustion chamber at TDC, it's really that simple.
To change that ratio on an existing engine you have to alter one of those two values, there are a number of things that can be changed.
When designing an engine those values are determined by a number of factors.
Convey insists compression ratio is determined by the shape of the piston, shape of the head and the deck height, nothing else. This is clearly incorrect. Those three things will contribute towards the two values in paragraph one, but are not the only things that determine those values. There are several things that effect those values, which i have posted before, con rod length, bore, stroke (determined by crank shaft throw) piston design, head design etc.
We are still being told (using the silly hand analogy) that flat pistons and flat heads produce a higher compression ratio, although we have seen images of hundreds of dished diesel piston, some even posted by Convey.
"deck height" and "squish" have now been thrown into the mix. Deck height is simply the distance between the top of the piston (at it's perimeter in the case of dished or domed pistons) and the surface of the cylinder bock. Changing deck height can, of course, change the ratio, we all know about head skimming and different head gasket thicknesses. Squish is a red Herring, thrown in to what end anyone can guess. Squish is the clearance between the piston and cylinder head, again measured at the perimeter. This is not changed to alter the compression ratio, so no need to have previously mentioned it. It may need to be adjusted as a result of other changes made to adjust the ratio. Too large a squish and detonation will occur, too small a squish and the piston will hit the head.
Static (geometric) compression ratio is determined by swept volume and the volume of the combustion chamber at TDC, it's really that simple.
To change that ratio on an existing engine you have to alter one of those two values, there are a number of things that can be changed.
When designing an engine those values are determined by a number of factors.
Convey insists compression ratio is determined by the shape of the piston, shape of the head and the deck height, nothing else. This is clearly incorrect. Those three things will contribute towards the two values in paragraph one, but are not the only things that determine those values. There are several things that effect those values, which i have posted before, con rod length, bore, stroke (determined by crank shaft throw) piston design, head design etc.
We are still being told (using the silly hand analogy) that flat pistons and flat heads produce a higher compression ratio, although we have seen images of hundreds of dished diesel piston, some even posted by Convey.
"deck height" and "squish" have now been thrown into the mix. Deck height is simply the distance between the top of the piston (at it's perimeter in the case of dished or domed pistons) and the surface of the cylinder bock. Changing deck height can, of course, change the ratio, we all know about head skimming and different head gasket thicknesses. Squish is a red Herring, thrown in to what end anyone can guess. Squish is the clearance between the piston and cylinder head, again measured at the perimeter. This is not changed to alter the compression ratio, so no need to have previously mentioned it. It may need to be adjusted as a result of other changes made to adjust the ratio. Too large a squish and detonation will occur, too small a squish and the piston will hit the head.
179580
Active member
Lycoming, Continental, Porsche, Same, Lamborghini Deutz just to name a few that shim deck height.
What did you say regarding a lack of engineering?
PaulRainbow
Well-known member
Beneteau381
Well-known member
Oh dear me.
rogerthebodger
Well-known member
As Paul says this is PBO (Practical Boat Owner)
I don't know haw many Boats particularly Sailing Boats have Lycoming, Continental, Porsche, Lamborghini engines
These are all petrol engine and the aero engines are air cooled so not suitable of even safe for marine use.
I know some of the Deutz engines are/were marinsed by Vetus for boats but I don't know any details.
Lets stay in the real world marine engines of mass produced engine for marine and most normal persons cars.
I don't know haw many Boats particularly Sailing Boats have Lycoming, Continental, Porsche, Lamborghini engines
These are all petrol engine and the aero engines are air cooled so not suitable of even safe for marine use.
I know some of the Deutz engines are/were marinsed by Vetus for boats but I don't know any details.
Lets stay in the real world marine engines of mass produced engine for marine and most normal persons cars.
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