Jamie Dundee
Well-known member
Jeez, bloke asks a perfectly mundane question and look what happens 
Running engine (diesel) with the ignition turned off
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penberth3
Well-known member
Jeez, bloke asks a perfectly mundane question and look what happens
We're in difficult times - nothing wrong with a bit of free entertainment.
Jamie Dundee
Well-known member
My times are always difficult, it’s only the depth that varies....
JumbleDuck
Well-known member
And I was happy to be corrected, because I like learning new things.
JumbleDuck
Well-known member
Did anyone else have "Some Adventures of Samson Cogg" by Ronald Clark, as a child? The only story I can remember is the one where he manages to get a teenage friend off a charge of driving a moped under 50cc on the motorway (or at least I think that was the charge) by pointing out that a previous rebore had increased the swept volume to fractionally over 50cc.
Thinks ... checks ... good heavens, my 1296cc Triumph Herald is actually a 1323cc Triumph Herald now.
RichardS
N/A
What you are conveniently forgetting, Convey, is that this all stems from where you said:
"My only criticism of this video is that it shows the cylinderhead to have a hemispherical shape, which would reduce compression, when most diesels would have a flat top piston, meeting a flat cylinderhead, which would increase compression"
What Paul has done is correct that sentence because most of us can appreciate that it is total and utter nonsense.
Since then you have dug yourself a deeper and deeper hole rather than correct your mistake but you are unable to get away from the fact that your above sentence is total gibberish. The only correct response to your sentence is that the shape of the piston crown or cylinder head does not affect (as in the sense you are using meaning determine) the compression ratio.
Please simply confirm that you accept that the shape of the piston crown or cylinder head does not determine the compression ratio and the discussion is over.
Richard
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Gixer
Well-known member
sorry I wasn’t clear. Do you need to wait from Turing the key to hitting the starter on a 1GM?
black mercury
Active member
No, doesn't make any difference.
You probably do it out of habit now, but you could be sailing for an extra 10 seconds.
Gixer
Well-known member
Corr, you add those up over 15 years. Thank you.
JumbleDuck
Well-known member
One of my cars is a Citroën DS from the 70s, in which you have to wait anything up to two minutes for the hydraulics systems to come up to pressure after starting the engine. Even when I haven't driven it for a while, I find that I wait the same way in other cars.
VicS
Well-known member
delete
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VicS
Well-known member
No . It has no glow plug. Nothing to wait for
Just follow the procedure in the owners manual, which you can find here if you have mislaid your copy, YANMAR 1GM10 OPERATION MANUAL Pdf Download | ManualsLib
JumbleDuck
Well-known member
While that's true, I liked to pause for a couple of seconds just to check that everything lit up and beeeeeped as it should before trying to start. As you say, though, there is no need to.
convey
N/A
We're getting there's slowly ... I just need to ensure everyone understands the basic principles.
The shape of the piston crown*,
the shape of the cylinder head combustion chamber,
along with one other factor
determines the compression ratio. The complete opposite of what you are still insisting on writing.
Can our resident 9,000 post expert tell us what that other factor is?
If you don't understand how and why, you're not qualified to discuss this issue. If we can establish the fundaments, I can show you how that statement is absolutely true.
Reboring to a simple oversize will not significantly affect the compression ratio, therefore that's not it. I'm just talking about how the compression ratio of an engine is set or affected as it comes out the factory (it would still have an affect of you changed the bore or stroke later). Seriously, it's really basic.
* (strictly speaking you might also argue the pin height too but that's too esoteric and very rarely changeable).
Just to keep it relevent, a Yanmar head and piston (note basically flat and flat - it has a pre-combustion chamber)
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RichardS
N/A
OK, like the other knowledgeable posters on here, I finally give up as the depth of your misunderstanding of i/c engineering as exemplified by your above statement is too fundamental to be corrected on here.
I'll keep an eye on the thread as it will be interesting to see if a single forumite ever comes along to support your statement .... and, contrary to your belief, VicS did not.
If I were to list what determines the compression ratio in the broadest sense, I would basically be writing a book called "The Fundamentals of Internal Combustion Engine Design" rather than listing your supposed three factors.
Keep learning and smiling.
Richard
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penberth3
Well-known member
Just so we're singing from the same hymn sheet.
Compression ratio is (swept volume + clearance volume)/(clearance volume).
Agreed?
JumbleDuck
Well-known member
An almost fanatical devotion to the pope?
rogerthebodger
Well-known member
We used to take a 1275 cooper S and bore it and fit oversize pistons to get 1293 cc as close to the 1300cc class limit.
JumbleDuck
Well-known member
People used to bore out the original Triumph Vitesse engine to take Herald 1200 pistons, increasing its capacity from 1596cc to 1720cc. It means adding 3mm to the bore, though, and apparently that could go through to a waterway, in which case you either tried again with another block or went the whole hog and put in a liner.
rogerthebodger
Well-known member
Yes the they put the 2 lit 6 cylinder into the vitesse and in the 2000. I had a 2,5 pi that has an uprated 6 cylinder with Lucas mechanical fuel injection which I got working OK but when I fitted twin 1 3/4" SU's it went much better 120 mph on the motorway up to the north east.
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