Engine downsizing comes with downside
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What is the reason for Ca and LSPI? Incandescent ash particles in the chamber?
Originally Posted By: PimTac
Something is being lost in translation over the interwebs so I'll leave it at that. Thanks for the explanations.
Nothing is being "lost in translation" Some things are being stated correctly (by, for example, me and barryh), some things are being stated incorrectly (by, for example, you and sonofjoe).
There are two separate, distinct, but similar and associated phenomena here.
1. Detonation
2. Pre-ignition.
You can either observe the distinction, and try and use the terms correctly, or you can relax, chill out, wave your hands about a bit, use the terms interchangeably, and maybe make up a few of your own that you think sound kind of cool and techy. Its very popular. "Pre-detonation" , for example, combines maximimum combination with minimum meaning.
Originally Posted By: SonofJoe
Classic knock (or pinking) is caused by pre-ignition of the fuel,
No it isn't. Classic knock (or pinking) is caused by detonation of the fuel.
Originally Posted By: SonofJoe
The octane rating of the gasoline is it's ability to resist pre-combustion.
I don't know if "pre-combustion" is a recognised term, but it seems a reasonable (if unnecessary) alternative name for pre-ignition, which is.
I do, however, know that the octane rating of the gasoline is NOT its ability to resist pre-combustion (whatever it is).
The octane rating of gasoline is its ability to resist detonation, as operationally defined and measured in a special test engine. It will correlate with resistance to pre-ignition but it is not defined by it and they are not the same thing.
Here's an article that explains the difference in some detail.
http://www.contactmagazine.com/Issue54/EngineBasics.html
Something is being lost in translation over the interwebs so I'll leave it at that. Thanks for the explanations.
Nothing is being "lost in translation" Some things are being stated correctly (by, for example, me and barryh), some things are being stated incorrectly (by, for example, you and sonofjoe).
There are two separate, distinct, but similar and associated phenomena here.
1. Detonation
2. Pre-ignition.
You can either observe the distinction, and try and use the terms correctly, or you can relax, chill out, wave your hands about a bit, use the terms interchangeably, and maybe make up a few of your own that you think sound kind of cool and techy. Its very popular. "Pre-detonation" , for example, combines maximimum combination with minimum meaning.
Originally Posted By: SonofJoe
Classic knock (or pinking) is caused by pre-ignition of the fuel,
No it isn't. Classic knock (or pinking) is caused by detonation of the fuel.
Originally Posted By: SonofJoe
The octane rating of the gasoline is it's ability to resist pre-combustion.
I don't know if "pre-combustion" is a recognised term, but it seems a reasonable (if unnecessary) alternative name for pre-ignition, which is.
I do, however, know that the octane rating of the gasoline is NOT its ability to resist pre-combustion (whatever it is).
The octane rating of gasoline is its ability to resist detonation, as operationally defined and measured in a special test engine. It will correlate with resistance to pre-ignition but it is not defined by it and they are not the same thing.
Here's an article that explains the difference in some detail.
http://www.contactmagazine.com/Issue54/EngineBasics.html
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"You can either observe the distinction, and try and use the terms correctly, or you can relax, chill out, wave your hands about a bit, use the terms interchangeably, and maybe make up a few of your own that you think sound kind of cool and techy. Its very popular. "Pre-detonation" , for example, combines maximimum combination with minimum meaning."
There is no need to be snide and rude about this. Let's just leave it as is.
There is no need to be snide and rude about this. Let's just leave it as is.
Originally Posted By: Kibitoshin
Not really a huge fan where a turbo on a tiny engine makes most of it's power. I doubt morons who drive these things will keep it out of boost to reap the fuel economy benefits.
Well, full boost can be as low as 1500 RPM, hard to stay under that.
Originally Posted By: grampi
I like lots of low RPM torque, and for that you need cubic inches...
My car is at max boost at 1800 RPM, which will be 420 lb.ft. I would consider that lots of low end torque, my tires sure do.
Not really a huge fan where a turbo on a tiny engine makes most of it's power. I doubt morons who drive these things will keep it out of boost to reap the fuel economy benefits.
Well, full boost can be as low as 1500 RPM, hard to stay under that.
Originally Posted By: grampi
I like lots of low RPM torque, and for that you need cubic inches...
My car is at max boost at 1800 RPM, which will be 420 lb.ft. I would consider that lots of low end torque, my tires sure do.
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Originally Posted By: mightymousetech
Originally Posted By: Kibitoshin
Not really a huge fan where a turbo on a tiny engine makes most of it's power. I doubt morons who drive these things will keep it out of boost to reap the fuel economy benefits.
Well, full boost can be as low as 1500 RPM, hard to stay under that.
Originally Posted By: grampi
I like lots of low RPM torque, and for that you need cubic inches...
My car is at max boost at 1800 RPM, which will be 420 lb.ft. I would consider that lots of low end torque, my tires sure do.
Sorry, I should've said "I like lots of low end torque with a naturally aspirated engine"....that requires cubic inches...
Originally Posted By: Kibitoshin
Not really a huge fan where a turbo on a tiny engine makes most of it's power. I doubt morons who drive these things will keep it out of boost to reap the fuel economy benefits.
Well, full boost can be as low as 1500 RPM, hard to stay under that.
Originally Posted By: grampi
I like lots of low RPM torque, and for that you need cubic inches...
My car is at max boost at 1800 RPM, which will be 420 lb.ft. I would consider that lots of low end torque, my tires sure do.
Sorry, I should've said "I like lots of low end torque with a naturally aspirated engine"....that requires cubic inches...
Could this be a problem with the choice of piston rings?
btw..small turbos decrease turbo lag so I don't see them going away any time soon.
btw..small turbos decrease turbo lag so I don't see them going away any time soon.
Originally Posted By: Ducked
You can either observe the distinction, and try and use the terms correctly, or you can relax, chill out, wave your hands about a bit, use the terms interchangeably, and maybe make up a few of your own that you think sound kind of cool and techy. Its very popular. "Pre-detonation" , for example, combines maximimum combination with minimum meaning.
You're right. I can assure you that predetonation does not happen in internal combustion engines.
You can either observe the distinction, and try and use the terms correctly, or you can relax, chill out, wave your hands about a bit, use the terms interchangeably, and maybe make up a few of your own that you think sound kind of cool and techy. Its very popular. "Pre-detonation" , for example, combines maximimum combination with minimum meaning.
You're right. I can assure you that predetonation does not happen in internal combustion engines.
Originally Posted By: Garak
Originally Posted By: Ducked
You can either observe the distinction, and try and use the terms correctly, or you can relax, chill out, wave your hands about a bit, use the terms interchangeably, and maybe make up a few of your own that you think sound kind of cool and techy. Its very popular. "Pre-detonation" , for example, combines maximimum combination with minimum meaning.
You're right. I can assure you that predetonation does not happen in internal combustion engines.
I dunno if it happens, because I dunno what it means.
I THINK it doesn't mean anything, because its just a term various good ol' boys made up and posted in various places on the internyet.
However, that article I linked to mentions that there is sometimes an interaction between detonation and pre-ignition, with heating caused by detonation leading to subsequent pre-ignition. That doesn't really affect the distinction.
What it doesn't mention is the other way around. I don't know if this happens, but I can't see why not.
IF pre-ignition were to be followed by a detonation ahead of an expanding flame front started by the pre-ignition event, then that detonation might occur before the timed spark. This would seem to "break" part of the definition of "classic" knock/ping/detonation etc.
I suppose it'd be defendable to reserve the term "pre-detonation" for that situation, IF it occurs.
Originally Posted By: Ducked
You can either observe the distinction, and try and use the terms correctly, or you can relax, chill out, wave your hands about a bit, use the terms interchangeably, and maybe make up a few of your own that you think sound kind of cool and techy. Its very popular. "Pre-detonation" , for example, combines maximimum combination with minimum meaning.
You're right. I can assure you that predetonation does not happen in internal combustion engines.
I dunno if it happens, because I dunno what it means.
I THINK it doesn't mean anything, because its just a term various good ol' boys made up and posted in various places on the internyet.
However, that article I linked to mentions that there is sometimes an interaction between detonation and pre-ignition, with heating caused by detonation leading to subsequent pre-ignition. That doesn't really affect the distinction.
What it doesn't mention is the other way around. I don't know if this happens, but I can't see why not.
IF pre-ignition were to be followed by a detonation ahead of an expanding flame front started by the pre-ignition event, then that detonation might occur before the timed spark. This would seem to "break" part of the definition of "classic" knock/ping/detonation etc.
I suppose it'd be defendable to reserve the term "pre-detonation" for that situation, IF it occurs.
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Originally Posted By: Ducked
I dunno if it happens, because I dunno what it means.
It happens, but it's a nuclear physics thing, not an internal combustion thing.
I dunno if it happens, because I dunno what it means.
It happens, but it's a nuclear physics thing, not an internal combustion thing.
Originally Posted By: Ducked
There are two separate, distinct, but similar and associated phenomena here.
1. Detonation
2. Pre-ignition.
Detonation is post ignition...it happens after the ignition event. That's my way to define it.
There are two separate, distinct, but similar and associated phenomena here.
1. Detonation
2. Pre-ignition.
Detonation is post ignition...it happens after the ignition event. That's my way to define it.
Originally Posted By: PimTac
@Ducked,
Who was the poster that first mentioned the term "pre-detonation"? It wasn't I.
Never said it was.
I was using it as an example of sloppy terminology. Didn't say that anyone had used it in this thread.
Quick search finds a couple, don't have time to look for more right now. Grading deadlines.
https://www.youtube.com/watch?v=qYo3qZTrqdE
http://www.volkswagenmalaysia.club/vwclubmalaysia/pre-detonation-knocking-ron-rating/
@Ducked,
Who was the poster that first mentioned the term "pre-detonation"? It wasn't I.
Never said it was.
I was using it as an example of sloppy terminology. Didn't say that anyone had used it in this thread.
Quick search finds a couple, don't have time to look for more right now. Grading deadlines.
https://www.youtube.com/watch?v=qYo3qZTrqdE
http://www.volkswagenmalaysia.club/vwclubmalaysia/pre-detonation-knocking-ron-rating/
Originally Posted By: Silk
Originally Posted By: Ducked
There are two separate, distinct, but similar and associated phenomena here.
1. Detonation
2. Pre-ignition.
Detonation is post ignition...it happens after the ignition event. That's my way to define it.
Well, yes, as I understand it that's the way its "classically" defined, but now that we've established that basic principle, couldn't detonation (as in its general definition of explosive/supersonically propagating reaction) happen as a result of pre-ignition?
And if not, WHY not?
This thread
http://www.f150ecoboost.net/forum/14-f150-ecoboost-maintenance/14736-low-speed-pre-ignition.html
includes the statement:
"Knock sensors DO pickup PI in Ford ECUs, and its used to set a Pre-Ignition Detection Level.
Preignition from a cylinder pressure and noise viewpoint looks the same as knock, but it happens earlier."
I don't know if that's true, but if it is it doesn't sound like "classic" pre-ignition, (as described in the article I linked to) since that doesn't necessarily involve the supersonic-style "detonation" and cylinder "ringing".
In fact that article suggests that's one of the reasons its especially dangerous, because knock sensors can't detect it.
This makes me wonder if pre-ignition induced "detonation"-stylee behaviour is specifically relevant in an LSPI context.
Originally Posted By: Ducked
There are two separate, distinct, but similar and associated phenomena here.
1. Detonation
2. Pre-ignition.
Detonation is post ignition...it happens after the ignition event. That's my way to define it.
Well, yes, as I understand it that's the way its "classically" defined, but now that we've established that basic principle, couldn't detonation (as in its general definition of explosive/supersonically propagating reaction) happen as a result of pre-ignition?
And if not, WHY not?
This thread
http://www.f150ecoboost.net/forum/14-f150-ecoboost-maintenance/14736-low-speed-pre-ignition.html
includes the statement:
"Knock sensors DO pickup PI in Ford ECUs, and its used to set a Pre-Ignition Detection Level.
Preignition from a cylinder pressure and noise viewpoint looks the same as knock, but it happens earlier."
I don't know if that's true, but if it is it doesn't sound like "classic" pre-ignition, (as described in the article I linked to) since that doesn't necessarily involve the supersonic-style "detonation" and cylinder "ringing".
In fact that article suggests that's one of the reasons its especially dangerous, because knock sensors can't detect it.
This makes me wonder if pre-ignition induced "detonation"-stylee behaviour is specifically relevant in an LSPI context.
Originally Posted By: gregk24
Originally Posted By: Kibitoshin
Not really a huge fan where a turbo on a tiny engine makes most of it's power. I doubt morons who drive these things will keep it out of boost to reap the fuel economy benefits.
Morons? Wow thanks! I'm a fan of VW turbos, they seem to be tuned very well.
Why even respond to a 12 year old who takes his user name from Dragon Ball?
It only encourages the child...
Originally Posted By: Kibitoshin
Not really a huge fan where a turbo on a tiny engine makes most of it's power. I doubt morons who drive these things will keep it out of boost to reap the fuel economy benefits.
Morons? Wow thanks! I'm a fan of VW turbos, they seem to be tuned very well.
Why even respond to a 12 year old who takes his user name from Dragon Ball?
It only encourages the child...
Originally Posted By: Ducked
I dunno if it happens, because I dunno what it means.
I suppose it'd be defendable to reserve the term "pre-detonation" for that situation, IF it occurs.
For your edification:
Pre-detonation is what happens in an atomic weapon if the sub-critical fuel masses are exposed to stray neutrons and undergo spontaneous fission, destroying the fuel before it can be taken super-critical.
Ed
I dunno if it happens, because I dunno what it means.
I suppose it'd be defendable to reserve the term "pre-detonation" for that situation, IF it occurs.
For your edification:
Pre-detonation is what happens in an atomic weapon if the sub-critical fuel masses are exposed to stray neutrons and undergo spontaneous fission, destroying the fuel before it can be taken super-critical.
Ed
Originally Posted By: edhackett
Originally Posted By: Ducked
I dunno if it happens, because I dunno what it means.
I suppose it'd be defendable to reserve the term "pre-detonation" for that situation, IF it occurs.
For your edification:
Pre-detonation is what happens in an atomic weapon if the sub-critical fuel masses are exposed to stray neutrons and undergo spontaneous fission, destroying the fuel before it can be taken super-critical.
Ed
OK, then:-
In the context of IC engines, I suppose it'd be defendable to apply the term "pre-detonation" to the pre-ignition-induced detonation situation I described, IF it occurs.
(Sheesh!)
Originally Posted By: Ducked
I dunno if it happens, because I dunno what it means.
I suppose it'd be defendable to reserve the term "pre-detonation" for that situation, IF it occurs.
For your edification:
Pre-detonation is what happens in an atomic weapon if the sub-critical fuel masses are exposed to stray neutrons and undergo spontaneous fission, destroying the fuel before it can be taken super-critical.
Ed
OK, then:-
In the context of IC engines, I suppose it'd be defendable to apply the term "pre-detonation" to the pre-ignition-induced detonation situation I described, IF it occurs.
(Sheesh!)
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