Brian Nystrom wrote:

> Matt Whiting wrote:
>
>> gerry wrote:
>>
>>> [original post is likely clipped to save bandwidth]
>>> On Sat, 28 Jan 2006 02:26:46 GMT, Matt Whiting <whiting@epix.net> wrote:
>>>
>>>> gerry wrote:
>>>>
>>>>> [original post is likely clipped to save bandwidth]
>>>>> On Fri, 27 Jan 2006 02:42:51 GMT, Matt Whiting <whiting@epix.net>
>>>>> wrote:
>>>>>
>>>>>> My point is that either the valves weren't chattering and the OP
>>>>>> was hearing detonation, or the valves are making noise and
>>>>>> something is wrong other than octane. The two simply aren't
>>>>>> related. The valves are closed against their seats when the
>>>>>> combustion (or detonation) occurs.
>>>>>>
>>>>>> Matt
>>>>>
>>>>>
>>>>> Read the reference you posted
>>>>>
>>>>> http://www.streetrodstuff.com/Articl...ion/Page_2.php
>>>>>
>>>>> According to that, "detonation"
>>>>> "can actually cause fracture of valves-intake or exhaust"
>>>>
>>>>
>>>> I saw the above statement.
>>>>
>>>>> The resonance can cause the valves to unseat briefly and force them
>>>>> closed
>>>>> with force.
>>>>
>>>>
>>>> I don't find this statement in the article, even using the search
>>>> function. Where do you find this?
>>>>
>>>> Matt
>>>
>>>
>>> The article states resonance and the structure of the engine to
>>> vibrating.
>>> There is no reason to presume a valve held closed only by spring action
>>> stays firmly seated and unaffected by the engine structure vibration.
>>
>>
>> OK, so you made up the above statement. I just wanted to confirm that.
>
>
> I appears so. It's hard to see how a pressure spike in a sealed
> combustion chamber could cause the valves to open, since they'd be under
> extremely high pressure holding them closed.

I won't go so far as to say it is impossible. I have never, however,
seen any data to suggest that it occurs. And the valves I've seen that
have failed due to detonation, failed due to weakness induced by high
temperatures, not pressure or resonance induced forces.

If someone can produce some data that shows this, I'll certainly change
my view. However, the poster above was just making stuff up and that
won't change my view. :-)


Matt

 

[original post is likely clipped to save bandwidth]
On Sun, 29 Jan 2006 12:53:41 GMT, Matt Whiting <whiting@epix.net> wrote:

>gerry wrote:
>
>> [original post is likely clipped to save bandwidth]
>> On Sat, 28 Jan 2006 02:26:46 GMT, Matt Whiting <whiting@epix.net> wrote:
>>
>>
>>>gerry wrote:
>>>
>>>
>>>>[original post is likely clipped to save bandwidth]
>>>>On Fri, 27 Jan 2006 02:42:51 GMT, Matt Whiting <whiting@epix.net> wrote:
>>>>
>>>>
>>>>
>>>>
>>>>>My point is that either the valves weren't chattering and the OP was
>>>>>hearing detonation, or the valves are making noise and something is
>>>>>wrong other than octane. The two simply aren't related. The valves are
>>>>>closed against their seats when the combustion (or detonation) occurs.
>>>>>
>>>>>
>>>>>Matt
>>>>
>>>>
>>>>Read the reference you posted
>>>>
>>>>http://www.streetrodstuff.com/Articl...ion/Page_2.php
>>>>
>>>>According to that, "detonation"
>>>>
>>>>"can actually cause fracture of valves-intake or exhaust"
>>>
>>>I saw the above statement.
>>>
>>>
>>>
>>>>The resonance can cause the valves to unseat briefly and force them closed
>>>>with force.
>>>
>>>I don't find this statement in the article, even using the search
>>>function. Where do you find this?
>>>
>>>
>>>Matt
>>
>>
>> The article states resonance and the structure of the engine to vibrating.
>> There is no reason to presume a valve held closed only by spring action
>> stays firmly seated and unaffected by the engine structure vibration.
>
>OK, so you made up the above statement. I just wanted to confirm that.
>
>Matt

Well, I just commented that your statement:

Specifically your statement "But this still has nothing to do with the
valve train."

Was contradicted by the references you provided.

gerry

--

Personal home page - http://gogood.com

gerry misspelled in my email address to confuse robots

 

[original post is likely clipped to save bandwidth]
On Sun, 29 Jan 2006 12:53:41 GMT, Matt Whiting <whiting@epix.net> wrote:

>gerry wrote:
>
>> [original post is likely clipped to save bandwidth]
>> On Sat, 28 Jan 2006 02:26:46 GMT, Matt Whiting <whiting@epix.net> wrote:
>>
>>
>>>gerry wrote:
>>>
>>>
>>>>[original post is likely clipped to save bandwidth]
>>>>On Fri, 27 Jan 2006 02:42:51 GMT, Matt Whiting <whiting@epix.net> wrote:
>>>>
>>>>
>>>>
>>>>
>>>>>My point is that either the valves weren't chattering and the OP was
>>>>>hearing detonation, or the valves are making noise and something is
>>>>>wrong other than octane. The two simply aren't related. The valves are
>>>>>closed against their seats when the combustion (or detonation) occurs.
>>>>>
>>>>>
>>>>>Matt
>>>>
>>>>
>>>>Read the reference you posted
>>>>
>>>>http://www.streetrodstuff.com/Articl...ion/Page_2.php
>>>>
>>>>According to that, "detonation"
>>>>
>>>>"can actually cause fracture of valves-intake or exhaust"
>>>
>>>I saw the above statement.
>>>
>>>
>>>
>>>>The resonance can cause the valves to unseat briefly and force them closed
>>>>with force.
>>>
>>>I don't find this statement in the article, even using the search
>>>function. Where do you find this?
>>>
>>>
>>>Matt
>>
>>
>> The article states resonance and the structure of the engine to vibrating.
>> There is no reason to presume a valve held closed only by spring action
>> stays firmly seated and unaffected by the engine structure vibration.
>
>OK, so you made up the above statement. I just wanted to confirm that.
>
>Matt

Well, I just commented that your statement:

Specifically your statement "But this still has nothing to do with the
valve train."

Was contradicted by the references you provided.

gerry

--

Personal home page - http://gogood.com

gerry misspelled in my email address to confuse robots

 

[original post is likely clipped to save bandwidth]
On Sun, 29 Jan 2006 12:53:41 GMT, Matt Whiting <whiting@epix.net> wrote:

>gerry wrote:
>
>> [original post is likely clipped to save bandwidth]
>> On Sat, 28 Jan 2006 02:26:46 GMT, Matt Whiting <whiting@epix.net> wrote:
>>
>>
>>>gerry wrote:
>>>
>>>
>>>>[original post is likely clipped to save bandwidth]
>>>>On Fri, 27 Jan 2006 02:42:51 GMT, Matt Whiting <whiting@epix.net> wrote:
>>>>
>>>>
>>>>
>>>>
>>>>>My point is that either the valves weren't chattering and the OP was
>>>>>hearing detonation, or the valves are making noise and something is
>>>>>wrong other than octane. The two simply aren't related. The valves are
>>>>>closed against their seats when the combustion (or detonation) occurs.
>>>>>
>>>>>
>>>>>Matt
>>>>
>>>>
>>>>Read the reference you posted
>>>>
>>>>http://www.streetrodstuff.com/Articl...ion/Page_2.php
>>>>
>>>>According to that, "detonation"
>>>>
>>>>"can actually cause fracture of valves-intake or exhaust"
>>>
>>>I saw the above statement.
>>>
>>>
>>>
>>>>The resonance can cause the valves to unseat briefly and force them closed
>>>>with force.
>>>
>>>I don't find this statement in the article, even using the search
>>>function. Where do you find this?
>>>
>>>
>>>Matt
>>
>>
>> The article states resonance and the structure of the engine to vibrating.
>> There is no reason to presume a valve held closed only by spring action
>> stays firmly seated and unaffected by the engine structure vibration.
>
>OK, so you made up the above statement. I just wanted to confirm that.
>
>Matt

Well, I just commented that your statement:

Specifically your statement "But this still has nothing to do with the
valve train."

Was contradicted by the references you provided.

gerry

--

Personal home page - http://gogood.com

gerry misspelled in my email address to confuse robots

 

[original post is likely clipped to save bandwidth]
On Sun, 29 Jan 2006 13:47:39 GMT, Brian Nystrom
<brian.nystrom@verizon.net> wrote:

>Matt Whiting wrote:
>> gerry wrote:
>>
>>> [original post is likely clipped to save bandwidth]
>>> On Sat, 28 Jan 2006 02:26:46 GMT, Matt Whiting <whiting@epix.net> wrote:
>>>
>>>> gerry wrote:
>>>>
>>>>> [original post is likely clipped to save bandwidth]
>>>>> On Fri, 27 Jan 2006 02:42:51 GMT, Matt Whiting <whiting@epix.net>
>>>>> wrote:
>>>>>
>>>>>> My point is that either the valves weren't chattering and the OP
>>>>>> was hearing detonation, or the valves are making noise and
>>>>>> something is wrong other than octane. The two simply aren't
>>>>>> related. The valves are closed against their seats when the
>>>>>> combustion (or detonation) occurs.
>>>>>>
>>>>>> Matt
>>>>>
>>>>> Read the reference you posted
>>>>>
>>>>> http://www.streetrodstuff.com/Articl...ion/Page_2.php
>>>>>
>>>>> According to that, "detonation"
>>>>> "can actually cause fracture of valves-intake or exhaust"
>>>>
>>>> I saw the above statement.
>>>>
>>>>> The resonance can cause the valves to unseat briefly and force them
>>>>> closed
>>>>> with force.
>>>>
>>>> I don't find this statement in the article, even using the search
>>>> function. Where do you find this?
>>>>
>>>> Matt
>>>
>>> The article states resonance and the structure of the engine to
>>> vibrating.
>>> There is no reason to presume a valve held closed only by spring action
>>> stays firmly seated and unaffected by the engine structure vibration.
>>
>> OK, so you made up the above statement. I just wanted to confirm that.
>
>I appears so. It's hard to see how a pressure spike in a sealed
>combustion chamber could cause the valves to open, since they'd be under
>extremely high pressure holding them closed.


Not to be argumentative but study the fluid dynamics of detonation in a
compressible gas some time. You will find the shock wave often has
reaction zone behind it that include negative pressures. The movie "Back
draft" demonstrated that several times.

There also is no reason to assume the engine structure vibration from
"detonation" only affects the valves of the cylinder currently igniting.

Again, just food for thought. The whole structure vibrates thus it is very
difficult to know what components may be affected. How can one preclude
the valve train vibrating if the entire engine structure has been shown to
vibrate?

I neither claim proof of such nor accept such has been demonstrated to
never occur.


gerry

--

Personal home page - http://gogood.com

gerry misspelled in my email address to confuse robots

 

[original post is likely clipped to save bandwidth]
On Sun, 29 Jan 2006 13:47:39 GMT, Brian Nystrom
<brian.nystrom@verizon.net> wrote:

>Matt Whiting wrote:
>> gerry wrote:
>>
>>> [original post is likely clipped to save bandwidth]
>>> On Sat, 28 Jan 2006 02:26:46 GMT, Matt Whiting <whiting@epix.net> wrote:
>>>
>>>> gerry wrote:
>>>>
>>>>> [original post is likely clipped to save bandwidth]
>>>>> On Fri, 27 Jan 2006 02:42:51 GMT, Matt Whiting <whiting@epix.net>
>>>>> wrote:
>>>>>
>>>>>> My point is that either the valves weren't chattering and the OP
>>>>>> was hearing detonation, or the valves are making noise and
>>>>>> something is wrong other than octane. The two simply aren't
>>>>>> related. The valves are closed against their seats when the
>>>>>> combustion (or detonation) occurs.
>>>>>>
>>>>>> Matt
>>>>>
>>>>> Read the reference you posted
>>>>>
>>>>> http://www.streetrodstuff.com/Articl...ion/Page_2.php
>>>>>
>>>>> According to that, "detonation"
>>>>> "can actually cause fracture of valves-intake or exhaust"
>>>>
>>>> I saw the above statement.
>>>>
>>>>> The resonance can cause the valves to unseat briefly and force them
>>>>> closed
>>>>> with force.
>>>>
>>>> I don't find this statement in the article, even using the search
>>>> function. Where do you find this?
>>>>
>>>> Matt
>>>
>>> The article states resonance and the structure of the engine to
>>> vibrating.
>>> There is no reason to presume a valve held closed only by spring action
>>> stays firmly seated and unaffected by the engine structure vibration.
>>
>> OK, so you made up the above statement. I just wanted to confirm that.
>
>I appears so. It's hard to see how a pressure spike in a sealed
>combustion chamber could cause the valves to open, since they'd be under
>extremely high pressure holding them closed.


Not to be argumentative but study the fluid dynamics of detonation in a
compressible gas some time. You will find the shock wave often has
reaction zone behind it that include negative pressures. The movie "Back
draft" demonstrated that several times.

There also is no reason to assume the engine structure vibration from
"detonation" only affects the valves of the cylinder currently igniting.

Again, just food for thought. The whole structure vibrates thus it is very
difficult to know what components may be affected. How can one preclude
the valve train vibrating if the entire engine structure has been shown to
vibrate?

I neither claim proof of such nor accept such has been demonstrated to
never occur.


gerry

--

Personal home page - http://gogood.com

gerry misspelled in my email address to confuse robots

 

[original post is likely clipped to save bandwidth]
On Sun, 29 Jan 2006 13:47:39 GMT, Brian Nystrom
<brian.nystrom@verizon.net> wrote:

>Matt Whiting wrote:
>> gerry wrote:
>>
>>> [original post is likely clipped to save bandwidth]
>>> On Sat, 28 Jan 2006 02:26:46 GMT, Matt Whiting <whiting@epix.net> wrote:
>>>
>>>> gerry wrote:
>>>>
>>>>> [original post is likely clipped to save bandwidth]
>>>>> On Fri, 27 Jan 2006 02:42:51 GMT, Matt Whiting <whiting@epix.net>
>>>>> wrote:
>>>>>
>>>>>> My point is that either the valves weren't chattering and the OP
>>>>>> was hearing detonation, or the valves are making noise and
>>>>>> something is wrong other than octane. The two simply aren't
>>>>>> related. The valves are closed against their seats when the
>>>>>> combustion (or detonation) occurs.
>>>>>>
>>>>>> Matt
>>>>>
>>>>> Read the reference you posted
>>>>>
>>>>> http://www.streetrodstuff.com/Articl...ion/Page_2.php
>>>>>
>>>>> According to that, "detonation"
>>>>> "can actually cause fracture of valves-intake or exhaust"
>>>>
>>>> I saw the above statement.
>>>>
>>>>> The resonance can cause the valves to unseat briefly and force them
>>>>> closed
>>>>> with force.
>>>>
>>>> I don't find this statement in the article, even using the search
>>>> function. Where do you find this?
>>>>
>>>> Matt
>>>
>>> The article states resonance and the structure of the engine to
>>> vibrating.
>>> There is no reason to presume a valve held closed only by spring action
>>> stays firmly seated and unaffected by the engine structure vibration.
>>
>> OK, so you made up the above statement. I just wanted to confirm that.
>
>I appears so. It's hard to see how a pressure spike in a sealed
>combustion chamber could cause the valves to open, since they'd be under
>extremely high pressure holding them closed.


Not to be argumentative but study the fluid dynamics of detonation in a
compressible gas some time. You will find the shock wave often has
reaction zone behind it that include negative pressures. The movie "Back
draft" demonstrated that several times.

There also is no reason to assume the engine structure vibration from
"detonation" only affects the valves of the cylinder currently igniting.

Again, just food for thought. The whole structure vibrates thus it is very
difficult to know what components may be affected. How can one preclude
the valve train vibrating if the entire engine structure has been shown to
vibrate?

I neither claim proof of such nor accept such has been demonstrated to
never occur.


gerry

--

Personal home page - http://gogood.com

gerry misspelled in my email address to confuse robots

 

[original post is likely clipped to save bandwidth]
On Sat, 28 Jan 2006 02:17:03 GMT, Matt Whiting <whiting@epix.net> wrote:

>gerry wrote:
>
>> Look up " detonate" in a good dictionary and you will find it is not as
>> defined as used in the above reference! It is not "spontaneous
>> combustion"!
>>
>> An example is
>>
>> http://www.yourdictionary.com/ahd/d/d0172500.html
>>
>> "To explode or cause to explode."
>>
>> http://en.wikipedia.org/wiki/Detonate
>>
>> states
>>
>> "involves a shock wave and a reaction zone behind it"
>
>Detonation used in the automotive sense isn't all that different. The
>spontaneous combustion is in effect an explosion. That is what makes
>all of the noise. It is the shock wave hitting the cylinder walls,
>piston and head that makes the racket.
>
>
>
>> Indeed one detonates a thermo nuclear weapon and that sure is not
>> spontaneous combustion as defined in the reference you choose
>>
>> This is just to point out that different groups use different jargon. Thus
>> I indicated not to worry too much about folks using different wording. I
>> concede I use the words in more general engineering context, not
>> automotive jargon.
>
>It makes sense to use automotive jargon when talking about an internal
>combustion engine, which was the topic at hand.
>
>
>
>> In context of this discussion and using your choice of wording, octane
>> affects both "pre-ignition" and "detonation", inhibiting both.
>
>Octane inhibits detonation, but has almost no affect on pre-ignition.
>Pre-ignition typically occurs from hot spots in the combustion chamber.
> Octane slows down the burn rate and lessens the chance of spontaneous
>combustion, but it doesn't prevent hot spots and it doesn't prevent
>ignition so it has littly if any affect on pre-ignition.
>
>
>Matt

This is intended as an interesting dialog and learning exercise, not an
argument!

Since Octane rating explicitly affects the fuel's flash temperature, it
certainly affects how hot a hot spot must be to cause a problem and does
affect pre-ignition significantly.

An interesting site that discusses octane and pre-ignition explicitly is

http://www.eric-gorr.com/techarticles/Fuel_Basics.htm

"As you may have guessed from the earlier discussion of octane numbers,
high octane fuels have a considerably higher auto ignition temperature to
keep these pre-flame reactions from causing sudden uncontrolled pressure
rises. If the charge burns fast enough or the fuel is resistant enough to
auto ignition (high octane) then all is well and the pressure rise isn't
too extreme." ... "We defined pre-ignition previously as the starting of
the burning process by a source other than the plug"

gerry

--

Personal home page - http://gogood.com

gerry misspelled in my email address to confuse robots

 

[original post is likely clipped to save bandwidth]
On Sat, 28 Jan 2006 02:17:03 GMT, Matt Whiting <whiting@epix.net> wrote:

>gerry wrote:
>
>> Look up " detonate" in a good dictionary and you will find it is not as
>> defined as used in the above reference! It is not "spontaneous
>> combustion"!
>>
>> An example is
>>
>> http://www.yourdictionary.com/ahd/d/d0172500.html
>>
>> "To explode or cause to explode."
>>
>> http://en.wikipedia.org/wiki/Detonate
>>
>> states
>>
>> "involves a shock wave and a reaction zone behind it"
>
>Detonation used in the automotive sense isn't all that different. The
>spontaneous combustion is in effect an explosion. That is what makes
>all of the noise. It is the shock wave hitting the cylinder walls,
>piston and head that makes the racket.
>
>
>
>> Indeed one detonates a thermo nuclear weapon and that sure is not
>> spontaneous combustion as defined in the reference you choose
>>
>> This is just to point out that different groups use different jargon. Thus
>> I indicated not to worry too much about folks using different wording. I
>> concede I use the words in more general engineering context, not
>> automotive jargon.
>
>It makes sense to use automotive jargon when talking about an internal
>combustion engine, which was the topic at hand.
>
>
>
>> In context of this discussion and using your choice of wording, octane
>> affects both "pre-ignition" and "detonation", inhibiting both.
>
>Octane inhibits detonation, but has almost no affect on pre-ignition.
>Pre-ignition typically occurs from hot spots in the combustion chamber.
> Octane slows down the burn rate and lessens the chance of spontaneous
>combustion, but it doesn't prevent hot spots and it doesn't prevent
>ignition so it has littly if any affect on pre-ignition.
>
>
>Matt

This is intended as an interesting dialog and learning exercise, not an
argument!

Since Octane rating explicitly affects the fuel's flash temperature, it
certainly affects how hot a hot spot must be to cause a problem and does
affect pre-ignition significantly.

An interesting site that discusses octane and pre-ignition explicitly is

http://www.eric-gorr.com/techarticles/Fuel_Basics.htm

"As you may have guessed from the earlier discussion of octane numbers,
high octane fuels have a considerably higher auto ignition temperature to
keep these pre-flame reactions from causing sudden uncontrolled pressure
rises. If the charge burns fast enough or the fuel is resistant enough to
auto ignition (high octane) then all is well and the pressure rise isn't
too extreme." ... "We defined pre-ignition previously as the starting of
the burning process by a source other than the plug"

gerry

--

Personal home page - http://gogood.com

gerry misspelled in my email address to confuse robots

 

[original post is likely clipped to save bandwidth]
On Sat, 28 Jan 2006 02:17:03 GMT, Matt Whiting <whiting@epix.net> wrote:

>gerry wrote:
>
>> Look up " detonate" in a good dictionary and you will find it is not as
>> defined as used in the above reference! It is not "spontaneous
>> combustion"!
>>
>> An example is
>>
>> http://www.yourdictionary.com/ahd/d/d0172500.html
>>
>> "To explode or cause to explode."
>>
>> http://en.wikipedia.org/wiki/Detonate
>>
>> states
>>
>> "involves a shock wave and a reaction zone behind it"
>
>Detonation used in the automotive sense isn't all that different. The
>spontaneous combustion is in effect an explosion. That is what makes
>all of the noise. It is the shock wave hitting the cylinder walls,
>piston and head that makes the racket.
>
>
>
>> Indeed one detonates a thermo nuclear weapon and that sure is not
>> spontaneous combustion as defined in the reference you choose
>>
>> This is just to point out that different groups use different jargon. Thus
>> I indicated not to worry too much about folks using different wording. I
>> concede I use the words in more general engineering context, not
>> automotive jargon.
>
>It makes sense to use automotive jargon when talking about an internal
>combustion engine, which was the topic at hand.
>
>
>
>> In context of this discussion and using your choice of wording, octane
>> affects both "pre-ignition" and "detonation", inhibiting both.
>
>Octane inhibits detonation, but has almost no affect on pre-ignition.
>Pre-ignition typically occurs from hot spots in the combustion chamber.
> Octane slows down the burn rate and lessens the chance of spontaneous
>combustion, but it doesn't prevent hot spots and it doesn't prevent
>ignition so it has littly if any affect on pre-ignition.
>
>
>Matt

This is intended as an interesting dialog and learning exercise, not an
argument!

Since Octane rating explicitly affects the fuel's flash temperature, it
certainly affects how hot a hot spot must be to cause a problem and does
affect pre-ignition significantly.

An interesting site that discusses octane and pre-ignition explicitly is

http://www.eric-gorr.com/techarticles/Fuel_Basics.htm

"As you may have guessed from the earlier discussion of octane numbers,
high octane fuels have a considerably higher auto ignition temperature to
keep these pre-flame reactions from causing sudden uncontrolled pressure
rises. If the charge burns fast enough or the fuel is resistant enough to
auto ignition (high octane) then all is well and the pressure rise isn't
too extreme." ... "We defined pre-ignition previously as the starting of
the burning process by a source other than the plug"

gerry

--

Personal home page - http://gogood.com

gerry misspelled in my email address to confuse robots

 

gerry wrote:
> [original post is likely clipped to save bandwidth]
> On Sun, 29 Jan 2006 12:53:41 GMT, Matt Whiting <whiting@epix.net> wrote:
>
>
>>gerry wrote:
>>
>>
>>>[original post is likely clipped to save bandwidth]
>>>On Sat, 28 Jan 2006 02:26:46 GMT, Matt Whiting <whiting@epix.net> wrote:
>>>
>>>
>>>
>>>>gerry wrote:
>>>>
>>>>
>>>>
>>>>>[original post is likely clipped to save bandwidth]
>>>>>On Fri, 27 Jan 2006 02:42:51 GMT, Matt Whiting <whiting@epix.net> wrote:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>My point is that either the valves weren't chattering and the OP was
>>>>>>hearing detonation, or the valves are making noise and something is
>>>>>>wrong other than octane. The two simply aren't related. The valves are
>>>>>>closed against their seats when the combustion (or detonation) occurs.
>>>>>>
>>>>>>
>>>>>>Matt
>>>>>
>>>>>
>>>>>Read the reference you posted
>>>>>
>>>>>http://www.streetrodstuff.com/Articl...ion/Page_2.php
>>>>>
>>>>>According to that, "detonation"
>>>>>
>>>>>"can actually cause fracture of valves-intake or exhaust"
>>>>
>>>>I saw the above statement.
>>>>
>>>>
>>>>
>>>>
>>>>>The resonance can cause the valves to unseat briefly and force them closed
>>>>>with force.
>>>>
>>>>I don't find this statement in the article, even using the search
>>>>function. Where do you find this?
>>>>
>>>>
>>>>Matt
>>>
>>>
>>>The article states resonance and the structure of the engine to vibrating.
>>>There is no reason to presume a valve held closed only by spring action
>>>stays firmly seated and unaffected by the engine structure vibration.
>>
>>OK, so you made up the above statement. I just wanted to confirm that.
>>
>>Matt
>
>
> Well, I just commented that your statement:
>
> Specifically your statement "But this still has nothing to do with the
> valve train."

I was specifically referring to the "valves chattering" or whatever
terminology was first used. I've still seen no evidence that this occurs.

Matt

 

gerry wrote:
> [original post is likely clipped to save bandwidth]
> On Sun, 29 Jan 2006 12:53:41 GMT, Matt Whiting <whiting@epix.net> wrote:
>
>
>>gerry wrote:
>>
>>
>>>[original post is likely clipped to save bandwidth]
>>>On Sat, 28 Jan 2006 02:26:46 GMT, Matt Whiting <whiting@epix.net> wrote:
>>>
>>>
>>>
>>>>gerry wrote:
>>>>
>>>>
>>>>
>>>>>[original post is likely clipped to save bandwidth]
>>>>>On Fri, 27 Jan 2006 02:42:51 GMT, Matt Whiting <whiting@epix.net> wrote:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>My point is that either the valves weren't chattering and the OP was
>>>>>>hearing detonation, or the valves are making noise and something is
>>>>>>wrong other than octane. The two simply aren't related. The valves are
>>>>>>closed against their seats when the combustion (or detonation) occurs.
>>>>>>
>>>>>>
>>>>>>Matt
>>>>>
>>>>>
>>>>>Read the reference you posted
>>>>>
>>>>>http://www.streetrodstuff.com/Articl...ion/Page_2.php
>>>>>
>>>>>According to that, "detonation"
>>>>>
>>>>>"can actually cause fracture of valves-intake or exhaust"
>>>>
>>>>I saw the above statement.
>>>>
>>>>
>>>>
>>>>
>>>>>The resonance can cause the valves to unseat briefly and force them closed
>>>>>with force.
>>>>
>>>>I don't find this statement in the article, even using the search
>>>>function. Where do you find this?
>>>>
>>>>
>>>>Matt
>>>
>>>
>>>The article states resonance and the structure of the engine to vibrating.
>>>There is no reason to presume a valve held closed only by spring action
>>>stays firmly seated and unaffected by the engine structure vibration.
>>
>>OK, so you made up the above statement. I just wanted to confirm that.
>>
>>Matt
>
>
> Well, I just commented that your statement:
>
> Specifically your statement "But this still has nothing to do with the
> valve train."

I was specifically referring to the "valves chattering" or whatever
terminology was first used. I've still seen no evidence that this occurs.

Matt

 

gerry wrote:
> [original post is likely clipped to save bandwidth]
> On Sun, 29 Jan 2006 12:53:41 GMT, Matt Whiting <whiting@epix.net> wrote:
>
>
>>gerry wrote:
>>
>>
>>>[original post is likely clipped to save bandwidth]
>>>On Sat, 28 Jan 2006 02:26:46 GMT, Matt Whiting <whiting@epix.net> wrote:
>>>
>>>
>>>
>>>>gerry wrote:
>>>>
>>>>
>>>>
>>>>>[original post is likely clipped to save bandwidth]
>>>>>On Fri, 27 Jan 2006 02:42:51 GMT, Matt Whiting <whiting@epix.net> wrote:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>My point is that either the valves weren't chattering and the OP was
>>>>>>hearing detonation, or the valves are making noise and something is
>>>>>>wrong other than octane. The two simply aren't related. The valves are
>>>>>>closed against their seats when the combustion (or detonation) occurs.
>>>>>>
>>>>>>
>>>>>>Matt
>>>>>
>>>>>
>>>>>Read the reference you posted
>>>>>
>>>>>http://www.streetrodstuff.com/Articl...ion/Page_2.php
>>>>>
>>>>>According to that, "detonation"
>>>>>
>>>>>"can actually cause fracture of valves-intake or exhaust"
>>>>
>>>>I saw the above statement.
>>>>
>>>>
>>>>
>>>>
>>>>>The resonance can cause the valves to unseat briefly and force them closed
>>>>>with force.
>>>>
>>>>I don't find this statement in the article, even using the search
>>>>function. Where do you find this?
>>>>
>>>>
>>>>Matt
>>>
>>>
>>>The article states resonance and the structure of the engine to vibrating.
>>>There is no reason to presume a valve held closed only by spring action
>>>stays firmly seated and unaffected by the engine structure vibration.
>>
>>OK, so you made up the above statement. I just wanted to confirm that.
>>
>>Matt
>
>
> Well, I just commented that your statement:
>
> Specifically your statement "But this still has nothing to do with the
> valve train."

I was specifically referring to the "valves chattering" or whatever
terminology was first used. I've still seen no evidence that this occurs.

Matt

 

gerry wrote:

> [original post is likely clipped to save bandwidth]
> On Sat, 28 Jan 2006 02:17:03 GMT, Matt Whiting <whiting@epix.net> wrote:
>
>
>>gerry wrote:
>>
>>
>>>Look up " detonate" in a good dictionary and you will find it is not as
>>>defined as used in the above reference! It is not "spontaneous
>>>combustion"!
>>>
>>>An example is
>>>
>>>http://www.yourdictionary.com/ahd/d/d0172500.html
>>>
>>>"To explode or cause to explode."
>>>
>>>http://en.wikipedia.org/wiki/Detonate
>>>
>>>states
>>>
>>>"involves a shock wave and a reaction zone behind it"
>>
>>Detonation used in the automotive sense isn't all that different. The
>>spontaneous combustion is in effect an explosion. That is what makes
>>all of the noise. It is the shock wave hitting the cylinder walls,
>>piston and head that makes the racket.
>>
>>
>>
>>
>>>Indeed one detonates a thermo nuclear weapon and that sure is not
>>>spontaneous combustion as defined in the reference you choose
>>>
>>>This is just to point out that different groups use different jargon. Thus
>>>I indicated not to worry too much about folks using different wording. I
>>>concede I use the words in more general engineering context, not
>>>automotive jargon.
>>
>>It makes sense to use automotive jargon when talking about an internal
>>combustion engine, which was the topic at hand.
>>
>>
>>
>>
>>>In context of this discussion and using your choice of wording, octane
>>>affects both "pre-ignition" and "detonation", inhibiting both.
>>
>>Octane inhibits detonation, but has almost no affect on pre-ignition.
>>Pre-ignition typically occurs from hot spots in the combustion chamber.
>> Octane slows down the burn rate and lessens the chance of spontaneous
>>combustion, but it doesn't prevent hot spots and it doesn't prevent
>>ignition so it has littly if any affect on pre-ignition.
>>
>>
>>Matt
>
>
> This is intended as an interesting dialog and learning exercise, not an
> argument!
>
> Since Octane rating explicitly affects the fuel's flash temperature, it
> certainly affects how hot a hot spot must be to cause a problem and does
> affect pre-ignition significantly.
>
> An interesting site that discusses octane and pre-ignition explicitly is
>
> http://www.eric-gorr.com/techarticles/Fuel_Basics.htm
>
> "As you may have guessed from the earlier discussion of octane numbers,
> high octane fuels have a considerably higher auto ignition temperature to
> keep these pre-flame reactions from causing sudden uncontrolled pressure
> rises. If the charge burns fast enough or the fuel is resistant enough to
> auto ignition (high octane) then all is well and the pressure rise isn't
> too extreme." ... "We defined pre-ignition previously as the starting of
> the burning process by a source other than the plug"

Octane affects the auto-ignition temperature and the burn rate.
Pre-ignition is NOT auto ignition, that is the entire point. It is
simply ignition from a point source other than the spark plug. Keep
looking, maybe you can find a source that supports your assertion that
octane has a significant affect on pre-ignition, but I doubt it.

If it had a substantial affect on pre-ignition, it would also have a
substantial affect on regular ignition by the spark plug, and
suppressing such ignition in a spark ignition engine wouldn't be a very
good thing. :-)


Matt

 

gerry wrote:

> [original post is likely clipped to save bandwidth]
> On Sat, 28 Jan 2006 02:17:03 GMT, Matt Whiting <whiting@epix.net> wrote:
>
>
>>gerry wrote:
>>
>>
>>>Look up " detonate" in a good dictionary and you will find it is not as
>>>defined as used in the above reference! It is not "spontaneous
>>>combustion"!
>>>
>>>An example is
>>>
>>>http://www.yourdictionary.com/ahd/d/d0172500.html
>>>
>>>"To explode or cause to explode."
>>>
>>>http://en.wikipedia.org/wiki/Detonate
>>>
>>>states
>>>
>>>"involves a shock wave and a reaction zone behind it"
>>
>>Detonation used in the automotive sense isn't all that different. The
>>spontaneous combustion is in effect an explosion. That is what makes
>>all of the noise. It is the shock wave hitting the cylinder walls,
>>piston and head that makes the racket.
>>
>>
>>
>>
>>>Indeed one detonates a thermo nuclear weapon and that sure is not
>>>spontaneous combustion as defined in the reference you choose
>>>
>>>This is just to point out that different groups use different jargon. Thus
>>>I indicated not to worry too much about folks using different wording. I
>>>concede I use the words in more general engineering context, not
>>>automotive jargon.
>>
>>It makes sense to use automotive jargon when talking about an internal
>>combustion engine, which was the topic at hand.
>>
>>
>>
>>
>>>In context of this discussion and using your choice of wording, octane
>>>affects both "pre-ignition" and "detonation", inhibiting both.
>>
>>Octane inhibits detonation, but has almost no affect on pre-ignition.
>>Pre-ignition typically occurs from hot spots in the combustion chamber.
>> Octane slows down the burn rate and lessens the chance of spontaneous
>>combustion, but it doesn't prevent hot spots and it doesn't prevent
>>ignition so it has littly if any affect on pre-ignition.
>>
>>
>>Matt
>
>
> This is intended as an interesting dialog and learning exercise, not an
> argument!
>
> Since Octane rating explicitly affects the fuel's flash temperature, it
> certainly affects how hot a hot spot must be to cause a problem and does
> affect pre-ignition significantly.
>
> An interesting site that discusses octane and pre-ignition explicitly is
>
> http://www.eric-gorr.com/techarticles/Fuel_Basics.htm
>
> "As you may have guessed from the earlier discussion of octane numbers,
> high octane fuels have a considerably higher auto ignition temperature to
> keep these pre-flame reactions from causing sudden uncontrolled pressure
> rises. If the charge burns fast enough or the fuel is resistant enough to
> auto ignition (high octane) then all is well and the pressure rise isn't
> too extreme." ... "We defined pre-ignition previously as the starting of
> the burning process by a source other than the plug"

Octane affects the auto-ignition temperature and the burn rate.
Pre-ignition is NOT auto ignition, that is the entire point. It is
simply ignition from a point source other than the spark plug. Keep
looking, maybe you can find a source that supports your assertion that
octane has a significant affect on pre-ignition, but I doubt it.

If it had a substantial affect on pre-ignition, it would also have a
substantial affect on regular ignition by the spark plug, and
suppressing such ignition in a spark ignition engine wouldn't be a very
good thing. :-)


Matt