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

 

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

 

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

 

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

 

[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.

Something that "can actually cause fracture of valves-intake or exhaust"
surely implies severe stress on the valve train. Even if the valves stay
closed, a stress severe enough to deform them will be transmitted to the
cam assembly which is in positive contact (via hydraulic action).

There may well be a jargon issue as to this being "valve chatter" but the
reference clearly states valve involvement.

The below is on page two

"
Detonation

Unburned end gas, under increasing pressure and heat (from the normal
progressive burning process and hot combustion chamber metals)
spontaneously combusts, ignited solely by the intense heat and pressure.
The remaining fuel in the end gas simply lacks sufficient octane rating to
withstand this combination of heat and pressure.

Detonation causes a very high, very sharp pressure spike in the combustion
chamber but it is of a very short duration. If you look at a pressure
trace of the combustion chamber process, you would see the normal burn as
a normal pressure rise, then all of a sudden you would see a very sharp
spike when the detonation occurred. That spike always occurs after the
spark plug fires. The sharp spike in pressure creates a force in the
combustion chamber. It causes the structure of the engine to ring, or
resonate, much as if it were hit by a hammer. Resonance, which is
characteristic of combustion detonation, occurs at about 6400 Hertz. So
the pinging you hear is actually the structure of the engine reacting to
the pressure spikes. This noise of detonation is commonly called spark
knock. This noise changes only slightly between iron and aluminum. This
noise or vibration is what a knock sensor picks up. The knock sensors are
tuned to 6400 hertz and they will pick up that spark knock. Incidentally,
the knocking or pinging sound is not the result of "two flame fronts
meeting" as is often stated. Although this clash does generate a spike the
noise you sense comes from the vibration of the engine structure reacting
to the pressure spike.
"

.... "can actually cause fracture of valves-intake or exhaust"

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 02:26:46 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.

Something that "can actually cause fracture of valves-intake or exhaust"
surely implies severe stress on the valve train. Even if the valves stay
closed, a stress severe enough to deform them will be transmitted to the
cam assembly which is in positive contact (via hydraulic action).

There may well be a jargon issue as to this being "valve chatter" but the
reference clearly states valve involvement.

The below is on page two

"
Detonation

Unburned end gas, under increasing pressure and heat (from the normal
progressive burning process and hot combustion chamber metals)
spontaneously combusts, ignited solely by the intense heat and pressure.
The remaining fuel in the end gas simply lacks sufficient octane rating to
withstand this combination of heat and pressure.

Detonation causes a very high, very sharp pressure spike in the combustion
chamber but it is of a very short duration. If you look at a pressure
trace of the combustion chamber process, you would see the normal burn as
a normal pressure rise, then all of a sudden you would see a very sharp
spike when the detonation occurred. That spike always occurs after the
spark plug fires. The sharp spike in pressure creates a force in the
combustion chamber. It causes the structure of the engine to ring, or
resonate, much as if it were hit by a hammer. Resonance, which is
characteristic of combustion detonation, occurs at about 6400 Hertz. So
the pinging you hear is actually the structure of the engine reacting to
the pressure spikes. This noise of detonation is commonly called spark
knock. This noise changes only slightly between iron and aluminum. This
noise or vibration is what a knock sensor picks up. The knock sensors are
tuned to 6400 hertz and they will pick up that spark knock. Incidentally,
the knocking or pinging sound is not the result of "two flame fronts
meeting" as is often stated. Although this clash does generate a spike the
noise you sense comes from the vibration of the engine structure reacting
to the pressure spike.
"

.... "can actually cause fracture of valves-intake or exhaust"

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 02:26:46 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.

Something that "can actually cause fracture of valves-intake or exhaust"
surely implies severe stress on the valve train. Even if the valves stay
closed, a stress severe enough to deform them will be transmitted to the
cam assembly which is in positive contact (via hydraulic action).

There may well be a jargon issue as to this being "valve chatter" but the
reference clearly states valve involvement.

The below is on page two

"
Detonation

Unburned end gas, under increasing pressure and heat (from the normal
progressive burning process and hot combustion chamber metals)
spontaneously combusts, ignited solely by the intense heat and pressure.
The remaining fuel in the end gas simply lacks sufficient octane rating to
withstand this combination of heat and pressure.

Detonation causes a very high, very sharp pressure spike in the combustion
chamber but it is of a very short duration. If you look at a pressure
trace of the combustion chamber process, you would see the normal burn as
a normal pressure rise, then all of a sudden you would see a very sharp
spike when the detonation occurred. That spike always occurs after the
spark plug fires. The sharp spike in pressure creates a force in the
combustion chamber. It causes the structure of the engine to ring, or
resonate, much as if it were hit by a hammer. Resonance, which is
characteristic of combustion detonation, occurs at about 6400 Hertz. So
the pinging you hear is actually the structure of the engine reacting to
the pressure spikes. This noise of detonation is commonly called spark
knock. This noise changes only slightly between iron and aluminum. This
noise or vibration is what a knock sensor picks up. The knock sensors are
tuned to 6400 hertz and they will pick up that spark knock. Incidentally,
the knocking or pinging sound is not the result of "two flame fronts
meeting" as is often stated. Although this clash does generate a spike the
noise you sense comes from the vibration of the engine structure reacting
to the pressure spike.
"

.... "can actually cause fracture of valves-intake or exhaust"

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 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

 

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

 

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

 

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.

 

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.

 

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.

 

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

 

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