Specific question about octane rating with respect to compressionratio

N8N > wrote in
:

> On May 29, 9:40*am, Kevin Bottorff > wrote:
>> jim beam > wrote :
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> > On 05/28/2013 10:37 PM, Alan Baker wrote:
>> >> In article >, jim beam
>> >> > wrote:
>>
>> >>> On 05/28/2013 07:41 PM, Alan Baker wrote:
>> >>>> In article >, jim beam
>> >>>> > wrote:
>>
>> >>>>> On 05/28/2013 01:18 PM, Danny D wrote:
>> >>>>>> In an alt.home.repair thread, some were proposing 92 AKI
>> >>>>>> gasoline for lawn equipment, where I questioned the logic,
>> >>>>>> based on compression ratio alone.
>>
>> >>>>>> AFAIK, the octane rating just means the gas reacts differently
>> >>>>>> to a given compression ratio (and other detonation factors
>> >>>>>> such as heat & timing).
>>
>> >>>>>> For example, given whatever the compression ratio in my
>> >>>>>> lawn equipment is, I get along just fine with 87 AKI
>> >>>>>> California gasoline; yet some propose 92 AKI fuels instead.
>>
>> >>>>>> My question:
>> >>>>>> Of the engines that *require* high-octane fuels, is the
>> >>>>>> (main) *reason* for that requirement the compression
>> >>>>>> ratio? [We can ignore detergents for this discussion.]
>>
>> >>>>>> Or are there other factors (ignoring heat & timing,
>> >>>>>> which are a given) that increase the need for fuels
>> >>>>>> rated at a higher anti-knock index?
>>
>> >>>>>> Restated:
>> >>>>>> Q: Is the *need* for premium directly in proportion to
>> >>>>>> the compression ratio of the engine?
>>
>> >>>>> it used to be thought that octane requirement was a function of
>> >>>>> compression ratio, but that thinking has changed. *now, it more
>> >>>>> a function of cylinder head design. *correspondingly, motors
>> >>>>> that require high octane do so because of antiquated head
>> >>>>> design.
>>
>> >>>> Not exactly correct.
>>
>> >>>> Compression ratio is the largest factor in when an engine will
>> >>>> experience detonation, but not the only one.
>>
>> >>> respectfully, it's not that simple. *biggest factor in detonation
>> >>> i
> s
>> >>> cylinder head design. *modern heads go out of their way to make
>> >>> sur
> e
>> >>> all internal features are smoothed out, and that there are no
>> >>> combustion dead spots. *this ensures a smooth flame front
>> >>> progression, and that two fronts aren't meeting somewhere they
>> >>> shouldn't. *that's what causes detonation.
>>
>> >> No. By far the biggest factor is compression ratio and the heating
>> >> of the charge that it causes. Cylinder head design can certainly
>> >> be used to even out any hot spots, but without compression, there
>> >> would BE no hot spots.
>>
>> >>>> But increasing compression ratio remains a valid method for
>> >>>> extracting the most work from an engine, so the need for higher
>> >>>> octane gas will remain wherever a manufacturer has chosen to
>> >>>> pursue higher specific output.
>>
>> >>> see above. *there are standard production engines today running
>> >>> 15:
> 1
>> >>> compression with regular gasoline. *according to the old school,
>> >>> that's impossible. *good head design is the key.
>>
>> >> Which "standard production engines" are running 15:1 compression
>> >> on regular gasoline? And moreover, how does that negate what I've
>> >> said.
>>
>> >> Yes: by careful design of the cylinder head (and other things) you
>> >> can raise the compression ratio, but only by a smallish fraction.
>>
>> > you're about 30 years out of date.
>>
>> so you admit you pulled the 15 to 1 figure out of your butt, I
>> thought so. *KB
>
> I'm not aware of any, but he does have a valid point; I've seen
> production engines with 10+ to one compression and forced induction
> running on premium pump gas. Clearly this would have been impossible
> 30-40 years ago... head design, cam profiles, and sophisticated
> engine management systems all contribute to make it possible.
>
> Back in the day you could have 10:1 compression OR supercharging and
> either one by itself would require premium; both together would
> require high-octane race fuel.
>
> nate
>

there is a world of difference between 10 to 1 and 15 to 1. 15 to 1 is
low compression diesel range. your not running that in a gas eng with out
some real high octane or exotic fuel. nothing you can get at the pump,
except E85. KB

"Kevin Bottorff" > wrote in message
...
> there is a world of difference between 10 to 1 and 15 to 1. 15 to 1 is
> low compression diesel range. your not running that in a gas eng with out
> some real high octane or exotic fuel. nothing you can get at the pump,

One way would be to have an open valve during the compression
stroke such that the effective compression was significantly less
than would be expected with "normal" valve timing and a high
CR.

Kevin Bottorff > wrote in
:


>>
>
> there is a world of difference between 10 to 1 and 15 to 1. 15 to 1
> is low compression diesel range. your not running that in a gas eng
> with out some real high octane or exotic fuel. nothing you can get at
> the pump, except E85. KB



There are some "hybrid car" engines that are running 13:1. I think the
Prius is one of them. But those engines are meant to run in a very narrow
load-band, so the engineers can afford to run that kind of compression.

Compression ratios are meant to be suitable for the engine's entire range
of usage. Limit that range, and ultra-high compression ratios become more
practical without exotic solutions or fuels.


--
Tegger

In article
>,
N8N > wrote:

> On May 29, 9:40*am, Kevin Bottorff > wrote:
> > jim beam > wrote :
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > > On 05/28/2013 10:37 PM, Alan Baker wrote:
> > >> In article >, jim beam >
> > >> wrote:
> >
> > >>> On 05/28/2013 07:41 PM, Alan Baker wrote:
> > >>>> In article >, jim beam >
> > >>>> wrote:
> >
> > >>>>> On 05/28/2013 01:18 PM, Danny D wrote:
> > >>>>>> In an alt.home.repair thread, some were proposing 92 AKI
> > >>>>>> gasoline for lawn equipment, where I questioned the logic,
> > >>>>>> based on compression ratio alone.
> >
> > >>>>>> AFAIK, the octane rating just means the gas reacts differently
> > >>>>>> to a given compression ratio (and other detonation factors
> > >>>>>> such as heat & timing).
> >
> > >>>>>> For example, given whatever the compression ratio in my
> > >>>>>> lawn equipment is, I get along just fine with 87 AKI
> > >>>>>> California gasoline; yet some propose 92 AKI fuels instead.
> >
> > >>>>>> My question:
> > >>>>>> Of the engines that *require* high-octane fuels, is the
> > >>>>>> (main) *reason* for that requirement the compression
> > >>>>>> ratio? [We can ignore detergents for this discussion.]
> >
> > >>>>>> Or are there other factors (ignoring heat & timing,
> > >>>>>> which are a given) that increase the need for fuels
> > >>>>>> rated at a higher anti-knock index?
> >
> > >>>>>> Restated:
> > >>>>>> Q: Is the *need* for premium directly in proportion to
> > >>>>>> the compression ratio of the engine?
> >
> > >>>>> it used to be thought that octane requirement was a function of
> > >>>>> compression ratio, but that thinking has changed. *now, it more a
> > >>>>> function of cylinder head design. *correspondingly, motors that
> > >>>>> require high octane do so because of antiquated head design.
> >
> > >>>> Not exactly correct.
> >
> > >>>> Compression ratio is the largest factor in when an engine will
> > >>>> experience detonation, but not the only one.
> >
> > >>> respectfully, it's not that simple. *biggest factor in detonation is
> > >>> cylinder head design. *modern heads go out of their way to make sure
> > >>> all internal features are smoothed out, and that there are no
> > >>> combustion dead spots. *this ensures a smooth flame front
> > >>> progression, and that two fronts aren't meeting somewhere they
> > >>> shouldn't. *that's what causes detonation.
> >
> > >> No. By far the biggest factor is compression ratio and the heating of
> > >> the charge that it causes. Cylinder head design can certainly be used
> > >> to even out any hot spots, but without compression, there would BE no
> > >> hot spots.
> >
> > >>>> But increasing compression ratio remains a valid method for
> > >>>> extracting the most work from an engine, so the need for higher
> > >>>> octane gas will remain wherever a manufacturer has chosen to pursue
> > >>>> higher specific output.
> >
> > >>> see above. *there are standard production engines today running 15:1
> > >>> compression with regular gasoline. *according to the old school,
> > >>> that's impossible. *good head design is the key.
> >
> > >> Which "standard production engines" are running 15:1 compression on
> > >> regular gasoline? And moreover, how does that negate what I've said.
> >
> > >> Yes: by careful design of the cylinder head (and other things) you
> > >> can raise the compression ratio, but only by a smallish fraction.
> >
> > > you're about 30 years out of date.
> >
> > so you admit you pulled the 15 to 1 figure out of your butt, I thought
> > so. *KB
>
> I'm not aware of any, but he does have a valid point; I've seen
> production engines with 10+ to one compression and forced induction
> running on premium pump gas. Clearly this would have been impossible
> 30-40 years ago... head design, cam profiles, and sophisticated
> engine management systems all contribute to make it possible.
>
> Back in the day you could have 10:1 compression OR supercharging and
> either one by itself would require premium; both together would
> require high-octane race fuel.

So if compression ratio is such a minor factor, why not raise
compression ratios to 20:1, 50:1, 100:1?

--
Alan Baker
Vancouver, British Columbia
"If you raise the ceiling four feet, move the fireplace from that wall
to that wall, you'll still only get the full stereophonic effect if you
sit in the bottom of that cupboard."

On 05/29/2013 09:14 AM, Alan Baker wrote:
> In article
> >,
> N8N > wrote:
>
>> On May 29, 9:40�am, Kevin Bottorff > wrote:
>>> jim beam > wrote :
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>> On 05/28/2013 10:37 PM, Alan Baker wrote:
>>>>> In article >, jim beam >
>>>>> wrote:
>>>
>>>>>> On 05/28/2013 07:41 PM, Alan Baker wrote:
>>>>>>> In article >, jim beam >
>>>>>>> wrote:
>>>
>>>>>>>> On 05/28/2013 01:18 PM, Danny D wrote:
>>>>>>>>> In an alt.home.repair thread, some were proposing 92 AKI
>>>>>>>>> gasoline for lawn equipment, where I questioned the logic,
>>>>>>>>> based on compression ratio alone.
>>>
>>>>>>>>> AFAIK, the octane rating just means the gas reacts differently
>>>>>>>>> to a given compression ratio (and other detonation factors
>>>>>>>>> such as heat & timing).
>>>
>>>>>>>>> For example, given whatever the compression ratio in my
>>>>>>>>> lawn equipment is, I get along just fine with 87 AKI
>>>>>>>>> California gasoline; yet some propose 92 AKI fuels instead.
>>>
>>>>>>>>> My question:
>>>>>>>>> Of the engines that *require* high-octane fuels, is the
>>>>>>>>> (main) *reason* for that requirement the compression
>>>>>>>>> ratio? [We can ignore detergents for this discussion.]
>>>
>>>>>>>>> Or are there other factors (ignoring heat & timing,
>>>>>>>>> which are a given) that increase the need for fuels
>>>>>>>>> rated at a higher anti-knock index?
>>>
>>>>>>>>> Restated:
>>>>>>>>> Q: Is the *need* for premium directly in proportion to
>>>>>>>>> the compression ratio of the engine?
>>>
>>>>>>>> it used to be thought that octane requirement was a function of
>>>>>>>> compression ratio, but that thinking has changed. �now, it more a
>>>>>>>> function of cylinder head design. �correspondingly, motors that
>>>>>>>> require high octane do so because of antiquated head design.
>>>
>>>>>>> Not exactly correct.
>>>
>>>>>>> Compression ratio is the largest factor in when an engine will
>>>>>>> experience detonation, but not the only one.
>>>
>>>>>> respectfully, it's not that simple. �biggest factor in detonation is
>>>>>> cylinder head design. �modern heads go out of their way to make sure
>>>>>> all internal features are smoothed out, and that there are no
>>>>>> combustion dead spots. �this ensures a smooth flame front
>>>>>> progression, and that two fronts aren't meeting somewhere they
>>>>>> shouldn't. �that's what causes detonation.
>>>
>>>>> No. By far the biggest factor is compression ratio and the heating of
>>>>> the charge that it causes. Cylinder head design can certainly be used
>>>>> to even out any hot spots, but without compression, there would BE no
>>>>> hot spots.
>>>
>>>>>>> But increasing compression ratio remains a valid method for
>>>>>>> extracting the most work from an engine, so the need for higher
>>>>>>> octane gas will remain wherever a manufacturer has chosen to pursue
>>>>>>> higher specific output.
>>>
>>>>>> see above. �there are standard production engines today running 15:1
>>>>>> compression with regular gasoline. �according to the old school,
>>>>>> that's impossible. �good head design is the key.
>>>
>>>>> Which "standard production engines" are running 15:1 compression on
>>>>> regular gasoline? And moreover, how does that negate what I've said.
>>>
>>>>> Yes: by careful design of the cylinder head (and other things) you
>>>>> can raise the compression ratio, but only by a smallish fraction.
>>>
>>>> you're about 30 years out of date.
>>>
>>> so you admit you pulled the 15 to 1 figure out of your butt, I thought
>>> so. �KB
>>
>> I'm not aware of any, but he does have a valid point; I've seen
>> production engines with 10+ to one compression and forced induction
>> running on premium pump gas. Clearly this would have been impossible
>> 30-40 years ago... head design, cam profiles, and sophisticated
>> engine management systems all contribute to make it possible.
>>
>> Back in the day you could have 10:1 compression OR supercharging and
>> either one by itself would require premium; both together would
>> require high-octane race fuel.
>
> So if compression ratio is such a minor factor, why not raise
> compression ratios to 20:1, 50:1, 100:1?
>

because you can't compress past liquefaction. up above the 20's, that's
what you're getting.

btw, reading back, i mis-typed earlier - i meant 12:1, not 15:1. honda
have a number of production engines with this ratio. race engines can
go much higher.


--
fact check required

In article >, jim beam >
wrote:

> On 05/29/2013 09:14 AM, Alan Baker wrote:
> > In article
> > >,
> > N8N > wrote:
> >
> >> On May 29, 9:40?am, Kevin Bottorff > wrote:
> >>> jim beam > wrote :
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>> On 05/28/2013 10:37 PM, Alan Baker wrote:
> >>>>> In article >, jim beam >
> >>>>> wrote:
> >>>
> >>>>>> On 05/28/2013 07:41 PM, Alan Baker wrote:
> >>>>>>> In article >, jim beam >
> >>>>>>> wrote:
> >>>
> >>>>>>>> On 05/28/2013 01:18 PM, Danny D wrote:
> >>>>>>>>> In an alt.home.repair thread, some were proposing 92 AKI
> >>>>>>>>> gasoline for lawn equipment, where I questioned the logic,
> >>>>>>>>> based on compression ratio alone.
> >>>
> >>>>>>>>> AFAIK, the octane rating just means the gas reacts differently
> >>>>>>>>> to a given compression ratio (and other detonation factors
> >>>>>>>>> such as heat & timing).
> >>>
> >>>>>>>>> For example, given whatever the compression ratio in my
> >>>>>>>>> lawn equipment is, I get along just fine with 87 AKI
> >>>>>>>>> California gasoline; yet some propose 92 AKI fuels instead.
> >>>
> >>>>>>>>> My question:
> >>>>>>>>> Of the engines that *require* high-octane fuels, is the
> >>>>>>>>> (main) *reason* for that requirement the compression
> >>>>>>>>> ratio? [We can ignore detergents for this discussion.]
> >>>
> >>>>>>>>> Or are there other factors (ignoring heat & timing,
> >>>>>>>>> which are a given) that increase the need for fuels
> >>>>>>>>> rated at a higher anti-knock index?
> >>>
> >>>>>>>>> Restated:
> >>>>>>>>> Q: Is the *need* for premium directly in proportion to
> >>>>>>>>> the compression ratio of the engine?
> >>>
> >>>>>>>> it used to be thought that octane requirement was a function of
> >>>>>>>> compression ratio, but that thinking has changed. ?now, it more a
> >>>>>>>> function of cylinder head design. ?correspondingly, motors that
> >>>>>>>> require high octane do so because of antiquated head design.
> >>>
> >>>>>>> Not exactly correct.
> >>>
> >>>>>>> Compression ratio is the largest factor in when an engine will
> >>>>>>> experience detonation, but not the only one.
> >>>
> >>>>>> respectfully, it's not that simple. ?biggest factor in detonation is
> >>>>>> cylinder head design. ?modern heads go out of their way to make sure
> >>>>>> all internal features are smoothed out, and that there are no
> >>>>>> combustion dead spots. ?this ensures a smooth flame front
> >>>>>> progression, and that two fronts aren't meeting somewhere they
> >>>>>> shouldn't. ?that's what causes detonation.
> >>>
> >>>>> No. By far the biggest factor is compression ratio and the heating of
> >>>>> the charge that it causes. Cylinder head design can certainly be used
> >>>>> to even out any hot spots, but without compression, there would BE no
> >>>>> hot spots.
> >>>
> >>>>>>> But increasing compression ratio remains a valid method for
> >>>>>>> extracting the most work from an engine, so the need for higher
> >>>>>>> octane gas will remain wherever a manufacturer has chosen to pursue
> >>>>>>> higher specific output.
> >>>
> >>>>>> see above. ?there are standard production engines today running 15:1
> >>>>>> compression with regular gasoline. ?according to the old school,
> >>>>>> that's impossible. ?good head design is the key.
> >>>
> >>>>> Which "standard production engines" are running 15:1 compression on
> >>>>> regular gasoline? And moreover, how does that negate what I've said.
> >>>
> >>>>> Yes: by careful design of the cylinder head (and other things) you
> >>>>> can raise the compression ratio, but only by a smallish fraction.
> >>>
> >>>> you're about 30 years out of date.
> >>>
> >>> so you admit you pulled the 15 to 1 figure out of your butt, I thought
> >>> so. ?KB
> >>
> >> I'm not aware of any, but he does have a valid point; I've seen
> >> production engines with 10+ to one compression and forced induction
> >> running on premium pump gas. Clearly this would have been impossible
> >> 30-40 years ago... head design, cam profiles, and sophisticated
> >> engine management systems all contribute to make it possible.
> >>
> >> Back in the day you could have 10:1 compression OR supercharging and
> >> either one by itself would require premium; both together would
> >> require high-octane race fuel.
> >
> > So if compression ratio is such a minor factor, why not raise
> > compression ratios to 20:1, 50:1, 100:1?
> >
>
> because you can't compress past liquefaction. up above the 20's, that's
> what you're getting.

WHAT????

Tell us all:

What component of the air/fuel mixture liquifies at a compression ratio
of 20:1? Please provide the appropriate phase diagram for confirmation.

>
> btw, reading back, i mis-typed earlier - i meant 12:1, not 15:1. honda
> have a number of production engines with this ratio. race engines can
> go much higher.

And thus you make my point.

1. The growth in compression ratios has been relatively small for all
that work on the head, etc.

2. Race engines run higher compression ratios because they use much
higher octane fuel.

--
Alan Baker
Vancouver, British Columbia
"If you raise the ceiling four feet, move the fireplace from that wall
to that wall, you'll still only get the full stereophonic effect if you
sit in the bottom of that cupboard."

On 06/01/2013 10:40 AM, Alan Baker wrote:
> In article >, jim beam >
> wrote:
>
>> On 05/29/2013 09:14 AM, Alan Baker wrote:
>>> In article
>>> >,
>>> N8N > wrote:
>>>
>>>> On May 29, 9:40?am, Kevin Bottorff > wrote:
>>>>> jim beam > wrote :
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>> On 05/28/2013 10:37 PM, Alan Baker wrote:
>>>>>>> In article >, jim beam >
>>>>>>> wrote:
>>>>>
>>>>>>>> On 05/28/2013 07:41 PM, Alan Baker wrote:
>>>>>>>>> In article >, jim beam >
>>>>>>>>> wrote:
>>>>>
>>>>>>>>>> On 05/28/2013 01:18 PM, Danny D wrote:
>>>>>>>>>>> In an alt.home.repair thread, some were proposing 92 AKI
>>>>>>>>>>> gasoline for lawn equipment, where I questioned the logic,
>>>>>>>>>>> based on compression ratio alone.
>>>>>
>>>>>>>>>>> AFAIK, the octane rating just means the gas reacts differently
>>>>>>>>>>> to a given compression ratio (and other detonation factors
>>>>>>>>>>> such as heat & timing).
>>>>>
>>>>>>>>>>> For example, given whatever the compression ratio in my
>>>>>>>>>>> lawn equipment is, I get along just fine with 87 AKI
>>>>>>>>>>> California gasoline; yet some propose 92 AKI fuels instead.
>>>>>
>>>>>>>>>>> My question:
>>>>>>>>>>> Of the engines that *require* high-octane fuels, is the
>>>>>>>>>>> (main) *reason* for that requirement the compression
>>>>>>>>>>> ratio? [We can ignore detergents for this discussion.]
>>>>>
>>>>>>>>>>> Or are there other factors (ignoring heat & timing,
>>>>>>>>>>> which are a given) that increase the need for fuels
>>>>>>>>>>> rated at a higher anti-knock index?
>>>>>
>>>>>>>>>>> Restated:
>>>>>>>>>>> Q: Is the *need* for premium directly in proportion to
>>>>>>>>>>> the compression ratio of the engine?
>>>>>
>>>>>>>>>> it used to be thought that octane requirement was a function of
>>>>>>>>>> compression ratio, but that thinking has changed. ?now, it more a
>>>>>>>>>> function of cylinder head design. ?correspondingly, motors that
>>>>>>>>>> require high octane do so because of antiquated head design.
>>>>>
>>>>>>>>> Not exactly correct.
>>>>>
>>>>>>>>> Compression ratio is the largest factor in when an engine will
>>>>>>>>> experience detonation, but not the only one.
>>>>>
>>>>>>>> respectfully, it's not that simple. ?biggest factor in detonation is
>>>>>>>> cylinder head design. ?modern heads go out of their way to make sure
>>>>>>>> all internal features are smoothed out, and that there are no
>>>>>>>> combustion dead spots. ?this ensures a smooth flame front
>>>>>>>> progression, and that two fronts aren't meeting somewhere they
>>>>>>>> shouldn't. ?that's what causes detonation.
>>>>>
>>>>>>> No. By far the biggest factor is compression ratio and the heating of
>>>>>>> the charge that it causes. Cylinder head design can certainly be used
>>>>>>> to even out any hot spots, but without compression, there would BE no
>>>>>>> hot spots.
>>>>>
>>>>>>>>> But increasing compression ratio remains a valid method for
>>>>>>>>> extracting the most work from an engine, so the need for higher
>>>>>>>>> octane gas will remain wherever a manufacturer has chosen to pursue
>>>>>>>>> higher specific output.
>>>>>
>>>>>>>> see above. ?there are standard production engines today running 15:1
>>>>>>>> compression with regular gasoline. ?according to the old school,
>>>>>>>> that's impossible. ?good head design is the key.
>>>>>
>>>>>>> Which "standard production engines" are running 15:1 compression on
>>>>>>> regular gasoline? And moreover, how does that negate what I've said.
>>>>>
>>>>>>> Yes: by careful design of the cylinder head (and other things) you
>>>>>>> can raise the compression ratio, but only by a smallish fraction.
>>>>>
>>>>>> you're about 30 years out of date.
>>>>>
>>>>> so you admit you pulled the 15 to 1 figure out of your butt, I thought
>>>>> so. ?KB
>>>>
>>>> I'm not aware of any, but he does have a valid point; I've seen
>>>> production engines with 10+ to one compression and forced induction
>>>> running on premium pump gas. Clearly this would have been impossible
>>>> 30-40 years ago... head design, cam profiles, and sophisticated
>>>> engine management systems all contribute to make it possible.
>>>>
>>>> Back in the day you could have 10:1 compression OR supercharging and
>>>> either one by itself would require premium; both together would
>>>> require high-octane race fuel.
>>>
>>> So if compression ratio is such a minor factor, why not raise
>>> compression ratios to 20:1, 50:1, 100:1?
>>>
>>
>> because you can't compress past liquefaction. up above the 20's, that's
>> what you're getting.
>
> WHAT????
>
> Tell us all:
>
> What component of the air/fuel mixture liquifies at a compression ratio
> of 20:1? Please provide the appropriate phase diagram for confirmation.

i'm repeating this:
<http://www.ultimatecarpage.com/forum/showthread.php?t=20271>

but i think you want to make a point here, so i'd like to see /your/
phase diagram and where the boundary actually lies.


>
>>
>> btw, reading back, i mis-typed earlier - i meant 12:1, not 15:1. honda
>> have a number of production engines with this ratio. race engines can
>> go much higher.
>
> And thus you make my point.

you said: "the need for higher octane gas will remain wherever a
manufacturer has chosen to pursue higher specific output" which is not
true. f1 engines use 17:1 and gasoline that includes the octane of
ordinary pump gas. they're using better physical design and
understanding of both gas flows and flame front propagation to raise
compression ratios [and thus outputs] /without/ having to resort to high
octanes.


>
> 1. The growth in compression ratios has been relatively small for all
> that work on the head, etc.

"all that work" simply comprises removal of dead spots and angular
features that were previously left from machining and considered
irrelevant. but maybe you meant "all that research".


>
> 2. Race engines run higher compression ratios because they use much
> higher octane fuel.

no, the bottom end of the f1 fuel is the same as we buy on the road.
<http://www.roadandtrack.com/racing/formula-1-fuel>

even if it were 98, it's still below aviation gas.


--
fact check required

In article >, jim beam >
wrote:

> On 06/01/2013 10:40 AM, Alan Baker wrote:
> > In article >, jim beam >
> > wrote:
> >
> >> On 05/29/2013 09:14 AM, Alan Baker wrote:
> >>> In article
> >>> >,
> >>> N8N > wrote:
> >>>
> >>>> On May 29, 9:40?am, Kevin Bottorff > wrote:
> >>>>> jim beam > wrote :
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>> On 05/28/2013 10:37 PM, Alan Baker wrote:
> >>>>>>> In article >, jim beam >
> >>>>>>> wrote:
> >>>>>
> >>>>>>>> On 05/28/2013 07:41 PM, Alan Baker wrote:
> >>>>>>>>> In article >, jim beam >
> >>>>>>>>> wrote:
> >>>>>
> >>>>>>>>>> On 05/28/2013 01:18 PM, Danny D wrote:
> >>>>>>>>>>> In an alt.home.repair thread, some were proposing 92 AKI
> >>>>>>>>>>> gasoline for lawn equipment, where I questioned the logic,
> >>>>>>>>>>> based on compression ratio alone.
> >>>>>
> >>>>>>>>>>> AFAIK, the octane rating just means the gas reacts differently
> >>>>>>>>>>> to a given compression ratio (and other detonation factors
> >>>>>>>>>>> such as heat & timing).
> >>>>>
> >>>>>>>>>>> For example, given whatever the compression ratio in my
> >>>>>>>>>>> lawn equipment is, I get along just fine with 87 AKI
> >>>>>>>>>>> California gasoline; yet some propose 92 AKI fuels instead.
> >>>>>
> >>>>>>>>>>> My question:
> >>>>>>>>>>> Of the engines that *require* high-octane fuels, is the
> >>>>>>>>>>> (main) *reason* for that requirement the compression
> >>>>>>>>>>> ratio? [We can ignore detergents for this discussion.]
> >>>>>
> >>>>>>>>>>> Or are there other factors (ignoring heat & timing,
> >>>>>>>>>>> which are a given) that increase the need for fuels
> >>>>>>>>>>> rated at a higher anti-knock index?
> >>>>>
> >>>>>>>>>>> Restated:
> >>>>>>>>>>> Q: Is the *need* for premium directly in proportion to
> >>>>>>>>>>> the compression ratio of the engine?
> >>>>>
> >>>>>>>>>> it used to be thought that octane requirement was a function of
> >>>>>>>>>> compression ratio, but that thinking has changed. ?now, it more a
> >>>>>>>>>> function of cylinder head design. ?correspondingly, motors that
> >>>>>>>>>> require high octane do so because of antiquated head design.
> >>>>>
> >>>>>>>>> Not exactly correct.
> >>>>>
> >>>>>>>>> Compression ratio is the largest factor in when an engine will
> >>>>>>>>> experience detonation, but not the only one.
> >>>>>
> >>>>>>>> respectfully, it's not that simple. ?biggest factor in detonation is
> >>>>>>>> cylinder head design. ?modern heads go out of their way to make sure
> >>>>>>>> all internal features are smoothed out, and that there are no
> >>>>>>>> combustion dead spots. ?this ensures a smooth flame front
> >>>>>>>> progression, and that two fronts aren't meeting somewhere they
> >>>>>>>> shouldn't. ?that's what causes detonation.
> >>>>>
> >>>>>>> No. By far the biggest factor is compression ratio and the heating of
> >>>>>>> the charge that it causes. Cylinder head design can certainly be used
> >>>>>>> to even out any hot spots, but without compression, there would BE no
> >>>>>>> hot spots.
> >>>>>
> >>>>>>>>> But increasing compression ratio remains a valid method for
> >>>>>>>>> extracting the most work from an engine, so the need for higher
> >>>>>>>>> octane gas will remain wherever a manufacturer has chosen to pursue
> >>>>>>>>> higher specific output.
> >>>>>
> >>>>>>>> see above. ?there are standard production engines today running 15:1
> >>>>>>>> compression with regular gasoline. ?according to the old school,
> >>>>>>>> that's impossible. ?good head design is the key.
> >>>>>
> >>>>>>> Which "standard production engines" are running 15:1 compression on
> >>>>>>> regular gasoline? And moreover, how does that negate what I've said.
> >>>>>
> >>>>>>> Yes: by careful design of the cylinder head (and other things) you
> >>>>>>> can raise the compression ratio, but only by a smallish fraction.
> >>>>>
> >>>>>> you're about 30 years out of date.
> >>>>>
> >>>>> so you admit you pulled the 15 to 1 figure out of your butt, I thought
> >>>>> so. ?KB
> >>>>
> >>>> I'm not aware of any, but he does have a valid point; I've seen
> >>>> production engines with 10+ to one compression and forced induction
> >>>> running on premium pump gas. Clearly this would have been impossible
> >>>> 30-40 years ago... head design, cam profiles, and sophisticated
> >>>> engine management systems all contribute to make it possible.
> >>>>
> >>>> Back in the day you could have 10:1 compression OR supercharging and
> >>>> either one by itself would require premium; both together would
> >>>> require high-octane race fuel.
> >>>
> >>> So if compression ratio is such a minor factor, why not raise
> >>> compression ratios to 20:1, 50:1, 100:1?
> >>>
> >>
> >> because you can't compress past liquefaction. up above the 20's, that's
> >> what you're getting.
> >
> > WHAT????
> >
> > Tell us all:
> >
> > What component of the air/fuel mixture liquifies at a compression ratio
> > of 20:1? Please provide the appropriate phase diagram for confirmation.
>
> i'm repeating this:
> <http://www.ultimatecarpage.com/forum/showthread.php?t=20271>

What part? Neither "liqui" nor "ratio" appear in the entire piece

>
> but i think you want to make a point here, so i'd like to see /your/
> phase diagram and where the boundary actually lies.

Nope. This is your claim to support, so go for it.

>
>
> >
> >>
> >> btw, reading back, i mis-typed earlier - i meant 12:1, not 15:1. honda
> >> have a number of production engines with this ratio. race engines can
> >> go much higher.
> >
> > And thus you make my point.
>
> you said: "the need for higher octane gas will remain wherever a
> manufacturer has chosen to pursue higher specific output" which is not
> true. f1 engines use 17:1 and gasoline that includes the octane of
> ordinary pump gas. they're using better physical design and
> understanding of both gas flows and flame front propagation to raise
> compression ratios [and thus outputs] /without/ having to resort to high
> octanes.

Got proof of F1 compression ratio? And that they [sic] "use gasoline
that includes the octane of ordinary pump gas"?

>
>
>
> > 1. The growth in compression ratios has been relatively small for all
> > that work on the head, etc.
>
> "all that work" simply comprises removal of dead spots and angular
> features that were previously left from machining and considered
> irrelevant. but maybe you meant "all that research".

Research is work.

>
>
> >
> > 2. Race engines run higher compression ratios because they use much
> > higher octane fuel.
>
> no, the bottom end of the f1 fuel is the same as we buy on the road.
> <http://www.roadandtrack.com/racing/formula-1-fuel>
>
> even if it were 98, it's still below aviation gas.

1. "the bottom end" implies there is a "top end", right?

2. 2009.

3. The other large factor in detonation is TIME and at F1 RPMs, there's
a lot less time for the conditions of detonation to develop.

--
Alan Baker
Vancouver, British Columbia
"If you raise the ceiling four feet, move the fireplace from that wall
to that wall, you'll still only get the full stereophonic effect if you
sit in the bottom of that cupboard."

On 06/02/2013 11:58 AM, Alan Baker wrote:
> In article >, jim beam >
> wrote:
>
>> On 06/01/2013 10:40 AM, Alan Baker wrote:
>>> In article >, jim beam >
>>> wrote:
>>>
>>>> On 05/29/2013 09:14 AM, Alan Baker wrote:
>>>>> In article
>>>>> >,
>>>>> N8N > wrote:
>>>>>
>>>>>> On May 29, 9:40?am, Kevin Bottorff > wrote:
>>>>>>> jim beam > wrote :
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>> On 05/28/2013 10:37 PM, Alan Baker wrote:
>>>>>>>>> In article >, jim beam >
>>>>>>>>> wrote:
>>>>>>>
>>>>>>>>>> On 05/28/2013 07:41 PM, Alan Baker wrote:
>>>>>>>>>>> In article >, jim beam >
>>>>>>>>>>> wrote:
>>>>>>>
>>>>>>>>>>>> On 05/28/2013 01:18 PM, Danny D wrote:
>>>>>>>>>>>>> In an alt.home.repair thread, some were proposing 92 AKI
>>>>>>>>>>>>> gasoline for lawn equipment, where I questioned the logic,
>>>>>>>>>>>>> based on compression ratio alone.
>>>>>>>
>>>>>>>>>>>>> AFAIK, the octane rating just means the gas reacts differently
>>>>>>>>>>>>> to a given compression ratio (and other detonation factors
>>>>>>>>>>>>> such as heat & timing).
>>>>>>>
>>>>>>>>>>>>> For example, given whatever the compression ratio in my
>>>>>>>>>>>>> lawn equipment is, I get along just fine with 87 AKI
>>>>>>>>>>>>> California gasoline; yet some propose 92 AKI fuels instead.
>>>>>>>
>>>>>>>>>>>>> My question:
>>>>>>>>>>>>> Of the engines that *require* high-octane fuels, is the
>>>>>>>>>>>>> (main) *reason* for that requirement the compression
>>>>>>>>>>>>> ratio? [We can ignore detergents for this discussion.]
>>>>>>>
>>>>>>>>>>>>> Or are there other factors (ignoring heat & timing,
>>>>>>>>>>>>> which are a given) that increase the need for fuels
>>>>>>>>>>>>> rated at a higher anti-knock index?
>>>>>>>
>>>>>>>>>>>>> Restated:
>>>>>>>>>>>>> Q: Is the *need* for premium directly in proportion to
>>>>>>>>>>>>> the compression ratio of the engine?
>>>>>>>
>>>>>>>>>>>> it used to be thought that octane requirement was a function of
>>>>>>>>>>>> compression ratio, but that thinking has changed. ?now, it more a
>>>>>>>>>>>> function of cylinder head design. ?correspondingly, motors that
>>>>>>>>>>>> require high octane do so because of antiquated head design.
>>>>>>>
>>>>>>>>>>> Not exactly correct.
>>>>>>>
>>>>>>>>>>> Compression ratio is the largest factor in when an engine will
>>>>>>>>>>> experience detonation, but not the only one.
>>>>>>>
>>>>>>>>>> respectfully, it's not that simple. ?biggest factor in detonation is
>>>>>>>>>> cylinder head design. ?modern heads go out of their way to make sure
>>>>>>>>>> all internal features are smoothed out, and that there are no
>>>>>>>>>> combustion dead spots. ?this ensures a smooth flame front
>>>>>>>>>> progression, and that two fronts aren't meeting somewhere they
>>>>>>>>>> shouldn't. ?that's what causes detonation.
>>>>>>>
>>>>>>>>> No. By far the biggest factor is compression ratio and the heating of
>>>>>>>>> the charge that it causes. Cylinder head design can certainly be used
>>>>>>>>> to even out any hot spots, but without compression, there would BE no
>>>>>>>>> hot spots.
>>>>>>>
>>>>>>>>>>> But increasing compression ratio remains a valid method for
>>>>>>>>>>> extracting the most work from an engine, so the need for higher
>>>>>>>>>>> octane gas will remain wherever a manufacturer has chosen to pursue
>>>>>>>>>>> higher specific output.
>>>>>>>
>>>>>>>>>> see above. ?there are standard production engines today running 15:1
>>>>>>>>>> compression with regular gasoline. ?according to the old school,
>>>>>>>>>> that's impossible. ?good head design is the key.
>>>>>>>
>>>>>>>>> Which "standard production engines" are running 15:1 compression on
>>>>>>>>> regular gasoline? And moreover, how does that negate what I've said.
>>>>>>>
>>>>>>>>> Yes: by careful design of the cylinder head (and other things) you
>>>>>>>>> can raise the compression ratio, but only by a smallish fraction.
>>>>>>>
>>>>>>>> you're about 30 years out of date.
>>>>>>>
>>>>>>> so you admit you pulled the 15 to 1 figure out of your butt, I thought
>>>>>>> so. ?KB
>>>>>>
>>>>>> I'm not aware of any, but he does have a valid point; I've seen
>>>>>> production engines with 10+ to one compression and forced induction
>>>>>> running on premium pump gas. Clearly this would have been impossible
>>>>>> 30-40 years ago... head design, cam profiles, and sophisticated
>>>>>> engine management systems all contribute to make it possible.
>>>>>>
>>>>>> Back in the day you could have 10:1 compression OR supercharging and
>>>>>> either one by itself would require premium; both together would
>>>>>> require high-octane race fuel.
>>>>>
>>>>> So if compression ratio is such a minor factor, why not raise
>>>>> compression ratios to 20:1, 50:1, 100:1?
>>>>>
>>>>
>>>> because you can't compress past liquefaction. up above the 20's, that's
>>>> what you're getting.
>>>
>>> WHAT????
>>>
>>> Tell us all:
>>>
>>> What component of the air/fuel mixture liquifies at a compression ratio
>>> of 20:1? Please provide the appropriate phase diagram for confirmation.
>>
>> i'm repeating this:
>> <http://www.ultimatecarpage.com/forum/showthread.php?t=20271>
>
> What part? Neither "liqui" nor "ratio" appear in the entire piece

you're trying to misinterpret. it says:
"the fuel mixture is compressed into nearly-solid form before ignition.
Cylinders run on the verge of hydraulic lock."

"hydraulics" means liquids, by definition. as does "near solid" for
most substances, but that wouldn't suit your argument either.


>
>>
>> but i think you want to make a point here, so i'd like to see /your/
>> phase diagram and where the boundary actually lies.
>
> Nope. This is your claim to support, so go for it.

you're the one saying it's wrong, so show me what i apparently don't
know. i can't even find a phase diagram for air [since you mentioned it].


>
>>
>>
>>>
>>>>
>>>> btw, reading back, i mis-typed earlier - i meant 12:1, not 15:1. honda
>>>> have a number of production engines with this ratio. race engines can
>>>> go much higher.
>>>
>>> And thus you make my point.
>>
>> you said: "the need for higher octane gas will remain wherever a
>> manufacturer has chosen to pursue higher specific output" which is not
>> true. f1 engines use 17:1 and gasoline that includes the octane of
>> ordinary pump gas. they're using better physical design and
>> understanding of both gas flows and flame front propagation to raise
>> compression ratios [and thus outputs] /without/ having to resort to high
>> octanes.
>
> Got proof of F1 compression ratio? And that they [sic] "use gasoline
> that includes the octane of ordinary pump gas"?

i've got the same resources as you. if i can find these numbers, so can
you.


>
>>
>>
>>
>>> 1. The growth in compression ratios has been relatively small for all
>>> that work on the head, etc.
>>
>> "all that work" simply comprises removal of dead spots and angular
>> features that were previously left from machining and considered
>> irrelevant. but maybe you meant "all that research".
>
> Research is work.

so say "research" then! unless you're deliberately being imprecise to
give yourself more "opportunities" to pick nits. there's no additional
"work" required to the head during manufacture.


>
>>
>>
>>>
>>> 2. Race engines run higher compression ratios because they use much
>>> higher octane fuel.
>>
>> no, the bottom end of the f1 fuel is the same as we buy on the road.
>> <http://www.roadandtrack.com/racing/formula-1-fuel>
>>
>> even if it were 98, it's still below aviation gas.
>
> 1. "the bottom end" implies there is a "top end", right?

didn't you read the article? or are you trying to avoid some of the
other material it contained regarding properties of lower octane use?


>
> 2. 2009.

so find a more recent one!


>
> 3. The other large factor in detonation is TIME and at F1 RPMs, there's
> a lot less time for the conditions of detonation to develop.

from what i can gather, knock is typically a sub-millisecond event.
even at 18krpm, that's still an order of magnitude less time than the
engine speed window.


--
fact check required

In article >, jim beam >
wrote:

> On 06/02/2013 11:58 AM, Alan Baker wrote:
> > In article >, jim beam >
> > wrote:
> >
> >> On 06/01/2013 10:40 AM, Alan Baker wrote:
> >>> In article >, jim beam >
> >>> wrote:
> >>>
> >>>> On 05/29/2013 09:14 AM, Alan Baker wrote:
> >>>>> In article
> >>>>> >,
> >>>>> N8N > wrote:
> >>>>>
> >>>>>> On May 29, 9:40?am, Kevin Bottorff > wrote:
> >>>>>>> jim beam > wrote :
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>> On 05/28/2013 10:37 PM, Alan Baker wrote:
> >>>>>>>>> In article >, jim beam
> >>>>>>>>> >
> >>>>>>>>> wrote:
> >>>>>>>
> >>>>>>>>>> On 05/28/2013 07:41 PM, Alan Baker wrote:
> >>>>>>>>>>> In article >, jim beam
> >>>>>>>>>>> >
> >>>>>>>>>>> wrote:
> >>>>>>>
> >>>>>>>>>>>> On 05/28/2013 01:18 PM, Danny D wrote:
> >>>>>>>>>>>>> In an alt.home.repair thread, some were proposing 92 AKI
> >>>>>>>>>>>>> gasoline for lawn equipment, where I questioned the logic,
> >>>>>>>>>>>>> based on compression ratio alone.
> >>>>>>>
> >>>>>>>>>>>>> AFAIK, the octane rating just means the gas reacts differently
> >>>>>>>>>>>>> to a given compression ratio (and other detonation factors
> >>>>>>>>>>>>> such as heat & timing).
> >>>>>>>
> >>>>>>>>>>>>> For example, given whatever the compression ratio in my
> >>>>>>>>>>>>> lawn equipment is, I get along just fine with 87 AKI
> >>>>>>>>>>>>> California gasoline; yet some propose 92 AKI fuels instead.
> >>>>>>>
> >>>>>>>>>>>>> My question:
> >>>>>>>>>>>>> Of the engines that *require* high-octane fuels, is the
> >>>>>>>>>>>>> (main) *reason* for that requirement the compression
> >>>>>>>>>>>>> ratio? [We can ignore detergents for this discussion.]
> >>>>>>>
> >>>>>>>>>>>>> Or are there other factors (ignoring heat & timing,
> >>>>>>>>>>>>> which are a given) that increase the need for fuels
> >>>>>>>>>>>>> rated at a higher anti-knock index?
> >>>>>>>
> >>>>>>>>>>>>> Restated:
> >>>>>>>>>>>>> Q: Is the *need* for premium directly in proportion to
> >>>>>>>>>>>>> the compression ratio of the engine?
> >>>>>>>
> >>>>>>>>>>>> it used to be thought that octane requirement was a function of
> >>>>>>>>>>>> compression ratio, but that thinking has changed. ?now, it more
> >>>>>>>>>>>> a
> >>>>>>>>>>>> function of cylinder head design. ?correspondingly, motors that
> >>>>>>>>>>>> require high octane do so because of antiquated head design.
> >>>>>>>
> >>>>>>>>>>> Not exactly correct.
> >>>>>>>
> >>>>>>>>>>> Compression ratio is the largest factor in when an engine will
> >>>>>>>>>>> experience detonation, but not the only one.
> >>>>>>>
> >>>>>>>>>> respectfully, it's not that simple. ?biggest factor in detonation
> >>>>>>>>>> is
> >>>>>>>>>> cylinder head design. ?modern heads go out of their way to make
> >>>>>>>>>> sure
> >>>>>>>>>> all internal features are smoothed out, and that there are no
> >>>>>>>>>> combustion dead spots. ?this ensures a smooth flame front
> >>>>>>>>>> progression, and that two fronts aren't meeting somewhere they
> >>>>>>>>>> shouldn't. ?that's what causes detonation.
> >>>>>>>
> >>>>>>>>> No. By far the biggest factor is compression ratio and the heating
> >>>>>>>>> of
> >>>>>>>>> the charge that it causes. Cylinder head design can certainly be
> >>>>>>>>> used
> >>>>>>>>> to even out any hot spots, but without compression, there would BE
> >>>>>>>>> no
> >>>>>>>>> hot spots.
> >>>>>>>
> >>>>>>>>>>> But increasing compression ratio remains a valid method for
> >>>>>>>>>>> extracting the most work from an engine, so the need for higher
> >>>>>>>>>>> octane gas will remain wherever a manufacturer has chosen to
> >>>>>>>>>>> pursue
> >>>>>>>>>>> higher specific output.
> >>>>>>>
> >>>>>>>>>> see above. ?there are standard production engines today running
> >>>>>>>>>> 15:1
> >>>>>>>>>> compression with regular gasoline. ?according to the old school,
> >>>>>>>>>> that's impossible. ?good head design is the key.
> >>>>>>>
> >>>>>>>>> Which "standard production engines" are running 15:1 compression on
> >>>>>>>>> regular gasoline? And moreover, how does that negate what I've
> >>>>>>>>> said.
> >>>>>>>
> >>>>>>>>> Yes: by careful design of the cylinder head (and other things) you
> >>>>>>>>> can raise the compression ratio, but only by a smallish fraction.
> >>>>>>>
> >>>>>>>> you're about 30 years out of date.
> >>>>>>>
> >>>>>>> so you admit you pulled the 15 to 1 figure out of your butt, I
> >>>>>>> thought
> >>>>>>> so. ?KB
> >>>>>>
> >>>>>> I'm not aware of any, but he does have a valid point; I've seen
> >>>>>> production engines with 10+ to one compression and forced induction
> >>>>>> running on premium pump gas. Clearly this would have been impossible
> >>>>>> 30-40 years ago... head design, cam profiles, and sophisticated
> >>>>>> engine management systems all contribute to make it possible.
> >>>>>>
> >>>>>> Back in the day you could have 10:1 compression OR supercharging and
> >>>>>> either one by itself would require premium; both together would
> >>>>>> require high-octane race fuel.
> >>>>>
> >>>>> So if compression ratio is such a minor factor, why not raise
> >>>>> compression ratios to 20:1, 50:1, 100:1?
> >>>>>
> >>>>
> >>>> because you can't compress past liquefaction. up above the 20's, that's
> >>>> what you're getting.
> >>>
> >>> WHAT????
> >>>
> >>> Tell us all:
> >>>
> >>> What component of the air/fuel mixture liquifies at a compression ratio
> >>> of 20:1? Please provide the appropriate phase diagram for confirmation.
> >>
> >> i'm repeating this:
> >> <http://www.ultimatecarpage.com/forum/showthread.php?t=20271>
> >
> > What part? Neither "liqui" nor "ratio" appear in the entire piece
>
> you're trying to misinterpret. it says:
> "the fuel mixture is compressed into nearly-solid form before ignition.
> Cylinders run on the verge of hydraulic lock."
>
> "hydraulics" means liquids, by definition. as does "near solid" for
> most substances, but that wouldn't suit your argument either.
>

And a dragster running nitro-methane which has its own oxygen for
combustion bound in it is relevant to our discussion how? They could be
running "on the verge", because the cylinder is nearly filled with
liquid to begin with.

>
> >
> >>
> >> but i think you want to make a point here, so i'd like to see /your/
> >> phase diagram and where the boundary actually lies.
> >
> > Nope. This is your claim to support, so go for it.
>
> you're the one saying it's wrong, so show me what i apparently don't
> know. i can't even find a phase diagram for air [since you mentioned it].
>
>
> >
> >>
> >>
> >>>
> >>>>
> >>>> btw, reading back, i mis-typed earlier - i meant 12:1, not 15:1. honda
> >>>> have a number of production engines with this ratio. race engines can
> >>>> go much higher.
> >>>
> >>> And thus you make my point.
> >>
> >> you said: "the need for higher octane gas will remain wherever a
> >> manufacturer has chosen to pursue higher specific output" which is not
> >> true. f1 engines use 17:1 and gasoline that includes the octane of
> >> ordinary pump gas. they're using better physical design and
> >> understanding of both gas flows and flame front propagation to raise
> >> compression ratios [and thus outputs] /without/ having to resort to high
> >> octanes.
> >
> > Got proof of F1 compression ratio? And that they [sic] "use gasoline
> > that includes the octane of ordinary pump gas"?
>
> i've got the same resources as you. if i can find these numbers, so can
> you.

I don't believe you have "found these numbers". That's why I'm asking.

>
>
> >
> >>
> >>
> >>
> >>> 1. The growth in compression ratios has been relatively small for all
> >>> that work on the head, etc.
> >>
> >> "all that work" simply comprises removal of dead spots and angular
> >> features that were previously left from machining and considered
> >> irrelevant. but maybe you meant "all that research".
> >
> > Research is work.
>
> so say "research" then! unless you're deliberately being imprecise to
> give yourself more "opportunities" to pick nits. there's no additional
> "work" required to the head during manufacture.

No. Because there's more to it that simply research.

>
>
> >
> >>
> >>
> >>>
> >>> 2. Race engines run higher compression ratios because they use much
> >>> higher octane fuel.
> >>
> >> no, the bottom end of the f1 fuel is the same as we buy on the road.
> >> <http://www.roadandtrack.com/racing/formula-1-fuel>
> >>
> >> even if it were 98, it's still below aviation gas.
> >
> > 1. "the bottom end" implies there is a "top end", right?
>
> didn't you read the article? or are you trying to avoid some of the
> other material it contained regarding properties of lower octane use?
>
>
> >
> > 2. 2009.
>
> so find a more recent one!

Nope. YOU find one.

>
>
> >
> > 3. The other large factor in detonation is TIME and at F1 RPMs, there's
> > a lot less time for the conditions of detonation to develop.
>
> from what i can gather, knock is typically a sub-millisecond event.
> even at 18krpm, that's still an order of magnitude less time than the
> engine speed window.

The knock itself? Yes.

The time it takes for the air/fuel mixture to develop the conditions
which will lead to knock? Not so much.

--
Alan Baker
Vancouver, British Columbia
"If you raise the ceiling four feet, move the fireplace from that wall
to that wall, you'll still only get the full stereophonic effect if you
sit in the bottom of that cupboard."