85 vs 87 Octane
09-03-2007, 10:18 AM
#61
Guest
Posts: n/a
Re: 85 vs 87 Octane
SnoMan wrote:
> On Sun, 02 Sep 2007 22:26:01 -0500, c <c@me.org> wrote:
>
>> I have a 350 in my S10 truck that runs on 89 octane with a true
>> blueprinted 10.7 compression ratio and cast iron heads, but it also has
>> a cam with quite a bit of overlap and the combustion chambers are highly
>> polished. The quench distance between the top of the piston and the head
>> is .038" which is the tightest recommended distance, but also the best
>> for reducing detonation. I do not have to compromise my ignition timing
>> with this setup. I am running 12 degrees initial timing and 24 degrees
>> mechanical.
>
> I would run more octane and a bit more spark too. I used to race SB's
> years ago and 38 to 40 degress total advance is sweet spot for SB. You
> want to start mech advance at about 1200 to 1500 and have it fully in
> by about 3800 RPM. (1900 distributor RPM) You have a fairly nice build
> but it would do more with better fuel and more timing tweaks.
> -----------------
> TheSnoMan.com
Well, in my case the added timing doesn't help. I've run my truck at the
strip, and did lots of testing with it. Anything more than 36 degrees
and it slows down in the quarter mile, even with higher octane fuel.
Most of the engines I've built in the past ran best with 38 degrees, but
they were much more race oriented than this engine one is.
Chris
> On Sun, 02 Sep 2007 22:26:01 -0500, c <c@me.org> wrote:
>
>> I have a 350 in my S10 truck that runs on 89 octane with a true
>> blueprinted 10.7 compression ratio and cast iron heads, but it also has
>> a cam with quite a bit of overlap and the combustion chambers are highly
>> polished. The quench distance between the top of the piston and the head
>> is .038" which is the tightest recommended distance, but also the best
>> for reducing detonation. I do not have to compromise my ignition timing
>> with this setup. I am running 12 degrees initial timing and 24 degrees
>> mechanical.
>
> I would run more octane and a bit more spark too. I used to race SB's
> years ago and 38 to 40 degress total advance is sweet spot for SB. You
> want to start mech advance at about 1200 to 1500 and have it fully in
> by about 3800 RPM. (1900 distributor RPM) You have a fairly nice build
> but it would do more with better fuel and more timing tweaks.
> -----------------
> TheSnoMan.com
Well, in my case the added timing doesn't help. I've run my truck at the
strip, and did lots of testing with it. Anything more than 36 degrees
and it slows down in the quarter mile, even with higher octane fuel.
Most of the engines I've built in the past ran best with 38 degrees, but
they were much more race oriented than this engine one is.
Chris
09-03-2007, 02:10 PM
#62
Guest
Posts: n/a
Re: 85 vs 87 Octane
Mindy proclaimed:
> my 2001 grand cherokee runs on 87 octane in Texas where I live....flat land
> driving and good power in metro driving in the Dallas area....now I took a
> trip to Vail, Colorado and of course buying the cheapest gas at 3.29,it
> being 85.... is it me or do you loose power to the lower octane and high
> altitude....
Altitude always causes power loss. It also cuts down on the octane
requirement, at sea level octane 87 tends to be regular, at altitude 85.
Only way to get the power back is to raise the compression ratio or add
a turbo.
> my 2001 grand cherokee runs on 87 octane in Texas where I live....flat land
> driving and good power in metro driving in the Dallas area....now I took a
> trip to Vail, Colorado and of course buying the cheapest gas at 3.29,it
> being 85.... is it me or do you loose power to the lower octane and high
> altitude....
Altitude always causes power loss. It also cuts down on the octane
requirement, at sea level octane 87 tends to be regular, at altitude 85.
Only way to get the power back is to raise the compression ratio or add
a turbo.
09-03-2007, 02:10 PM
#63
Guest
Posts: n/a
Re: 85 vs 87 Octane
Mindy proclaimed:
> my 2001 grand cherokee runs on 87 octane in Texas where I live....flat land
> driving and good power in metro driving in the Dallas area....now I took a
> trip to Vail, Colorado and of course buying the cheapest gas at 3.29,it
> being 85.... is it me or do you loose power to the lower octane and high
> altitude....
Altitude always causes power loss. It also cuts down on the octane
requirement, at sea level octane 87 tends to be regular, at altitude 85.
Only way to get the power back is to raise the compression ratio or add
a turbo.
> my 2001 grand cherokee runs on 87 octane in Texas where I live....flat land
> driving and good power in metro driving in the Dallas area....now I took a
> trip to Vail, Colorado and of course buying the cheapest gas at 3.29,it
> being 85.... is it me or do you loose power to the lower octane and high
> altitude....
Altitude always causes power loss. It also cuts down on the octane
requirement, at sea level octane 87 tends to be regular, at altitude 85.
Only way to get the power back is to raise the compression ratio or add
a turbo.
09-03-2007, 02:10 PM
#64
Guest
Posts: n/a
Re: 85 vs 87 Octane
Mindy proclaimed:
> my 2001 grand cherokee runs on 87 octane in Texas where I live....flat land
> driving and good power in metro driving in the Dallas area....now I took a
> trip to Vail, Colorado and of course buying the cheapest gas at 3.29,it
> being 85.... is it me or do you loose power to the lower octane and high
> altitude....
Altitude always causes power loss. It also cuts down on the octane
requirement, at sea level octane 87 tends to be regular, at altitude 85.
Only way to get the power back is to raise the compression ratio or add
a turbo.
> my 2001 grand cherokee runs on 87 octane in Texas where I live....flat land
> driving and good power in metro driving in the Dallas area....now I took a
> trip to Vail, Colorado and of course buying the cheapest gas at 3.29,it
> being 85.... is it me or do you loose power to the lower octane and high
> altitude....
Altitude always causes power loss. It also cuts down on the octane
requirement, at sea level octane 87 tends to be regular, at altitude 85.
Only way to get the power back is to raise the compression ratio or add
a turbo.
09-03-2007, 02:10 PM
#65
Guest
Posts: n/a
Re: 85 vs 87 Octane
Mindy proclaimed:
> my 2001 grand cherokee runs on 87 octane in Texas where I live....flat land
> driving and good power in metro driving in the Dallas area....now I took a
> trip to Vail, Colorado and of course buying the cheapest gas at 3.29,it
> being 85.... is it me or do you loose power to the lower octane and high
> altitude....
Altitude always causes power loss. It also cuts down on the octane
requirement, at sea level octane 87 tends to be regular, at altitude 85.
Only way to get the power back is to raise the compression ratio or add
a turbo.
> my 2001 grand cherokee runs on 87 octane in Texas where I live....flat land
> driving and good power in metro driving in the Dallas area....now I took a
> trip to Vail, Colorado and of course buying the cheapest gas at 3.29,it
> being 85.... is it me or do you loose power to the lower octane and high
> altitude....
Altitude always causes power loss. It also cuts down on the octane
requirement, at sea level octane 87 tends to be regular, at altitude 85.
Only way to get the power back is to raise the compression ratio or add
a turbo.
09-03-2007, 02:15 PM
#66
Guest
Posts: n/a
Re: 85 vs 87 Octane
The only way you would get any "power" back is if your engine has
variable ignition timing and has retarded the spark due to 85 octane.
You don't really get any power back except when the engine is
lugging...the computer will allow a slightly higher spark advance if
there is no ping. Note that this does not mean your engine HAS knock
sensors and spark retard. It also doesn't mean you'd gain one
mousepower if you waste money on more expensive gas...particularly
around Vail.
Your engine is an air pump. If it can pump more air and compress it to
a higher pressure, you get more power. The fuel just provides the
energy to pump the air. Used to be you could get special high altitude
engines with a slightly higher compression ratio, often called Denver
Heads.
Mindy proclaimed:
> sooo, if I increase my octane to 87 at say 9,000 or so altitude, I will gain
> some power back ?? my jeep is a 2001 grand with the straight 6, 4.0
> engine...
>
>
> "SnoMan" <admin@snoman.com> wrote in message
> news:nlrmd3lugankvqmfpcps6k2rmlqmivcfk0@4ax.com...
>
>>On Sun, 2 Sep 2007 20:05:19 -0500, "DougW"
>><I.only.read.usenet@invalid.address> wrote:
>>
>>
>>>First, do not confuse power with octane rating, they arn't related.
>>
>>Actually they are a LOT more related than you think in some engine
>>that have knock sensing timing control
>>
>>
>>
>>>The higher the octane number the harder the fuel is to ignite.
>>
>>No it will light just as easy, the differnece is that it has a higher
>>auto ignite tempature and a slightly slower flame speed but it is no
>>harder to light its fuse with a spark
>>
>>
>>>And higher octane fuel has no more power than lower octane fuel.
>>
>>Actually it has a few less BTU in it but in a higher compression
>>engine it allows for a more favorable ignition and expansion cycle
>>than low octane fuel does (which has to use a retarded curve to
>>prevent to rapid of a pressure build up and auto ignition or
>>detenation)
>>
>>
>>>What your experiencing is lower air pressure at altitude. The same
>>>thing that makes you tire more easily at higher elevations also means
>>>your engine is not getting the same amount of oxygen with each intake.
>>>Less oxygen means less fuel can be burned. Less fuel of course means
>>>less power unless you can push more air into the engine with a
>>>supercharger or turbocharger.
>>
>>Mostly true. In the old days you would advance base line timing about
>>2 degrees for each 1000 feet above 1000 MSL up to a max of 12 degrees
>>or so. It did not restore all power but it does help some. Some modern
>>cars can advance timing a bit more automatically as well as lean
>>mixture out. At start up it reads MAP sensor just before engine cranks
>>to set elevation data. The problem with this is if you start engine at
>>4000 feet and drive to 9000 feet the computer does not know it is at
>>9000 feet until you shut it out and restart it.
>>
>>
>>>You want to use the lowest octane fuel that does not cause ping.
>>
>>This is not cut and dried as it seems. This works with old fixed
>>timing engine but not with some modern engine with knock sensor
>>because many of them (especailly GM's ) will never knock no matter
>>what, performance will just suffer. BTW, octane requirements do
>>decrease generally with elevation and this is why above 4000 MSL or so
>>you start seeing 85 or 85.5 octane fuel for regular, 88 or so for plus
>>and 91 for premium. You do not want a tank of 85 when you are headed
>>to lower elevations especailly in hot weather (ambent temp effects
>>octane needs too) Generally if your engine has a CR of 9 to 1 or
>>higher you cannot burn 87 at sea level without some spark timing
>>trickery as 9 to 1 and above really needs 89 or more (especailly in
>>warm weather) for optimal timing curving. At 10 to one and above you
>>really need 91 or better unless you run a compromised timing curve
>>which also reduces efficency and power too.
>>
>>-----------------
>>TheSnoMan.com
>
>
>
variable ignition timing and has retarded the spark due to 85 octane.
You don't really get any power back except when the engine is
lugging...the computer will allow a slightly higher spark advance if
there is no ping. Note that this does not mean your engine HAS knock
sensors and spark retard. It also doesn't mean you'd gain one
mousepower if you waste money on more expensive gas...particularly
around Vail.
Your engine is an air pump. If it can pump more air and compress it to
a higher pressure, you get more power. The fuel just provides the
energy to pump the air. Used to be you could get special high altitude
engines with a slightly higher compression ratio, often called Denver
Heads.
Mindy proclaimed:
> sooo, if I increase my octane to 87 at say 9,000 or so altitude, I will gain
> some power back ?? my jeep is a 2001 grand with the straight 6, 4.0
> engine...
>
>
> "SnoMan" <admin@snoman.com> wrote in message
> news:nlrmd3lugankvqmfpcps6k2rmlqmivcfk0@4ax.com...
>
>>On Sun, 2 Sep 2007 20:05:19 -0500, "DougW"
>><I.only.read.usenet@invalid.address> wrote:
>>
>>
>>>First, do not confuse power with octane rating, they arn't related.
>>
>>Actually they are a LOT more related than you think in some engine
>>that have knock sensing timing control
>>
>>
>>
>>>The higher the octane number the harder the fuel is to ignite.
>>
>>No it will light just as easy, the differnece is that it has a higher
>>auto ignite tempature and a slightly slower flame speed but it is no
>>harder to light its fuse with a spark
>>
>>
>>>And higher octane fuel has no more power than lower octane fuel.
>>
>>Actually it has a few less BTU in it but in a higher compression
>>engine it allows for a more favorable ignition and expansion cycle
>>than low octane fuel does (which has to use a retarded curve to
>>prevent to rapid of a pressure build up and auto ignition or
>>detenation)
>>
>>
>>>What your experiencing is lower air pressure at altitude. The same
>>>thing that makes you tire more easily at higher elevations also means
>>>your engine is not getting the same amount of oxygen with each intake.
>>>Less oxygen means less fuel can be burned. Less fuel of course means
>>>less power unless you can push more air into the engine with a
>>>supercharger or turbocharger.
>>
>>Mostly true. In the old days you would advance base line timing about
>>2 degrees for each 1000 feet above 1000 MSL up to a max of 12 degrees
>>or so. It did not restore all power but it does help some. Some modern
>>cars can advance timing a bit more automatically as well as lean
>>mixture out. At start up it reads MAP sensor just before engine cranks
>>to set elevation data. The problem with this is if you start engine at
>>4000 feet and drive to 9000 feet the computer does not know it is at
>>9000 feet until you shut it out and restart it.
>>
>>
>>>You want to use the lowest octane fuel that does not cause ping.
>>
>>This is not cut and dried as it seems. This works with old fixed
>>timing engine but not with some modern engine with knock sensor
>>because many of them (especailly GM's ) will never knock no matter
>>what, performance will just suffer. BTW, octane requirements do
>>decrease generally with elevation and this is why above 4000 MSL or so
>>you start seeing 85 or 85.5 octane fuel for regular, 88 or so for plus
>>and 91 for premium. You do not want a tank of 85 when you are headed
>>to lower elevations especailly in hot weather (ambent temp effects
>>octane needs too) Generally if your engine has a CR of 9 to 1 or
>>higher you cannot burn 87 at sea level without some spark timing
>>trickery as 9 to 1 and above really needs 89 or more (especailly in
>>warm weather) for optimal timing curving. At 10 to one and above you
>>really need 91 or better unless you run a compromised timing curve
>>which also reduces efficency and power too.
>>
>>-----------------
>>TheSnoMan.com
>
>
>
09-03-2007, 02:15 PM
#67
Guest
Posts: n/a
Re: 85 vs 87 Octane
The only way you would get any "power" back is if your engine has
variable ignition timing and has retarded the spark due to 85 octane.
You don't really get any power back except when the engine is
lugging...the computer will allow a slightly higher spark advance if
there is no ping. Note that this does not mean your engine HAS knock
sensors and spark retard. It also doesn't mean you'd gain one
mousepower if you waste money on more expensive gas...particularly
around Vail.
Your engine is an air pump. If it can pump more air and compress it to
a higher pressure, you get more power. The fuel just provides the
energy to pump the air. Used to be you could get special high altitude
engines with a slightly higher compression ratio, often called Denver
Heads.
Mindy proclaimed:
> sooo, if I increase my octane to 87 at say 9,000 or so altitude, I will gain
> some power back ?? my jeep is a 2001 grand with the straight 6, 4.0
> engine...
>
>
> "SnoMan" <admin@snoman.com> wrote in message
> news:nlrmd3lugankvqmfpcps6k2rmlqmivcfk0@4ax.com...
>
>>On Sun, 2 Sep 2007 20:05:19 -0500, "DougW"
>><I.only.read.usenet@invalid.address> wrote:
>>
>>
>>>First, do not confuse power with octane rating, they arn't related.
>>
>>Actually they are a LOT more related than you think in some engine
>>that have knock sensing timing control
>>
>>
>>
>>>The higher the octane number the harder the fuel is to ignite.
>>
>>No it will light just as easy, the differnece is that it has a higher
>>auto ignite tempature and a slightly slower flame speed but it is no
>>harder to light its fuse with a spark
>>
>>
>>>And higher octane fuel has no more power than lower octane fuel.
>>
>>Actually it has a few less BTU in it but in a higher compression
>>engine it allows for a more favorable ignition and expansion cycle
>>than low octane fuel does (which has to use a retarded curve to
>>prevent to rapid of a pressure build up and auto ignition or
>>detenation)
>>
>>
>>>What your experiencing is lower air pressure at altitude. The same
>>>thing that makes you tire more easily at higher elevations also means
>>>your engine is not getting the same amount of oxygen with each intake.
>>>Less oxygen means less fuel can be burned. Less fuel of course means
>>>less power unless you can push more air into the engine with a
>>>supercharger or turbocharger.
>>
>>Mostly true. In the old days you would advance base line timing about
>>2 degrees for each 1000 feet above 1000 MSL up to a max of 12 degrees
>>or so. It did not restore all power but it does help some. Some modern
>>cars can advance timing a bit more automatically as well as lean
>>mixture out. At start up it reads MAP sensor just before engine cranks
>>to set elevation data. The problem with this is if you start engine at
>>4000 feet and drive to 9000 feet the computer does not know it is at
>>9000 feet until you shut it out and restart it.
>>
>>
>>>You want to use the lowest octane fuel that does not cause ping.
>>
>>This is not cut and dried as it seems. This works with old fixed
>>timing engine but not with some modern engine with knock sensor
>>because many of them (especailly GM's ) will never knock no matter
>>what, performance will just suffer. BTW, octane requirements do
>>decrease generally with elevation and this is why above 4000 MSL or so
>>you start seeing 85 or 85.5 octane fuel for regular, 88 or so for plus
>>and 91 for premium. You do not want a tank of 85 when you are headed
>>to lower elevations especailly in hot weather (ambent temp effects
>>octane needs too) Generally if your engine has a CR of 9 to 1 or
>>higher you cannot burn 87 at sea level without some spark timing
>>trickery as 9 to 1 and above really needs 89 or more (especailly in
>>warm weather) for optimal timing curving. At 10 to one and above you
>>really need 91 or better unless you run a compromised timing curve
>>which also reduces efficency and power too.
>>
>>-----------------
>>TheSnoMan.com
>
>
>
variable ignition timing and has retarded the spark due to 85 octane.
You don't really get any power back except when the engine is
lugging...the computer will allow a slightly higher spark advance if
there is no ping. Note that this does not mean your engine HAS knock
sensors and spark retard. It also doesn't mean you'd gain one
mousepower if you waste money on more expensive gas...particularly
around Vail.
Your engine is an air pump. If it can pump more air and compress it to
a higher pressure, you get more power. The fuel just provides the
energy to pump the air. Used to be you could get special high altitude
engines with a slightly higher compression ratio, often called Denver
Heads.
Mindy proclaimed:
> sooo, if I increase my octane to 87 at say 9,000 or so altitude, I will gain
> some power back ?? my jeep is a 2001 grand with the straight 6, 4.0
> engine...
>
>
> "SnoMan" <admin@snoman.com> wrote in message
> news:nlrmd3lugankvqmfpcps6k2rmlqmivcfk0@4ax.com...
>
>>On Sun, 2 Sep 2007 20:05:19 -0500, "DougW"
>><I.only.read.usenet@invalid.address> wrote:
>>
>>
>>>First, do not confuse power with octane rating, they arn't related.
>>
>>Actually they are a LOT more related than you think in some engine
>>that have knock sensing timing control
>>
>>
>>
>>>The higher the octane number the harder the fuel is to ignite.
>>
>>No it will light just as easy, the differnece is that it has a higher
>>auto ignite tempature and a slightly slower flame speed but it is no
>>harder to light its fuse with a spark
>>
>>
>>>And higher octane fuel has no more power than lower octane fuel.
>>
>>Actually it has a few less BTU in it but in a higher compression
>>engine it allows for a more favorable ignition and expansion cycle
>>than low octane fuel does (which has to use a retarded curve to
>>prevent to rapid of a pressure build up and auto ignition or
>>detenation)
>>
>>
>>>What your experiencing is lower air pressure at altitude. The same
>>>thing that makes you tire more easily at higher elevations also means
>>>your engine is not getting the same amount of oxygen with each intake.
>>>Less oxygen means less fuel can be burned. Less fuel of course means
>>>less power unless you can push more air into the engine with a
>>>supercharger or turbocharger.
>>
>>Mostly true. In the old days you would advance base line timing about
>>2 degrees for each 1000 feet above 1000 MSL up to a max of 12 degrees
>>or so. It did not restore all power but it does help some. Some modern
>>cars can advance timing a bit more automatically as well as lean
>>mixture out. At start up it reads MAP sensor just before engine cranks
>>to set elevation data. The problem with this is if you start engine at
>>4000 feet and drive to 9000 feet the computer does not know it is at
>>9000 feet until you shut it out and restart it.
>>
>>
>>>You want to use the lowest octane fuel that does not cause ping.
>>
>>This is not cut and dried as it seems. This works with old fixed
>>timing engine but not with some modern engine with knock sensor
>>because many of them (especailly GM's ) will never knock no matter
>>what, performance will just suffer. BTW, octane requirements do
>>decrease generally with elevation and this is why above 4000 MSL or so
>>you start seeing 85 or 85.5 octane fuel for regular, 88 or so for plus
>>and 91 for premium. You do not want a tank of 85 when you are headed
>>to lower elevations especailly in hot weather (ambent temp effects
>>octane needs too) Generally if your engine has a CR of 9 to 1 or
>>higher you cannot burn 87 at sea level without some spark timing
>>trickery as 9 to 1 and above really needs 89 or more (especailly in
>>warm weather) for optimal timing curving. At 10 to one and above you
>>really need 91 or better unless you run a compromised timing curve
>>which also reduces efficency and power too.
>>
>>-----------------
>>TheSnoMan.com
>
>
>
09-03-2007, 02:15 PM
#68
Guest
Posts: n/a
Re: 85 vs 87 Octane
The only way you would get any "power" back is if your engine has
variable ignition timing and has retarded the spark due to 85 octane.
You don't really get any power back except when the engine is
lugging...the computer will allow a slightly higher spark advance if
there is no ping. Note that this does not mean your engine HAS knock
sensors and spark retard. It also doesn't mean you'd gain one
mousepower if you waste money on more expensive gas...particularly
around Vail.
Your engine is an air pump. If it can pump more air and compress it to
a higher pressure, you get more power. The fuel just provides the
energy to pump the air. Used to be you could get special high altitude
engines with a slightly higher compression ratio, often called Denver
Heads.
Mindy proclaimed:
> sooo, if I increase my octane to 87 at say 9,000 or so altitude, I will gain
> some power back ?? my jeep is a 2001 grand with the straight 6, 4.0
> engine...
>
>
> "SnoMan" <admin@snoman.com> wrote in message
> news:nlrmd3lugankvqmfpcps6k2rmlqmivcfk0@4ax.com...
>
>>On Sun, 2 Sep 2007 20:05:19 -0500, "DougW"
>><I.only.read.usenet@invalid.address> wrote:
>>
>>
>>>First, do not confuse power with octane rating, they arn't related.
>>
>>Actually they are a LOT more related than you think in some engine
>>that have knock sensing timing control
>>
>>
>>
>>>The higher the octane number the harder the fuel is to ignite.
>>
>>No it will light just as easy, the differnece is that it has a higher
>>auto ignite tempature and a slightly slower flame speed but it is no
>>harder to light its fuse with a spark
>>
>>
>>>And higher octane fuel has no more power than lower octane fuel.
>>
>>Actually it has a few less BTU in it but in a higher compression
>>engine it allows for a more favorable ignition and expansion cycle
>>than low octane fuel does (which has to use a retarded curve to
>>prevent to rapid of a pressure build up and auto ignition or
>>detenation)
>>
>>
>>>What your experiencing is lower air pressure at altitude. The same
>>>thing that makes you tire more easily at higher elevations also means
>>>your engine is not getting the same amount of oxygen with each intake.
>>>Less oxygen means less fuel can be burned. Less fuel of course means
>>>less power unless you can push more air into the engine with a
>>>supercharger or turbocharger.
>>
>>Mostly true. In the old days you would advance base line timing about
>>2 degrees for each 1000 feet above 1000 MSL up to a max of 12 degrees
>>or so. It did not restore all power but it does help some. Some modern
>>cars can advance timing a bit more automatically as well as lean
>>mixture out. At start up it reads MAP sensor just before engine cranks
>>to set elevation data. The problem with this is if you start engine at
>>4000 feet and drive to 9000 feet the computer does not know it is at
>>9000 feet until you shut it out and restart it.
>>
>>
>>>You want to use the lowest octane fuel that does not cause ping.
>>
>>This is not cut and dried as it seems. This works with old fixed
>>timing engine but not with some modern engine with knock sensor
>>because many of them (especailly GM's ) will never knock no matter
>>what, performance will just suffer. BTW, octane requirements do
>>decrease generally with elevation and this is why above 4000 MSL or so
>>you start seeing 85 or 85.5 octane fuel for regular, 88 or so for plus
>>and 91 for premium. You do not want a tank of 85 when you are headed
>>to lower elevations especailly in hot weather (ambent temp effects
>>octane needs too) Generally if your engine has a CR of 9 to 1 or
>>higher you cannot burn 87 at sea level without some spark timing
>>trickery as 9 to 1 and above really needs 89 or more (especailly in
>>warm weather) for optimal timing curving. At 10 to one and above you
>>really need 91 or better unless you run a compromised timing curve
>>which also reduces efficency and power too.
>>
>>-----------------
>>TheSnoMan.com
>
>
>
variable ignition timing and has retarded the spark due to 85 octane.
You don't really get any power back except when the engine is
lugging...the computer will allow a slightly higher spark advance if
there is no ping. Note that this does not mean your engine HAS knock
sensors and spark retard. It also doesn't mean you'd gain one
mousepower if you waste money on more expensive gas...particularly
around Vail.
Your engine is an air pump. If it can pump more air and compress it to
a higher pressure, you get more power. The fuel just provides the
energy to pump the air. Used to be you could get special high altitude
engines with a slightly higher compression ratio, often called Denver
Heads.
Mindy proclaimed:
> sooo, if I increase my octane to 87 at say 9,000 or so altitude, I will gain
> some power back ?? my jeep is a 2001 grand with the straight 6, 4.0
> engine...
>
>
> "SnoMan" <admin@snoman.com> wrote in message
> news:nlrmd3lugankvqmfpcps6k2rmlqmivcfk0@4ax.com...
>
>>On Sun, 2 Sep 2007 20:05:19 -0500, "DougW"
>><I.only.read.usenet@invalid.address> wrote:
>>
>>
>>>First, do not confuse power with octane rating, they arn't related.
>>
>>Actually they are a LOT more related than you think in some engine
>>that have knock sensing timing control
>>
>>
>>
>>>The higher the octane number the harder the fuel is to ignite.
>>
>>No it will light just as easy, the differnece is that it has a higher
>>auto ignite tempature and a slightly slower flame speed but it is no
>>harder to light its fuse with a spark
>>
>>
>>>And higher octane fuel has no more power than lower octane fuel.
>>
>>Actually it has a few less BTU in it but in a higher compression
>>engine it allows for a more favorable ignition and expansion cycle
>>than low octane fuel does (which has to use a retarded curve to
>>prevent to rapid of a pressure build up and auto ignition or
>>detenation)
>>
>>
>>>What your experiencing is lower air pressure at altitude. The same
>>>thing that makes you tire more easily at higher elevations also means
>>>your engine is not getting the same amount of oxygen with each intake.
>>>Less oxygen means less fuel can be burned. Less fuel of course means
>>>less power unless you can push more air into the engine with a
>>>supercharger or turbocharger.
>>
>>Mostly true. In the old days you would advance base line timing about
>>2 degrees for each 1000 feet above 1000 MSL up to a max of 12 degrees
>>or so. It did not restore all power but it does help some. Some modern
>>cars can advance timing a bit more automatically as well as lean
>>mixture out. At start up it reads MAP sensor just before engine cranks
>>to set elevation data. The problem with this is if you start engine at
>>4000 feet and drive to 9000 feet the computer does not know it is at
>>9000 feet until you shut it out and restart it.
>>
>>
>>>You want to use the lowest octane fuel that does not cause ping.
>>
>>This is not cut and dried as it seems. This works with old fixed
>>timing engine but not with some modern engine with knock sensor
>>because many of them (especailly GM's ) will never knock no matter
>>what, performance will just suffer. BTW, octane requirements do
>>decrease generally with elevation and this is why above 4000 MSL or so
>>you start seeing 85 or 85.5 octane fuel for regular, 88 or so for plus
>>and 91 for premium. You do not want a tank of 85 when you are headed
>>to lower elevations especailly in hot weather (ambent temp effects
>>octane needs too) Generally if your engine has a CR of 9 to 1 or
>>higher you cannot burn 87 at sea level without some spark timing
>>trickery as 9 to 1 and above really needs 89 or more (especailly in
>>warm weather) for optimal timing curving. At 10 to one and above you
>>really need 91 or better unless you run a compromised timing curve
>>which also reduces efficency and power too.
>>
>>-----------------
>>TheSnoMan.com
>
>
>
09-03-2007, 02:15 PM
#69
Guest
Posts: n/a
Re: 85 vs 87 Octane
The only way you would get any "power" back is if your engine has
variable ignition timing and has retarded the spark due to 85 octane.
You don't really get any power back except when the engine is
lugging...the computer will allow a slightly higher spark advance if
there is no ping. Note that this does not mean your engine HAS knock
sensors and spark retard. It also doesn't mean you'd gain one
mousepower if you waste money on more expensive gas...particularly
around Vail.
Your engine is an air pump. If it can pump more air and compress it to
a higher pressure, you get more power. The fuel just provides the
energy to pump the air. Used to be you could get special high altitude
engines with a slightly higher compression ratio, often called Denver
Heads.
Mindy proclaimed:
> sooo, if I increase my octane to 87 at say 9,000 or so altitude, I will gain
> some power back ?? my jeep is a 2001 grand with the straight 6, 4.0
> engine...
>
>
> "SnoMan" <admin@snoman.com> wrote in message
> news:nlrmd3lugankvqmfpcps6k2rmlqmivcfk0@4ax.com...
>
>>On Sun, 2 Sep 2007 20:05:19 -0500, "DougW"
>><I.only.read.usenet@invalid.address> wrote:
>>
>>
>>>First, do not confuse power with octane rating, they arn't related.
>>
>>Actually they are a LOT more related than you think in some engine
>>that have knock sensing timing control
>>
>>
>>
>>>The higher the octane number the harder the fuel is to ignite.
>>
>>No it will light just as easy, the differnece is that it has a higher
>>auto ignite tempature and a slightly slower flame speed but it is no
>>harder to light its fuse with a spark
>>
>>
>>>And higher octane fuel has no more power than lower octane fuel.
>>
>>Actually it has a few less BTU in it but in a higher compression
>>engine it allows for a more favorable ignition and expansion cycle
>>than low octane fuel does (which has to use a retarded curve to
>>prevent to rapid of a pressure build up and auto ignition or
>>detenation)
>>
>>
>>>What your experiencing is lower air pressure at altitude. The same
>>>thing that makes you tire more easily at higher elevations also means
>>>your engine is not getting the same amount of oxygen with each intake.
>>>Less oxygen means less fuel can be burned. Less fuel of course means
>>>less power unless you can push more air into the engine with a
>>>supercharger or turbocharger.
>>
>>Mostly true. In the old days you would advance base line timing about
>>2 degrees for each 1000 feet above 1000 MSL up to a max of 12 degrees
>>or so. It did not restore all power but it does help some. Some modern
>>cars can advance timing a bit more automatically as well as lean
>>mixture out. At start up it reads MAP sensor just before engine cranks
>>to set elevation data. The problem with this is if you start engine at
>>4000 feet and drive to 9000 feet the computer does not know it is at
>>9000 feet until you shut it out and restart it.
>>
>>
>>>You want to use the lowest octane fuel that does not cause ping.
>>
>>This is not cut and dried as it seems. This works with old fixed
>>timing engine but not with some modern engine with knock sensor
>>because many of them (especailly GM's ) will never knock no matter
>>what, performance will just suffer. BTW, octane requirements do
>>decrease generally with elevation and this is why above 4000 MSL or so
>>you start seeing 85 or 85.5 octane fuel for regular, 88 or so for plus
>>and 91 for premium. You do not want a tank of 85 when you are headed
>>to lower elevations especailly in hot weather (ambent temp effects
>>octane needs too) Generally if your engine has a CR of 9 to 1 or
>>higher you cannot burn 87 at sea level without some spark timing
>>trickery as 9 to 1 and above really needs 89 or more (especailly in
>>warm weather) for optimal timing curving. At 10 to one and above you
>>really need 91 or better unless you run a compromised timing curve
>>which also reduces efficency and power too.
>>
>>-----------------
>>TheSnoMan.com
>
>
>
variable ignition timing and has retarded the spark due to 85 octane.
You don't really get any power back except when the engine is
lugging...the computer will allow a slightly higher spark advance if
there is no ping. Note that this does not mean your engine HAS knock
sensors and spark retard. It also doesn't mean you'd gain one
mousepower if you waste money on more expensive gas...particularly
around Vail.
Your engine is an air pump. If it can pump more air and compress it to
a higher pressure, you get more power. The fuel just provides the
energy to pump the air. Used to be you could get special high altitude
engines with a slightly higher compression ratio, often called Denver
Heads.
Mindy proclaimed:
> sooo, if I increase my octane to 87 at say 9,000 or so altitude, I will gain
> some power back ?? my jeep is a 2001 grand with the straight 6, 4.0
> engine...
>
>
> "SnoMan" <admin@snoman.com> wrote in message
> news:nlrmd3lugankvqmfpcps6k2rmlqmivcfk0@4ax.com...
>
>>On Sun, 2 Sep 2007 20:05:19 -0500, "DougW"
>><I.only.read.usenet@invalid.address> wrote:
>>
>>
>>>First, do not confuse power with octane rating, they arn't related.
>>
>>Actually they are a LOT more related than you think in some engine
>>that have knock sensing timing control
>>
>>
>>
>>>The higher the octane number the harder the fuel is to ignite.
>>
>>No it will light just as easy, the differnece is that it has a higher
>>auto ignite tempature and a slightly slower flame speed but it is no
>>harder to light its fuse with a spark
>>
>>
>>>And higher octane fuel has no more power than lower octane fuel.
>>
>>Actually it has a few less BTU in it but in a higher compression
>>engine it allows for a more favorable ignition and expansion cycle
>>than low octane fuel does (which has to use a retarded curve to
>>prevent to rapid of a pressure build up and auto ignition or
>>detenation)
>>
>>
>>>What your experiencing is lower air pressure at altitude. The same
>>>thing that makes you tire more easily at higher elevations also means
>>>your engine is not getting the same amount of oxygen with each intake.
>>>Less oxygen means less fuel can be burned. Less fuel of course means
>>>less power unless you can push more air into the engine with a
>>>supercharger or turbocharger.
>>
>>Mostly true. In the old days you would advance base line timing about
>>2 degrees for each 1000 feet above 1000 MSL up to a max of 12 degrees
>>or so. It did not restore all power but it does help some. Some modern
>>cars can advance timing a bit more automatically as well as lean
>>mixture out. At start up it reads MAP sensor just before engine cranks
>>to set elevation data. The problem with this is if you start engine at
>>4000 feet and drive to 9000 feet the computer does not know it is at
>>9000 feet until you shut it out and restart it.
>>
>>
>>>You want to use the lowest octane fuel that does not cause ping.
>>
>>This is not cut and dried as it seems. This works with old fixed
>>timing engine but not with some modern engine with knock sensor
>>because many of them (especailly GM's ) will never knock no matter
>>what, performance will just suffer. BTW, octane requirements do
>>decrease generally with elevation and this is why above 4000 MSL or so
>>you start seeing 85 or 85.5 octane fuel for regular, 88 or so for plus
>>and 91 for premium. You do not want a tank of 85 when you are headed
>>to lower elevations especailly in hot weather (ambent temp effects
>>octane needs too) Generally if your engine has a CR of 9 to 1 or
>>higher you cannot burn 87 at sea level without some spark timing
>>trickery as 9 to 1 and above really needs 89 or more (especailly in
>>warm weather) for optimal timing curving. At 10 to one and above you
>>really need 91 or better unless you run a compromised timing curve
>>which also reduces efficency and power too.
>>
>>-----------------
>>TheSnoMan.com
>
>
>
09-04-2007, 01:56 PM
#70
Guest
Posts: n/a
Re: 85 vs 87 Octane vs 36 IQ
On Mon, 03 Sep 2007 00:35:11 -0700, L.W. (Bill) ------ III wrote:
> This from the biggest spammer of them all! The jealous, really jealous,
> I can't believe how jealous this little draft dodging coward schizophrenic
> psychopath liar hiding in Vancouver via S0106000ea6ba70e7.vn.shawcable.net
> 24.86.24.251 intrepidator@shaw.ca who's only way to get attention is to make
> a fool of its self using foul language, like it did back in elementary
> school yard. But, too afraid to use it's name and address, and take on
> responsibility like a grown up. With an obsession with perverts and goats,
> where it writes via remailers, @news.alt.net, and cross posts to other
> perverts to no one's surprise. With extreme jealous ranting over my
> documents, possessions, successes, manliness and fine, Southern California
> surfing body, beard, and loving Christian family. Committing forgery over
> many of my posts, proving I'm a responsible American man. You remind me of a
> little rat dog, like a Mexican Chiwawa with its senseless barking, me too,
> me too. You're even more senile than I first thought. And the poor thing,
> you're too girlie to take responsibility for yourself again, by signing your
> statement like a man.
> That really thinks the group's members are so stupid not to know it's
> the same coward, posting over and over again using a schizophrenic
> psychopath forged up names?
> You're not worth any more time when a cut and paste this same
> paragraphs it fits so well!
> But, now worth a forwarding to: internet.help@shaw.ca,
> security@shaw.ca, abuse@shaw.ca, internet.abuse@sjrb.ca, abuse@aioe.org,
> admin@***.net for forgery.
> Who said it also likes baby monkeys sucking their -----, like his buddy
> posted on an auto picture group at:
> news:0u7g43dkje4pdkqi07hl66s8kpifo564k1@4ax.com
> I thought this traitor's attacks were just over personal disagreements,
> but in reality these attacks stemming from my love of God and America on
> Independents Week, I realized you are actually attacking my country, and
> that's what you've been doing all along is declaring your hatred for the
> United States of America, with each declaration of my signature, but just
> too cowardly and stupid to be a ---------. It's America, love it, or leave
> it, so keep the f*ck out!
> Or let me know when you cross my American border, so I may arrest you!
> YOU ARE A TRAITOR and lost all rights to my American border, and
> someday I'll have you in jail where you belong! Any time, I'll fly and meant
> with other patriots guarding our borders against vermin like you.
> Forwarded to: alt.binaries.pictures.autos,
> alt.binaries.automobile.pictures groups so they may to see what an a**hole
> you, aka SW really is!!!!!
> Why don't you call the San Diego Sheriffs Department at 858-974-2020
> YOU NEED HELP!
> The moral majority say you are not only *******, but cowards
> You wouldn't know about business as you have never succeeded and
> anything.
> Tell me when you are about to cross my American border and I'll fly up
> and arrange at meeting with the U.S. Border patrol and Minutemen for your
> arrest, after you give me your name, address, date, and meeting place.
> I would appreciate the name and address of these trolls, Square Wheel:
> S0106000ea6ba70e7.vn.shawcable.net 24.86.24.251 intrepidator@shaw.ca and
> 24bit:
> 12.205.158.32 AT&T WorldNet Services ATT Mediacom Communications Corp. I
> will keep your name in confidence, kindly email -------------------- or
> LW------@------.net
> Sincerely,
> Llewellyn W. (Bill) ------ III
>
> You are so... incredibly stupid!!!!!
> God Bless America, Bill O|||||||O
> mailto:-------------------- http://www.----------.com/
>
>
> "y" <y@y-not.net> wrote in message news:DuOCi.119235$fJ5.59039@pd7urf1no...
>>
>>
>> Your body has less forced induction?
>>
>> Your body has less oxygen to burn fuel in?
>>
>> Well, if you hadn't already, you can certainly add physiology to that
>> ever-growing list of topics you know absolutely nothing about.
>>
>> Wow.
>>
>>
>>
>> Aw, you first, Moby. You can be the Pace Slug.
>>
>>
>> If you ran a block in under 2 days and didn't end up in Expensive Care
>> somewhere, you'd be on the cover of USA Today or other fine journals.
>>
>>
>> You'd have been a real hoot up in the Peruvian Andes. Gasping like a
>> trout, twitching like a baby covered in poison ivy and crying for
>> mommy-goat.
>>
>>
>> Yeah, supper southern fried california body, dripping grease and oozing
>> body-fat on the carpet.
>>
>>
>> You know what they say, once a lazy fatass greaser coward, always a lazy
>> fatass greaser coward.
>>
>>
>> Go play with your toy soldiers, Billie, the real ones don't want you.
>>
>>
>> In fact, 'real' anythings want no part of you.
>>
>>
>> OK, folks, gather 'round for the highly clever C&P sketch......!
>>
Damned clever answer, Cooyon.
> This from the biggest spammer of them all! The jealous, really jealous,
> I can't believe how jealous this little draft dodging coward schizophrenic
> psychopath liar hiding in Vancouver via S0106000ea6ba70e7.vn.shawcable.net
> 24.86.24.251 intrepidator@shaw.ca who's only way to get attention is to make
> a fool of its self using foul language, like it did back in elementary
> school yard. But, too afraid to use it's name and address, and take on
> responsibility like a grown up. With an obsession with perverts and goats,
> where it writes via remailers, @news.alt.net, and cross posts to other
> perverts to no one's surprise. With extreme jealous ranting over my
> documents, possessions, successes, manliness and fine, Southern California
> surfing body, beard, and loving Christian family. Committing forgery over
> many of my posts, proving I'm a responsible American man. You remind me of a
> little rat dog, like a Mexican Chiwawa with its senseless barking, me too,
> me too. You're even more senile than I first thought. And the poor thing,
> you're too girlie to take responsibility for yourself again, by signing your
> statement like a man.
> That really thinks the group's members are so stupid not to know it's
> the same coward, posting over and over again using a schizophrenic
> psychopath forged up names?
> You're not worth any more time when a cut and paste this same
> paragraphs it fits so well!
> But, now worth a forwarding to: internet.help@shaw.ca,
> security@shaw.ca, abuse@shaw.ca, internet.abuse@sjrb.ca, abuse@aioe.org,
> admin@***.net for forgery.
> Who said it also likes baby monkeys sucking their -----, like his buddy
> posted on an auto picture group at:
> news:0u7g43dkje4pdkqi07hl66s8kpifo564k1@4ax.com
> I thought this traitor's attacks were just over personal disagreements,
> but in reality these attacks stemming from my love of God and America on
> Independents Week, I realized you are actually attacking my country, and
> that's what you've been doing all along is declaring your hatred for the
> United States of America, with each declaration of my signature, but just
> too cowardly and stupid to be a ---------. It's America, love it, or leave
> it, so keep the f*ck out!
> Or let me know when you cross my American border, so I may arrest you!
> YOU ARE A TRAITOR and lost all rights to my American border, and
> someday I'll have you in jail where you belong! Any time, I'll fly and meant
> with other patriots guarding our borders against vermin like you.
> Forwarded to: alt.binaries.pictures.autos,
> alt.binaries.automobile.pictures groups so they may to see what an a**hole
> you, aka SW really is!!!!!
> Why don't you call the San Diego Sheriffs Department at 858-974-2020
> YOU NEED HELP!
> The moral majority say you are not only *******, but cowards
> You wouldn't know about business as you have never succeeded and
> anything.
> Tell me when you are about to cross my American border and I'll fly up
> and arrange at meeting with the U.S. Border patrol and Minutemen for your
> arrest, after you give me your name, address, date, and meeting place.
> I would appreciate the name and address of these trolls, Square Wheel:
> S0106000ea6ba70e7.vn.shawcable.net 24.86.24.251 intrepidator@shaw.ca and
> 24bit:
> 12.205.158.32 AT&T WorldNet Services ATT Mediacom Communications Corp. I
> will keep your name in confidence, kindly email -------------------- or
> LW------@------.net
> Sincerely,
> Llewellyn W. (Bill) ------ III
>
> You are so... incredibly stupid!!!!!
> God Bless America, Bill O|||||||O
> mailto:-------------------- http://www.----------.com/
>
>
> "y" <y@y-not.net> wrote in message news:DuOCi.119235$fJ5.59039@pd7urf1no...
>>
>>
>> Your body has less forced induction?
>>
>> Your body has less oxygen to burn fuel in?
>>
>> Well, if you hadn't already, you can certainly add physiology to that
>> ever-growing list of topics you know absolutely nothing about.
>>
>> Wow.
>>
>>
>>
>> Aw, you first, Moby. You can be the Pace Slug.
>>
>>
>> If you ran a block in under 2 days and didn't end up in Expensive Care
>> somewhere, you'd be on the cover of USA Today or other fine journals.
>>
>>
>> You'd have been a real hoot up in the Peruvian Andes. Gasping like a
>> trout, twitching like a baby covered in poison ivy and crying for
>> mommy-goat.
>>
>>
>> Yeah, supper southern fried california body, dripping grease and oozing
>> body-fat on the carpet.
>>
>>
>> You know what they say, once a lazy fatass greaser coward, always a lazy
>> fatass greaser coward.
>>
>>
>> Go play with your toy soldiers, Billie, the real ones don't want you.
>>
>>
>> In fact, 'real' anythings want no part of you.
>>
>>
>> OK, folks, gather 'round for the highly clever C&P sketch......!
>>
Damned clever answer, Cooyon.