Alternative Power sources - better mileage with higher octane?

Author

better mileage with higher octane?

dido

2007-01-06, 8:29 pm

is there any truth to the statement that using a higher octane gasoline will result in
better gas mileage? I understand that it may have other beneficial properties ie.
anti-knock, acceleration, etc..

how would one calculate such a statement?

for reference, I usually fillup between 16-20 gallons, regular gas is 87 octane,
supreme 92 octane and in our area the price difference appears to be about 20c-30c
between regular and supreme.

2007-01-06, 8:29 pm

"dido" <dido@north.za> wrote in message
news:4vv3viF1d8ujsU1@mid.individual.net...
> is there any truth to the statement that using a higher octane gasoline
will result in
> better gas mileage? I understand that it may have other beneficial
properties ie.
> anti-knock, acceleration, etc..
>
> how would one calculate such a statement?

Dont worry about calculating anything. Octane rating has no direct
relationship
to gas mileage. Antiknock properties are the key.

stu

2007-01-06, 8:29 pm

<HLS@nospam.nix> wrote in message
news:ZXsmh.56001$qO4.54069@newssvr13.news.prodigy.net...
>
> "dido" <dido@north.za> wrote in message
> news:4vv3viF1d8ujsU1@mid.individual.net...
> will result in
> properties ie.
>
> Dont worry about calculating anything. Octane rating has no direct
> relationship
> to gas mileage. Antiknock properties are the key.
>
and just what do you think Octane rating a measure of?

2007-01-06, 8:29 pm

"stu" <nowhere@justyet.com> wrote in message
news:459a5e10$0$5748$afc38c87@news.optusnet.com.au...
>
> <HLS@nospam.nix> wrote in message
> news:ZXsmh.56001$qO4.54069@newssvr13.news.prodigy.net...
gasoline[color=darkred]
> and just what do you think Octane rating a measure of?

The octane rating is, just as I said, a number related to antiknock
properties.

Eeyore

2007-01-06, 8:29 pm

dido wrote:

> is there any truth to the statement that using a higher octane gasoline will result in
> better gas mileage? I understand that it may have other beneficial properties ie.
> anti-knock, acceleration, etc..
>
> how would one calculate such a statement?
>
> for reference, I usually fillup between 16-20 gallons, regular gas is 87 octane,
> supreme 92 octane and in our area the price difference appears to be about 20c-30c
> between regular and supreme.

It varies from car to car depending how clever the ECU is typically.

European and Japanese cars typically prefer higher octane fuels btw. In the UK I've never
seen less than 95RON fuel ( that's 91 in your US PON figures ) and 98 RON is our commonly
available top grade ( 94 PON ).

http://www.btinternet.com/~madmole/.../RONMONPON.html

Graham

2007-01-06, 8:29 pm

Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote in article
<459A666F.AD243C2C@hotmail.com>...
>
>
> HLS@nospam.nix wrote:
>
>
> And good anti-knock properties ( higher octane ) allow the ignition to be
> advanced which *may* improve engine efficiency. It pretty much invariably
> improves performance.
>
> Graham
>
>
>

In the scenario you describe, the improved performance would come from
physically advancing the timing - NOT from the fuel switch alone.

You could probably see a similar increase by just advancing the timing and
NOT switching fuels - but the engine might suffer.

The simple act of pumping $10 worth of "high test" into the tank of a car
that doesn't require it, really does nothing but improve the bottom line at
corporate headquarters.

E Meyer

2007-01-06, 8:29 pm

On 1/2/07 7:11 AM, in article 4vv3viF1d8ujsU1@mid.individual.net, "dido"
<dido@north.za> wrote:

> is there any truth to the statement that using a higher octane gasoline will
> result in
> better gas mileage? I understand that it may have other beneficial properties
> ie.
> anti-knock, acceleration, etc..
>
> how would one calculate such a statement?
>
> for reference, I usually fillup between 16-20 gallons, regular gas is 87
> octane,
> supreme 92 octane and in our area the price difference appears to be about
> 20c-30c
> between regular and supreme.
>
>

There is qualified truth in your statement. It depends on a number of
factors whether better gas mileage will result from higher octane gas. The
number one factor being that the engine is designed for higher octane gas in
the first place.

Most modern engines have a knock sensor that detunes the engine when it
detects pinging, which is usually due to gas with too low an octane rating.
When it does this the mileage and performance are compromised. Using higher
octane gas in such an engine doesn't necessarily guarantee better gas
mileage but rather it corrects the worse gas mileage that resulted from
running it on the wrong gas.

So, if your owner's manual says you should be using higher octane gas, it
should give better results if you do. If it says you should be using
regular, premium gas will most likely be a waste of money.

C. E. White

2007-01-06, 8:29 pm

"dido" <dido@north.za> wrote in message
news:4vv3viF1d8ujsU1@mid.individual.net...
> is there any truth to the statement that using a higher octane gasoline
> will result in better gas mileage? I understand that it may have other
> beneficial properties ie. anti-knock, acceleration, etc..
>
> how would one calculate such a statement?
>
> for reference, I usually fillup between 16-20 gallons, regular gas is 87
> octane, supreme 92 octane and in our area the price difference appears to
> be about 20c-30c between regular and supreme.

Whether or not you get better fuel economy with higher octane gasoline is a
function of the vehicle's PCM (Powertrain Control Module - aka, the engine
computer). If your engine has a knock sensor (or sensors) the PCM may be
able to adjust the engine parameters (mostly spark advance) to increase
performance and fuel economy when you use premium fuel. I've had a couple of
Fords with 5.4L engines. It was claimed that the use of premium fuel would
allow for a 5 to 10 HP increase and a 1% to 3% increase in fuel economy. For
both of these vehicles I ran premium fuel for a significant period of time
(5K+ miles) and compared it to similar periods when I was using regular
fuel. I saw no significant difference in fuel economy. Neither could I tell
there was any difference in performance, although I don't think I could
detect a 10HP increase without a dynometer. The results may vary for other
vehicles. I have noticed that many of the Japanese manufacturers have
started specifying premium fuel for their higher cost engines. I assume that
the major reason for this is achieving slightly better CAFE numbers. I am
confident that most of the vehicles would run OK on regular, perhaps with
slightly worse fuel economy and performance (you should check the owners
guide).

If you are going for maximum MONEY economy (as opposed to maximum fuel
economy), then there is little chance that purchasing premium fuel is a
smart decision. I doubt you will ever increase your fuel economy by more
than 3% by using premium, and since premium costs at least 5% more than
regular, it is a clear loser if you are trying to save money.

A word of caution - you can't really make any determination on the relative
fuel economy difference between regular and premium by comparing single tank
fulls of gas. Besides the inaccuracy of single tank full fuel economy
calculations, you must also consider the actual octane of the fuel mix in
your tank and how quickly the PCM adjusts to different fuels. The PCM will
not instantaneously advance the timing if you start using premium fuel. It
will make the adjustment over a period of time. So if you want to do the
comparison, I'd suggest making the measurement over at least 5 tank fulls of
each type of fuel. I'd also not include two tank fulls when you are
transitioning from one fuel to the other.

Ed

Derek Broughton

2007-01-06, 8:29 pm

dido wrote:

> is there any truth to the statement that using a higher octane gasoline
> will result in better gas mileage? I understand that it may have other
> beneficial properties ie. anti-knock, acceleration, etc..

I certainly hope so, since my Volvo dealer insists that I need "supreme" and
says exactly that.
>
> how would one calculate such a statement?

By recording the mileage between fillups, and the size of the fillup.
--
derek

Scott Dorsey

2007-01-06, 8:29 pm

>"dido" <dido@north.za> wrote in message
> is there any truth to the statement that using a higher octane gasoline
will result in
> better gas mileage? I understand that it may have other beneficial
properties ie.
> anti-knock, acceleration, etc..

No, there is no truth to this at all. The higher octane ONLY has better
antiknock properties.

Now, if you have a knocking problem with your car, and the knock sensor
starts delaying the timing, you will get poorer gas mileage. So in that
regard, if you HAVE a knocking problem, higher octane gas will give you
better acceleration and better mileage. But it would strike me that,
unless the car is designed to run on high octane gas, it would be better
to fix the problem causing the knocking.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

CJT

2007-01-06, 8:29 pm

Derek Broughton wrote:

> dido wrote:
>
>
>
>
> I certainly hope so,

I expect those hopes to be dashed.

since my Volvo dealer insists that I need "supreme" and
> says exactly that.
>
>
>
> By recording the mileage between fillups, and the size of the fillup.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form che...@prodigy.net.

CJT

2007-01-06, 8:29 pm

HLS@nospam.nix wrote:

> "dido" <dido@north.za> wrote in message
> news:4vv3viF1d8ujsU1@mid.individual.net...
>
>
> will result in
>
>
> properties ie.
>
>
>
> Dont worry about calculating anything. Octane rating has no direct
> relationship
> to gas mileage. Antiknock properties are the key.
>
>
Precisely. Just think about it -- at one time, octane was increased
by adding lead compounds. Why would lead increase a fuel's energy?

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form che...@prodigy.net.

Derek Broughton

2007-01-06, 8:29 pm

CJT wrote:
[color=darkred]
> Derek Broughton wrote:
>
>
> I expect those hopes to be dashed.
>
> since my Volvo dealer insists that I need "supreme" and

....and my wife does what he tells her...
--
derek

Eeyore

2007-01-06, 8:29 pm

* wrote:

> Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote
>
>
> In the scenario you describe, the improved performance would come from
> physically advancing the timing - NOT from the fuel switch alone.
>
> You could probably see a similar increase by just advancing the timing and
> NOT switching fuels - but the engine might suffer.
>
> The simple act of pumping $10 worth of "high test" into the tank of a car
> that doesn't require it, really does nothing but improve the bottom line at
> corporate headquarters.

I don't understand your point.

You can't just advance the timing willy nilly. In any case the ECU should
control it and any advantage will be gained automatically.

Graham

Eeyore

2007-01-06, 8:29 pm

CJT wrote:

> HLS@nospam.nix wrote:
> beneficial
> Precisely. Just think about it -- at one time, octane was increased
> by adding lead compounds. Why would lead increase a fuel's energy?

It doesn't. Energy has nothing to do with it.

High octane fuel has less energy than low octane in any case.

Graham

Eeyore

2007-01-06, 8:29 pm

"C. E. White" wrote:

> "dido" <dido@north.za> wrote in message
>
>
> Whether or not you get better fuel economy with higher octane gasoline is a
> function of the vehicle's PCM (Powertrain Control Module

Most ppl call it an ECU.
http://en.wikipedia.org/wiki/Engine_Control_Unit

Graham

Mike Romain

2007-01-06, 8:29 pm

It depends on your engine. You need to check the gas mileage between
fills to see if there is a difference.

I have a computer controlled Jeep engine in one and it makes absolutely
no difference in gas mileage between 87 and 91 octanes. I have another
non computer controlled Jeep engine and the gas mileage difference is
close to a hundred miles per tank. It loses all top end power so has to
be held to the floor on the highway. This just drinks the gas.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/p...l?id=2115147590
(More Off Road album links at bottom of the view page)

dido wrote:
>
> is there any truth to the statement that using a higher octane gasoline will result in
> better gas mileage? I understand that it may have other beneficial properties ie.
> anti-knock, acceleration, etc..
>
> how would one calculate such a statement?
>
> for reference, I usually fillup between 16-20 gallons, regular gas is 87 octane,
> supreme 92 octane and in our area the price difference appears to be about 20c-30c
> between regular and supreme.

2007-01-06, 8:29 pm

Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote in article
<459AA2A1.9F1B5A35@hotmail.com>...
>
>
> * wrote:
>
direct[color=darkred]
to be[color=darkred]
invariably[color=darkred]
and[color=darkred]
car[color=darkred]
line at[color=darkred]
>
> I don't understand your point.
>
> You can't just advance the timing willy nilly. In any case the ECU should
> control it and any advantage will be gained automatically.
>

I was thinking pre-computerized ignitions.

So, the ECU has been programmed to advance the timing within safe limits of
regular fuel....no more.

How do YOU get it to exceed those limits?

clare at snyder.on.ca

2007-01-06, 8:29 pm

On Tue, 2 Jan 2007 11:04:16 -0500, "C. E. White"
<cewhite3@removemindspring.com> wrote:

>"dido" <dido@north.za> wrote in message
>news:4vv3viF1d8ujsU1@mid.individual.net...
>
>Whether or not you get better fuel economy with higher octane gasoline is a
>function of the vehicle's PCM (Powertrain Control Module - aka, the engine
>computer). If your engine has a knock sensor (or sensors) the PCM may be
>able to adjust the engine parameters (mostly spark advance) to increase
>performance and fuel economy when you use premium fuel. I've had a couple of
>Fords with 5.4L engines. It was claimed that the use of premium fuel would
>allow for a 5 to 10 HP increase and a 1% to 3% increase in fuel economy. For
>both of these vehicles I ran premium fuel for a significant period of time
>(5K+ miles) and compared it to similar periods when I was using regular
>fuel. I saw no significant difference in fuel economy. Neither could I tell
>there was any difference in performance, although I don't think I could
>detect a 10HP increase without a dynometer. The results may vary for other
>vehicles. I have noticed that many of the Japanese manufacturers have
>started specifying premium fuel for their higher cost engines. I assume that
>the major reason for this is achieving slightly better CAFE numbers. I am
>confident that most of the vehicles would run OK on regular, perhaps with
>slightly worse fuel economy and performance (you should check the owners
>guide).
>
>If you are going for maximum MONEY economy (as opposed to maximum fuel
>economy), then there is little chance that purchasing premium fuel is a
>smart decision. I doubt you will ever increase your fuel economy by more
>than 3% by using premium, and since premium costs at least 5% more than
>regular, it is a clear loser if you are trying to save money.
>
>A word of caution - you can't really make any determination on the relative
>fuel economy difference between regular and premium by comparing single tank
>fulls of gas. Besides the inaccuracy of single tank full fuel economy
>calculations, you must also consider the actual octane of the fuel mix in
>your tank and how quickly the PCM adjusts to different fuels. The PCM will
>not instantaneously advance the timing if you start using premium fuel. It
>will make the adjustment over a period of time. So if you want to do the
>comparison, I'd suggest making the measurement over at least 5 tank fulls of
>each type of fuel. I'd also not include two tank fulls when you are
>transitioning from one fuel to the other.
>
>Ed
>
I have personally had vehicles that cost less to run on premium than
regular - but that was back when the price difference was
significantly less. My daughter's twin cam Neon gets enough better
mileage on mid premium to almost pay the difference (at $0.05 per
liter difference), and it doesn't ping like it does on regular.
Recommendation is premium on that car.

--
Posted via a free Usenet account from http://www.teranews.com

clare at snyder.on.ca

2007-01-06, 8:29 pm

On Tue, 02 Jan 2007 17:33:30 GMT, CJT <abujlehc@prodigy.net> wrote:

>HLS@nospam.nix wrote:
>
>Precisely. Just think about it -- at one time, octane was increased
>by adding lead compounds. Why would lead increase a fuel's energy?

It didn't - but it allowed the engine to extract more of the energy
that the fuel contained by running at a more efficient setting.

--
Posted via a free Usenet account from http://www.teranews.com

clare at snyder.on.ca

2007-01-06, 8:29 pm

On Tue, 02 Jan 2007 18:23:01 +0000, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

>
>
>CJT wrote:
>
>
>It doesn't. Energy has nothing to do with it.
>
>High octane fuel has less energy than low octane in any case.
>
>Graham

Not necessarily (and usually not) true. This is a MYTH that has been
going around for years. If octane is increased by adding ethanol, it
is true. If it is inproved by catylitic cracking og the feed stock, it
is not true.

--
Posted via a free Usenet account from http://www.teranews.com

clare at snyder.on.ca

2007-01-06, 8:29 pm

On Tue, 02 Jan 2007 12:40:11 -0600, "*" <nospam@this.addy.com> wrote:

>
>
>Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote in article
><459AA2A1.9F1B5A35@hotmail.com>...
>direct
>to be
>invariably
>and
>car
>line at
>
>I was thinking pre-computerized ignitions.
>
>So, the ECU has been programmed to advance the timing within safe limits of
>regular fuel....no more.
>
>How do YOU get it to exceed those limits?
>
>
Depends on the ECU. Some can be "chipped" for more advance.Some OBD2
boxes can be "reflashed" Some that still have a distributor can have
the timing physically advanced. On some you can adjust the cam sensor
to provide more advance. On most, it's pretty well "cast in stone"

--
Posted via a free Usenet account from http://www.teranews.com

Arnold Walker

2007-01-06, 8:29 pm

Arnold Walker

2007-01-06, 8:29 pm

"*" <nospam@this.addy.com> wrote in message
news:01c72e9c$e49515a0$5791c3d8@race...
>
>
> Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote in article
> <459AA2A1.9F1B5A35@hotmail.com>...
> direct
> to be
> invariably
> and
> car
> line at
>
> I was thinking pre-computerized ignitions.
>
> So, the ECU has been programmed to advance the timing within safe limits
> of
> regular fuel....no more.
>
> How do YOU get it to exceed those limits?
With a performance chip set.......sold at any rod shop.
And while you are there pick-up your turbocharger kit....and if you want to
use premium
switch to bi-turbo.
>
>
>
>

----== Posted via droptable.com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.droptable.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----

news

2007-01-06, 8:29 pm

Eeyore wrote:
>
> HLS@nospam.nix wrote:
>
>
> And good anti-knock properties ( higher octane ) allow the ignition to be
> advanced which *may* improve engine efficiency. It pretty much invariably
> improves performance.
>
> Graham
>
>

but only if the computer calls for more timing with higher octane.
If your computer calls for a max of 35 degrees and you can reach that on
regular gas, 91 won't do anything.

That said, I have a Trans Am that will ping if you put in anything lower
than 91. Manual says so, and I accidentially put in a tank of 87 by
accident. Stopped 50 miles later and bought a shot of octane boost and
then filled up again at 1/2 tank to stop the pinging.

Ray

cyberzl1@yahoo.com

2007-01-06, 8:29 pm

dido wrote:
> is there any truth to the statement that using a higher octane gasoline will result in
> better gas mileage? I understand that it may have other beneficial properties ie.
> anti-knock, acceleration, etc..
>
> how would one calculate such a statement?
>
> for reference, I usually fillup between 16-20 gallons, regular gas is 87 octane,
> supreme 92 octane and in our area the price difference appears to be about 20c-30c
> between regular and supreme.

It may.

As others have stated, octane in itself has nothing to do with fuel
mileage. But increased octance may allow for more spark advance and
more power.

I had a '91 Caprice that I typically ran on 87 octane, but did run on
91/92 octane depending on price. I would typically get 2-3 mpg
better(28 vs 25) on the higher octane fuel. I no longer have the car,
but the price difference between grades has grown to the point that it
probably wouldn't make sense any more anyways.

Try it and find out. But it is unlikely that it will make enough
difference to acount for 30c of price difference.

JW

Eeyore

2007-01-06, 8:29 pm

news wrote:

> Eeyore wrote:
>
>
> but only if the computer calls for more timing with higher octane.
> If your computer calls for a max of 35 degrees and you can reach that on
> regular gas, 91 won't do anything.
>
> That said, I have a Trans Am that will ping if you put in anything lower
> than 91. Manual says so, and I accidentially put in a tank of 87 by
> accident. Stopped 50 miles later and bought a shot of octane boost and
> then filled up again at 1/2 tank to stop the pinging.

Saab's Trionic ECUs will deliberately advance the timing until the engine *does*
pink intentionally so. And much much more besides. They even use spark plug
ionisation levels to determine mixture richness ( on a per cylinder basis ) !

They're probably the most advanced around. Many cars have clueless ECUs by
comparison. So it does depend hugely on the car.

Graham

Eeyore

2007-01-06, 8:29 pm

Richard P.

2007-01-06, 8:29 pm

Very true. I used to work for Imperial Oil and they said to use the highest
octane you can use before there was no improvement in fuel mileage. It
takes repeated mileage tests averaged out to determine the best fuel
required.

My 1971 Datsun 240Z had to run on "supreme" 91+ octane fuel to maximize
power and fuel mileage. Funny to think that 13 years ago I used to cringe
at the price I was paying for it which was less than the regular priced
today.

I once owned a beater 1976 Toyota Celica GT hatchback who's carbs I leaned
out for maximum fuel mileage and I found it ran best on 87 octane fuel.
Thank god as I was a student at that time and needed cheap transportation.
Until I got my new Civic, this car gave me the best highway mileage.

I had a 1994 Pontiac Sunbird (w/EFI electronic fuel injection) that
recommends minimum 87 octane fuel. But I found thru repeated tests that I
got slightly better fuel mileage using 89 octane. Anything higher provided
no gain and was a drain on expenses.

My current car, a 2006 Honda Civic recommends a minimum of 87 octane as
well. But I almost run it exclusively on E5 89 octane (5% ethanol blend)
and I have found virtually no difference in mileage. I pay about 5 cents
more per litre but that turns out to be about $10 more per month in fuel
expense, a small price i'm willing to pay for reduced GHG emissions.

"Mike Romain" <romainm@sympatico.ca> wrote
> It depends on your engine. You need to check the gas mileage between
> fills to see if there is a difference.

Eeyore

2007-01-06, 8:29 pm

"Richard P." wrote:

> Very true. I used to work for Imperial Oil and they said to use the highest
> octane you can use before there was no improvement in fuel mileage. It
> takes repeated mileage tests averaged out to determine the best fuel
> required.
>
> My 1971 Datsun 240Z had to run on "supreme" 91+ octane fuel to maximize
> power and fuel mileage. Funny to think that 13 years ago I used to cringe
> at the price I was paying for it which was less than the regular priced
> today.
>
> I once owned a beater 1976 Toyota Celica GT hatchback who's carbs I leaned
> out for maximum fuel mileage and I found it ran best on 87 octane fuel.
> Thank god as I was a student at that time and needed cheap transportation.
> Until I got my new Civic, this car gave me the best highway mileage.
>
> I had a 1994 Pontiac Sunbird (w/EFI electronic fuel injection) that
> recommends minimum 87 octane fuel. But I found thru repeated tests that I
> got slightly better fuel mileage using 89 octane. Anything higher provided
> no gain and was a drain on expenses.
>
> My current car, a 2006 Honda Civic recommends a minimum of 87 octane as
> well. But I almost run it exclusively on E5 89 octane (5% ethanol blend)
> and I have found virtually no difference in mileage. I pay about 5 cents
> more per litre but that turns out to be about $10 more per month in fuel
> expense, a small price i'm willing to pay for reduced GHG emissions.

It may possibly help keep your engine cleaner too.

Graham

clare at snyder.on.ca

2007-01-06, 8:29 pm

On Wed, 03 Jan 2007 01:17:49 GMT, "Richard P." <not@home.eh> wrote:

>Very true. I used to work for Imperial Oil and they said to use the highest
>octane you can use before there was no improvement in fuel mileage. It
>takes repeated mileage tests averaged out to determine the best fuel
>required.
>
>My 1971 Datsun 240Z had to run on "supreme" 91+ octane fuel to maximize
>power and fuel mileage. Funny to think that 13 years ago I used to cringe
>at the price I was paying for it which was less than the regular priced
>today.
>
>I once owned a beater 1976 Toyota Celica GT hatchback who's carbs I leaned
>out for maximum fuel mileage and I found it ran best on 87 octane fuel.
>Thank god as I was a student at that time and needed cheap transportation.
>Until I got my new Civic, this car gave me the best highway mileage.

With the gearing on the '75 Celica GT hatch (longer legs than the '76)
I got 55MPG at 70+mph if I could hold steady speed. (Waterloo to
Peterborough Ontario at 2AM Saturday morning, 1979 0r 1980)That trip
was closer to 75MPH than 70 - and at 55 I never got more than 45. 5th
gear, right on the cam (4200rpm) seemed to be where it was happiest
>

--
Posted via a free Usenet account from http://www.teranews.com

River

2007-01-06, 8:29 pm

You MIGHT get better MPG but you will not get better MP$.

On Tue, 2 Jan 2007 15:11:14 +0200, "dido" <dido@north.za> wrote:

>is there any truth to the statement that using a higher octane gasoline will result in
>better gas mileage? I understand that it may have other beneficial properties ie.
>anti-knock, acceleration, etc..
>
>how would one calculate such a statement?
>
>for reference, I usually fillup between 16-20 gallons, regular gas is 87 octane,
>supreme 92 octane and in our area the price difference appears to be about 20c-30c
>between regular and supreme.
>

Solar Flare

2007-01-06, 8:29 pm

Octane slows down the burn and allows more power to be extracted from
the fuel, stops the pinging but the engine timing must be adjusted to
suit. Lead had more cooling effect for lower temperature valves and
other parts.

"CJT" <abujlehc@prodigy.net> wrote in message
news:459A976A.6080102@prodigy.net...
> HLS@nospam.nix wrote:
>
> Precisely. Just think about it -- at one time, octane was increased
> by adding lead compounds. Why would lead increase a fuel's energy?
>
> --
> The e-mail address in our reply-to line is reversed in an attempt to
> minimize spam. Our true address is of the form che...@prodigy.net.

Eeyore

2007-01-06, 8:29 pm

Solar Flare wrote:

> Octane slows down the burn and allows more power to be extracted from
> the fuel, stops the pinging but the engine timing must be adjusted to
> suit.

A decent ECU will do that instantaneously 'on the fly'.

Graham

harry k

2007-01-06, 8:29 pm

Eeyore wrote:
> Solar Flare wrote:
>
>
> A decent ECU will do that instantaneously 'on the fly'.
>
> Graham

In any case and slight increase in mpg will be more than offset by the
additional cost. Just my opinion but I am on the side of 'no
increase'. I have seen this thing discussed and written about many
times. The "experts" all say it is just a waste of money.

Harry K

Eeyore

2007-01-06, 8:29 pm

harry k wrote:

> Eeyore wrote:
>
> In any case and slight increase in mpg will be more than offset by the
> additional cost. Just my opinion but I am on the side of 'no
> increase'. I have seen this thing discussed and written about many
> times. The "experts" all say it is just a waste of money.

You may not get any increase in mpg but decent cars will see an improvement in
performance.

I had one car in fact that allowed to me select the 'ideal' octane as either 95
or 98 ( RON ).

Graham

Buy_Sell

2007-01-06, 8:29 pm

Say, whatever happened to the water injection systems that they used in
the world war II fighter planes? They could advance the timing, reduce
the ping, get better performance and economy. So, how come these
brilliant automotive engineers aren't using this technology?

Eeyore

2007-01-06, 8:29 pm

Buy_Sell wrote:

> Say, whatever happened to the water injection systems that they used in
> the world war II fighter planes? They could advance the timing, reduce
> the ping, get better performance and economy. So, how come these
> brilliant automotive engineers aren't using this technology?

What water injection systems ?

There were ethanol and methanol injection sytems ( improve the octane rating )
but water ?

Graham

Paul Hovnanian P.E.

2007-01-06, 8:29 pm

E Meyer wrote:
>
> On 1/2/07 7:11 AM, in article 4vv3viF1d8ujsU1@mid.individual.net, "dido"
> <dido@north.za> wrote:
>
>
> There is qualified truth in your statement. It depends on a number of
> factors whether better gas mileage will result from higher octane gas. The
> number one factor being that the engine is designed for higher octane gas in
> the first place.
>
> Most modern engines have a knock sensor that detunes the engine when it
> detects pinging, which is usually due to gas with too low an octane rating.
> When it does this the mileage and performance are compromised. Using higher
> octane gas in such an engine doesn't necessarily guarantee better gas
> mileage but rather it corrects the worse gas mileage that resulted from
> running it on the wrong gas.

Right. If the engine's antiknock system isn't kicking in and retarding
timing, higher octane gas would be wasted.

It would be really nice what with all the brains built into ECUs if
they'd add a dashboard light that would signal the opreation of the
antiknock system. If you see the 'Bad Gas' light come on frequently,
higher octance might be of some value.

> So, if your owner's manual says you should be using higher octane gas, it
> should give better results if you do. If it says you should be using
> regular, premium gas will most likely be a waste of money.

Driving habits (and other conditions) can affect octane requirements.
Some people might get away with using lower octane gas if they are
easier on the gas pedal.

--
Paul Hovnanian mailto:Paul@Hovnanian.com
------------------------------------------------------------------
Madness takes its toll. Please have exact change.

Buy_Sell

2007-01-06, 8:29 pm

Well, let me see what Mr. Wikipedia has to say about the subject...
http://en.wikipedia.org/wiki/Water_injection_(engines)

---------------------
Eeyore wrote:
> What water injection systems ?
>
> There were ethanol and methanol injection sytems ( improve the octane rating )
> but water ?
>
> Graham

Buy_Sell

2007-01-06, 8:29 pm

Buy_Sell wrote:[color=darkred]
> Well, let me see what Mr. Wikipedia has to say about the subject...
> http://en.wikipedia.org/wiki/Water_...n_%28engines%29
>
> ---------------------
> Eeyore wrote:

Eeyore

2007-01-06, 8:29 pm

Buy_Sell wrote:

> Well, let me see what Mr. Wikipedia has to say about the subject...
> http://en.wikipedia.org/wiki/Water_injection_(engines)

It says very little. So ?

Maybe it was found not to be terribly useful ? I can see there would be logistical
issues.

Your turn.

Graham

Eeyore

2007-01-06, 8:29 pm

Buy_Sell wrote:

> Well, let me see what Mr. Wikipedia has to say about the subject...
> http://en.wikipedia.org/wiki/Water_injection_(engines)

Ok. 2nd take.

I notice the comment that water injection has fallen out of interest since the
advent of intercooled turbo engines.

One problem with turbo'ing is the that the intake air becomes very hot due to
compression and the air-fuel mixture can prematurely detonate in the cylinder.

My own Saab ( lpt ) without an intercooler is limited to about 0.3 bar boost for
example to avoid such a problem..

Water injection into the hot intake air would actually cool the mixture thus
resolving the problem.

However since intercoolers perform the same function without the added complexity of
water or water-alcohol injection there's simply no longer any need for it.
http://en.wikipedia.org/wiki/Intercooler

Graham

TE Chea

2007-01-06, 8:29 pm

| The octane rating is, just as I said, a number related to antiknock
| properties.

Wikipedia says lower octane petrol usually produces less heat
, this I find true in BP's RON92 compared with RON97 : both
my mitsubishi 4G15P & honda F20A ( original cr 9.2 & 9.6,
both have improved cooling via copper wires ) can use RON92
, esp in humid air here & on flat land ( no towing / climbing ),
but RON92 produces less heat ( & so torque ), so its 1.56%
lower price cannot justify 2-4 % less torque. My brother's
mitsubishi 6G72 ( cr is just 9 ) needs just RON92 per owner's
manual, but he buys RON97, & I agree as wise.

Venus

2007-01-06, 8:29 pm

clare at snyder.on.ca wrote in article
<nlblp21g1s649pvlogdp010qi4cvrgf60q@4ax.com>...
> On Tue, 02 Jan 2007 12:40:11 -0600, "*" <nospam@this.addy.com> wrote:
>
antiknock[color=darkred]
ignition[color=darkred]
from[color=darkred]
timing[color=darkred]
a[color=darkred]
should[color=darkred]
of[color=darkred]
> Depends on the ECU. Some can be "chipped" for more advance.Some OBD2
> boxes can be "reflashed" Some that still have a distributor can have
> the timing physically advanced. On some you can adjust the cam sensor
> to provide more advance. On most, it's pretty well "cast in stone"
>

Which, of course, is modifying the car - NOT gaining better mileage by
simply adding high octane gasoline...

2007-01-06, 8:29 pm

Arnold Walker <arnoldwalker@consolidated.net> wrote in article
<1167767707_22933@sp6iad.superfeed.net>...
>
> "*" <nospam@this.addy.com> wrote in message
> news:01c72e9c$e49515a0$5791c3d8@race...
antiknock[color=darkred]
ignition[color=darkred]
from[color=darkred]
timing[color=darkred]
a[color=darkred]
should[color=darkred]
limits[color=darkred]
> With a performance chip set.......sold at any rod shop.
> And while you are there pick-up your turbocharger kit....and if you want
to
> use premium
> switch to bi-turbo.

Which, of course, is modifying the car - NOT gaining better mileage by
simply adding high octane gasoline...

2007-01-06, 8:29 pm

news <rollingviolation@domain.invalid.com> wrote in article
<24zmh.543160$1T2.206797@pd7urf2no>...
>
> That said, I have a Trans Am that will ping if you put in anything lower
> than 91. Manual says so, and I accidentially put in a tank of 87 by
> accident. Stopped 50 miles later and bought a shot of octane boost and
> then filled up again at 1/2 tank to stop the pinging.
>

Which "octane boost" did you buy?

104+ used to say right on the can that it "...enhances the octane
effect..." by cleaning carbon out of the combustion chamber - thus lowering
compression and knocking.

IOW - It didn't INCREASE the actual octane of the fuel, it simply DECREASED
the need for higher octane caused by higher compression pressures created
by carbon deposits.

2007-01-06, 8:29 pm

Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote in article
<459B3611.D785D2B9@hotmail.com>...
>
>

>
> You may not get any increase in mpg but decent cars will see an
improvement in
> performance.
>

Talk about hi-jacking a thread.....

The OP's question concerned using hogh octane for better fuel mileage, and
you've morphed it into discussing better performance.

2007-01-06, 8:29 pm

Venus______________________________________________________________________
___________________________________________________________________________
___________________________________________________Yes X-Complaints-To:
abuse@supernews.com <VenusGplanet.com

Yes
X-Complaints-To: abuse@supernews.com> wrote in article
<M6Nmh.5918$pQ3.702@newsread4.news.pas.earthlink.net>...
>
> "dido" <dido@north.za> wrote in message
> news:4vv3viF1d8ujsU1@mid.individual.net...
[color=darkred]
87[color=darkred]
to[color=darkred]
>
> "dido"
> I heard about this gimmick high Octane, I already spent $200-$300 on all
> sorts of additives and high octanes gas to see if I can save moneyl. I
> ended up with +/- 2-3 miles. Now I am so glad I've found a better
solution,
> now I doubled the mileage (or pay 1/2 price what I normally paid in the
> past.) The engineering in our car is wrong, that's what caused Global
> Warming, and that's what took all our dollars.
>
> I will not give this idea away freely, perhaps some ones know about this
but
> they just wanted to make big bugs on their Petrol stock, I don't know or
> perhaps they are dumb for many years.

Hang on!!!!

As soon as your brother deposits that multi-million dollar General Mumboola
Nigerian inheritance cash that he managed to smuggle out of Africa into my
bank account, and I can collect my share for doing nothing but give away my
entire financial identity, I'll be happy to invest with you....

That, or when I reach week four (or was it six?) and my $6.00 investment in
the chain letter starts to pay off big bucks!

BTW - Nice twist on working "global warming" into a snake oil pitch......

digitalmaster

2007-01-06, 8:29 pm

"*" <nospam@this.addy.com> wrote in message
news:01c72e9c$e49515a0$5791c3d8@race...
>
>
> Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote in article
> <459AA2A1.9F1B5A35@hotmail.com>...
> direct
> to be
> invariably
> and
> car
> line at
>
> I was thinking pre-computerized ignitions.
>
> So, the ECU has been programmed to advance the timing within safe limits
> of
> regular fuel....no more.
>
> How do YOU get it to exceed those limits?
>
>
>
most vehicles have a knock sensor and will try to constantly adjust the
timing.If you use higher octane fuel the ecu will advance the timing
further.The question is will the added mileage make up for the price
difference?

Buy_Sell

2007-01-06, 8:29 pm

I think that the message that I was trying to get across was that water
injection effectively raises the octane level and performance of an
engine. The wikipedia link was talking about the same thing.

http://en.wikipedia.org/wiki/Water_...n_%28engines%29
----------------
* wrote:
> Talk about hi-jacking a thread.....
>
> The OP's question concerned using hogh octane for better fuel mileage, and
> you've morphed it into discussing better performance.

harry k

2007-01-06, 8:29 pm

Eeyore wrote:
> Buy_Sell wrote:
>
>
> What water injection systems ?
>
> There were ethanol and methanol injection sytems ( improve the octane rating )
> but water ?
>
> Graham

Used to be add-ons sold through places like J.C. Whitney. Running the
old 30s and 40s cars, there was a very noticeable improvesment in
performance (don't know about economy) when the humidity was high or it
was raining. Never noticed it after the advent of modern engine
control systems.

Harry K

Scott Dorsey

2007-01-06, 8:29 pm

harry k <turnkey4099@hotmail.com> wrote:
>Eeyore wrote:
>
>Used to be add-ons sold through places like J.C. Whitney. Running the
>old 30s and 40s cars, there was a very noticeable improvesment in
>performance (don't know about economy) when the humidity was high or it
>was raining. Never noticed it after the advent of modern engine
>control systems.

Water injection was a big deal in the 1940s and was used in a lot of WWII
aircraft engines. The notion here is that you get the phase change of
the water during combustion, which produces additional effective power
(ie. more energy into the piston stroke, less energy wasted as exhaust heat)
as it turns to steam.

I don't think I have seen it on anything modern.... but it was one of
the big secret features on the B-29.

Normally it's not just water either, but a water/surfactant mixture so
that the fuel-air-water mixture would be more even.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Steve

2007-01-06, 8:29 pm

Scott Dorsey wrote:

> harry k <turnkey4099@hotmail.com> wrote:
>

They are used (beyond their designers' wildest dreams, in fact) every
year at the Reno National Championship Air Races ;-)
[color=darkred]
> They could advance the timing, reduce

Advancing the timing wasn't the goal, raising the BOOST PRESSURE from
supercharger or turbochargers was the goal. Advancing timing is
counter-productive beyond a certain point because combustion is just
pushing "the wrong way" on the piston. But raising boost pressure is
advantageous in many ways. The problem is that thanks to good ol PV=nRT,
compressing the intake charger with a super- or turbo-charger raises the
temperature of the intake charge. Too high an intake temperature results
in detonation regardless of the ignition timing, and can also result in
manifold explosions. Aftercoolers (air-to-air or air-to water) help, but
are limited in how much heat they can reject and also add weight to the
aircraft. Water injection in WWII aircraft engines primarily reduced the
temperature of the intake charge to a manageable level because the
evaporating water absorbs a LOT of heat (latent heat of vaporization.)
Running the engine excessively rich also does the same thing using the
fuel itself to absorb heat, but the drawback is that over-rich
combustion produces less power than stoichiometric combustion.

In addition, the water adds inert gas to the combustion cycle, and that
slows down the flame front and reduces the peak temperature in the
cylinder and further suppresses harmful detonation of the type where a
pocket of charge in a remote corner of the cylinder self-ignites after
the primary flame-front starts increasing cylinder pressure. Modern
automobile engines (since the late 70s) actually use a metered dose of
their own exhaust gas (exhaust gas recirculation or EGR) to do this
(slow combustion, reduce peak combustion temperature) as well as to
reduce nitrogen oxide emissions.

The big drawback to water injection is maintenance. Corrosion in the
plumbing, pumps, valving, etc. is a big problem. Also, the water/ethanol
mixture has to be replenished along with fuel and oil and it has to be
PURE water which requires reverse-osmosis, distillation, or at least
deionization. Otherwise deposits build up in the system and in the
engine. Water injection really isn't practical for cars, especially
since most drivers can't even be persuaded to check their own oil these
days.

[color=darkred]
> Water injection was a big deal in the 1940s and was used in a lot of WWII
> aircraft engines. The notion here is that you get the phase change of
> the water during combustion, which produces additional effective power
> (ie. more energy into the piston stroke, less energy wasted as exhaust heat)
> as it turns to steam.

My understanding is that the water/alcohol is fully vaporized well
before it passes through the intake valve(s).

Derek Broughton

2007-01-06, 8:29 pm

Steve wrote:

> Water injection really isn't practical for cars, especially
> since most drivers can't even be persuaded to check their own oil these
> days.

Did they ever? Ah, for the good old days when the guy at the pumps always
asked if I wanted the oil checked...
--
derek

Steve

2007-01-06, 8:29 pm

Derek Broughton wrote:

> Steve wrote:
>
>
>
>
> Did they ever?

Yeah. The summer of 1975...

> Ah, for the good old days when the guy at the pumps always
> asked if I wanted the oil checked...

I miss that. I'm sure some folks DON'T miss the occasional crook at the
pumps who made sure to put the stick in "short" so it read a quart low,
the guys who dropped antacid tablets in the battery and said that the
foam was due to the alternator overcharging the battery, etc. etc. etc.
Gladly those guys were a small minority, but they were out there!

clare at snyder.on.ca

2007-01-06, 8:29 pm

On 2 Jan 2007 21:22:08 -0800, "Buy_Sell" <werkspace@hotmail.com>
wrote:

>Say, whatever happened to the water injection systems that they used in
>the world war II fighter planes? They could advance the timing, reduce
>the ping, get better performance and economy. So, how come these
>brilliant automotive engineers aren't using this technology?

GM did, back in '60 to '63 with the turbo Olds Jetfire and IIRC, the
Turbo Monza Corvair. Don't think it was standard on the Monza, but I
know some did use it (possibly a "dealer add-on" using Olds parts)

--
Posted via a free Usenet account from http://www.teranews.com

clare at snyder.on.ca

2007-01-06, 8:29 pm

On Tue, 2 Jan 2007 22:04:38 -0500, "Solar Flare"
<solaerfart@hootmail.invalidated> wrote:

>Octane slows down the burn and allows more power to be extracted from
>the fuel, stops the pinging but the engine timing must be adjusted to
>suit. Lead had more cooling effect for lower temperature valves and
>other parts.

Not true.
Higher octane fuel, generally, does NOT burn slower. In many cases it
can actually burn FASTER. High octane fuel simply resists
dis-associating the hydrogen radicals(H1, not H2) from the hydrocarbon
fuel under heat and pressure. It is the presence of these "free
radicals" which causes the fuel to detonate in the cyl.

To reduce detonation you either increase the Octane rating of the fuel
or reduce the amount of heat acting on the end gas. This is done by
reducing compression, retarding spark, increasing RPM, or engineering
the combustion chamber for a FASTER burn.

Lead did not have a "cooling effect". The lead COATING acted as both
an insulator and a lubricant on the valve seats, preventing the valve
from being "hammer welded" to the seat, pulling metal from the seat
and causing "seat errosion". This was a side benefit - TEL was added
to act as a "negative catalyst" to prevent the breakdown of the
end-gasses, reducing the production of the highly unstable hydrogen
radicals.
>
>"CJT" <abujlehc@prodigy.net> wrote in message
>news:459A976A.6080102@prodigy.net...
>

--
Posted via a free Usenet account from http://www.teranews.com

clare at snyder.on.ca

2007-01-06, 8:29 pm

On Wed, 03 Jan 2007 07:59:40 -0600, "*" <nospam@this.addy.com> wrote:

>
>
>Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote in article
><459B3611.D785D2B9@hotmail.com>...
>
>improvement in
>
>Talk about hi-jacking a thread.....
>
>The OP's question concerned using hogh octane for better fuel mileage, and
>you've morphed it into discussing better performance.
>
>
>
So?
Better performance GENERALLY also translates to better fuel mileage if
you do not use the extra power available.

--
Posted via a free Usenet account from http://www.teranews.com

Buy_Sell

2007-01-06, 8:29 pm

Two could play at that game. I remember when you could reset the
counter on the gas pump ever $5.00 just by flipping it off and on.
That way a fillup only ever costed $5.00
Oh wait a minute, it only cost $5.00 to fill up then anyway. Sorry...

------------------
Steve wrote:
> Derek Broughton wrote:
>
>
> Yeah. The summer of 1975...
>
>
> I miss that. I'm sure some folks DON'T miss the occasional crook at the
> pumps who made sure to put the stick in "short" so it read a quart low,
> the guys who dropped antacid tablets in the battery and said that the
> foam was due to the alternator overcharging the battery, etc. etc. etc.
> Gladly those guys were a small minority, but they were out there!

Eeyore

2007-01-06, 8:29 pm

clare, at, snyder.on.ca wrote:

> On Wed, 03 Jan 2007 07:59:40 -0600, "*" <nospam@this.addy.com> wrote:
> So?
> Better performance GENERALLY also translates to better fuel mileage if
> you do not use the extra power available.

LOL. And sometimes it's *so* tempting to do just that.

Graham

y_p_w

2007-01-06, 8:29 pm

Solar Flare wrote:
> Octane slows down the burn and allows more power to be extracted from
> the fuel, stops the pinging but the engine timing must be adjusted to
> suit. Lead had more cooling effect for lower temperature valves and
> other parts.

High octane unleaded racing fuel supposedly burns faster once ignited.
However - it has a higher resistance to detonation or preignition. A
spark is usually hot enough to ignite the mixture.

y_p_w

2007-01-06, 8:29 pm

Eeyore wrote:

> European and Japanese cars typically prefer higher octane fuels btw.
> In the UK I've never seen less than 95RON fuel ( that's 91 in your US
> PON figures ) and 98 RON is our commonly available top grade ( 94
> PON ).

I'm not sure about those numbers. The difference is highly dependent
on the individual fuel. It's also called Anti-Knock Index (AKI), and
on the pump the label typically says (R+M)/2, as the average of the
RON and MON. I remember there was a recommended set of RON and
AKI octanes in a 2001 Toyota Camry owner's manual. I don't recall
off the top of my head.

Derek Broughton

2007-01-06, 8:29 pm

Steve wrote:

> Derek Broughton wrote:
>
>
> Yeah. The summer of 1975...

Ah, yes. Those were the days when I didn't ever have to check my oil -
every 100 miles it needed another quart.
>
>
> I miss that. I'm sure some folks DON'T miss the occasional crook at the
> pumps

Well, me neither, but it does come as a huge surprise these days when
someone asks...
--
derek

Solar Flare

2007-01-06, 8:29 pm

Water cannot increase the octane level but it can make the engine
perform like a higher octane fuel is present by slowing the explosion
down so more thrust can be harnessed with less cylinder head damage.

"Buy_Sell" <werkspace@hotmail.com> wrote in message
news:1167836036.761267.120340@n51g2000cwc.googlegroups.com...
>I think that the message that I was trying to get across was that
>water
> injection effectively raises the octane level and performance of an
> engine. The wikipedia link was talking about the same thing.
>
> http://en.wikipedia.org/wiki/Water_...n_%28engines%29
> ----------------
> * wrote:
>

Solar Flare

2007-01-06, 8:29 pm

In order to use unleaded fuels car engines has to increase the
temperature handling of the valves and seats. Lead acted like a
coolant.

<clare at snyder.on.ca> wrote in message
news:rv7op25dl6dq02gkecq73afhiq6q8t22n2@4ax.com...
> On Tue, 2 Jan 2007 22:04:38 -0500, "Solar Flare"
> <solaerfart@hootmail.invalidated> wrote:
>
>
> Not true.
> Higher octane fuel, generally, does NOT burn slower. In many cases
> it
> can actually burn FASTER. High octane fuel simply resists
> dis-associating the hydrogen radicals(H1, not H2) from the
> hydrocarbon
> fuel under heat and pressure. It is the presence of these "free
> radicals" which causes the fuel to detonate in the cyl.
>
> To reduce detonation you either increase the Octane rating of the
> fuel
> or reduce the amount of heat acting on the end gas. This is done by
> reducing compression, retarding spark, increasing RPM, or
> engineering
> the combustion chamber for a FASTER burn.
>
> Lead did not have a "cooling effect". The lead COATING acted as both
> an insulator and a lubricant on the valve seats, preventing the
> valve
> from being "hammer welded" to the seat, pulling metal from the seat
> and causing "seat errosion". This was a side benefit - TEL was added
> to act as a "negative catalyst" to prevent the breakdown of the
> end-gasses, reducing the production of the highly unstable hydrogen
> radicals.
>
>
> --
> Posted via a free Usenet account from http://www.teranews.com
>

Solar Flare

2007-01-06, 8:29 pm

High compression needed it to reduce dieseling.

"y_p_w" <y_p_w@hotmail.com> wrote in message
news:1167868074.935903.139570@42g2000cwt.googlegroups.com...
> Solar Flare wrote:
>
> High octane unleaded racing fuel supposedly burns faster once
> ignited.
> However - it has a higher resistance to detonation or preignition.
> A
> spark is usually hot enough to ignite the mixture.
>

clare at snyder.on.ca

2007-01-06, 8:29 pm

On Wed, 3 Jan 2007 20:20:18 -0500, "Solar Flare"
<solaerfart@hootmail.invalidated> wrote:

>Water cannot increase the octane level but it can make the engine
>perform like a higher octane fuel is present by slowing the explosion
>down so more thrust can be harnessed with less cylinder head damage.
>

Water injection reduces the octane requirement of the engine by
cooling the combustion chamber. This is partly due to the latent heat
of vaporization of water. The water "sucks up" some of the heat that
would otherwize work on the end-gasses.
>"Buy_Sell" <werkspace@hotmail.com> wrote in message
>news:1167836036.761267.120340@n51g2000cwc.googlegroups.com...
>

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clare at snyder.on.ca

2007-01-06, 8:29 pm

On Wed, 3 Jan 2007 20:22:19 -0500, "Solar Flare"
<solaerfart@hootmail.invalidated> wrote:

>In order to use unleaded fuels car engines has to increase the
>temperature handling of the valves and seats. Lead acted like a
>coolant.

No it did not. It was a lubricant and prevented the valve face from
"welding" to the seats. Seat recession was caused by pits being torn
out of the valve seats. Stelite or induction hardened seats resist
this action. It also took VERY LITTLE lead to have this effect. One
gallon of leaded fuel per 100 gallons is enough to protect the valves
of a "lead era" car. The result is also quite long lasting. A car that
has run leaded fuel can and will survive for many many hours without
valve damage on unleaded fuel.
>
><clare at snyder.on.ca> wrote in message
>news:rv7op25dl6dq02gkecq73afhiq6q8t22n2@4ax.com...
>

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clare at snyder.on.ca

2007-01-06, 8:29 pm

On Wed, 3 Jan 2007 20:22:52 -0500, "Solar Flare"
<solaerfart@hootmail.invalidated> wrote:

>High compression needed it to reduce dieseling.

Dieseling is part of it - but you can totally eliminate dieselling by
totally closing the throttle on shut-down.Dieseling is more
pre-ignition (or auto ignition) than detonation. It is still a
"normal" slow burn. No air and/or no fuel means no dieseling. It is
DETONATION that is prevented by higher octane fuel. Detonation, if
unchecked, will almost invariably also cause pre-ignition. The
combination of the two ia almost always deadly. Detonation scrubs the
barrier layer off the pistons - the pistons absorb excessive heat and
start to melt down. The hot piston lights the fuel before the
prescribed ignition point and the pressure peaks while the piston is
still coming up. This blows the weakened overheatred piston.

Funny thing - chicken and egg type - pre-ignition can cause
detonation. Detonation can cause pre-ignition. Knowing which came
first is essential to prevent the problem repeating itself.
>
>"y_p_w" <y_p_w@hotmail.com> wrote in message
>news:1167868074.935903.139570@42g2000cwt.googlegroups.com...
>

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Solar Flare

2007-01-06, 8:29 pm

OK the valves and seats had to be hardened to stop the "sticking"
action of the valve due to less lubrication from the lead but not the
higher temperature. My bad.

However you stated that higher octane fuels do not burn slower and
then proceded to say they do again. Most articles will agree that
octane stops pinging by slowing down the detonation of the fuel under
heat and presure. This is not faster and the chemical reason doesn't
really matter, as it appears to support my statement and disagree with
yours.

When you disagree and then set out to re-enforce the other posters
statement it appears as an obsession.

<clare at snyder.on.ca> wrote in message
news:rv7op25dl6dq02gkecq73afhiq6q8t22n2@4ax.com...[color=darkred]
> On Tue, 2 Jan 2007 22:04:38 -0500, "Solar Flare"
> <solaerfart@hootmail.invalidated> wrote:
>
>
> Not true.
> Higher octane fuel, generally, does NOT burn slower. In many cases
> it
> can actually burn FASTER. High octane fuel simply resists
> dis-associating the hydrogen radicals(H1, not H2) from the
> hydrocarbon
> fuel under heat and pressure. It is the presence of these "free
> radicals" which causes the fuel to detonate in the cyl.
>
> To reduce detonation you either increase the Octane rating of the
> fuel
> or reduce the amount of heat acting on the end gas. This is done by
> reducing compression, retarding spark, increasing RPM, or
> engineering
> the combustion chamber for a FASTER burn.
>
> Lead did not have a "cooling effect". The lead COATING acted as both
> an insulator and a lubricant on the valve seats, preventing the
> valve
> from being "hammer welded" to the seat, pulling metal from the seat
> and causing "seat errosion". This was a side benefit - TEL was added
> to act as a "negative catalyst" to prevent the breakdown of the
> end-gasses, reducing the production of the highly unstable hydrogen
> radicals.

harry k

2007-01-06, 8:29 pm

Steve wrote:
> Scott Dorsey wrote:
>

>
>
> My understanding is that the water/alcohol is fully vaporized well
> before it passes through the intake valve(s).

My understanding (not very good I admit) is that you get nothing for
free. Seems to me any power produced by flashing to steam has been
from heat stolen from the fuel combustion. I doubt that there is any
additional power produced by steam. The basic theory seems to have
been to cool the intake mixture thus getting a denser (and more fuel)
charge into the cyslinder.

Harry K

Eeyore

2007-01-06, 8:29 pm

y_p_w wrote:

> Eeyore wrote:
>
>
> I'm not sure about those numbers. The difference is highly dependent
> on the individual fuel. It's also called Anti-Knock Index (AKI), and
> on the pump the label typically says (R+M)/2, as the average of the
> RON and MON. I remember there was a recommended set of RON and
> AKI octanes in a 2001 Toyota Camry owner's manual. I don't recall
> off the top of my head.

They're typical numbers according to a site I found. (R+M)/2 is the same as PON
btw.

Graham

Arnold Walker

2007-01-06, 8:29 pm

"harry k" <turnkey4099@hotmail.com> wrote in message
news:1167877795.270264.53410@i80g2000cwc.googlegroups.com...
>
> Steve wrote:
>
>
> My understanding (not very good I admit) is that you get nothing for
> free. Seems to me any power produced by flashing to steam has been
> from heat stolen from the fuel combustion. I doubt that there is any
> additional power produced by steam. The basic theory seems to have
> been to cool the intake mixture thus getting a denser (and more fuel)
> charge into the cyslinder.
>
> Harry K
Steam expanses more for a given temperature than air.
And with the improved heat expansion and anti-ping control offered by water
injection.
You did indeed got more power and the exhaust would be half as hot at the
same time.
In piston engine a 1/3 more and on turbines double the horsepower.You got to
remember
the piston engines were running 50psi boost(22+:1 effective compression
ratio or in otherwords
the compression stroke would heat the air to 900F before you burned any
fuel ) in the air,not automotive turbo pressures.
With the exception of Stubaker ,whose car engines did with a blower on their
sports model.
They did water injection and avgas.....to contol the ping.and like the
aircraft had a switch in the
water tank/pump to kill the ignition advance and blowoff the boost psi, if
the tank ran low.
In both the Stubaker and the plane,if the water switch failed the engine was
trash in seconds
from preignition detonation.But when it worked a Stubaker Commander could
hang with 427 high performance
engines running half the engine displacement.The engine was dropped because
of complex construction ....little did they know that
modern engines now make they look simple ,50years later.

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Dan_Thomas_nospam@yahoo.com

2007-01-06, 8:29 pm

Solar Flare wrote:
> OK the valves and seats had to be hardened to stop the "sticking"
> action of the valve due to less lubrication from the lead but not the
> higher temperature. My bad.
>
> However you stated that higher octane fuels do not burn slower and
> then proceded to say they do again. Most articles will agree that
> octane stops pinging by slowing down the detonation of the fuel under
> heat and presure. This is not faster and the chemical reason doesn't
> really matter, as it appears to support my statement and disagree with
> yours.

Mustn't confuse detonation with normal combustion. The fuel/air
mixture should burn across the chamber at about 100 feet per second.
Detonation is a different process and flame fronts can reach 5000 fps
or more. The enormous pressure spikes and abrupt release of heat does
plenty of damage.
Detonation happens when the complex fuel molecules, under the
rising pressure ahead of the flame front of normal combustion, begin to
break down into simpler structures that can autoignite; they don't wait
for the flame front to set them off in a normal chain reaction. The
whole works might go off at once just becuse they're being squeezed and
their temp is rising.
Detonation requires time for those molecules to break down, so
low RPM is a problem, large combustion chambers (which require more
flame-travel time) are a problem, lean mixtures (which burn more slowly
due to the distance between molcules) are a problem.
Normal combustion is not an explosion; it's a controlled burn.
Detonation is an explosion, totally uncontrolled, and higher octane
fuels were designed to increase the capability of handling the higher
pressures and temps without breaking down into autoignitable
components.
In aircraft we're still using leaded fuels because the engine
technology is stuck in the 1950s. Some avgas grades have large amounts
of lead in them, and sparkplug fouling is a big problem, even in the
heat of an aircooled engine. Those amounts of TEL are necessary for the
big cylinders found on aircraft engines, their low operating RPM, and
the higher operating temps (cylinder head temps to 550=B0F, depending on
the engine).
We've been promised unleaded avgas for some time now but
haven't seen it yet.

Dan

clare at snyder.on.ca

2007-01-06, 8:29 pm

On Wed, 3 Jan 2007 21:29:50 -0500, "Solar Flare"
<solaerfart@hootmail.invalidated> wrote:

>OK the valves and seats had to be hardened to stop the "sticking"
>action of the valve due to less lubrication from the lead but not the
>higher temperature. My bad.
>
>However you stated that higher octane fuels do not burn slower and
>then proceded to say they do again. Most articles will agree that
>octane stops pinging by slowing down the detonation of the fuel under
>heat and presure. This is not faster and the chemical reason doesn't
>really matter, as it appears to support my statement and disagree with
>yours.

You are being nitpicky and don't know what you are talking about. It
is NOT the speed of the burning of the gasoline that is slowed down.
It is the virtual explosion of the dis-associated end gasses that is
ELIMINATED.
Slower fuel burn INCREASES the tendancy of an engine to detonate.
>
>When you disagree and then set out to re-enforce the other posters
>statement it appears as an obsession.
>
><clare at snyder.on.ca> wrote in message
>news:rv7op25dl6dq02gkecq73afhiq6q8t22n2@4ax.com...
>

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clare at snyder.on.ca

2007-01-06, 8:29 pm

On 3 Jan 2007 18:29:56 -0800, "harry k" <turnkey4099@hotmail.com>
wrote:

>
>Steve wrote:
>
>
>My understanding (not very good I admit) is that you get nothing for
>free. Seems to me any power produced by flashing to steam has been
>from heat stolen from the fuel combustion. I doubt that there is any
>additional power produced by steam. The basic theory seems to have
>been to cool the intake mixture thus getting a denser (and more fuel)
>charge into the cyslinder.
>
>Harry K
Almost. Getting higher density of the air charge is no problem on a
turbo engine. It is the cooling of the COMBUSTION CHAMBER that was the
challenge - and water injection helped significantly. It DID have the
side effect of acting a bit like an intercooler - but any heat
absorbed in the intake reduced it's primary effect in the cyl.

A higher density intake charge actually INCREASED the tendancy to
detonate by increasing the effective cyl compression - which was part
of the problem in the first place (wouldn't ping without boost)

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clare at snyder.on.ca

2007-01-06, 8:29 pm

On 4 Jan 2007 08:15:31 -0800, Dan_Thomas_nospam@yahoo.com wrote:

>
> Mustn't confuse detonation with normal combustion. The fuel/air
>mixture should burn across the chamber at about 100 feet per second.
>Detonation is a different process and flame fronts can reach 5000 fps
>or more. The enormous pressure spikes and abrupt release of heat does
>plenty of damage.
> Detonation happens when the complex fuel molecules, under the
>rising pressure ahead of the flame front of normal combustion, begin to
>break down into simpler structures that can autoignite; they don't wait
>for the flame front to set them off in a normal chain reaction. The
>whole works might go off at once just becuse they're being squeezed and
>their temp is rising.
> Detonation requires time for those molecules to break down, so
>low RPM is a problem, large combustion chambers (which require more
>flame-travel time) are a problem, lean mixtures (which burn more slowly
>due to the distance between molcules) are a problem.
> Normal combustion is not an explosion; it's a controlled burn.
>Detonation is an explosion, totally uncontrolled, and higher octane
>fuels were designed to increase the capability of handling the higher
>pressures and temps without breaking down into autoignitable
>components.
> In aircraft we're still using leaded fuels because the engine
>technology is stuck in the 1950s. Some avgas grades have large amounts
>of lead in them, and sparkplug fouling is a big problem, even in the
>heat of an aircooled engine. Those amounts of TEL are necessary for the
>big cylinders found on aircraft engines, their low operating RPM, and
>the higher operating temps (cylinder head temps to 550Â°F, depending on
>the engine).
> We've been promised unleaded avgas for some time now but

Right on Dan,
So much misinformation flying around about Octane - good to see there
are a few others who understand it. (Are you a Canuk? Member of RAA?
Perhaps read my artical the other month?)

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2007-01-06, 8:29 pm

"*" <nospam@this.addy.com> wrote in message
news:01c72f41$003c9ae0$2991c3d8@race...

> BTW - Nice twist on working "global warming" into a snake oil pitch......

Well, it has generated about as much comment as the great toilet roll wars
of the 80's;> )

Steve

2007-01-06, 8:29 pm

Steve

2007-01-06, 8:29 pm

harry k wrote:

> Steve wrote:
>
>
>
>
>
> My understanding (not very good I admit) is that you get nothing for
> free. Seems to me any power produced by flashing to steam has been
> from heat stolen from the fuel combustion. I doubt that there is any
> additional power produced by steam. The basic theory seems to have
> been to cool the intake mixture thus getting a denser (and more fuel)
> charge into the cyslinder.
>
> Harry K
>

You're right in that the main gain is getting a denser cooler mixture
into the cylinder, but I think there is a *small* additional gain when
water vapor is present in the combustion chamber because we're not
dealing with ideal gasses. If all the gasses involved were truly ideal,
then you would be correct. In addition, most WWII aircraft engines made
some small use of the jet thrust from the exhaust stacks, and water
certainly adds mass-flow to the engine and would add some jet thrust.
IIRC, I've seen an estimate that a P-51's Merlin engine produces a few
hundred pounds of jet thrust from its exhaust at full power. Not enough
to even move the aircraft on the ground by itself, but certainly enough
to offset the drag of the exhaust system itself sticking out into the
slipstream, and therefore a net benefit.

y_p_w

2007-01-06, 8:29 pm

Eeyore wrote:
> y_p_w wrote:
>
>
> They're typical numbers according to a site I found. (R+M)/2 is the same
> as PON btw.

Yep.

I've heard of a typical RON 4 higher than (R+M)/2. However - different
fuels will have different RON/MON spreads, so it's not a given that
it's going to be close to 4. Pure octane has an RON of 100 and a MON
of 100. So pure octane is 100 (R+M)/2.

y_p_w

2007-01-06, 8:29 pm

Solar Flare wrote:
> High compression needed it [higher octane] to reduce dieseling.

Or forced induction. Pretty much anything that increases the
fuel/air pressure in the cylinders would require higher octane fuel.

My 2004 WRX with a 2.0L turbo four engine has a compression
ratio of 8.0:1. It sounds low, but then you add the boost.

Steve

2007-01-06, 8:29 pm

y_p_w wrote:

> Solar Flare wrote:
>
>
>
> Or forced induction. Pretty much anything that increases the
> fuel/air pressure in the cylinders would require higher octane fuel.
>
> My 2004 WRX with a 2.0L turbo four engine has a compression
> ratio of 8.0:1. It sounds low, but then you add the boost.
>
7:1 isn't uncommon when boost is anticipated. And the other cool thing
about boosted engines is that they have cam profiles with very minimal
valve overlap so they generally idle as smooth as a Packard v12. Whereas
a normally aspirated engine with similar performance would have 10:1
compression and a wild cam that would lope at idle like a '67 426 Hemi.

Dan_Thomas_nospam@yahoo.com

2007-01-06, 8:29 pm

clare wrote:

> Right on Dan,
> So much misinformation flying around about Octane - good to see there
> are a few others who understand it. (Are you a Canuk? Member of RAA?
> Perhaps read my artical the other month?)

Canuck. Flight Instructor. Aircraft Maintenance Engineer.
Aircraft Systems instructor. Former member of EAA (1972-1992). Member
of COPA. Fly my Jodel D-11 when I have the time. Building a Hummelbird.
Should join RAA, but spend so much time working in aviation that by the
time I get home I don't want to read any more about it. Barely have
time for the H-Bird.

Dan

clare at snyder.on.ca

2007-01-06, 8:29 pm

On 4 Jan 2007 11:32:49 -0800, Dan_Thomas_nospam@yahoo.com wrote:

>
>clare wrote:
>
>
> Canuck. Flight Instructor. Aircraft Maintenance Engineer.
>Aircraft Systems instructor. Former member of EAA (1972-1992). Member
>of COPA. Fly my Jodel D-11 when I have the time. Building a Hummelbird.
>Should join RAA, but spend so much time working in aviation that by the
>time I get home I don't want to read any more about it. Barely have
>time for the H-Bird.
>
> Dan
Wherere you located?

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y_p_w

2007-01-06, 8:29 pm

Steve wrote:
> y_p_w wrote:
>
> 7:1 isn't uncommon when boost is anticipated. And the other cool thing
> about boosted engines is that they have cam profiles with very minimal
> valve overlap so they generally idle as smooth as a Packard v12. Whereas
> a normally aspirated engine with similar performance would have 10:1
> compression and a wild cam that would lope at idle like a '67 426 Hemi.

Well - mine is a horizontally opposed four, so I do feel a bit of
shake at idle. :-(

Dan_Thomas_nospam@yahoo.com

2007-01-06, 8:29 pm

clare wrote:
> On 4 Jan 2007 11:32:49 -0800, Dan_Thomas_nospam@yahoo.com wrote:
>
> Wherere you located?

Three Hills, Alberta.

Venus

2007-01-06, 8:29 pm

Dan,
You seemed to know what you're talking about. Me too I have seen what you
described, however there is a way to control the Detonation into a
controllable burn. And the trick is, I can't share until I get paid for my
research. The saving is huge.

Venus

<Dan_Thomas_nospam@yahoo.com> wrote in message
news:1167927330.475624.304180@v33g2000cwv.googlegroups.com...

Solar Flare wrote:
> OK the valves and seats had to be hardened to stop the "sticking"
> action of the valve due to less lubrication from the lead but not the
> higher temperature. My bad.
>
> However you stated that higher octane fuels do not burn slower and
> then proceded to say they do again. Most articles will agree that
> octane stops pinging by slowing down the detonation of the fuel under
> heat and presure. This is not faster and the chemical reason doesn't
> really matter, as it appears to support my statement and disagree with
> yours.

Mustn't confuse detonation with normal combustion. The fuel/air
mixture should burn across the chamber at about 100 feet per second.
Detonation is a different process and flame fronts can reach 5000 fps
or more. The enormous pressure spikes and abrupt release of heat does
plenty of damage.
Detonation happens when the complex fuel molecules, under the
rising pressure ahead of the flame front of normal combustion, begin to
break down into simpler structures that can autoignite; they don't wait
for the flame front to set them off in a normal chain reaction. The
whole works might go off at once just becuse they're being squeezed and
their temp is rising.
Detonation requires time for those molecules to break do