From: John De Armond
X-Source: The Hotrod Mailing list
Date: Apr 1992
Subject: Re: octane ratings

>I have acess to 135 octane fuel for $2.15 per gallon.  if I were to
>run this in my car (at the track only, of course) would it go to waste
>on a 10.5:1 compression ratio? or would it make any improvement over
>105 octane at all?

Thoroughly wasted.  You can gain some benefit with higher octane fuel
by advancing the timing.  However you quickly reach a point where
your gains are offset by the thermodynamic losses of compressing
already burning mix.  More compression is the way to go but even
there you have to be careful because lots of compression can sometimes
leave a chamber with so much squish that ignition is poor and turbulence
is actually impeded resulting in poor flame travel (low power).

BTW, what brand fuel is that?  Never see that hi octane before.
I'd like to get some and play with it.

John

From: emory!fraser.sfu.ca!jimd (Jim Davies)
X-Source: The Hotrod Mailing list
Date: Feb 1993
Subject: Re: Hot Rod Lincoln

hotrod@dixie.com (The Hotrod List) writes:


>-> On another issue: have found some info on high octane aviation gas,
>-> and its development and production in WW2. Would you believe octane
>-> ratings over 200 were available? Any interest in consuming bandwidth
>-> for this topic??

> How 'dey do 'dat?  Different rating system?
                                   
Octane=100, as we all know, so apperantly anything above 100 octane is a
--Performance Number-- or, PN. The PN scale was not introduced until 1943,
although a predecessor was in use by the British. The PN scale was
introduced after the US Army/Navy specified a fuel with a lean rating of
100 octane and a rich rating equal to octane plus 1 cc lead. This was
grade 100/125. The PN scale was developed because the military personnel
were confronted with the inability of making the brass understand that
you could not assign an octane number to isooctane plus 1cc lead. Service
personnel started to arbitrarily assigning octane numbers above 100, and
so marking fuel trucks.  Chaos reigned, as different fields labeled fuel
as 108 octane or any other number, causing pilots to refuse the lower
octane stuff as unsiutable. SNAFU, anyone? Anyway, the army/navy and the
brits got together and decided on th PN system, where isooctane=100,
giving 100% power in a supercharged engine, 130 PN giving 130% power, and
so on. PN numbers below 100 were evolved later, but never were used in
fuel specs. An example of lower PN is:  76PN=91 Octane

An interesting fact is that a water-cooled engine is often described
as mild, compared to an air-cooled engine, which is regarded as severe
in its octane, or PN demands *these are highly supercharged, high output
engines, of course* Anyhow, grade 115/145 avgas would effectively
be 145/145 in a mild engine, allowing around 40-45 psig manilfold
pressure, with intercooling, before detonation. Then, of course, there
was 150 PN fuel, which the brits used inpreference to Nitrous. Couldnt
catch a V-1 with a Spitfire using 100/130 gas, but fill it with 150 grade...
no problem :-) Further tinkering yielded 270PN fuel, which they never
were able to make detonate, although they busted lots of engines trying.
Allison used some of this stuff mixed with 100/130 to up the power on a
1710 from around 1500 HP to 2800 HP "for a short period" Bits were
coming out of engines, but not from detonation, they just werent strong
enough for the forces of normal combustion :-) Merlins put out 2200 HP
on about 45 psig manifold pressure, so the 1710 was getting about *SWAG mode*
say 65-70 psig at the intake valve.

Hope there are some fuel specialist type out there. Anyone?

Jim Davies

From: emory!sfu.ca!jimd (Jim Davies)
X-Source: The Hotrod Mailing list
Date: Feb 1993
Subject: Re: Hot Rod Lincoln

hotrod@dixie.com (The Hotrod List) writes:


>[very interesting fuel rating article deleted]

> Thanks!


>-> coming out of engines, but not from detonation, they just werent
>-> strong enough for the forces of normal combustion :-) Merlins put out
>-> 2200 HP on about 45 psig manifold pressure, so the 1710 was getting
>-> about *SWAG mode* say 65-70 psig at the intake valve.

> 1710 what?  1710 cubic inch?

> That doesn't sound like a whole lot of power for 50-55 pounds of boost.
          
Dont forget, the above was a guess, as the source didnt state the boost,
or the exact blend for the 2800hp-V1710 test. Something to keep in mind
is that IC engines dont scale up well, in other words, if you doubled the
size of an engine you wouldnt get double the HP. This assumes you are
doubling the displacement without increasing the number of cylinders.
Another thing to remember about these HP aircraft piston engines is that
even though they used all the latest types of design ideas eg Aluminum
blocks/heads, usually 4 valves/cylinder, OHCams, sodium cooled valves
(invented for A/C engines) turbos, superchargers, charge cooling etc.,
there duty cycle was similar to a boat or truck engine. In other words,
an engine rated at, say, 1500 HP would operate for hours ata time at a
large percentage of this rating, say, 1200 HP. Consider doing that in
your average car engine. 

Found some specs from Rolls-Royce re the merlin (V-1650) which might
be of interest:
merlin 66--2050 HP @ 25 lb. boost(dry) or, 1.24 hp/cu. in
merlin RM17SM--2200 HP @ 30 lb. boost(dry)
--max. endurance tested @ 36 lb. boost (wet)--2640 HP
they also endurance tested a few for 100 hrs @ 18 lbs boost
Note: all tests done at 3000 RPM, which is 3000 FPM piston speed,
or the same piston speed as a 302 Ford turning 6000 RPM. To put
it into a context we can understand, this would be equivelant to
testing a 302 at about 380 HP @ 6000 RPM for 100 hours. All this
military engine stuff was limited in HP output by detonation, and
few engines were at WOT at maximum HP ratings. Some could get 30-40%
increase in power if suitable fuel was available, simply by opening
the throttle more.

JD

From: emory!sfu.ca!jimd (Jim Davies)
X-Source: The Hotrod Mailing list
Date: Feb 1993
Subject: Re: Hot Rod Lincoln

hotrod@dixie.com (The Hotrod List) writes:


>emory!wal.hp.com!lupienj (John Lupien) writes:
>>Seems like I must have flipped a bit in the tens digit - 1650ci is 27
>>liters. The story in AutoWeek was about a wealthy German industrialist
>>who commissioned a "special" from Rolls Royce when his old Rolls was a
>>bit "too slow" - a fiberglass bodied, Merlin-engined monster that he
>>claim was too fast for the photo-radar to identify. The Rolls Royce
>>company indicated that performance of this special was "adequate".

>and to further confuse the issue, here's another data point:  the
>merlin was one of a family of engines.  there was a larger member, the
>37L griffin, and at least one smaller member, the kestrel.  it may have
>been about 17L.  i believe it was used in tanks.

Well, since you brought it up ... the Kestrel was first, had o one piece
block, and was too small, so was replaced by the merlin, which reverted to
a crankcase/blocks setup, aluminum, of course. The griffon was developed
during the war, although it was the same displacement as the Buzzard, 
which predated all of these other engines. All were aluminum V12s with
double cross-bolted mains, marine type rods, forged everything, shaft
drive OHC, 4 valves/cyl. Reading RRs development story about valves
is a rather interesting trip through steel metalurgical development,
with the sodium cooled valve being the final solution. The tank engine,
BTW, was called the meteor, and was a derated merlin, which put out
5-800 hp depending on vintage, etc. RR wound up more or less redesigning
all brit tank powertrains on the fly during the war as their tanks
were a classic example of british chunderheadedness. The merlin, of 
course, was built under licence by packard during the war. The original
deal was for ford to do it. but henry was getting pretty far out
of it by then and finally refused to do it.  The real interesting A/C
engines of war2 were the piston engines under development to replace
all the prewar stuff that was used. Sadly, the gas turbine ended interest
in them even though some were all ready to go. Short strokes, high revs
and lots of power. Then there was the RR Crecy- a V12, two stroke, sleeve
valve, stratified charge, direct injection drop in replacement for the 
merlin. Ricardo was pulling 360 HP out of a one cylinder development
engine on gas. 

JD

From: emory!sfu.ca!jimd (Jim Davies)
X-Source: The Hotrod Mailing list
Date: Mar 1993
Subject: octane ratings/performance numbers
X-Sequence: 4396

Further to the discussion on octane ratings and avgas performance
numbers, I have dug up some source material, so will attempt to
explain...
...PN knock rating system takes into account the following differences
between aircraft and automotive requirements.

1 In general, improvements in resistance to detonation are used to increase
inlet pressure rather than to increase compression ratios
2 At maximum power, aircraft engines are likely to use fuel-air ratios as
high as Fr=1.8** while in motor vehicles Fr** seldom exceeds 1.3
3 Many fuels available for aircraft have a resistance to knock greater than
that of isooctane

...PN determination methods differ from the methods used for motor fuels 
chiefly in that;
1 the engine is run at higher speed
2 the variable used to produce knock is inlet pressure, rather than
compression ratio
3 the complete useful range of fuel-air ratios are explored

note: the standard CFR test engine is used

**havent found the definition of Fr yet, but best guess is Fr=stoichiometric

Lean and rich performance numbers are determined from KLIMEP* as follows:

(100 x klimep) / klimep0     lean

and

(100 x klimep) / klimep0     rich

*KLIMEP --> knock limited indicated mean effective pressure, obtained
by varying the inlet pressure at constant compression ratio and inlet
pressure.

klimep0 --> is klimep for isooctane

In other words, PN is derived from, and based on isooctane as a
standard for detonation resistance. It is an AN standard, with
data derived from the standard CFR knock engine. Some examples
of the relationship between octane/PN are;

100 octane = 100 PN
95 octane = 85 PN
90 octane = 75 PN
            108 PN = isooctane plus .25cc TEL/gallon
            115 PN = isooctane plus .5cc TEL/gallon
NOTE: TEL appears to change knock ratings a great deal with some
fuel types, and much less with other things, such as benzol.

Jim Davies

From: emory!kcbbs.gen.nz!Steve_Baldwin (Steve Baldwin)
X-Source: The Hotrod Mailing list
Subject: Octane ratings
Date: 5 Feb 93 18:30:26 EST (Fri)

>[Must be some other system.  Both research and motor octane scales end at
>125.

Is that by definition or observation ?

[By definition, which I'm inclined to believe is based on observation.
The best book I've ever seen on the topic is "Automotive Fuels Handbook"
by Ownes and Coley.  Available from SAE.  In addition to about 700 pages
of fuel handbook, it is a venerable encyclopedia of references.  Each
chapter typically has a couple hundred references listed.  Book is pricey
at about $120 but well worth it for the fuel tinkerer.

The testing methods are ASTM D2699 for Research method and D2700 for
Motor method.  The methods differ in the "severity" of the test
environment.  Severity is generally defined as conditions conducive to
knock.  The spread between motor and research numbers (research is always
larger) is the "sensitivity" rating of the fuel.  High sensitivity
fuels are likely to knock prematurely when conditions differ markedly
from the test engine.  Since the research engine runs at 600 rpm
and the motor at 900, most any modern engine differs markedly :-)
That is why low sensitivity fuels are desired.  Example:  Toluene's
RON is 120 and MON is 109.  Xylene's RON is 118 and MON is 115.  Even
if an engine could normally run on toluene's MON of 109, xylene would be
a better fuel because it is less sensitive and thus less likely to knock.

The testing is done in a Waukesha patent test engine developed under
the supervision of the Cooperative Fuel Research (CFR) Committee in the 1930s.
It is a variable compression, variable timing, 3 carburator single
cylinder engine.  Testing is done by introducing the unknown into one
carburator and known references assumed to bracket the unknown in the others.
Each carb is switched in and the compression (research) or compression and
timing (motor) is adjusted to achieve the same indication on the "knockometer",
a knock sensor with an arbitrary 0-100 scale.  The Waukesha engine, also
known as the CFR engine is incapable of testing beyond 125 octane by
either method.

There has been much work done in areas like gas chromatography in an effort
to develop a test method that does not use this engine but yields the
same results.  Most have been unsuccessful.  Most, if not all gas blending
is still controlled by on-line CFR engines.  Foxboro makes a neat on-line
octane controller that consists of a small CFR-style engine and sufficient
electronics to generate a 4-20 ma (and presumably digital data) proportional
to octane.  Fills a full size instrument rack.
JGD]

My current bedtime reading says "A scale of 0 to 100 is devised by
assigning a value of 0 to n-heptane (a fuel prone to knock), and a value
of 100 to iso-octane (a fuel resistant to knock)."
It then babbles on a bit about British and American standards, etc.

[The fuels handbook, in the definitions section, says of octane, "Above
the level of 100, the octane rating is based on the number of milliliters
of TEL per gallon which is added to isooctane to give the same knock
intensity as the fuel under test."  There is a whole chapter on the effects
of TEL.  In a nutshell, TEL's effect is less, the higher quality the
base stock.  That is probably why the scale ends at 125.  Probably reaches
a plateau.  The table of octane ratings lists toluene's RON as 120 and
notest that benzine's rating is off-scale.  JGD]

The book is "Introduction to internal combustion engines" by Richard
Stone. Don't know why it's called an _introduction_, it's way over the
head of any mechanic I have ever met and it cost $100 for a bloody
paperback !!

[I have a book like that!  "Internal Combustion engine Fundimentals" by
Heywood.  Da bible.  JGD]

Steve.

'62 Fairlane 351W,C4,etc
'37 Ford 7Y original
'54 Ford Pop - Flathead V8 (P.E. target)
'64 wife - rough but not bad for age

From: emory!sfu.ca!jimd
X-Source: The Hotrod Mailing list
Date: Feb 1993
Subject: Re: Hot Rod Lincoln

In alt.hotrod you write:

>>Dont forget, the above was a guess, as the source didnt state the boost,
>>or the exact blend for the 2800hp-V1710 test. Something to keep in mind
>...
>>testing a 302 at about 380 HP @ 6000 RPM for 100 hours. All this
>>military engine stuff was limited in HP output by detonation, and
>>few engines were at WOT at maximum HP ratings. Some could get 30-40%
>>increase in power if suitable fuel was available, simply by opening
>>the throttle more.
>>
>>JD
>>Posted by: emory!sfu.ca!jimd (Jim Davies)

>Very interesting.  Any idea what the composition of that 270 PN fuel was?

this was triptane *trimethylbutane* plus 4cc TEL gives 270 PN rich, or, in
a liquid cooled engine 270/270 PN. In other words, a rich A/F mixture is
of no extra value in knock suppression in a *mild* engine.

[Fuels handbook lists triptane as RON 112, MON 101.  Elsewhere it is
rated as equal in octane to isooctane with 1.8 ml/gal TEL.  JGD]


Others of possible interest include:

octane *trimethylpentane* plus 1 cc TEL/US gallon gives 125 PN, which
sounds like the same number JGD mentioned.

octane plus 4 cc lead gives a grade 153/153

--there are only about 6 hydrocarbons known that will give a lean PN
of around 150 wth 4cc TEL

there were various 150 PN fuels. The brits made 100/130 into 100/150 by:
adding 2 to 2 1/2% methyl aniline, plus total TEL raised to 6 cc/ US gal.

US version of 100/150 used 100/130 plus 3% Xylidine

>Also, was the 145 PN fuel basically an aromatic base stock with lots of
>lead?

lean PN was important for cruise RANGE, especially in severe engines, therefor
the interest in raising this. This was a goal of the US navy, due to there
large numbers of air-cooled engines. They wanted grade 120/150 but settled
for 115/145 which went into production around VE day, and cost a large
price in 100/130 production- for every gallon of 115/145 produced, 100/130
production dropped 2 gallons, because only selected octanes could be used,
therefor, 100/130 could not be reblended into 115/145. TEL about 4cc/gallon.



Jim Davies

From: emory!sfu.ca!jimd (Jim Davies)
X-Source: The Hotrod Mailing list
Date: Feb 1993
Subject: Re: Hot Rod Lincoln

Regarding octane ratings of TRIPTANE:
John, your ratings numbers sound like original research octane numbers
for this stuff. Apperantly there was some early controversy about the
value of this product. A rough and ready account:

Lovell (from NACA, predecessor of NASA) finds triptane to be better than
isooctane, *a great deal better*

Later tests using a different test engine/operating conditions *undefined*
show triptane to be only slightly better than isooctane

In 1938, a quantity of triptane sufficient to test in a supercharged
engine *of laboratory type* was produced and tested by the ethyl corp.--
this gave the same answer as Lovell "from this time triptane was regarded as
the last word in high PN aviation fuel"

In 1941, an army test found triptane, without TEL to have a PN of 100/165, in
other words, equal to isooctane (lean) and much better rich. The view was that
it was "the best hydrocarbon for an aviation fuel that had been seen to that
date"

Later tests by Curtiss-Wright confirmed this test

Subsequent to this, GM (research laboratories div.) built and operated
a 150 gal. per day triptane plant from '43 to '45, this product going
to an army sponsored but NACA run program. "as a whole fuel, triptane
plus 4cc TEL was explored in single cylinders of various aircraft
engines but none had sufficient mechanical strength to produce knock on
this fuel without wrecking the cylinder.  In fact, very few lab engines
used for fuel evaluation were strong enough to permit triptane plus 4cc
TEL to be appraised. NACA, however, carried out a very complete
evaluation of triptane in blends with 100/130....The NACA tests showed
triptane to have the highest effective PN of any then known possible
hydrocarbon component of aviation fuels."

Some other info on knock testing:
The method developed was initially known as the ASTM C3 method, later
the number was changed to F4. This used a supercharged CFR engine, supplied
by Waukesha. This was based on a "long established technique used for
motor (car) fuels" BTW. isooctane plus 1cc TEL gives 125 octane fuel.
Wasnt this the upper octane limit you mentioned? Can you repeat the
name etc. of your source, I didnt get it the first time. Maybe I can
find a copy, locally.

Jim Davies

[The book is "Automotive Fuels Handbook" by Owen and Coley.  From the SAE
press.  Very expensive (>$100).

The triptane thread is very interesting.  This jives with a conversation I
had with a chemist affiliated with BP.  I asked him what was in the
Formula 1 "wundergas".  He didn't know for sure but he suspected it to be
a mix of a heavy aromatic to get the heating value up, triptane and lots
of TEL to get the octane and flame propagation enhancers (proprietary
compounds) to make the stuff burn fast enough to let the engines turn
the RPM they do.  He said he was positive, based on the smell, that a lot
of triptane was involved.  Now to find a source......  JGD]

From: emory!sfu.ca!jimd (Jim Davies)
X-Source: The Hotrod Mailing list
Date: Feb 1993
Subject: Re: Hot Rod Lincoln

hotrod@dixie.com (The Hotrod List) writes:

>The triptane thread is very interesting.  This jives with a conversation I
>had with a chemist affiliated with BP.  I asked him what was in the
>Formula 1 "wundergas".  He didn't know for sure but he suspected it to be
>a mix of a heavy aromatic to get the heating value up, triptane and lots
>of TEL to get the octane and flame propagation enhancers (proprietary
>compounds) to make the stuff burn fast enough to let the engines turn
>the RPM they do.  He said he was positive, based on the smell, that a lot
>of triptane was involved.  Now to find a source......  JGD]
>----------

Re: triptane sources, some trivia
prewar price--$30.00/gallon
supplied by Dow Chemical, using a synthesis method evolved by the Ethyl
Corp. and reqiuring 2 lbs of magnesium for each gallon of triptane

GMs plant used a different process, not requiring magnesium

NACAs triptane evaluation papers are probably still available through
the usual sources.

triptane is a paraffin
two objections to triptane: relatively high freezing point, curable by
blending with about 15% isopentane, such blending being necessary in any
case to obtain the volatility required...other objection being the cost,
circa '45, "several dollars" a gallon, together with equally large
manpower requirements, and, the "entire US production of chlorine"

The Allies consumed 19 Billion US gallons of 100/130 avgas in war2

trivia question for today: how much water can a IC gas engine ingest
before in ceases to run?

[Lots.  To the point the exhaust looks like a steam locomotive, as
several unfortunate 'Vette and Porch drivers have gotten to see
while following my Z :-)  With too much water, the engine starts feeling
soggy :-) before it actually stops running.  JGD]

JD

From: emory!helix.nih.gov!ijames
X-Source: The Hotrod Mailing list
Date: Feb 1993
Subject: Re: More Octane Stuff

Jim Davies posted (along with other extremely interesting stuff):

Regarding octane ratings of TRIPTANE:

In 1941, an army test found triptane, without TEL to have a PN of 100/165,
in other words, equal to isooctane (lean) and much better rich. The view
was that it was "the best hydrocarbon for an aviation fuel that had been
seen to that date", and isooctane + 1 cc TEL has a PN of 125.
>

Earlier, someone (JGD, I think) posted octane ratings for toluene and
xylene, and make the point that the smaller the difference between MON and
RON the lower the sensitivity to changes in operating conditions.  Is there
any simple correlation between MON/RON and the lean/rich PN's?  Also,
xylene was about 120 octane without any TEL, so wouldn't it take less TEL
to make 100/130 (say) aviation fuel from xylene (or a mixed aromatic  base
stock) than from isooctane and other aliphatic hydrocarbons?  Also,
wouldn't this be a better starting point for the /150 fuel, or does a given
amount of TEL not raise the octane (or PN) of xylene as much as it does
isooctane?

[I don't think there is any relationship between the ratings.  The octane
scale is nominally based on n-heptane having a value of 0 and iso-octane
having a value of 100 under a given set of conditions.  Problem is, these
conditions are entirely arbitrary.  The effect of TEL is not constant.
It has less effect on high quality base stock.  There are a series of
charts on pages 95-98 of the fuels handbook on the effects of TEL.
All the curves are leveling off at about 0.8 gm/L.  From the chart,
a naptha base has an octane rating of about 72 without TEL.  One gm/L
boosts the rating to about 87 or 15 points.  A catalytic reformate base
has a rating of about 97 without TEL and only 103 with it, or only
6 points increase.  These are all RONs.  JGD]

On another subject, about 6 years ago Pop Hot Rodding tested octane
boosters and recommended SoCal octane booster.  This was an 8 oz bottle
which would treat 60 gallons of gas (or 30, if you doubled the
concentration for even more octane), raising the octane about 2 points.  I
recall them starting with 92 octane and getting 94 or 95, adding the double
dose.  We analyzed some for fun, and it turned out to be red dye, an
aromatic solvent mixture, and a white waxy solid (whose name is in my notes
at home, not here at the lab, but was a bicyclic, branched hydrocarbon).
Did anyone ever use this stuff, what were your impressions, and why don't I
see it advertised anymore?  Would a small amount of paraffin, either this
stuff or triptane, in fuel, be a problem clogging fuel injectors?

Thanks for all the info; the discussions here are great.

Carl Ijames     ijames@helix.nih.gov

From: emory!sfu.ca!jimd (Jim Davies)
X-Source: The Hotrod Mailing list
Date: Feb 1993
Subject: Re: Hot Rod Lincoln

>trivia question for today: how much water can a IC gas engine ingest
>before in ceases to run?

>[Lots.  To the point the exhaust looks like a steam locomotive, as
>several unfortunate 'Vette and Porch drivers have gotten to see
>while following my Z :-)  With too much water, the engine starts feeling
>soggy :-) before it actually stops running.  JGD]

Well, heck, thats close enough ;-) The answer, according to Pratt&Wwhitney,
is that an engine will take two gallons of water for every gallon of fuel,
before firing ceases. BTW, apperantle H20/wood alky is USUALLY better
than H20/grain alky for injection, although *certain chemicals* are
considerably better than either alchohol. *sigh* another sleuthing job!
Although nitrous was used by all combatants in war2, before becoming
obsolete  in '44, the allies preferred either/or high octane fuel or
water injection.
JD

[2:1 sounds about right.  I've never sat down and figured what the ratio
works out to on my Z motor.  I do know the 2.5 gal tank seems to last
only minutes.  I use 50-50 methanol and water most of the time.  I've
actually not seen that much, if any difference between pure water and
the mix but the mix doesn't freeze.

Another very effective knock control scheme is to inject pure toluene
or xylene through aux injectors when needed.  Pure toluene or xylene
sucks as a carburated fuel because it has a high, single vapor pressure.
Not terrible but still not real hot with PFI.  When combined with premium
gasoline, it works great.

I've not yet tried a combination of water and toluene.  Could be  interesting.
JGD]

Subject: Re: Octane Booster
From: edh@wheeler.unr.edu (Ed Hackett)
Date: Aug 22 1995
Newsgroups: rec.motorcycles

In article <415636$ld6@mozo.cc.purdue.edu> feiereis@widget.ecn.purdue.edu
(John M Feiereisen) writes:

>In article <413o6v$3gam@news-s02.ny.us.ibm.net> mestier@ibm.net writes:
>
>>Toluene paint thinner is one major component of octane boosters due to
>>its high octane (about 110 or so) as reported in cage mags of the '80s.
>>You can buy it cheaply at paint supply houses and it works about as good
>>as "108" stuff at 1/10 the cost or less. I was able to use 1+ bar boost
>>pressure with about 10% toluene in the olde turbo cage days but for
>>cycle use about 4 oz per US gal in 87 octane gas should get you close to
>>the '90s. Perhaps John F. or somebody who knows can clarify the exact
>>stoichiometry involved.
>
>As far as mixing to achieve a target octane rating:  you got me.
>I don't know if equal parts of 108 and 92 fuels will give you a 100.
>I'd suspect it's close, but I have no idea if it's exact (i.e. do
>they mix linearly?).

Here's some fuel formulas that I pulled from the Alfa list a
while back.  I've long lost the original author, but he is
correct in his calculations.  The only place I would disagree
is with the MTBE causing the fuel to release more energy.
Anybody forced to run this stuff in the winter months, as I
do, sees a drop in milage corresponding to the drop in energy
content.

Note the part about the 12-16 oz bottles of octane boost
raising the octane number by just several _points_.  An octane
boost that promises to raise the octane by 8 points gets
exactly that. It raises the octane of 92 to 92.8 (which in
borderline cases of knocking is enough to make a difference).

Formula #1 - Toluene
=============================
R+M/2.........114
Cost...........$2.50/gal

Mixtures with 92 Octane Premium
--------------------------------
10%...........94.2 Octane
20%...........96.4 Octane
30%...........98.6 Octane

Notes: Common ingredient in Octane Boosters in a can.  12-16 ounces will only
raise octane 2-3 *points*, i.e. from 92 to 92.3.  Often costs $3-5 for 12-16
ounces, when it can be purchased for less than $3/gal at chemical supply houses
or paint stores.

Formula #2 - Xylene
=============================
R+M/2.........117
Cost...........$2.75/gal

Mixtures with 92 Octane Premium
--------------------------------
10%...........94.5 Octane
20%...........97.0 Octane
30%...........99.5 Octane

Notes: Similar to Toluene.  12-16 ounces will only raise octane 2-3 *points*,
i.e. from 92 to 92.3.  Usually mixed with Toluene and advertised as *race
formula*.

Formula #3 - Methyl-tertiary-butyl-ether (MTBE)
=============================
R+M/2.........118
Cost...........$3.50/gal

Mixtures with 92 Octane Premium
--------------------------------
10%...........94.6 Octane
20%...........97.2 Octane
30%...........99.8 Octane

Notes: Oxygenate.  Very common in octane booster products.  Has lower BTU
content than toluene or xylene, but oxygenate effect makes the gasoline burn
better and produce more energy.

Formula #4 - Methanol or Ethanol
=============================
R+M/2.........101
Cost...........$0.60 - $1.75/gal

Mixtures with 92 Octane Premium
--------------------------------
10%...........94.3 Octane (Methanol)
10%...........94.7 Octane (Ethanol)
20%...........Not Recommended

Notes: Methanol is wood alcohol.  Ethanol is grain alcohol and found in Gasohol
in 10% ratios.  Both alcohols are mildly corrosive and will eat gas tank
linings, rubber and aluminum if used in excessive ratios.  Main ingredient in
"Gas Dryers", combine with water.

Formula #5 - Isopropyl Alcohol and Tertiary Butyl Alcohol
=============================
R+M/2.........101
Cost...........$0.60-$1.50/gal

Mixtures with 92 Octane Premium
--------------------------------
10%...........94.5 Octane
20%...........Not Recommended
30%...........Not Recommended

Notes: Similar to Methanol/Ethanol.  Isopropyl Alcohol is simply rubbing
alcohol.

How to make your own octane booster (this is the basic formula of one of the
popular octane booster products).  To make eight 16 ounce bottles (128 oz = 1
gal):

100 oz of toluene for octane boost
 25 oz of mineral spirits (cleaning agent)
  3 oz of transmission fluid (lubricating agent)

This product is advertised as "octane booster with cleaning agent *and*
lubricating agent!".  Diesel fuel or kerosene can be substituted for mineral
spirits and light turbine oil can be substituted for transmission fluid.  Color
can be added with petroleum dyes.

P.S.  In order for a fuel injected engine to take advantage ot
high octane fuel it must have a knock sensor.  Knock sensors
are the exception, rather than the rule.  BMW motorcycles do
not have knock sensors.

 Ed Hackett   edh@maxey.dri.edu           The Desert Research Institute 
 DoD #0200  WMTC  BMWRA  DIOC             Reno, Nevada   (702) 673-7380   
 KotLS  KotLE  DotD #0003            I'm not really a chemist, I'm just one of
 BMW K100RS, Moto Morini Camel       them motorsickle sonsabitches.  __=o&o>__

From: dheister@magnus.acs.ohio-state.edu (David J Heisterberg)
Newsgroups: rec.autos.tech
Subject: Re: Efficiency Gas vs Diesel
Date: 15 Dec 1995 17:08:31 GMT

In article <EENG01-1512950709140001@145.2.120.41>,
Dan Dusing <EENG01@email.mot.com> wrote:
>Better go back and do your home work. I believe another poster explained
>about the energy present in a gallon of diesel vs gasoline. As far as flooring

Just so people don't start conjuring up theories about octane rating
versus energy content, there's a real simple reason why diesel fuel
has more energy per gallon -- it's denser.  Alkanes, the saturated
hydrocarbons that are the main component of gasoline and diesel, are
all pretty close to 11kcal/g, but as you get to the heavier alkanes,
the bulk liquid or solid gets denser, so you get more grams per gallon.

Dave Heisterberg

Newsgroups: sci.environment,sci.energy,alt.energy.renewable
Subject: Re: Ethanol and Gasoline
From: B.Hamilton@irl.cri.nz (Bruce Hamilton)
Date: Sun, 25 May 1997 18:14:17 GMT

ijames@netaxs.com (Carl Ijames) wrote:

> Bruce Hamilton <B.Hamilton@irl.cri.nz> wrote:

>>                                Methanol       Ethanol     Unleaded Gasoline
>>RON                               106            107           92 - 98
>>MON                                92             89           80 - 90
...
>>Published octane values vary a lot because the rating conditions are
>>significantly different to standard conditions, for example the API Project
>>45 numbers used above for the hydrocarbons, reported in 1957, gave MTBE
>>blending RON as 148 and MON as 146, however that was partly based on the
>>lead response, whereas today we use MTBE in place of lead.
>>                                      RON   MON    BP      d     AIT
>>        methanol                      133 : 105 :  65  : 0.796 : 385
>>        ethanol                       129 : 102 :  78  : 0.794 : 365

>Is this why these numbers are so different?  Are these blending octanes,
>and the above the octanes when used as a pure fuel?

Yes. I should have retained the following, but I cut it ( and a lot
more :-) ) to keep the post a tolerable length.

 The technique for obtaining Blending Octanes is different from rating the
 pure fuel, which often requires adjustment of the test engine conditions
 outside the acceptable limits of the rating methods. Generally, the actual
 octanes of the pure fuel are similar for the alkanes, but are up to 30
 octane numbers lower than the API Project 45 Blending Octanes for the
 aromatics and olefins [52].

The ASTM has recently issued guidelines for octane rating of
non-hydrocarbons. The issue is complicated by the fact that
methanol azeotropes with some of the hydrocarbons making the
fuel more volatile, and thus increasing the octane. The alcohols
have stoichiometric combustion conditions so far away from the
limits of the octane rating test that reported octane numbers
can vary very widely because of the changed conditions.

Note that as a blending agent, alcohols can have quite high sensitivity
( difference between RON and MON ) which can cause problems
if substituting them for alkyl leads, which tend to only have
a sensitivity of 5-7 in most common gasolines. This has meant
that many leaded fuel had what was known as "MON Giveaway"
in that most engines were designed for a sensitivity of around 10.
As unleaded fuels have replaced leaded fuels, most nations have
gradually moved the MON limit back to about 10 below RON.

In general, when using alcohol blends as substitutes for fossil
fuels, most engines have such low compression ratios that they
can't take advantage of any higher octane. When formulated into
oxygenated fuels ( ethanol - methanol is prohibited in US ) the
hydrocarbon fraction is modified to ensure octane distribution
is spread over the whole boiling range of the fuel, and when
possible, and octane giveaway is minimised - even oil companies
don't like giving things away :-).

      Bruce Hamilton