91 Octane vs. 87(recommended in manual)
Vjcvjc
If I use 91 octane even though the manual recommends 87; am I ruining
anything in my 96 SL2 ? Is the 96 SL2 tuned for 87 octane or whatever?
(I know that lower than 87 is harmful;
but, when you go to higher elevations even 85 is acceptable because of
less O2 in the atmosphere or less pressure; but, is 91 "harmful" in ANY
way at all?)
Thanks so much.
Victor
Hosmann95
The biggest harm running 91 octane gas will do is to your wallet. If your
car doesn't knock on "regular" unleaded, you gain nothing by putting in
"premium" gas. This nomenclature is misleading. Higher octane is not a
rating of a gasoline's quality, it's a measure of it's volatility.
I recently read that a lot of gas companies were asked by the FTC to stop
misleading ads which claimed that their premium gas increases the power
output of engines. This is entirely untrue unless your car requires
premium.
Dean
In article <19970108233...@ladder01.news.aol.com>, vjc...@aol.com (Vjcvjc) wrote:
>If I use 91 octane even though the manual recommends 87; am I ruining
>anything in my 96 SL2 ? Is the 96 SL2 tuned for 87 octane or whatever?
>
>(I know that lower than 87 is harmful;
>but, when you go to higher elevations even 85 is acceptable because of
>less O2 in the atmosphere or less pressure; but, is 91 "harmful" in ANY
I don't think it's harmful but it makes my car run worse. The cheapest gas I
can find makes my car run good but in my wifes S-10 she needs the best.
Whatever you like. The additives in the higher octane will keep the engine
cleaner.
Dean
Wavy Caver
However - volatility is a function of vaporization which *can* translate
to better combustion and more power.
If you have an engine that "pings", you probably need higher octane.
Both my Harleys will ping badly during accelleration if they do not get
thier recommended 92 or 93 octane.
Carberated engines seem to benefit more from higher octane gasolines
then do fuel-injected ones.
The Saturn manual recommends 87 octane. This is what the engine
computer expects to be using. Other than 87 octane in a Saturn will
result in an engine running on fuel which is different than what the
system is optimized to use.
Karl Brace
Dean wrote:
> The additives in the higher octane will keep the engine cleaner.
This was briefly true, but no longer. When fuel injection was
new and only more expensive cars had it, fuel companies figured
out that they could get these richer consumers to pay more for
fuel by only putting the detergents that fuel injectors need in
the higher octane (higher profit margin) fuel. But after BMW
(I think) started testing major fuel brands and grades for
their ability to keep injectors and such clean, and publishing
the results, many major brands began adding the detergents to
all grades. Those that didn't got bad press in the major
consumer and auto magazines, lost business, and soon everyone
was putting all necessary detergents (necessary to pass BMWs
test, at least) in all grades. This has been true for at least
5 years now.
Fuel companies still WANT YOU TO BELIEVE that you are doing your
car a favor by buying a higher grade, and some imply this in
their ads, but that's marketing, not science.
Karl
David Hanley
Mark Champine wrote:
>
> I have a 93 Saturn SL. It knocks badly with 87, less so, with 89, and
> runs well on 92. I hate paying the higher gas prices though. Am I
> just stuck with a finicky engine, or could this be fixed by a tuneup?
> (I just got the car so I don't know if this is a new problem).
The timing is probably retarded. This shouldn't be too hard to fix.
--
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of them
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Steven Kan
VAL N TIM wrote:
[snip]
> Also note that there is a normal ping that lasts several
> seconds on heavy accel or when engine is under a load. Basically you've
> caught the pcm by suprise and has to adjust the timing. there is no
> correction for this and Saturn considers it normal operation.
I'm curious about this because Saturn told me the same thing. But I've
driven a lot of other 4-bangers that don't do this. It this unique to
their design? It bugs me that my car pings even when nothing's wrong.
Thanks!
--
My Saturn's a car I'm more fonda #```````
Than Toyota, Nissan or Honda. # ```````
For driver enjoyment, # ```````
And U.S. employment, # ```````
It sure beats cars made over yonda! #. ```````
~ ~ . \_@_/ ```````
^_@ o . V ```````
Steven "Rocket Man" Kan `-' - \_@_ ~ . ######
Stanford GSB V \ ~ . ######
mailto:ste...@leland.stanford.edu ~ . #H2O##
http://www-leland.stanford.edu/~stevenk ~ .#POLO#
"Never refuse a breath mint." ~ ~ ~ ######
Eric J. Simpson
Hosmann95 wrote:
>
> The biggest harm running 91 octane gas will do is to your wallet. If your
> car doesn't knock on "regular" unleaded, you gain nothing by putting in
> "premium" gas. This nomenclature is misleading. Higher octane is not a
> rating of a gasoline's quality, it's a measure of it's volatility.
>
> I recently read that a lot of gas companies were asked by the FTC to stop
> misleading ads which claimed that their premium gas increases the power
> output of engines. This is entirely untrue unless your car requires
> premium.
It depends on the type of engine management system that is in place.
Some cars will indeed be more powerful with premium fuel. Allow me to
explain: There are knock sensors on all modern day fuel injected
automobile engines. The difference is in the management of the sensors.
Type 1 cars will advance the ignition (a timing issue) until it senses
knock, and then retard ignition a tad. Advancing the ignition timing
increases the horsepower output of the engine, especially at higher
engine speeds. A type 1 car will benefit from the premium fuel.
A type 2 engine has a set ignition timing schedule. If it detects
knocks (ping, or detonation, in other speak) it will retard the ignition
until it no longer senses it. In these types of engines there is no
benefit to using higher octane fuels.
I happen to know that the DOHC Saturn is a type 1 vehicle (don't ask me
my exact source, it has been a while since I was that deep into it.
I've owned 2 SC2s, though, and am confident that I'm correct). So the
upscale saturn models will have a slightly higher top end w/ premium
fuel. Add a super synthetic motor oil, like Mobil-1 5W30, and you'll be
bumping the top speed limiter in the (pre '97) SC2 in no time (127
mph)!!!
(I don't expect that the '97 model will be as fast as the '91 - '96
line)
Another car that is noticeably more powerful w/ premium fuel is the
newer Civic EX model.
I encourage all of you guys to subscribe to an informative automotive
magazine like Motor Trend for both technical and not so technical
edutainment.
Happy Trails!
Norm Dang
Vjcvjc wrote:
>... but, is 91 "harmful" in ANYway at all?)..
The answer is "it depends". Two problems can occur.
In very cold weather, 91+ octane does not vapourize as easily as 87. If
your fuel injectors are not in good condition, this will cause a
no-start condition/flooding. In extreme cases, the only solution is to
drain the tank and refill with 87. This is why I think there were all
those "no-start/dealer drained tank" postings last winter during a bad
cold snap.
The second problem is the possibility of deposits. Some states (and
Canada) allow the use of an additive called MMT to increase octane. MMT
forms deposits. These deposits can screw up the emissions sensors as
well as cause other problems.
On the plus side, a lot of computers (when equipped with a knock sensor)
can understand high octane. There was a post here last year which
someone indicated that they had talked to a Saturn engineer who said
that the Saturn computer can understand up to 91 octane. The computer
uses a more aggressive ingnition advance. You probably gain about 3-7 hp
(5%).
Hope that helps, Norm
Mark Champine
Dean wrote:
>
> In article <19970108233...@ladder01.news.aol.com>, vjc...@aol.com (Vjcvjc) wrote:
> >If I use 91 octane even though the manual recommends 87; am I ruining
> >anything in my 96 SL2 ? Is the 96 SL2 tuned for 87 octane or whatever?
> >
> >(I know that lower than 87 is harmful;
> >but, when you go to higher elevations even 85 is acceptable because of
> >less O2 in the atmosphere or less pressure; but, is 91 "harmful" in ANY
>
> I don't think it's harmful but it makes my car run worse. The cheapest gas I
> can find makes my car run good but in my wifes S-10 she needs the best.
> cleaner.
>
> Dean
I have a 93 Saturn SL. It knocks badly with 87, less so, with 89, and
runs well on 92. I hate paying the higher gas prices though. Am I
just stuck with a finicky engine, or could this be fixed by a tuneup?
(I just got the car so I don't know if this is a new problem).
Anyone else find they *need* to use high octane in their Saturns to
avoid pinging??
Thanks,
M.
Chris Mauritz
Mark Champine <cham...@apollo.hp.com> is rumoured to have written:
:) Dean wrote:
:) >
:) > In article <19970108233...@ladder01.news.aol.com>, vjc...@aol.com (Vjcvjc) wrote:
:) > >If I use 91 octane even though the manual recommends 87; am I ruining
:) > >anything in my 96 SL2 ? Is the 96 SL2 tuned for 87 octane or whatever?
:) > >
:) > >(I know that lower than 87 is harmful;
:) > >but, when you go to higher elevations even 85 is acceptable because of
:) > >less O2 in the atmosphere or less pressure; but, is 91 "harmful" in ANY
:) >
:) > I don't think it's harmful but it makes my car run worse. The cheapest gas I
:) > can find makes my car run good but in my wifes S-10 she needs the best.
:) > Whatever you like. The additives in the higher octane will keep the engine
:) > cleaner.
:) >
:) > Dean
:) I have a 93 Saturn SL. It knocks badly with 87, less so, with 89, and
:) runs well on 92. I hate paying the higher gas prices though. Am I
:) just stuck with a finicky engine, or could this be fixed by a tuneup?
:) (I just got the car so I don't know if this is a new problem).
:) Anyone else find they *need* to use high octane in their Saturns to
:) avoid pinging??
If I'm not mistaken, the computer in the Saturn has the capability
to "learn" what kind of gas you prefer and based on the input from
the knock sensors it advances or retards the timing accordingly.
Any comment from Saturn techs?
Chris
--
Christopher Mauritz | For info on internet access:
ri...@interactive.net | finger/mail in...@interactive.net OR
IBS Interactive, Inc. | http://www.interactive.net/
VAL N TIM
Mark wrote: am i ruining my engine running 92 octane?
The answer is no, you are not ruining your engine but your also not
getting all performance your car should have. The reason being is that the
car was originally designed to run on 87 octane from the start. It also
has a knock sensor to retard or advance the timing as needed(engines get
the best performance/mileage when the timing is set as high as possible
without knocking/pinging). Saturn also says that if the engine suffers
from constant ping it's okay to go up to 89 octane without causing undue
performance loss. Also note that there is a normal ping that lasts several
seconds on heavy accel or when engine is under a load. Basically you've
caught the pcm by suprise and has to adjust the timing. there is no
correction for this and Saturn considers it normal operation.
Tim Ashton
Hosmann95
--I happen to know that the DOHC Saturn is a type 1 vehicle (don't ask me
--my exact source, it has been a while since I was that deep into it.
--I've owned 2 SC2s, though, and am confident that I'm correct). So the
--upscale saturn models will have a slightly higher top end w/ premium
--fuel. Add a super synthetic motor oil, like Mobil-1 5W30, and you'll be
--bumping the top speed limiter in the (pre '97) SC2 in no time (127
--mph)!!!
This is true, the Saturn uses a knock sensor, but since it is designed to
run on 87 octane, it will not "advance" the timing in response to higher
octane fuel to give you more power. Premium gas does not contain more
energy than "regular" gas. Thus, you will NOT get more performance from
92 octane. I used to own one of the new Camaro Z28s with the LT1 350.
This high compression engine was designed to run on 92 octane (recommended
in the owner's manual). However, if you put 87 in, the knock sensor would
retard the timing to protect the motor, and cost about 30 horsepower in
exchange. The owner's manual said it was ok, but not recommended for best
performance.
However, this doesn't work in reverse for an engine designed for 87. The
computer won't advance the timing beyond it's normal setting to see how
far it can go before knock occurs.
Eric J. Simpson
Amen! Amen! Amen! Amen! Thank you norm! I love you (in that car-guy
way)!!!!
-EJS
Eric J. Simpson
Your Camaro may not have, but some engines do advance the ignition
timing until knock is sensed (like I said earlier) and then retard the
timing back just below the knock point to optimize performance.
It is more than an issue of compression. The Z28 is a relatively
low-tech design that gets its horsepower from cubic inches. It also
makes its horse-power at a relatively lower engine speed (not to mention
that the type 2 sensor is a simpler matter for the computer to manage).
Smaller engines must exploit other methods of power production and a
creaive ignition timing algorithm is a step in this direction.
Your Camaro obviously had a "type 2" engine management algorithm.
The "type 1" engine management system will optimize the engine
performance and indeed modify the timing to fit the fuel/engine
condition.
Saturn wisely recommends regular (87 octane) fuel for their vehicles
because it is good business: #1) The DOHC doesnt HAVE to have premium
fuel and #2) it gives an "inexpenive to operate" image.
You are 100% correct in that premium fuel contains no more energy than
regular. The engine can (through timing management) perform better with
the premium stuff, though.
Peace.
Hosmann95
In regard to the supposed fuel injector cleaner in premium fuel. It will
be a lot cheaper to run a $5 bottle of fuel injector cleaner with a tank
of gas every few months than pay $.30 a gallon more every time you fill up
(lets see... 10 gallons * $.30 * three months of driving...).
An article in one of the car magazines (I think it was Car and Driver)
said that higher octane gas really doesn't cost any more to manufacture
than regular gas. Thus, the extra money is either profit margin or goes
to pay for all the extra advertising the oil companies do to get you to
buy the stuff.
Dr. Frank N. Furter
On 11 Jan 1997 09:02:12 GMT, hosm...@aol.com (Hosmann95) wrote:
>--I happen to know that the DOHC Saturn is a type 1 vehicle (don't ask me
>--my exact source, it has been a while since I was that deep into it.
>--I've owned 2 SC2s, though, and am confident that I'm correct). So the
>--upscale saturn models will have a slightly higher top end w/ premium
>--fuel. Add a super synthetic motor oil, like Mobil-1 5W30, and you'll be
>--bumping the top speed limiter in the (pre '97) SC2 in no time (127
>--mph)!!!
>
>This is true, the Saturn uses a knock sensor, but since it is designed to
>run on 87 octane, it will not "advance" the timing in response to higher
>octane fuel to give you more power. Premium gas does not contain more
>energy than "regular" gas. Thus, you will NOT get more performance from
>92 octane.
-snip-
This is true if you have a "running" vehicle and just plug in 92, but
if you take that same car, remove the battery for 20 minutes and then
place the battery back on, the car will be in "learn" mode. It'll
learn the 92 octane and run (well) with it. Although it may ping if
you go back with out resetting the computer.
BTW, This is just MO!!!
Steven Kan
Dr. Frank N. Furter wrote:
> -snip-
> This is true if you have a "running" vehicle and just plug in 92, but
> if you take that same car, remove the battery for 20 minutes and then
> place the battery back on, the car will be in "learn" mode. It'll
> learn the 92 octane and run (well) with it. Although it may ping if
> you go back with out resetting the computer.
>
> BTW, This is just MO!!!
Has anyone tried this? I'd be curious to see data.
potter
Mark Champine wrote:
> I have a 93 Saturn SL. It knocks badly with 87, less so, with 89, and
>
>
> Thanks,
>
> M.
In SoCal, my 96 SL2 runs good on 87 (some initial knock on hard accel
on hot days until the sensor quickly adjusts). However with ARCO and
sometimes
MOBIL it asks for 89 (no knocking at all under any conditions).
I believe if your engine pings badly for more than a full second at a
time
your ignition knock sensor may be faulty, and you also have to wonder
because it should never ping at all with 89.
What brand of gas do you use?
Where do you live?
-eric p.
Eric J. Simpson
Dr. Frank N. Furter wrote:
>
>
> >--I happen to know that the DOHC Saturn is a type 1 vehicle (don't ask me
> >--my exact source, it has been a while since I was that deep into it.
> >--I've owned 2 SC2s, though, and am confident that I'm correct). So the
> >--upscale saturn models will have a slightly higher top end w/ premium
> >--fuel. Add a super synthetic motor oil, like Mobil-1 5W30, and you'll be
> >--bumping the top speed limiter in the (pre '97) SC2 in no time (127
> >--mph)!!!
> >
> >This is true, the Saturn uses a knock sensor, but since it is designed to
> >run on 87 octane, it will not "advance" the timing in response to higher
> >octane fuel to give you more power. Premium gas does not contain more
> >energy than "regular" gas. Thus, you will NOT get more performance from
> >92 octane.
> This is true if you have a "running" vehicle and just plug in 92, but
> if you take that same car, remove the battery for 20 minutes and then
> place the battery back on, the car will be in "learn" mode. It'll
> learn the 92 octane and run (well) with it. Although it may ping if
> you go back with out resetting the computer.
>
> BTW, This is just MO!!!
Hmmm, interesting! I'll do a bit-O-research....
Thomas Wynsen
If your car knocking then put in a higer octane, if not leave it alone, you'll just be wasting money.
Ron Todaro
Steven Kan wrote:
>
> VAL N TIM wrote:
> [snip]
> > seconds on heavy accel or when engine is under a load. Basically you've
> > caught the pcm by suprise and has to adjust the timing. there is no
> > correction for this and Saturn considers it normal operation.
>
> driven a lot of other 4-bangers that don't do this. It this unique to
> their design? It bugs me that my car pings even when nothing's wrong.
>
I recently brought my 92 SL1 in for the same problem. They removed
carbon
from the pistons and head with top cylinder cleaner. That relieved the
problem
(at least temporarily). However, I agree that the pinging should not be
considered "normal". You can do some serious engine damage if it is
severe.
The anti-knock sensor should trigger a reduction in timing, but either
the
sensor is not working or the timing is already being set back as far as
it will go.
Or there are a number of other possibilities like a temperature sensor
that
is out of calibration, improper EGR operation, etc.
There is a way to find out using a scan tool (the sophisticated ones
that the dealers
have, not the ones you buy for $35 in the auto supply store), however,
the
technician working on my car didn't test it. I'll wait until the carbon
builds
up again (and the pinging starts), then I'll call Saturn and complain.
I wouldn't be surprised if there is a service bulletin out on this one.
How many miles do you have on the car and how long has it been pinging?
--
Ron Todaro
Jeff Shank
In article <32DBBC...@scis.nova.edu>, tod...@scis.nova.edu says...
I have a 93 sl2 with 65k on it, and it does not ping. I also
only put 93 or 94 octane in it.
jeff
Jo...@paonline.com
>sc2
My 92SC2 didn't ping even under the heaviest acceleration when new.
However, pinging started at 30k and gradually it got really bad by
60,000 miles. The car was also burning 1qt of oil in 1200 miles. At
this point the dealer replaced the rings, valve guides, seals and
decarbonized the head. They also replace the EGR valve on this visit.
The oil burning was corrected and so was the pinging. I really don't
know which solved the pinging. You may want to try replacing the EGR
1st.. If this doesn't solve your problem and your car is an oil
burner, then its probally carbon buildup.
John92SC2