Honda Car Forum

"Michael Pardee" <michaeltnull@cybertrails.com> wrote in message news:<DNKdnZm-a6KEUzTcRVn-pA@sedona.net>...
> "K-town" <jdu52580@carolina.stopspam.rr.com> wrote in message
> news6cqd.7794$Mu3.802926@twister.southeast.rr.co m...
> > Hello,
> >
> > Not being an engine expert, I figured I'd throw this question out to
> > this NG. I have a 1990 Civic LX, 1.5L DPFI 5-speed, and usually I put
> > regular unleaded (87 octane) in it. Every once in awhile I'll put
> > mid-grade (89 octane) or premium (92 or 93 octane) in it because I heard
> > that doing so will keep your injectors clean. (Is that true?) Once I
> > really splurged and put 100 octane fuel in it (only 5 gallons) and it did
> > run pretty good. One thing I noticed, is that if I run premium (93) in it
> > several tanks in a row, it will actually not run quite as good. It's a
> > very minuscule difference, but I can tell there is a slight decrease in
> > performance. If I drop it back down to mid-grade or even back to regular
> > on the next tank, it seems to go back to running better. Is this all in
> > my head, or is it possible to have an "octane overkill" on such a small
> > 4-cylinder engine?
> >
> > Thanx in advance,
> >
> > Jonathan
> >
> High octane fuel is for high compression engines, to prevent detonation
> (ping). Your owner's manual will tell you what grade to use - probably 87
> octane. Rather than going to a premium grade (which, it's true, often has
> higher detergency), stick with the recommended octane. Some brands have more
> detergents than others, and they advertise that. (I like Shell/Texaco and
> Chevron.) I had a Nissan 300ZX that would get balky - the clutch would start
> to feel grabby - if I ran 76 in it for a couple months but would straighten
> right out about halfway through a tank of Texaco. My other cars never seem
> to care.
>
> We also have a Toyota Prius, and on the Prius newsgroup others have warned
> me it won't run right and will even set the "check engine" light if premium
> grades are used. (The Prius has what Toyota calls a "modified
> Atkinson/Miller cycle" engine - it uses valve timing to tame the 13:1
> expansion ratio to a variable compression ratio.)
>
> Mike

Hey Mike
I thought you might be interested in some test that were run with high
octane E85 in a prius. Check out page 10 at
http://www.creedproject.org/stream_v7n2.pdf and observe a 20% increase
in power when the "Forbidden" fuel was tested.
I have made a bunch of post at The Temple of VTEC about this subject.
I post as cleverlever. You also might be interested in my patent
4,961,406 which demonstates how to change the burn rate of a given
fuel at low rpm

Edward Quinn wrote:
> ive been using amoco ultimate in my 04 accord should i switch to
> regular??

Only if you want to save money.

I once did a study when I was commuting 100 miles each way to work in the
mid 90's (late 80's GM Bonneville 6 cyl). I clocked my mileage and input
gallons closely for a month using 87 octane gas and another month using 91
octane. Both months were during summer, and no AC was used.

My mileage per tank was about 8% higher on average with the 91 octane. Of
course, the 91 octane was 10% higher cost.

>
> "K-town" <jdu52580@carolina.stopspam.rr.com> wrote in message
> news6cqd.7794$Mu3.802926@twister.southeast.rr.co m...
>> Hello,
>>
>> Not being an engine expert, I figured I'd throw this question out
>> to this NG. I have a 1990 Civic LX, 1.5L DPFI 5-speed, and usually
>> I put regular unleaded (87 octane) in it. Every once in awhile I'll
>> put mid-grade (89 octane) or premium (92 or 93 octane) in it because
>> I heard that doing so will keep your injectors clean. (Is that
>> true?) Once I really splurged and put 100 octane fuel in it (only 5
>> gallons) and it did run pretty good. One thing I noticed, is that
>> if I run premium (93) in it several tanks in a row, it will actually
>> not run quite as good. It's a very minuscule difference, but I can
>> tell there is a slight decrease in performance. If I drop it back
>> down to mid-grade or even back to regular on the next tank, it seems
>> to go back to running better. Is this all in my head, or is it
>> possible to have an "octane overkill" on such a small 4-cylinder
>> engine? Thanx in advance,
>>
>> Jonathan

cleverlever99@hotmail.com (Cleverlever) wrote in message news:<3fffe09a.0411291847.134f3f5d@posting.google. com>...
> "Michael Pardee" <michaeltnull@cybertrails.com> wrote in message news:<DNKdnZm-a6KEUzTcRVn-pA@sedona.net>...
> > "K-town" <jdu52580@carolina.stopspam.rr.com> wrote in message
> > news6cqd.7794$Mu3.802926@twister.southeast.rr.co m...
> > > Hello,
> > >
> > > Not being an engine expert, I figured I'd throw this question out to
> > > this NG. I have a 1990 Civic LX, 1.5L DPFI 5-speed, and usually I put
> > > regular unleaded (87 octane) in it. Every once in awhile I'll put
> > > mid-grade (89 octane) or premium (92 or 93 octane) in it because I heard
> > > that doing so will keep your injectors clean. (Is that true?) Once I
> > > really splurged and put 100 octane fuel in it (only 5 gallons) and it did
> > > run pretty good. One thing I noticed, is that if I run premium (93) in it
> > > several tanks in a row, it will actually not run quite as good. It's a
> > > very minuscule difference, but I can tell there is a slight decrease in
> > > performance. If I drop it back down to mid-grade or even back to regular
> > > on the next tank, it seems to go back to running better. Is this all in
> > > my head, or is it possible to have an "octane overkill" on such a small
> > > 4-cylinder engine?
> > >
> > > Thanx in advance,
> > >
> > > Jonathan
> > >
> > High octane fuel is for high compression engines, to prevent detonation
> > (ping). Your owner's manual will tell you what grade to use - probably 87
> > octane. Rather than going to a premium grade (which, it's true, often has
> > higher detergency), stick with the recommended octane. Some brands have more
> > detergents than others, and they advertise that. (I like Shell/Texaco and
> > Chevron.) I had a Nissan 300ZX that would get balky - the clutch would start
> > to feel grabby - if I ran 76 in it for a couple months but would straighten
> > right out about halfway through a tank of Texaco. My other cars never seem
> > to care.
> >
> > We also have a Toyota Prius, and on the Prius newsgroup others have warned
> > me it won't run right and will even set the "check engine" light if premium
> > grades are used. (The Prius has what Toyota calls a "modified
> > Atkinson/Miller cycle" engine - it uses valve timing to tame the 13:1
> > expansion ratio to a variable compression ratio.)
> >
> > Mike
>
> Hey Mike
> I thought you might be interested in some test that were run with high
> octane E85 in a prius. Check out page 10 at
> http://www.creedproject.org/stream_v7n2.pdf and observe a 20% increase
> in power when the "Forbidden" fuel was tested.
> I have made a bunch of post at The Temple of VTEC about this subject.
> I post as cleverlever. You also might be interested in my patent
> 4,961,406 which demonstates how to change the burn rate of a given
> fuel at low rpm


Yes, they also got a check engine light. Cold start emissions were
higher, and overall MPG was lower. They did not perform any long-term
tests (ethanol can break down parts of the car over time).

The Prius is only rated to use E10.

this is great! an expert named
"jim beam" bought a computer and figured out how to wire it up. once he
read something on the internet and provided the following nugget of BS for
us to enjoy.

wrote in message

> increasing octane effectively = slower flame front propagation speed.
no. close though. the rate or speed of flame is the same regardless of
octane. increasing the octane does decrease breakdown components that tend
to ignite behind the flame front.

*dont take my word for it, buy a real book wioth real facts from real
research, not something some dude with a BMW once posted on the net.*

> that reduces detonation in combustion chambers with poor flow/mixing
> configurations, sharp angles & extended reach. good mechanical design
> addresses these problems pretty much completely, therefore low octane
> can be used without detonation and with ignition timing matched
> accordingly.

you are a bit confused. the design of the combustion chamber is indeed
important, but ignition timing and compression are the primary components of
spark induced ping. combustion chamber design is a very narrow area of
concern and for all intents, it does not mean much of anything when speaking
of octane. not anymore

> using a high octane fuel in a low octane timed engine puts
> too much of the combustion energy out of the exhaust because it's still
> burning on the down stroke, not expanding and providing push for the
> pistons.

really? using an octane over your requirements does not waste fuel. it
does not decrease efficiancy or power or anything. it will just cost you
more.


> that said, you may notice a slight increase in power for a mid grade
> fuel in that motor without a detonation sensor. partly because, in the
> absense of a sensor, the engine timing used has to be a "compromise"
> range designed to be safe and partly because of fuel chemistry.

once an engine has had its octane requirements met, nothing, absolutely
nothing, will change as a result of the octane you are using. ie; if your
well tuned engine requires 87 RON MON, then it is the same as using 92 or 94
or 100. by definition, octane only has an effect on knock.


> here's an interesting post that touches on the subject:
> http://www.digest.net/bmw/archive/v9/msg04942.html

it must be true!

> it seems to assume that ignition timing is optimal for each different
> combustion characteristic of the different blends described. you can be
> assured that gas companies use all the cheap options for their lowest
> grade of gas.

what are you trying to say? the "lowest grade" as it applies to octane is
not a qwuality judgement. there si not anything cheap or inferior about 87
vs. 92 octane gas. just its anti knock capabilities. for the record, major
petroleum companies use the same additive package across the board.

i suggest that you do some resarch of your own. i am informed becuase i am
a consultant for petro comapnies and get paid to read about gasoline. i
dont know much about cnacer, but then im not posting crap at the oncology
NG!

being tired and cranky,
just do a deja news search with "Joe Lang" and octane.

"Joe Lang" <wjablonski@trcsolutions.comREMove> wrote in message
news:1101848317.Jz0aCVvlooIblociTKf9mA@teranews...
> this is great! an expert named
> "jim beam" bought a computer and figured out how to wire it up. once he
> read something on the internet and provided the following nugget of BS for
> us to enjoy.
>
>

In article <1101848317.Jz0aCVvlooIblociTKf9mA@teranews>,
"Joe Lang" <wjablonski@trcsolutions.comREMove> wrote:

> using an octane over your requirements does not waste fuel. it
> does not decrease efficiancy or power or anything.

um, yes, it's less efficient.

"Cleverlever" <cleverlever99@hotmail.com> wrote in message
news:3fffe09a.0411291847.134f3f5d@posting.google.c om...
> "Michael Pardee" <michaeltnull@cybertrails.com> wrote in message
> news:<DNKdnZm-a6KEUzTcRVn-pA@sedona.net>...
>> High octane fuel is for high compression engines, to prevent detonation
>> (ping). Your owner's manual will tell you what grade to use - probably 87
>> octane. Rather than going to a premium grade (which, it's true, often has
>> higher detergency), stick with the recommended octane. Some brands have
>> more
>> detergents than others, and they advertise that. (I like Shell/Texaco and
>> Chevron.) I had a Nissan 300ZX that would get balky - the clutch would
>> start
>> to feel grabby - if I ran 76 in it for a couple months but would
>> straighten
>> right out about halfway through a tank of Texaco. My other cars never
>> seem
>> to care.
>>
>> We also have a Toyota Prius, and on the Prius newsgroup others have
>> warned
>> me it won't run right and will even set the "check engine" light if
>> premium
>> grades are used. (The Prius has what Toyota calls a "modified
>> Atkinson/Miller cycle" engine - it uses valve timing to tame the 13:1
>> expansion ratio to a variable compression ratio.)
>>
>> Mike
>
> Hey Mike
> I thought you might be interested in some test that were run with high
> octane E85 in a prius. Check out page 10 at
> http://www.creedproject.org/stream_v7n2.pdf and observe a 20% increase
> in power when the "Forbidden" fuel was tested.
> I have made a bunch of post at The Temple of VTEC about this subject.
> I post as cleverlever. You also might be interested in my patent
> 4,961,406 which demonstates how to change the burn rate of a given
> fuel at low rpm

An interesting link. Thanks!

My understanding is that octane is not specifically about burn rate, but
about ignition point. If the mixture ignites because of the heat of
compression, or if the compression heating is high enough that the reaction
propagates by the pressure front instead of the flame front, the fuel
mixture changes from a low explosive to a high explosive.
See http://www.howstuffworks.com/question90.htm

Mike

Joe Lang wrote:
> being tired and cranky,
> just do a deja news search with "Joe Lang" and octane.
>
> "Joe Lang" <wjablonski@trcsolutions.comREMove> wrote in message
> news:1101848317.Jz0aCVvlooIblociTKf9mA@teranews...
>
>>this is great! an expert named
>>"jim beam" bought a computer and figured out how to wire it up. once he
>>read something on the internet and provided the following nugget of BS for
>>us to enjoy.
>>

tell me more about combustion chamber design. as i understand it,
morphology influces gas flow, density, turbulence and pressure wave
propagation. this in turn does affect the stability of the resulting
cylinder charge on compression, hence octane matters. i'm /not/ an
expert on this stuff joe, but i do have some books on the subject, so
please, enlighten me further.

and please, let's keep the flame limited to the spark-induced variety.

Thanx for all the advice, folks. I appreciate it. I'll vote for saving
money and stick with regular unleaded (87 octane) from now on. On this
note, I have one other question: Does gasoline lose its potency if it sits
for awhile? The reason I ask is because I notice that when my tank runs
almost on "E" and I refuel, my car seems to be more responsive and run a
little smoother. Does a fuller tank cause better fuel delivery somehow, or
what? (I'm thinking the level of fuel in the tank shouldn't matter...that's
what a fuel pressure regulator is for...to keep the fuel pressure constant)
Why does it seem to run a little better right after I refuel, regardless of
brand of gas?

Thanks again! :-)

Jonathan

In article <WV9rd.23969$Mu3.1347292@twister.southeast.rr.com> ,
"K-town" <jdu52580@carolina.stopspam.rr.com> wrote:

> Does gasoline lose its potency if it sits
> for awhile? The reason I ask is because I notice that when my tank runs
> almost on "E" and I refuel, my car seems to be more responsive and run a
> little smoother. Does a fuller tank cause better fuel delivery somehow, or
> what? (I'm thinking the level of fuel in the tank shouldn't matter...that's
> what a fuel pressure regulator is for...to keep the fuel pressure constant)
> Why does it seem to run a little better right after I refuel, regardless of
> brand of gas?

If you're running your tank out every week or so like normal drivers,
gasoline doesn't lose anything. It's in your mind.

If you're filling up every 6 months or so, there could be a problem.
Gas does get old.