On Fri, 15 Apr 2005 12:10:28 -0400, Douglas Dou
<douglas_dou@yahoo.com> wrote:

>I have a civic 05. My dealer told me that I could just use 87 gasoline
>as fuel. I followed his advice and have been using it for four months.
>However, this morning when I checked the user manual, I found that I am
>supposed to use 91. It amazed me since in my mind 91 is for luxury car,
>which my civic apparently is not. Is there any deep reason why Civic has
>to use 91? I'd appreciate if you could share me your thought.

Lately Honda seems to be engaging in a marketing ploy. Premium fuel is
expensive, and people aren't inclined to buy cars that need it, so
trusting to the efficiency of its engine knock sensors Honda has
recently been recommending regular gas for some of its products that
could really use premium! In those cars, the owner's manual says use
regular, but premium really will get you another ten HP or so! How do
you tell? Well short of a dyno test, check your compression ratio. As
a rough rule of thumb (there are a lot of variables) a 9.2 to 1
compression ratio Integra 1.8 litre engine only needs 86 octane, while
a 10 to 1 VTEC engine needs 91 octane to produce full power.

See also http://www.tegger.com/hondafaq/faq.html#premium

 

If you're light on the gas pedal, the most agreeable fuel will return the
best mileage (assuming there is no engine knocking).

Pars

"John Ings" <nodamned@spam.org> wrote in message
news:1cuv51t5539rv8avv3mgi79h2flugj23jo@4ax.com...
> On Fri, 15 Apr 2005 12:10:28 -0400, Douglas Dou
> <douglas_dou@yahoo.com> wrote:
>
> >I have a civic 05. My dealer told me that I could just use 87 gasoline
> >as fuel. I followed his advice and have been using it for four months.
> >However, this morning when I checked the user manual, I found that I am
> >supposed to use 91. It amazed me since in my mind 91 is for luxury car,
> >which my civic apparently is not. Is there any deep reason why Civic has
> >to use 91? I'd appreciate if you could share me your thought.
>
> Lately Honda seems to be engaging in a marketing ploy. Premium fuel is
> expensive, and people aren't inclined to buy cars that need it, so
> trusting to the efficiency of its engine knock sensors Honda has
> recently been recommending regular gas for some of its products that
> could really use premium! In those cars, the owner's manual says use
> regular, but premium really will get you another ten HP or so! How do
> you tell? Well short of a dyno test, check your compression ratio. As
> a rough rule of thumb (there are a lot of variables) a 9.2 to 1
> compression ratio Integra 1.8 litre engine only needs 86 octane, while
> a 10 to 1 VTEC engine needs 91 octane to produce full power.
>
> See also http://www.tegger.com/hondafaq/faq.html#premium
>
>

 

On Fri, 15 Apr 2005 17:49:46 -0400, "Pars" <sdaro(remove)@hotmail.com>
wrote:

>If you're light on the gas pedal, the most agreeable fuel will return the
>best mileage

Most agreeable? What unit of measure is agreeability calibrated in?
Can you find me agreeability ratings for common brands of gas?

>(assuming there is no engine knocking).

Knock sensors take care of that.

 

John Ings wrote:
> On Fri, 15 Apr 2005 12:10:28 -0400, Douglas Dou
> <douglas_dou@yahoo.com> wrote:
>
>
>>I have a civic 05. My dealer told me that I could just use 87 gasoline
>>as fuel. I followed his advice and have been using it for four months.
>>However, this morning when I checked the user manual, I found that I am
>>supposed to use 91. It amazed me since in my mind 91 is for luxury car,
>>which my civic apparently is not. Is there any deep reason why Civic has
>>to use 91? I'd appreciate if you could share me your thought.
>
>
> Lately Honda seems to be engaging in a marketing ploy. Premium fuel is
> expensive, and people aren't inclined to buy cars that need it, so
> trusting to the efficiency of its engine knock sensors Honda has
> recently been recommending regular gas for some of its products that
> could really use premium! In those cars, the owner's manual says use
> regular, but premium really will get you another ten HP or so! How do
> you tell? Well short of a dyno test, check your compression ratio. As
> a rough rule of thumb (there are a lot of variables) a 9.2 to 1
> compression ratio Integra 1.8 litre engine only needs 86 octane, while
> a 10 to 1 VTEC engine needs 91 octane to produce full power.
>
> See also http://www.tegger.com/hondafaq/faq.html#premium
>
>
Thanks for the link. The link essentially says that 87 in pump station
is the same thing as 91 recommended in manual. Can't understand why
Honda does not put 87 in it since the cars are sold in America.

 

On Fri, 15 Apr 2005 19:09:09 -0400, Douglas Dou
<douglas_dou@yahoo.com> wrote:

>Thanks for the link. The link essentially says that 87 in pump station
>is the same thing as 91 recommended in manual.

No. If the manual says 91 is suitable, then that's the octane that
will give you the most power. If economy is more important to you than
performance, then you can use 87.

>Can't understand why
>Honda does not put 87 in it since the cars are sold in America.

The reason is compression ratio. If you have a high enough compression
ratio, then 91 octane is able to give you more power. If you want
economy, the knock sensor will dial back your ignition advance, you
will have less power, but better fuel econmy.

 

Douglas Dou wrote:
> John Ings wrote:
> > On Fri, 15 Apr 2005 12:10:28 -0400, Douglas Dou
> > <douglas_dou@yahoo.com> wrote:
> >
> >
> >>I have a civic 05. My dealer told me that I could just use 87
gasoline
> >>as fuel. I followed his advice and have been using it for four
months.
> >>However, this morning when I checked the user manual, I found that
I am
> >>supposed to use 91. It amazed me since in my mind 91 is for luxury
car,
> >>which my civic apparently is not. Is there any deep reason why
Civic has
> >>to use 91? I'd appreciate if you could share me your thought.
> >
> >
> > Lately Honda seems to be engaging in a marketing ploy. Premium fuel
is
> > expensive, and people aren't inclined to buy cars that need it, so
> > trusting to the efficiency of its engine knock sensors Honda has
> > recently been recommending regular gas for some of its products
that
> > could really use premium! In those cars, the owner's manual says
use
> > regular, but premium really will get you another ten HP or so! How
do
> > you tell? Well short of a dyno test, check your compression ratio.
As
> > a rough rule of thumb (there are a lot of variables) a 9.2 to 1
> > compression ratio Integra 1.8 litre engine only needs 86 octane,
while
> > a 10 to 1 VTEC engine needs 91 octane to produce full power.
> >
> > See also http://www.tegger.com/hondafaq/faq.html#premium
> >
> >
> Thanks for the link. The link essentially says that 87 in pump
station
> is the same thing as 91 recommended in manual. Can't understand why
> Honda does not put 87 in it since the cars are sold in America.

Can you spell out what it says exactly,what type of Civic you
have, and where you're posting from? There's always been a problem
with differences in octane rating scales outside the US and Canada
(where RON is typically the pump rating) versus the US and Canada
(where (R+M)/2 - the average of two measurements) is used.

87 octane measured by (R+M)/2 is considered "regular". 91 octane
measured by (R+M)/2 is considered "premium". That 87 (R+M)/2 is
generally equivalent to 91 RON, while that 91 octane (R+M)/2 is pretty
much equivalent to 95 octane RON.

I looked it up, and Honda says the US-spec 2005 Civic Si requires
regular unleaded, but that might be a hedge that it can use it without
destroying itself. The compression ratio of the various Civics
seem to be high - from 9.5 to 9.9. The compression ratio of th
EX and HX versions is slightly higher at 9.9 than that of the Si
at 9.8.

 

On Fri, 15 Apr 2005 23:51:44 GMT, John Ings <nodamned@spam.org>
wrote:

>On Fri, 15 Apr 2005 19:09:09 -0400, Douglas Dou
><douglas_dou@yahoo.com> wrote:
>
>>Thanks for the link. The link essentially says that 87 in pump station
>>is the same thing as 91 recommended in manual.
>
>No. If the manual says 91 is suitable, then that's the octane that
>will give you the most power. If economy is more important to you than
>performance, then you can use 87.
>
>>Can't understand why
>>Honda does not put 87 in it since the cars are sold in America.
>
>The reason is compression ratio. If you have a high enough compression
>ratio, then 91 octane is able to give you more power. If you want
>economy, the knock sensor will dial back your ignition advance, you
>will have less power, but better fuel econmy.

In the FAQ, I thought it said "less power and LESS fuel economy."
Which is correct? If the lower octane will definitely give better
fuel economy, then I can live with less power, but that's not how I
thought it worked. Please explain further.

>

Ron

 

Sounds like a sales person... buncha words, makes no sense whatsoever. But
it does use a lot of optimistic sounding words though... gotta love the
psychology classes these days :/

"Pars" <sdaro(remove)@hotmail.com> wrote in message
news:ZMidnVkne8VDq_3fRVn-3Q@rogers.com...
> If you're light on the gas pedal, the most agreeable fuel will return the
> best mileage (assuming there is no engine knocking).
>
> Pars
>
> "John Ings" <nodamned@spam.org> wrote in message
> news:1cuv51t5539rv8avv3mgi79h2flugj23jo@4ax.com...
> > On Fri, 15 Apr 2005 12:10:28 -0400, Douglas Dou
> > <douglas_dou@yahoo.com> wrote:
> >
> > >I have a civic 05. My dealer told me that I could just use 87 gasoline
> > >as fuel. I followed his advice and have been using it for four months.
> > >However, this morning when I checked the user manual, I found that I am
> > >supposed to use 91. It amazed me since in my mind 91 is for luxury car,
> > >which my civic apparently is not. Is there any deep reason why Civic
has
> > >to use 91? I'd appreciate if you could share me your thought.
> >
> > Lately Honda seems to be engaging in a marketing ploy. Premium fuel is
> > expensive, and people aren't inclined to buy cars that need it, so
> > trusting to the efficiency of its engine knock sensors Honda has
> > recently been recommending regular gas for some of its products that
> > could really use premium! In those cars, the owner's manual says use
> > regular, but premium really will get you another ten HP or so! How do
> > you tell? Well short of a dyno test, check your compression ratio. As
> > a rough rule of thumb (there are a lot of variables) a 9.2 to 1
> > compression ratio Integra 1.8 litre engine only needs 86 octane, while
> > a 10 to 1 VTEC engine needs 91 octane to produce full power.
> >
> > See also http://www.tegger.com/hondafaq/faq.html#premium
> >
> >
>
>

 

On Sat, 16 Apr 2005 05:00:54 GMT, Milleron
<millerdot90@SPAMlessosu.edu> wrote:

>>The reason is compression ratio. If you have a high enough compression
>>ratio, then 91 octane is able to give you more power. If you want
>>economy, the knock sensor will dial back your ignition advance, you
>>will have less power, but better fuel econmy.
>
>In the FAQ, I thought it said "less power and LESS fuel economy."

Less economy in actual miles per gallon. But if the gallon costs
appreciably less...

>Which is correct? If the lower octane will definitely give better
>fuel economy, then I can live with less power, but that's not how I
>thought it worked. Please explain further.

Fill your tank with 87. See how many miles it gets you for how many $
Fill your tank with 91. See how many miles it gets you for how many $

Ignore miles per gallon. How many miles per dollar did you get?

 

On Sat, 16 Apr 2005 12:17:43 GMT, John Ings <nodamned@spam.org>
wrote:

>On Sat, 16 Apr 2005 05:00:54 GMT, Milleron
><millerdot90@SPAMlessosu.edu> wrote:
>
>>>The reason is compression ratio. If you have a high enough compression
>>>ratio, then 91 octane is able to give you more power. If you want
>>>economy, the knock sensor will dial back your ignition advance, you
>>>will have less power, but better fuel econmy.
>>
>>In the FAQ, I thought it said "less power and LESS fuel economy."
>
>Less economy in actual miles per gallon. But if the gallon costs
>appreciably less...
>
>>Which is correct? If the lower octane will definitely give better
>>fuel economy, then I can live with less power, but that's not how I
>>thought it worked. Please explain further.
>
>Fill your tank with 87. See how many miles it gets you for how many $
>Fill your tank with 91. See how many miles it gets you for how many $
>
>Ignore miles per gallon. How many miles per dollar did you get?

I understand that principle, however, (call me lazy if you want), I'm
looking for a simpler answer.
I have NO engineering background, so this stuff isn't at all intuitive
to me, but it seems as though the only scientific way to do that is to
repeat a long trip under exactly the same weather conditions with the
ONLY variable being the octane of the fuel used. That's pretty
difficult to do in the real world if you're expecting reproducible
accuracy. Isn't there an answer that can be derived from the theory
or measured in dynamometer testing, assuming that 91 (pump) octane
costs 5% more than 89 octane, and 93 octane costs 10% more?

My guess is that using "plus" or "premium" fuel is not going to give
me a 5% or 10% increase in mileage, but I would have thought that
someone would already have worked this out -- i.e., calculated how
MUCH less the lower octane would have to cost in order to yield an
increase in economy. No? I realize that the EXACT answer depends on
each vehicle's engine-management system, but I'm hoping that there
might be a rule-of-thumb figure. (My car is an '03 Accord EX V6,
BTW.)

Thanks

Ron