use of higher octane gasoline

I have a 1999 Honda Accord LX six cylinder with about 31,000 miles on it. I
have always used unleaded gasoline 87 octane (manual says use 86 or higher)
and had no problems. However a friend of mine said I would get better
performance and mileage if I used premium grade higher octane gasoline.
Other than paying a higher price per gallon is there really any difference
in performance or mileage using higher octane fuel if the compression ratio
remains unchanged?
John

 

He's wrong.

Have him show us his degree in chemistry, and his certifications from
the auto engineering or petroleum industries. What? He doesn't have
any? Imagine that.

He's wrong.

In your case, there's no difference other than (a) you'll spend more
money, and (b) you'll actually get slightly *in*ferior gas mileage and
power due to the higher octane fuel's requirements for burning.

Do you know what octane is? Better yet, let's ask him. Does HE know
what octane is?

Octane is not a "power booster".

 

Hi,
Would you believe your friend's advice or the owner's manual?
Have money to burn? You said your car is running fine.
Tony

 

Apparently if you use the 93 oct gas, you get 10 extra hp from the new V6
240hp Honda engine, according to some Honda engineer. Not sure about better
mileage though. However, I haven't heard anything of this sort about the
older 200hp V6 engine. Personally, I'd stick with the 87 octane.

Cheers,

Pete

 

Ah, the net. Great source for random crap.

Other than this anonymous Honda engineer that no one has ever actually
seen or talked to, is there any other source for this? No, I didn't
think so.

And even if this were true, it would be true IF and ONLY IF the engine
control computer were designed specifically for this situation.

This guy's 99 Accord most definitely isn't designed for this.

 

Yup, it's pretty much a hearsay. I wouldn't bet my life on it, that's for
sure.

It may be smart enough to adjust timing - many ECUs can do it these days.

Didn't I say it only applied to the new V6 (2003 and up)? ;-)

Cheers,

Pete

 

VTEC The VT stands for variable timing. The 2003 models will adjust
themsleves to the octane used. Is 10hp worth $0.20+ per gallon? Not to
me. My V6 Accord runs just fine on 87.

 

The Octane number means resistance to detonation.
Higher Octane does not mean higher energy content in the gasoline.

Some engines (for example the Mistubishi 6 cylinder), can adjust to higher
Octane gasoline. By using the knock sensor, they can sense the higher
Octane number, then advance the ingition or something that would give you
more HP.

AFAIK, the stock Honda engine cannot make use of higher Octane than 87.
Older, worn and/or modified engines MAY benefit from higher Octane. You may
want to try to switch gasoline and determine for yourself. YMMV.

 

It may be smart enough to adjust timing - many ECUs can do it these days.[/QUOTE]

But generally not in family haulers.

 

And just where is this documented?

It's not a feature of VTEC. If that were so, my 92 Civic Si would have
done that. And it didn't.

No, it's a feature of the engine control computer, pure and simple.
Nothing more, nothing less. It's how the computer is programmed to
respond to certain sensory inputs.

That the engine has variable valve timing and lift control doesn't mean
the computer that controls it was programmed to do anything with higher
octane fuel. The two have nothing to do with one another.

I'm still waiting for Honda documentation that says the 03 Accord V6
will advance its timing in response to higher octane fuel. So far, it's
just a net rumor. And you know what those are. They're like
opinions--and you know what THOSE are like.

 

Falling asleep through Paul Cardoza's post...

VTEC engages another cam at higher engine speeds. It does not increase
compression. Only Saab has that tech in the works right now. Unless
you're forcing air into the combustion chamber, you haven't increase the
compression ratio. Which would be the only way that you would need to run
93 octane gas.

--
"If you can't change a tire, you're not allowed to have a beard. It's the
most basic part of a car: If you don't know that much about a car, you
really shouldn't be driving, should you?" - Jimmy Kimmel
http://www.cafeshops.com/creexul.2534632
Owner of the following: Henry Cotter - A.G.F.F., Eric Dreher AND mark
digital© - A.A.T., wiru the tired - A.F.D., and that Gino guy who keeps
chaning his nick on A.A.Acura.
http://acfsliars.0catch.com/todd

 

Increasing the advance of the ignition timing could also necessitate higher
octane fuel.

 

Falling asleep through Jafir Elkurd's post...

I know they can retard advance, but I haven't heard of a brand that
advances it. Unless you can name one :O

--
"If you can't change a tire, you're not allowed to have a beard. It's the
most basic part of a car: If you don't know that much about a car, you
really shouldn't be driving, should you?" - Jimmy Kimmel
http://www.cafeshops.com/creexul.2534632
Owner of the following: Henry Cotter - A.G.F.F., Eric Dreher AND mark
digital© - A.A.T., wiru the tired - A.F.D., and that Gino guy who keeps
chaning his nick on A.A.Acura.
http://acfsliars.0catch.com/todd

 

I know they can retard advance, but I haven't heard of a brand that
advances it. Unless you can name one :O[/QUOTE]

You're right. The engine control computer is designed to operate the
engine at its performance parameters. A Corvette, for example, is
designed such that higher octane fuels allow the engine to operate to
its design limits--but using lower octane fuels won't damage the engine,
because the computer will do what it takes to elminate knocking and
pinging caused by lower octane fuels.

But putting avgas into this same Vette won't do anything extra for it.
Octane isn't a power booster. The octane level of a gas may allow the
engine to perform to its designed limits, but a higher octane gas won't
do anything to make the engine perform beyond that.

That being said, the question becomes: where did Honda engineers put
the design limits of the 03 Accord V6? They say use 86 octane fuel, and
you'll get the performance they advertise. But did they design the
engine and the computer such that the limits of the engine are beyond
that?

Some people are saying yes. I think it's bunk, so far. People who
really want to believe that octane levels are an indication of power are
trying to justify their use of higher octane fuels, when probably
they're just throwing their money away.

Until we see something documented--even a series of dyno runs--it
remains a net myth. And we know about those.

 

The source may be the USA Today review, 8-2-02: "(Charles) Baker (head of
Accord development) claims that - based on what we'll call field research by
him and Honda V-6 engineer Yasuaki Asaki - the four-cylinder Accord, rated
160 horsepower, accelerates head-to-head with the four-cylinder Altima,
rated 175 hp. And the 240-hp Accord V-6 outsprints the 240-hp Altima V-6, he
says....The Accord V-6 ratings assume regular-grade fuel, and Honda will
market it as a regular-fuel engine. But - pssst - it's good for another 10
hp and 10-plus lbs.-ft. on premium, acknowledges V-6 engineer Asaki."
http://www.usatoday.com/money/autos/reviews/2002-08-01-accord_x.htm

 

But generally not in family haulers.[/QUOTE]

Honda says that my 2001 Odyssey (a family hauler if there ever was one)
produces more horsepower with 93 octane fuel. I can't swear what the
numbers are, but my recollection is 210 or 215 vs. 205 with 87 octane.
This may very well be a feature of the 2003 Accord V6 - my 2003 Accord
is the 4-banger, and I never saw reference to this.

RFT!!!
Dave Kelsen

 

Honda says that my 2001 Odyssey (a family hauler if there ever was one)
produces more horsepower with 93 octane fuel.[/QUOTE]

Right. I said generally, and notice how for 2002 they flat out changed
everything.

Also notice that they documented the power increase for those original
engines, but there's absolutely no such documentation for the 03 Accord.

Somebody just wants to justify his unnecessary spending of more money on
higher octane fuel, that's all.

 

They don't advance it.... many cars with complete computer controlled
advance (but I'm not saying Honda here) are set a little high to start with,
and then the computer retards it based on info from the knock sensor... so
if you run higher octane, you'll get slightly higher advance.

 

On Honda's with coil over plug ignition the computer uses a TDC sensor
and a Knock sensor to actively adjust timing for the best
performance/economy at any given time. Honda's VTEC system uses a
computer controlled third intake rocker/cam lobe to increase the fuel
flow to the cylinder.

 

Bottom line: How many miles per DOLLAR do you get with different octane
gasolines?

--
Bob Burns
Mill Hall PA

Right. I said generally, and notice how for 2002 they flat out changed
everything.

Also notice that they documented the power increase for those original
engines, but there's absolutely no such documentation for the 03 Accord.

Somebody just wants to justify his unnecessary spending of more money on
higher octane fuel, that's all.
[/QUOTE]