Regular Gas in a Premium Engine

On Tue, 22 Feb 2005 02:25:55 GMT, "Michael Arber"
<thearbers@worldnet.att.net> wrote:
[color=blue]
>I was just reading about the new 2005 Toyota Avalon. It sounds great! But in
>the literature I noticed they point out the 280 hp engine uses premium 91 octane
>fuel. Although it seems you can use regular 87 octane without harming the
>engine, you won't get 280 hp. My question is how much horsepower and torque
>would the engine make with 87 octane fuel?
>
>I suppose many engines run fine on 87 octane but only get their maximum
>horsepower with premium fuel. So in general - on any such engine - how much
>power would be lost when using regular fuel?
>
>Thanks in advance!
>Michael
>[/color]
Michael,

Use premium fuel. You shouldn't have to worry about fuel cost if you
have an 05 Avalon.

In article <TKwSd.257887$w62.58629@bgtnsc05-news.ops.worldnet.att.net>,
"Michael Arber" <thearbers@worldnet.att.net> wrote:
[color=blue]
> I was just reading about the new 2005 Toyota Avalon. It sounds great! But
> in
> the literature I noticed they point out the 280 hp engine uses premium 91
> octane
> fuel. Although it seems you can use regular 87 octane without harming the
> engine, you won't get 280 hp. My question is how much horsepower and torque
> would the engine make with 87 octane fuel?
>
> I suppose many engines run fine on 87 octane but only get their maximum
> horsepower with premium fuel. So in general - on any such engine - how much
> power would be lost when using regular fuel?
>
> Thanks in advance!
> Michael[/color]

I've used both in my 04 Sienna and can notice a performance difference
and a bit of gas mileage difference too. I prefer to use 91 when I can
get it for only a penny more than 87 at my local gas for less place,
otherwise 87 does the job.

To answer your question I don't know. I would think you could get it on
a dyno and do a comparison, but why bother.
--

[email]diel@spam.com[/email] wrote:
[color=blue]
> In article <TKwSd.257887$w62.58629@bgtnsc05-news.ops.worldnet.att.net>,
> "Michael Arber" <thearbers@worldnet.att.net> wrote:
>
>[color=green]
>>I was just reading about the new 2005 Toyota Avalon. It sounds great! But
>>in
>>the literature I noticed they point out the 280 hp engine uses premium 91
>>octane
>>fuel. Although it seems you can use regular 87 octane without harming the
>>engine, you won't get 280 hp. My question is how much horsepower and torque
>>would the engine make with 87 octane fuel?
>>
>>I suppose many engines run fine on 87 octane but only get their maximum
>>horsepower with premium fuel. So in general - on any such engine - how much
>>power would be lost when using regular fuel?
>>
>>Thanks in advance!
>>Michael[/color]
>
>
> I've used both in my 04 Sienna and can notice a performance difference
> and a bit of gas mileage difference too. I prefer to use 91 when I can
> get it for only a penny more than 87 at my local gas for less place,
> otherwise 87 does the job.[/color]

As much as it says "requires premium fuel", it has to be able
to run on regular gas to be sold. So it will be a bit less
powerful, but maybe 5-10%. Hardly worth mentioning unless
you push your car hard and/or have a manual transmission.

250-260HP is still a lot. Most people couldn't tell the difference
between 250HP and 280 anyways - it's a lot of power. HP to weight
ratio-wise, it's better than most V8 muscle cars from the 60s and
70s.

Joseph Oberlander wrote:[color=blue]
> [email]diel@spam.com[/email] wrote:
>snip<[color=green]
>> I've used both in my 04 Sienna and can notice a performance
>> difference and a bit of gas mileage difference too. I prefer to use 91
>> when I
>> can get it for only a penny more than 87 at my local gas for less place,
>> otherwise 87 does the job.[/color]
>
> As much as it says "requires premium fuel", it has to be able
> to run on regular gas to be sold. So it will be a bit less
> powerful, but maybe 5-10%. Hardly worth mentioning unless
> you push your car hard and/or have a manual transmission.[/color]

Now Joey ... how far up your ass did you reach to pull out that "5-10%"
figure? Eh?
--

- Philip

C. E. White wrote:
[color=blue]
>
> Joseph Oberlander wrote:
>
>[color=green]
>>As much as it says "requires premium fuel", it has to be able
>>to run on regular gas to be sold. So it will be a bit less
>>powerful, but maybe 5-10%. Hardly worth mentioning unless
>>you push your car hard and/or have a manual transmission.[/color]
>
>
> Do you have a reference for your statement that "it has to
> be able to run on regular gas to be sold?"[/color]

Simple liability. Otherwise, they'd have to make a different
sized pump nozzle like they do for diesel fuel, to keep you from
putting sometihng in that will damage the engine.

Now, it won't run as well, but it will run.

Philip wrote:
[color=blue]
> Joseph Oberlander wrote:
>[color=green]
>>diel@spam.com wrote:
>>snip<
>>[color=darkred]
>>>I've used both in my 04 Sienna and can notice a performance
>>>difference and a bit of gas mileage difference too. I prefer to use 91
>>>when I
>>>can get it for only a penny more than 87 at my local gas for less place,
>>>otherwise 87 does the job.[/color]
>>
>>As much as it says "requires premium fuel", it has to be able
>>to run on regular gas to be sold. So it will be a bit less
>>powerful, but maybe 5-10%. Hardly worth mentioning unless
>>you push your car hard and/or have a manual transmission.[/color]
>
> Now Joey ... how far up your ass did you reach to pull out that "5-10%"
> figure? Eh?[/color]

Given the octane difference in percentages, it can't be more
than twice that. We're talking about 4 octane, afterall,
which is a very small amount. Even if it was squared,
which would be the largest impact likely possible, it would be
16% less power.

So, let's say 16% less power. Out of 280HP. I get 235HP.
I doubt that it is even close to this much of a difference, though,
since the computers compensate quite a bit.

Joseph Oberlander wrote:
[color=blue]
> Given the octane difference in percentages, it can't be more
> than twice that. We're talking about 4 octane, afterall,
> which is a very small amount. Even if it was squared,
> which would be the largest impact likely possible, it would be
> 16% less power.
>
> So, let's say 16% less power. Out of 280HP. I get 235HP.
> I doubt that it is even close to this much of a difference, though,
> since the computers compensate quite a bit.[/color]

You are losing me here. Octane has nothing to do with
"power" except that higher octane gas is less likely to "pre
ignite," which for a given engine configuration allows a
higher compression ratio and/or more advanced ignition
timing. These factors can allow an engine to develop more
power (all other things being equal). In the really old
days, gas with higher octane actually had less "power"
(energy) per unit volume than regular gas. These days that
is not necessarily true. However, unless your vehicle has
some method for taking advantage of the higher octane (like
a knock sensor, that allows the PCM to advance the timing),
then there is no power advantage attributable directly to
the use of higher octane gas. A few years back, Ford
acknowledged that the 5.4L V-8 installed in trucks could
gain 5 to 10 horsepower if premium fuel was used instead of
the regular specified (because the PCM would adjust the
timing based on the knock sensor input). This is a 2% to 4%
increase. I tried premium in my Expedition for a significant
period of time (15,000 miles). I never could detect the
increased power and the gas mileage was not detectably
different. On the other hand, if your vehicle can't
compensate for the use of regular gas when premium is
specified (insufficient timing adjustment available to the
PCM), then the use of regular gas in an engine intended to
run on premium gas can result in engine damage due to pre
ignition. Since almost all vehicles that specify premium gas
include knock sensor, damage is unlikely unless you highly
stress the engine (towing heavy loads, driving at very high
speeds, lots of hard acceleration runs, etc.).

Ed

Joseph Oberlander wrote:[color=blue]
>
> C. E. White wrote:
>[color=green]
> >
> > Joseph Oberlander wrote:
> >
> >[color=darkred]
> >>As much as it says "requires premium fuel", it has to be able
> >>to run on regular gas to be sold. So it will be a bit less
> >>powerful, but maybe 5-10%. Hardly worth mentioning unless
> >>you push your car hard and/or have a manual transmission.[/color]
> >
> >
> > Do you have a reference for your statement that "it has to
> > be able to run on regular gas to be sold?"[/color]
>
> Simple liability. Otherwise, they'd have to make a different
> sized pump nozzle like they do for diesel fuel, to keep you from
> putting sometihng in that will damage the engine.[/color]

So this is just a suposition on your part? I was hoping it
was some sort of EPA rule. If you had not noticed, the
diesel nozzle will fit in the unleaded gas filler neck on
your car. Now that is real liability!

Ed

"C. E. White" <cewhite3@nospam.com> wrote:
[color=blue]
>
>
>Joseph Oberlander wrote:
>[color=green]
>> As much as it says "requires premium fuel", it has to be able
>> to run on regular gas to be sold. So it will be a bit less
>> powerful, but maybe 5-10%. Hardly worth mentioning unless
>> you push your car hard and/or have a manual transmission.[/color]
>
>Do you have a reference for your statement that "it has to
>be able to run on regular gas to be sold?"
>
>Ed[/color]

Gotta agree with Philip and Ed here Joe...I'd say that you have a
pretty active imagination with your statements...try to appear
sensible, don't make statements like that, everyone knows that
you have no frickin idea how much HP you lose...if the
manufacturer says use premium then use premium. I'll guarantee
that he knows more about his engine than you ever will.
--

-Gord.
(use gordon in email)

"Joseph Oberlander" <josephoberlander@earthlink.net> wrote in message
news:fOJSd.3409$873.398@newsread3.news.pas.earthlink.net...[color=blue]
>
>
> Philip wrote:
>[color=green]
>> Joseph Oberlander wrote:
>>[color=darkred]
>>>diel@spam.com wrote:
>>>snip<
>>>
>>>>I've used both in my 04 Sienna and can notice a performance
>>>>difference and a bit of gas mileage difference too. I prefer to use 91
>>>>when I
>>>>can get it for only a penny more than 87 at my local gas for less place,
>>>>otherwise 87 does the job.
>>>
>>>As much as it says "requires premium fuel", it has to be able
>>>to run on regular gas to be sold. So it will be a bit less
>>>powerful, but maybe 5-10%. Hardly worth mentioning unless
>>>you push your car hard and/or have a manual transmission.[/color]
>>
>> Now Joey ... how far up your ass did you reach to pull out that "5-10%"
>> figure? Eh?[/color]
>
> Given the octane difference in percentages, it can't be more
> than twice that. We're talking about 4 octane, afterall,
> which is a very small amount. Even if it was squared,
> which would be the largest impact likely possible, it would be
> 16% less power.
>
> So, let's say 16% less power. Out of 280HP. I get 235HP.
> I doubt that it is even close to this much of a difference, though,
> since the computers compensate quite a bit.
>[/color]
Joseph,

Making uninformed, purely speculative guesses and posting them as if they
are facts is something Cliff from Cheers would do.

Think about the price of premium gas vs. the price of regular unleaded. In
Chicago, premium costs in the neighborhood of 3% to 6% more than regular
unleaded. Wouldn't it be logical that every car manufacturer would spec
premium gas if a 6% investment in gas got you 10% or 16% more horsepower?

What do you mean when you say "the computers compensate quite a bit?"
--
Ray O
correct the return address punctuation to reply

Michael Arber wrote:[color=blue]
> I was just reading about the new 2005 Toyota Avalon. It sounds
> great! But in the literature I noticed they point out the 280 hp
> engine uses premium 91 octane fuel. Although it seems you can use
> regular 87 octane without harming the engine, you won't get 280 hp.
> My question is how much horsepower and torque would the engine make
> with 87 octane fuel?
>
> I suppose many engines run fine on 87 octane but only get their
> maximum horsepower with premium fuel. So in general - on any such
> engine - how much power would be lost when using regular fuel?
>
> Thanks in advance!
> Michael[/color]

Here is an interesting article:
[url]http://www.usatoday.com/money/autos/2003-07-30-premiumgas_x.htm[/url]
Automakers say they don't test premium engines on regular to check the
difference, but some auto engineers estimate that power declines roughly
5%.

I think Ed's answer is best. The engine may knock with a lower octane fuel
and that is always undesirable. On the other side of the argument, I work
with several folks that insist on putting premium in their vehicles because
they feel it must somehow be better for their engines. I think it is best to
simply go with the manufacturer's recommendation in most cases.
jor
"Michael Arber" <thearbers@worldnet.att.net> wrote in message
news:TKwSd.257887$w62.58629@bgtnsc05-news.ops.worldnet.att.net...[color=blue]
>I was just reading about the new 2005 Toyota Avalon. It sounds great! But
>in
> the literature I noticed they point out the 280 hp engine uses premium 91
> octane
> fuel. Although it seems you can use regular 87 octane without harming the
> engine, you won't get 280 hp. My question is how much horsepower and
> torque
> would the engine make with 87 octane fuel?
>
> I suppose many engines run fine on 87 octane but only get their maximum
> horsepower with premium fuel. So in general - on any such engine - how
> much
> power would be lost when using regular fuel?
>
> Thanks in advance!
> Michael
>
>[/color]

Joseph Oberlander <josephoberlander@earthlink.net> wrote:
snip[color=blue]
>Given the octane difference in percentages, it can't be more
>than twice that. We're talking about 4 octane, afterall,
>which is a very small amount. Even if it was squared,
>which would be the largest impact likely possible, it would be
>16% less power.
>
>So, let's say 16% less power. Out of 280HP. I get 235HP.
>I doubt that it is even close to this much of a difference, though,
>since the computers compensate quite a bit.[/color]

Joe, you really do need to read up some...do you know that the
higher the octane rating then the less volatile the fuel?,,,it's
true, there's less energy in high octane fuel than there is in
lower octane fuel. The increased HP is obtained by increasing the
compression and increasing the fuel air charge with blowers and
increasing the charge pressure by advancing the spark...BUT when
you do all that you MUST increase the octane rating to prevent
detonation. Modern automobile engines use a knock sensor which
retards the ignition to prevent detonation.
--

-Gord.
(use gordon in email)

"jor" <jor@jor.com> wrote:
[color=blue]
>I think Ed's answer is best. The engine may knock with a lower octane fuel
>and that is always undesirable. On the other side of the argument, I work
>with several folks that insist on putting premium in their vehicles because
>they feel it must somehow be better for their engines. I think it is best to
>simply go with the manufacturer's recommendation in most cases.
>jor[/color]

OF COURSE!!...Jesus, when will people learn that after spending
millions of dollars in research and development an automobile
company's technical dept knows a huge amount about the engines
that they manufactured and tweaked at great expense to make them
as reliable and efficient as possible keeping inside very
stringent design and expense specs?.

They KNOW their engines, they know what fuel octane rating they
need to operate properly. They know what oil specs are best. They
know what oil change intervals to recommend. How could ANYONE who
buys and operates one casually presume to know them BETTER? This
makes one look like a flake to boldly get up on his hind legs and
bray on in public stuff which makes NO SENSE to sensible
people...and is often at large variance to recommendations of the
manufacturer.

<sigh>

--

-Gord.
(use gordon in email)

Gord Beaman wrote:[color=blue]
> Joseph Oberlander <josephoberlander@earthlink.net> wrote:
> snip
>[color=green]
>>Given the octane difference in percentages, it can't be more
>>than twice that. We're talking about 4 octane, afterall,
>>which is a very small amount. Even if it was squared,
>>which would be the largest impact likely possible, it would be
>>16% less power.
>>
>>So, let's say 16% less power. Out of 280HP. I get 235HP.
>>I doubt that it is even close to this much of a difference, though,
>>since the computers compensate quite a bit.[/color]
>
>
> Joe, you really do need to read up some...do you know that the
> higher the octane rating then the less volatile the fuel?,,,it's
> true, there's less energy in high octane fuel than there is in
> lower octane fuel. The increased HP is obtained by increasing the
> compression and increasing the fuel air charge with blowers and
> increasing the charge pressure by advancing the spark...BUT when
> you do all that you MUST increase the octane rating to prevent
> detonation. Modern automobile engines use a knock sensor which
> retards the ignition to prevent detonation.[/color]

I know this, which is why, even with the knock sensor kicking
in and the computers compensating - it can't be more than 10-15%
power loss or else the engine wouldn't run correctly.