wow... this topic swerved away from point quick... im j/k!

 

I've known a few Grand Prix owners that run normal octane gas on the street, but empty the tank at the track and fill it with racing fuel while drag racing. Once the racing day is done, the regular octane goes back in. They haven't had a problem yet. Maybe they've just been lucky???

 

Sorry, back on topic:

Won't the computer compensate for octanes of up to 100 or is there a cut-off point?

 

i usually run93 anyway and pour in some octane booster while going to the track.

 

wayyyy toooo much good info on gas.

http://www.faqs.org/faqs/autos/gasoline-faq/

6.13 Can higher octane fuels give me more power?

On modern engines with sophisticated engine management systems, the engine
can operate efficiently on fuels of a wider range of octane rating, but there
remains an optimum octane for the engine under specific driving conditions.
Older cars without such systems are more restricted in their choice of fuel,
as the engine can not automatically adjust to accommodate lower octane fuel.
Because knock is so destructive, owners of older cars must use fuel that will
not knock under the most demanding conditions they encounter, and must
continue to use that fuel, even if they only occasionally require the octane.

If you are already using the proper octane fuel, you will not obtain more
power from higher octane fuels. The engine will be already operating at
optimum settings, and a higher octane should have no effect on the management
system. Your driveability and fuel economy will remain the same. The higher
octane fuel costs more, so you are just throwing money away. If you are
already using a fuel with an octane rating slightly below the optimum, then
using a higher octane fuel will cause the engine management system to move to
the optimum settings, possibly resulting in both increased power and improved
fuel economy. You may be able to change octanes between seasons ( reduce
octane in winter ) to obtain the most cost-effective fuel without loss of
driveability.

Once you have identified the fuel that keeps the engine at optimum settings,
there is no advantage in moving to an even higher octane fuel. The
manufacturer's recommendation is conservative, so you may be able to
carefully reduce the fuel octane. The penalty for getting it badly wrong,
and not realising that you have, could be expensive engine damage.

 

Info I always found or talked about and agreed on was with the computer controlled cars buying anything above regular unleaded was a waste of money. The computer is going to operate the engine at it's peak no matter what grade of fuel poured in the tank.

I had other car owners beat me down cause I posted I could feel a difference in performance by using a higher grade of gas. Many replied it was not so!!! The engine will only operate at whatever level the computer allows it to.

 

Octane is directly correlated to compression. Low compression engines have no improved effects from higher octane gases.

On the other hand, high compression engines suffer from lower octane gases. The ECM will help itrecover slightlythough.

 

Hmm, from my Aviation fuels training.. IIRC..

Your octane ratings are a basic measurement of detonation resistance. Higher octane levels in a fuel do not represent the deflagration (burning) of the fuel.

The octane level in basically an "activation" level of a fuel. The higher the number the less likely a fuel will ignite itself under the heat of compression. Hence why most forced induction engines and high compression engines require a minimum of 91 octane. If you use low octane fuel in a high compression engine, the engine will likely suffer from detonation as the compression of the fuel in the 2nd stroke of an engine will ignite the fuel before the spark happens.

Depending on the compression ratio of the engine, the engine will need special blended fuels that resist detonating at high compression for example.. 100 Octane (depending on the calculation method) is good up to 16:1 usually.

What can add power to an engine is simply the additives that are installed into the fuel at the refinery age.

Hows this affect your car? Easy. PCMS have no way of determining what kind of gas is in a fuel. The only thing the car can understand is if the octane level is too low through the knock sensor which can advance or retard timing as needed. No knock. No problem. To a degree.

Just a few FYI:

E-85 has a value of 105 octane. (But develops less power then standard gas)
Methanol Has a value of 113 octane. (Put this in your monte and you may be finding pistons a few blocks away.)

Essentially the point im dragging across is, that unless you have a lot of mods to your car, racing fuel is redundant and a waste.

Oh.. By the way.. DO NOT USE AVGAS (aircraft gasoline) this contains lead.

 

Yeah, but Peter Griffin did it on Family Guy and it made his pickup truck fly like a fighter jet.

(haha)[sm=joke.gif]

Thanks for the informative info Ian. I learned something about the higher octane gas. (Not about the AVGAS).