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100 octane fuel in West LA (archive)

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Posted by bmv on November 12, 2000 at 08:54:54:

If anyone from SoCal is interested, here's a thread from the Ferrari List:

----- Original Message -----
Sent: Saturday, November 11, 2000 10:26 AM
Subject: [Ferrari] NFC 100 octane gas


I stopped at a 76 station near work (west L.A.) last night and they had
100 octane fuel at the pump with the other three usual grades. What is
the street application for this fuel. Is it a gimmick for the street
rodders/boy racers or is there really a use for it? At $4.60 a gallon I
wasn't about to try it out. Does anyone know if this is the same as
aviation gas?
thanks
Brian

------REPLY--------------

<>

Not the same as Aviation gas. Av gas contains a buncha stuff to prevent
icing. Auto fuel contains a buncha stuff to work with our engines as
designed by fed regulations. You can also check out a place on, um, Vanowen
and Desoto. Trick racing fuel. As far as Avgas goes, the most octane (not
the most powerful) I have seen is for a Mustang, (not Ford, heh heh) = 130,
purple.

Unless you are pinging on normal fuel, there should be no advantage to the
100 octane. Well, no advantage unless you get a kick out of seeing Habibe
smile.

DOUG


------REPLY--------------

Well, I wouldn't call it a gimmick exactly, but depending on your
car, it's very likely useless to you. A higher compression motor
will require higher octane (slower burning) gas. Running a
supercharger or nitrous oxide is also a scenario where you
typically want high octane gas. But for "normal" cars, you want
to run the lowest octane that doesn't cause knock, and that's
usually whatever is stated in the owners manual, which will never
be 100 octane.

I run 100 octane at the race track when I'm using nitrous. Since
I don't have it in my car all the time on the street, I rarely
use my nitrous on the street.

I don't know about aviation gas, but certainly for most of
today's street cars you want unleaded gas.

Dave

------REPLY--------------

Aloha Brian!
A general rule of thumb: Your compression ratio X 10 = Fuel octane
requirement. Example: 308 compression ratio = 8.8 to 1. Fuel octane
requirement is 88. Get it?
The advantage to higher octane fuel is its resistance to detonation.
Personally, I take advantage of higher octane fuel; it allows me to run more
spark advance. I run 40 degrees advance in my 308gts; this provides maximum
yank off the bottom. However, don't try this in any vehicle. The ferrari
has the advantage of small displacement, all aluminum alloy construction,
the spark plug configured to the center of the combustion chamber and a
hemi-head. All these factors, including a higher-than-required octane (I
run 92) add up to allow for increased spark advance.
An avenue to power is increasing compression ratio. Into my first car, a
'66 Pontiac GTO, I installed a 'towing package' 421 from a Grand Prix. The
compression ratio from the factory was 13:1! I burned Gulf No-Nox, 124
Octane, if memory serves. The factory rated 370HP was a bald faced lie. My
guess is closer to 450 ponies and ungodly torque. This is the engine John
Delorean used to set the stock sedan 0-60 record; under 4 sec.
The harder something is squeezed, the higher the temperature, the higher the
temp, the greater the chance for detonation.
Ultimately, higher octane allows higher compression ratios, and more power.

yer pal,
Robin, in Hawaii




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