100 Octane & OCT

[Meradin]

So the other day I was visiting some friends in New Jersey and we came across a Sunoco selling 100 octane "race gas". I was just about empty and after filling up at $4 a gallon I didn't think that $7 a gallon was that bad for 100 octane. My seat of the pants feeling is that the engine is more responsive, revs more quickly ,and has a bit more power. Anyone else have any experience with 100 octane and the OCT software? I am wondering exactly how much it is able to use anything over the 93-94 octane I normally use?

[jerrym]

race gas is useless for naturally aspirated cars..
you only feel it on forced induction :)

[jerrym]

using 100 octane on naturally aspirated cars also clogs up your cats.

[B6_Rakete]

http://www.europeancarweb.com/tech/0...ted/index.html
http://members.rennlist.com/951_race...omparison.html

[Meradin]

Not very helpful information since those articles discuss octane boosters which is not what I am using. Also, Jerrym, it would be helpful if you backed up your statements with a little information. Also, Why would companies like GIAC offer a 100 octane program if it didn't do anything for an NA motor?

[91gl]

race gas is useless for naturally aspirated cars..
you only feel it on forced induction :)

wrong, any car benefits from higher octane gas and a car with aftermarket software benefits even more since the program can advance the time accordingly to take advantage of the higher octane thus quciker accelaration.

[91gl]

using 100 octane on naturally aspirated cars also clogs up your cats.

wrong again, unleaded race gas will not have any effects on your cats. leaded race gas can cause the inside of your cats to melt.

[2PUTT]

race gas = crack =)

[jerrym]

.. i get that information from other people.
so who knows :)

[Auditude2.0T]

if you have no cats you have nothing to worry about:)

[91gl]

if you have no cats you have nothing to worry about:)

you have nothing to worry about with cats unless you are using leaded gas

[b spot]

It's all in your head:
http://www.audizine.com/forum/showthread.php?t=206093

[VVG]

.. i get that information from other people.
so who knows :)

While it's okay to post info you heard about, please don't come across like it is an absolute fact or truth.

In this case, a higher octane fuel will register higher exhaust gas temp as well as a different signal coming from the oxygen sensors. If the ECU programming is such that it can accept these inputs and then advance timing, allow more airflow or both, you will produce more power with a normally aspirated motor. Putting 100 octane into a stock RS4 made my car feel noticeable more responsive. Of course, other parameters have to be right also. For example, the ECU may only allow timing advance with 100 octane if the intake air temp or coolant temp is registering within a certain range. If other conditions would lead to a hazardous condition for the engine, even with 100 octane, you may not see a gain in a given set of circumstances. In another set of circumstances, you would.

[37doc]

wrong, any car benefits from higher octane gas and a car with aftermarket software benefits even more since the program can advance the time accordingly to take advantage of the higher octane thus quciker accelaration.

Exactly, a NA engine ABSOLUTELY can benefit from higher octane, it allows the ECU to bring the spark in earlier (advance) on the compression stroke , thus giving a stronger power stroke.

[37doc]

While it's okay to post info you heard about, please don't come across like it is an absolute fact or truth.

In this case, a higher octane fuel will register higher exhaust gas temp as well as a different signal coming from the oxygen sensors. If the ECU programming is such that it can accept these inputs and then advance timing, allow more airflow or both, you will produce more power with a normally aspirated motor. Putting 100 octane into a stock RS4 made my car feel noticeable more responsive. Of course, other parameters have to be right also. For example, the ECU may only allow timing advance with 100 octane if the intake air temp or coolant temp is registering within a certain range. If other conditions would lead to a hazardous condition for the engine, even with 100 octane, you may not see a gain in a given set of circumstances. In another set of circumstances, you would.

DITTO , I love it when people post facts... or at least thats what ive heard from some guy... what a tool.