What Octanes R U Using?
Banned
Joined: Jun 2007
Posts: 1,138
91. It is recommended. The compression ratio is high. If you cheap out on gas, you lose power and maybe the warranty. The cars in Europe are mostly 91 and I rented a car that needed it. The contract said that if there's engine damage caused from using lower octane gas, I could be held liable.
4th Gear
Joined: Mar 2009
Posts: 3,042
From: Indiana
Premium vs. Regular... answers
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There is a small debate about whether Premium is really required for our cars. Some people say the run Regular for the entire time they have owned the car and have had no problems, so Audi must be, um.. conservative in their fuel recommendations. So, can you run Regular? Well yes and no. Yes you prolly can get away with it in the cooler climates and No you shouldnt becuase it hurts the power output. Here is what Audi has to say:
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Quote:
Detonation Retard:
Knock sensors consist of piezoelectric crystals encased in metal and plastic housings located on each cylinder head, under intake manifold. Vibrations in engine cause crystal to generate small amounts of voltage. This voltage signal is used by PCM to determine necessary timing retardation.
One knock sensor is installed on each head under intake manifold. Using 2 knock sensors makes it possible for system to be more accurate and responsive.
When knocking occurs, ignition timing is retarded until knocking is eliminated. Since engine knock limits vary from cylinder to cylinder, knock regulation is cylinder selective.
Knock control starts when coolant temperature is 104°F (40°C) or above. Ignition angle of knocking cylinder is retarded in steps to a maximum of 12 degrees or until knocking stops. If cylinder knock continues, PCM will switch from premium fuel ignition map to ignition map for regular fuel. This allows ignition timing to be retarded up to 3 additional degrees. /Quote
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So, as you can see, running Regular is possible and accounted for in the programing, but you could be running upto 15 degrees retarded! That, my friends, will kill power and mileage. Also, notice that the knock retard is cylinder selective. What this means is cyl #1 might be retarded the full15 degrees, and cyl 3 only 8-10. This introduces vibrations and harmonics into the system. This is never a good thing and could lead to a shorten life of the motor.
Is that $2-3 a full tank worth it?
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There is a small debate about whether Premium is really required for our cars. Some people say the run Regular for the entire time they have owned the car and have had no problems, so Audi must be, um.. conservative in their fuel recommendations. So, can you run Regular? Well yes and no. Yes you prolly can get away with it in the cooler climates and No you shouldnt becuase it hurts the power output. Here is what Audi has to say:
.............
Quote:
Detonation Retard:
Knock sensors consist of piezoelectric crystals encased in metal and plastic housings located on each cylinder head, under intake manifold. Vibrations in engine cause crystal to generate small amounts of voltage. This voltage signal is used by PCM to determine necessary timing retardation.
One knock sensor is installed on each head under intake manifold. Using 2 knock sensors makes it possible for system to be more accurate and responsive.
When knocking occurs, ignition timing is retarded until knocking is eliminated. Since engine knock limits vary from cylinder to cylinder, knock regulation is cylinder selective.
Knock control starts when coolant temperature is 104°F (40°C) or above. Ignition angle of knocking cylinder is retarded in steps to a maximum of 12 degrees or until knocking stops. If cylinder knock continues, PCM will switch from premium fuel ignition map to ignition map for regular fuel. This allows ignition timing to be retarded up to 3 additional degrees. /Quote
..........
So, as you can see, running Regular is possible and accounted for in the programing, but you could be running upto 15 degrees retarded! That, my friends, will kill power and mileage. Also, notice that the knock retard is cylinder selective. What this means is cyl #1 might be retarded the full15 degrees, and cyl 3 only 8-10. This introduces vibrations and harmonics into the system. This is never a good thing and could lead to a shorten life of the motor.
Is that $2-3 a full tank worth it?
Senior Member
Joined: Dec 2008
Posts: 170
From: Atlanta, GA
I would always run premium on a force fed engine as the pressures involved with turbo/super charges engines are much more likely to cause premature detonation and the subsequent loss of power/mileage from retarding the timing.
1st Gear
Joined: Jan 2009
Posts: 49
Keep consistant with your octane, Hell I have yet to use 94 but when i do I will try the 10point Octane booster and take it for one hell of a joy ride. I know it wont make a huge difference but with a chipped car you can kinda get more out of it.
The lowest you should ever go if you do is medium,silver, 89 what ever they call it over here its silver/89. Dont cheap out.. Trust me read into it.. its not somthing you want done to a 50K investment.
The lowest you should ever go if you do is medium,silver, 89 what ever they call it over here its silver/89. Dont cheap out.. Trust me read into it.. its not somthing you want done to a 50K investment.
