93 or 87 octane?
RE: 93 or 87 octane?
What is it lately with gay this gay that. I never knew gas pumps got it on with each other at night. But transmissions on the other hand, I saw my 5-hp19 the other day looking up the tail pipe of Mercedes 5-hp19, way to go buddy.
What is the point of putting in 94 octane fuel in your car when your car isn't able to benefit from it. Only vehicles with extremely high compression, or over boosted turbos will see an improvment. Stock A6's do not fall into either of those categories. Does anybody even know what octane does????? really anybody, we argue this topic over and over again with the same results. People spewing out a bunch of crap about only using 91, 92, 93, 94 octane in our cars. It is true that using 87 will decrease performance, and using 91 will allow the engine to run at peak efficiency, but using 92, 93, 94 adds no more benefit to stock engines/turbos than 91 does. And 87 does not damage a darn thing, because of modern electronics.
What is the point of putting in 94 octane fuel in your car when your car isn't able to benefit from it. Only vehicles with extremely high compression, or over boosted turbos will see an improvment. Stock A6's do not fall into either of those categories. Does anybody even know what octane does????? really anybody, we argue this topic over and over again with the same results. People spewing out a bunch of crap about only using 91, 92, 93, 94 octane in our cars. It is true that using 87 will decrease performance, and using 91 will allow the engine to run at peak efficiency, but using 92, 93, 94 adds no more benefit to stock engines/turbos than 91 does. And 87 does not damage a darn thing, because of modern electronics.
2nd Gear
Joined: Nov 2006
Posts: 934
From: LaCrescent, MN
RE: 93 or 87 octane?
Jeff, maybe there wont be a huge difference between 91 and 93 for people with stock cars. But for us that are chipped it sure does make a difference. You can't tell me there is no reason that GIAC and APR both have tunings for 91 and 93 specifically. The extra 2 octane in 93 gives you 11 more hp and 16 ft/lbs of tq. That most def is a big difference. And those are proven dyno numbers, not just hearsay.
2nd Gear
Joined: Nov 2006
Posts: 934
From: LaCrescent, MN
RE: 93 or 87 octane?
ORIGINAL: Oodles N Noodles
not get get on anyone bad side, but what does the owners book say to use?
not get get on anyone bad side, but what does the owners book say to use?
Senior Member
Joined: Jul 2007
Posts: 240
From:
RE: 93 or 87 octane?
ORIGINAL: Jeffla
What is it lately with gay this gay that. I never knew gas pumps got it on with each other at night. But transmissions on the other hand, I saw my 5-hp19 the other day looking up the tail pipe of Mercedes 5-hp19, way to go buddy.
What is the point of putting in 94 octane fuel in your car when your car isn't able to benefit from it. Only vehicles with extremely high compression, or over boosted turbos will see an improvment. Stock A6's do not fall into either of those categories. Does anybody even know what octane does????? really anybody, we argue this topic over and over again with the same results. People spewing out a bunch of crap about only using 91, 92, 93, 94 octane in our cars. It is true that using 87 will decrease performance, and using 91 will allow the engine to run at peak efficiency, but using 92, 93, 94 adds no more benefit to stock engines/turbos than 91 does. And 87 does not damage a darn thing, because of modern electronics.
What is it lately with gay this gay that. I never knew gas pumps got it on with each other at night. But transmissions on the other hand, I saw my 5-hp19 the other day looking up the tail pipe of Mercedes 5-hp19, way to go buddy.
What is the point of putting in 94 octane fuel in your car when your car isn't able to benefit from it. Only vehicles with extremely high compression, or over boosted turbos will see an improvment. Stock A6's do not fall into either of those categories. Does anybody even know what octane does????? really anybody, we argue this topic over and over again with the same results. People spewing out a bunch of crap about only using 91, 92, 93, 94 octane in our cars. It is true that using 87 will decrease performance, and using 91 will allow the engine to run at peak efficiency, but using 92, 93, 94 adds no more benefit to stock engines/turbos than 91 does. And 87 does not damage a darn thing, because of modern electronics.
http://en.wikipedia.org/wiki/Octane_rating These are some key points from the article.
In most countries (including all of Europe and Australia) the "headline" octane that would be shown on the pump is the RON, but in the United States, Canada and some other countries the headline number is the average of the RON and the MON, sometimes called the Anti-Knock Index (AKI), Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2. Because of the 8 to 10 point difference noted above, this means that the octane in the United States will be about 4 to 5 points lower than the same fuel elsewhere: 87 octane fuel, the "regular" gasoline in the US and Canada, would be 91-92 in Europe. However most European pumps deliver 95 (RON) as "regular", equivalent to 90-91 US (R+M)/2, and even deliver 98 (RON) or 100 (RON)....."Dose this mean we can use 87? I'm not goin to, but it looks like it."
Higher octane ratings correlate to higher activation energies. Activation energy is the amount of energy necessary to start a chemical reaction. Since higher octane fuels have higher activation energies, it is less likely that a given compression will cause knocking. (Note that it is the absolute pressure (compression) in the combustion chamber which is important - not the compression ratio. The compression ratio only governs the maximum compression that can be achieved).
RE: 93 or 87 octane?
So when people ask our advice on what gas we can run, we should say....
If you have a stock engine, then you can use 87+, as that is what my owners manual and gas door says. Gas door says 91 RON, 91 RON = 86/87 AKI.
alias747 I don't doubt that with a chip higher octane fuels increase performace. That is why I said in my previous post, stock engines/turbos will not benefit from anything over 91.
If you have a stock engine, then you can use 87+, as that is what my owners manual and gas door says. Gas door says 91 RON, 91 RON = 86/87 AKI.
alias747 I don't doubt that with a chip higher octane fuels increase performace. That is why I said in my previous post, stock engines/turbos will not benefit from anything over 91.
Thread Starter
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1st Gear
Joined: Sep 2007
Posts: 74
From: Bristol, Rhode Island.
RE: 93 or 87 octane?
My gas capdoor says minimum 91 octane. So, can you really tell a differnce between 89 and 91? Not sure why, but at least here in the north east, octane ratings include only87, 89, 93. There is no 91 offered here, so I'm going to use 89 and live with it.
By the way, I have noticed no difference between 87 and 93, no knocks-pings, or degraded performance. Why pay morefor no change?
By the way, I have noticed no difference between 87 and 93, no knocks-pings, or degraded performance. Why pay morefor no change?
3rd Gear
Joined: Sep 2006
Posts: 2,738
From: Holland MI
RE: 93 or 87 octane?
This has been beat to death in former postings. Most drivers use premium (91 or 93) and claim their car runs better and gets better mileage. I would suspectpremium helps under hard acceleration. If you check the manual, you'll see that the compression differences between the 2.7T, 2.8, and 4.2 are all diffferent. I believe the 2.7T actually has lower compression than the others and therefore should be able to tolerate lower octane gas more readily without knocking. However my manual is in my trunk in Michiganand I'm in Brazil, so I cannot check right now.
I have run midrange for 65k miles and tracked mileage for every tank. I've used premium formany tanks as well, including this summer for a 1200 mile trip to Minnesota and back. No difference in mileage. I don't accelerate hard so I detect no performance difference and no knocking. I found that with an occasional tank that contains ethanol, my mileage is worse, so I avoid it whenever possible. I also would NOT put regular gas in. I am also lucky to often find Shell selling midrange for the same price as regular.
My plugs were replaced during the 40k tune-up and were checked at 90k and were clean. I have not replaced them at 101k. But I do mostly highway driving at 70-80mph. PS - You can see in the signature that my car is mildly chipped, and it still tolerates midrange with no knocking or problems.
I have run midrange for 65k miles and tracked mileage for every tank. I've used premium formany tanks as well, including this summer for a 1200 mile trip to Minnesota and back. No difference in mileage. I don't accelerate hard so I detect no performance difference and no knocking. I found that with an occasional tank that contains ethanol, my mileage is worse, so I avoid it whenever possible. I also would NOT put regular gas in. I am also lucky to often find Shell selling midrange for the same price as regular.
My plugs were replaced during the 40k tune-up and were checked at 90k and were clean. I have not replaced them at 101k. But I do mostly highway driving at 70-80mph. PS - You can see in the signature that my car is mildly chipped, and it still tolerates midrange with no knocking or problems.
