What Octane rating do you use?
Instructor
Joined: Jul 2018
Posts: 139
Likes: 97
From: North Texas
i found it interesting that a Ford Mustang GT (coyote engine) only loses 5 hp when using 87 Octane fuel vs 93 Octane. Makes that the extra 5 hp very expensive. Cars all have sensors and modify timing to ensure no knocking and knocking is what needs to be avoided.
Melting Slicks
Joined: Oct 2009
Posts: 2,004
Likes: 392
From: Long Island New York
No, that's not it and you are completely wrong. Octane is a measure of resistance to ignition from cylinder pressure and dictates the speed of the explosion of the flame front. Higher octane fuel does not have any more energy than regular fuel. What is does is allow an engine to run at higher compression ratios and THAT is the reason for increased performance, not additional heat or energy content from the fuel. You can easily add octane to regular fuel by adding lead as they did years ago. It essentially just slowed down the flame front after ignition to prevent knocking. And I guarantee you that adding lead did not make the ignition temperature hotter or provide more energy.
Drifting
Joined: Jan 2005
Posts: 1,441
Likes: 557
What are you driving? A Z06 will pull timing on 91 octane. A Grandsport should not. Given you are in a hot spot of the word, I would run the highest octane available to control detonation and timing pull when running hard.
Race Director
Joined: May 2001
Posts: 15,323
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From: Guelph, Ontario
Team Owner
Joined: Aug 2000
Posts: 24,075
Likes: 1,322
From: Spring Texas
These are research octanes, not road octanes (R+M)/2 that is posted on pumps in the US. Generally you would subtract about 4 to 5 octanes to get an approximation of the road octane 91 research ~ 87 road, etc.
Last edited by CP; Aug 24, 2018 at 11:58 AM.
Instructor
Joined: Jul 2018
Posts: 139
Likes: 97
From: North Texas
Ethanol is a higher octane blend component, but contains much less energy. Because ethanol contains less energy, that is why one gets less miles per gallon from gasoline with ethanol.
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Drifting
Joined: Jan 2005
Posts: 1,940
Likes: 1,325
From: Houston Tx
Gosh, the octane and ethanol wars are getting cranked up again from a 2014 thread. Pro and anti ethanol fans always entertain me. The reality is that for E10 versus “pure gas”, the only difference that a normal human will notice in a normal car (including stock Vettes) is a slight decrease in gas mileage. There is simply no noticeable difference in power, drivability, or the laundry list of other supposed effects. Can you get a bit more power from E85? Sure, if your car is tuned for it. E85 is both higher octane, and because it has less energy per gallon, requires more fuel to be injected which in turn provides a bit of cylinder cooling which retards detonation even further than the octane would imply. But again, your car has to be tuned for it to take advantage of it. The difference between E10 and “pure gas” in power for a stock Vette? Let’s just say somewhere between zero and microscopic.
Melting Slicks
Joined: Nov 2017
Posts: 3,131
Likes: 671
Melting Slicks
Joined: Nov 2017
Posts: 3,131
Likes: 671
NO The computer handles the mix. Is the gas octane calculated like it is in the States? Anyway the higher the better just not low like under 90 I think the BOOK says it will lower performance
Melting Slicks
Joined: Nov 2017
Posts: 3,131
Likes: 671
ATTENDANT?? I didn't know there were any of those around anymore