87oct. vs 93oct.
Cobra Member
Joined: May 20, 2005
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I read early on that there WAS a power increase in this car using higher octane gas, but it wasn't significant. I just wish I could remember where I read it so I could link there. On the note of detonation, is a car detonating when you have it in too high a gear for the speed you're going (like going up a hill without downshifting)? It sometimes sounds like it, so I was wondering.
Shelby GT500 Member
Joined: January 30, 2004
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From: Riverside, CA
I'd like to add a bit more to the knowledge here for understandment.
Octane ratings are the rate of speed it burns
Isooctane is a chemical that burns just right (slower). It measures to be 100 octane
n-heptane is a chemical that burns really fast. It measures to be 0 octane
Gasolines octane is found out by relateing it to those two chemicals. An 87% mixture of Isooctane, and a 13% of n-heptane, would burn at the same rate as an 87 octane fuel. etc
Octane ratings are the rate of speed it burns
Isooctane is a chemical that burns just right (slower). It measures to be 100 octane
n-heptane is a chemical that burns really fast. It measures to be 0 octane
Gasolines octane is found out by relateing it to those two chemicals. An 87% mixture of Isooctane, and a 13% of n-heptane, would burn at the same rate as an 87 octane fuel. etc
Member
Joined: June 16, 2005
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Originally posted by Infinity@September 25, 2005, 3:47 PM
I read early on that there WAS a power increase in this car using higher octane gas, but it wasn't significant. I just wish I could remember where I read it so I could link there. On the note of detonation, is a car detonating when you have it in too high a gear for the speed you're going (like going up a hill without downshifting)? It sometimes sounds like it, so I was wondering.
I read early on that there WAS a power increase in this car using higher octane gas, but it wasn't significant. I just wish I could remember where I read it so I could link there. On the note of detonation, is a car detonating when you have it in too high a gear for the speed you're going (like going up a hill without downshifting)? It sometimes sounds like it, so I was wondering.
Again, what I wrote was an oversimplification, and was intended to illustrate how octane ratings can have an affect on detonation.
( ;-{)}
Bullitt Member
Joined: January 2, 2005
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I can't dazzle you with tech talk, but here's what happened on my car.
On a SuperFlow dyno:
With the Xcal2 we loaded the 93 octane DTP tune for the JLT that I bought from Jay . Along with tune we, of course, installed the JLT CAI and had just put in the 4.10's. No other mods.
My tuner, in a moment of brilliance, thought he had loaded the 87 octane tune and did a pull with 87 in the tank on the 93 tune.
Result: No pinging!
We then replaced the 87 with 93 and did another pull on the same 93 tune.
Result: 1 HP gain! Yes, ONE!
Now remember, this is on the 93 tune which should have taken advantage of the higher octane and caused pinging with 87 octane. No appreciable difference in power and no pinging. My tuner didn't really seem all that surprised and shrugged it off. I was a little freaked out, but what do I know? :scratch: Either way, I run 93 all the time and it runs great.
You results may vary.
On a SuperFlow dyno:
With the Xcal2 we loaded the 93 octane DTP tune for the JLT that I bought from Jay . Along with tune we, of course, installed the JLT CAI and had just put in the 4.10's. No other mods.
My tuner, in a moment of brilliance, thought he had loaded the 87 octane tune and did a pull with 87 in the tank on the 93 tune.
Result: No pinging!
We then replaced the 87 with 93 and did another pull on the same 93 tune.
Result: 1 HP gain! Yes, ONE!
Now remember, this is on the 93 tune which should have taken advantage of the higher octane and caused pinging with 87 octane. No appreciable difference in power and no pinging. My tuner didn't really seem all that surprised and shrugged it off. I was a little freaked out, but what do I know? :scratch: Either way, I run 93 all the time and it runs great.
You results may vary.
Bullitt Member
Joined: December 31, 2004
Posts: 389
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As I've said earlier in previous posts.....
Originally posted by My Blue Heaven@June 15, 2005, 6:37 AM
For what it's worth, 5.0 Mustang magazine in the latest issue mailed to me yesterday reported that Ford is relying on the Knock sensor to pull back timing for low octane gas and the fuel table that is in the computer is actually a premium octane program. Whether 91 or 93 I don't recall if they said.
How does this affect after market tunes and what they are programmed at, I have no idea.
So, the easiest upgrade so far is running premium gas.
If you're running a tuner that has diagnostic capability you can always keep bumping the timing up untill you see the knock sensor kick in.
Personally I'm running I drive around with a 91 octane tune using 92 gas. On track days I either get race gas or run NOS racing octane booster, put in the 93 tune and bump the global timing. It worked in the cold air, don't know how that will do with the hot weather we have now.
For what it's worth, 5.0 Mustang magazine in the latest issue mailed to me yesterday reported that Ford is relying on the Knock sensor to pull back timing for low octane gas and the fuel table that is in the computer is actually a premium octane program. Whether 91 or 93 I don't recall if they said.
How does this affect after market tunes and what they are programmed at, I have no idea.
So, the easiest upgrade so far is running premium gas.
If you're running a tuner that has diagnostic capability you can always keep bumping the timing up untill you see the knock sensor kick in.
Personally I'm running I drive around with a 91 octane tune using 92 gas. On track days I either get race gas or run NOS racing octane booster, put in the 93 tune and bump the global timing. It worked in the cold air, don't know how that will do with the hot weather we have now.
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