View Poll Results: What are you putting in your tank?
93+ Octane
40
74.07%
91 Octane
10
18.52%
89 Octane
0
0%
87 Octane
4
7.41%
Voters: 54. You may not vote on this poll
87, 91 or 93 Octane!
#1
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87, 91 or 93 Octane!
I was just wondering what most of you are putting in their tank (besides the tiger!)... In order to get maximum performance out of my new 5.0, I was planning to start right away with 93 octane fuel. One of my first mods on the list will be a Steeda CAI and tune anyways, so might as well go for it.
What are your thoughts and experiences?
What are your thoughts and experiences?
#7
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As with many modern computer controlled engines, the 5.0 has an optimum octane requirement (91 R+M/2) but can be run at lower octane levels. The computer compensates by retarding timing to prevent knocking but that also reduces performance. However, going to a higher octane than 91 will not improve performance.
OTOH, gasohol has less potential energy (by volume) than straight gasoline. So that "racing" 100 octane gas will likely give you better performance... not because it is 100 octane but because it has no ethanol. And the difference can be quite significant. When stations around here first started to switch to ethanol, I could feel a noticeable seat-of-the-pants performance difference when I filled up with gas compared to gasohol. Whether it's worth the added cost is an individual decision.
#11
I made the dealer give me the money and let me go fill it up to make sure it didnt get 87.
Phillips 66 Premium 93 currently. Its the only source of Top Tier rated G100 (No Ethanol) locally.
Phillips 66 Premium 93 currently. Its the only source of Top Tier rated G100 (No Ethanol) locally.
#12
Not the octane... but the lack of ethanol will increase performance. Octane is only a measure of resistance to pre-ignition and detonation (knocking). Higher octane gas is not better gas and using a higher octane than specified is just a waste of money (all other things being equal).
As with many modern computer controlled engines, the 5.0 has an optimum octane requirement (91 R+M/2) but can be run at lower octane levels. The computer compensates by retarding timing to prevent knocking but that also reduces performance. However, going to a higher octane than 91 will not improve performance.
OTOH, gasohol has less potential energy (by volume) than straight gasoline. So that "racing" 100 octane gas will likely give you better performance... not because it is 100 octane but because it has no ethanol. And the difference can be quite significant. When stations around here first started to switch to ethanol, I could feel a noticeable seat-of-the-pants performance difference when I filled up with gas compared to gasohol. Whether it's worth the added cost is an individual decision.
As with many modern computer controlled engines, the 5.0 has an optimum octane requirement (91 R+M/2) but can be run at lower octane levels. The computer compensates by retarding timing to prevent knocking but that also reduces performance. However, going to a higher octane than 91 will not improve performance.
OTOH, gasohol has less potential energy (by volume) than straight gasoline. So that "racing" 100 octane gas will likely give you better performance... not because it is 100 octane but because it has no ethanol. And the difference can be quite significant. When stations around here first started to switch to ethanol, I could feel a noticeable seat-of-the-pants performance difference when I filled up with gas compared to gasohol. Whether it's worth the added cost is an individual decision.
#15
I will say this. I have tried 4 different types of gas 3 were 91 octane with 10% ethanol from shell bp and whatever qt gas is then I found a phillips 66 that had 93 10% and have drove two tanks of that. It might be in my head but ill go back for that gas again for sure.
#16
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A gallon of 87 octane gasoline has exactly the same energy potential as a gallon of 93 octane gasoline - about 116,000 BTU. Ethanol has higher octane but lower energy potential. Pure ethanol has an octane rating of about 113 but only about 76,000 BTU of energy potential. That's why your performance (and mileage) suffer when using an ethanol blend. A gallon of E10 (10% ethanol) has only about 112,000 BTU.
So, all other things being equal, a gallon of pure gasoline (regardless of octane) will give you more performance than a gallon of an ethanol blend. The problem is... all other things are not equal. The computer will advance the timing with higher octane fuel to improve performance. I don't have numbers to quantify the difference between power produced with retarded timing for low octane fuel and power produced with advanced timing for higher octane fuel. My personal experience has been that retarding the timing to prevent knock has a bigger impact on performance than using an ethanol blend.
When gas reached $4 per gallon I tried switching from premium to midgrade to save 10 cents per gallon (knowing that the computer would compensate). That 3% drop in octane caused more than a 10% drop in gas mileage and probably about the same drop in performance. In the end, you should see better performance using the 93 octane ethanol blend than the 87 octane pure gas because the higher octane allows the computer to increase timing without risking knocking.
(This doesn't apply to the V6 engine which gains nothing by running higher octane.)
Last edited by WhiteBird00; 8/13/10 at 07:56 AM.
#18
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Anyone know where you can find no-ethanol gas in central Massachusetts, northern Rhode Island, or north-eastern Connecticut?
I'm guessing they made it illegal, but just checking.
I'm guessing they made it illegal, but just checking.
#20
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Yup, initially the E10 was promoted by the government by giving a five cent per gallon tax rebate but now it has become law. Starting 12/31/10, it will be illegal in Florida to sell gas unless it contains 9-10% ethanol. There are exceptions for aircraft, watercraft, collectible cars, off-road, motorcycles, and small engines (lawnmowers, generators, etc.). At this point the question is moot since there are no terminals in Florida storing pure gas anymore - stations would have to truck in from out of state if they wanted it.