mazdasp33d
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- Mazdaspeed 3
What do you use and why? I mean I put 93 in since day one and the manual say nothing lower then 91, and im not complaining about gas prices in anyway I was just curious. Thanks
91 v 93 Octane?
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I think, for most of us, it's more of a mental thing than anything else. I normally put 93 in... and had to put 91 in last week (only gas station around). Car didn't run any different... in fact, I got more mileage out of that tank than ever before. (I'm chalking that up to a fluke though) Based on the limited knowledge I have on this topic... premium fuels are designed to prevent knock and detonation on cars that require them. In the past, filling up with anything less than recommended could result in engine knocking. These days, with all the advanced computers in the car, that's not possible for most cars. The only downside, then, would be a slight lack of performance.
91 is the only thing available in California unless you go to a specialty station and pay rediculous prices. It's funny, we have the strictest emmissions and bs DOT laws and the worst gas... Higher octane will prevent premature detonation due to high compression as stated above. Basically is slows down the flash front of the fuel makingit burn slower kind of the same thing as retarding the timing. With tidays knock detectors and prevention systems all that will happen if you put low octane in is the computer will cut back the power to prevent detonation. When I plan on doing "spirited" driving I add an octane booster when I fill up, otherwise I go with 91 and go a little easy on it.
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MikeHTally
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- 2008.5 Speed3, 2006 Chrysler 300C, 2003 Ram 1500
No 91 here, so 93 since new.
blake_peanut
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- 2008 CWP MS3
I found the same thing, way better gas mileage with 91 then 94 (what is available for our highest octane here in Ontario at Sunoco). I was using 94 for a while and when gas went sky high last year I started using 91. I noticed immediately tank after tank better gas mileage. So I know use nothing but 91, really what are you gaining from 94? Nothing IMO...
just put some "92 in mine. couldnt make it to the usual pump palace. i dont think its the octane that matters as much when its between 91 and 93, rather the station and brand of gas you're filling up with. i work for the government, so i usually fill up on base. its no cheaper than in town, but i've gotten noticably better mileage when i do. makes me curious what some struggling stations will claim is gas nowadays.
STAY AWAY FROM PETRO!!
Sucks ass. Used same 91 map (half tank) with all major brands in AB and petro had the stupidest most f'd up knock ever. I was better off using 87 from anywhere else....
Husky/Mohawk 94eth - Best
Husky/Mohawk 92eth - Extremely Good
Shell 91 - Suprisingly, very good (would almost prefer over 92eth cause it's non-ethanol). Same knock results (for the most case) as the 92eth. Under 2 KR, if any...
Esso 91 - O.K. Knocking around 1-3 on full throttle runs
Petro 91 - Leave the hell alone.... higher than 6 KR
Isn't the 94 mostly due to the addition of ethanol in the gas? If I recall, ethanol will give you worse gas mileage, so maybe that's why you saw an increase going from 94 to 91. Of course, if the 91 has the same ethanol percentage as the 94, then my theory is full of crap.
You would need a ECU tune that takes full advantage of the 94 in order to get a little more power. I think you're right, no advantage of going to 94 if the car can't "adjust" to a 94 octane.
All you need is 91.
Anything above is a waste of money.
Octane requirement has to do with engine compression.
If manual says 91, then 91 be it.
The Industry enjoy people's lack of knowledge and are making all beleive that higher Octane is better, runs cleaner, bla bla bla. That is bulls***.
Using 94 when 91 is specified, is like using 91 in a Minivan! No need for it.
On higher compression engines, like the Speed 3, An Octane 87 air/fuel mix can detonate before the spark plug ignite (due to high pressure). Octane 91 fuel will prevent that. Octane 94 will also prevent that. But why pay more for getting the same job done?
If by any mean you mod you car in a way that increases the in-cylinder air/fuel pressure, you may need Oct 92, 93, or 94.
Anything above is a waste of money.
Octane requirement has to do with engine compression.
If manual says 91, then 91 be it.
The Industry enjoy people's lack of knowledge and are making all beleive that higher Octane is better, runs cleaner, bla bla bla. That is bulls***.
Using 94 when 91 is specified, is like using 91 in a Minivan! No need for it.
On higher compression engines, like the Speed 3, An Octane 87 air/fuel mix can detonate before the spark plug ignite (due to high pressure). Octane 91 fuel will prevent that. Octane 94 will also prevent that. But why pay more for getting the same job done?
If by any mean you mod you car in a way that increases the in-cylinder air/fuel pressure, you may need Oct 92, 93, or 94.
Same in Calgary... since the 'no more 87'. They're all 90, 92, 94 ethanol blends...
you will get slower burning fuel with a higher octane. if you put high octane fuel in a low compression engine the computer will counter act the slower burn by adding more fuel to get a denser charge in the cylinder before ignition. because the computer is adding more fuel than is really needed your fuel mileage will go down. putting 107 racing fuel in a car that is not tuned for it will actually hurt performance, gas mileage, and emissions systems...
i think anywhere from 91-93 octane is good for these cars, if i had any mods that leaned the A/F mixture out, i would consider running higher octane, but for a relatively stock car pump gas is just fine...
i think anywhere from 91-93 octane is good for these cars, if i had any mods that leaned the A/F mixture out, i would consider running higher octane, but for a relatively stock car pump gas is just fine...
squidmotion
Member
93 with a 10% ethanol blend (mileage killer right there... ethanol)... all it's had so far..
ethanol blend is all you can get in just about all of texas now.
ahhh i remember the 11.5:1 compression days with big cams and lots of timing... i used to run half a tank of av gas, and half unleaded or full race gas. oh, the smells coming out of the pipes were GREAT!... i guess in todays terminology you could call it a 'fuel mod'...
ethanol blend is all you can get in just about all of texas now.
ahhh i remember the 11.5:1 compression days with big cams and lots of timing... i used to run half a tank of av gas, and half unleaded or full race gas. oh, the smells coming out of the pipes were GREAT!... i guess in todays terminology you could call it a 'fuel mod'...
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