[clidefr0g]

I recently found out that one of the particular gas station chains where i live sells 92 94 and 96 octane, and for the same prices as the competitors 87 89 91, When i first put in 96 i noticed a huge difference, its like it cleaned out a bunch of shit and it ran really good, i also added it to about 1/4 of a tank of 89. This gas has 10% ethanol in it as well figured id mention that.

Now, it seems like car car runs ok, sometimes it idles high after stopping (may just be a dirty IAC) and also sometimes now it struggles to start, it wont ever not start but when its cold it will definatly rattle the car around a bit as its starting, fairly rough. when its warm it starts up NP.

So im wondering, is 96 octane TOO much? is it retarding detonation TOO much?

[C MY 4D]

Yes, timing has to be set for the gas that you are running. IMO 96 is way to much for a v6. Basically to describe octane levels briefly, the higher the octane the slower it burns. So if you have a vehicle tuned for 87, a good amount of the 96 will be burning in your exhaust.

[6ER THEN I 8ER!]

^
basically he's saying w/o a tune 89s about as high as you should run

[clidefr0g]

You guys think thats whats making it start rough? ive changed sparks/wires sofar.

[6ER THEN I 8ER!]

Originally Posted by clidefr0g You guys think thats whats making it start rough? ive changed sparks/wires sofar.

yes, basically all a higher octane will do for you will clean out everything. unfortunately there is such thing as too clean

[01stangV6]

do you think 93 is to much? i started runnin 93 for a couple of weeks now and noticed my stang runs a little smoother.

[skowvy]

All a higher octane rating really means is the less prone the fuel is to auto ignition (like in a diesel). That is why boosted cars require higher octane levels 99% of the time, because their intake temperature is much higher because of the compressed air. This means with a boosted vehicle is you were to use 87 fuel as soon as the injectors sprayed it into the hotter intake it would auto ignite causing what is known as detonation. Take the same scenario with say 91, And the fuel will behave as normal, sprayed into the air mixture then waiting till the spark plugs fire to ignite. In a NA car though since you don't (shouldn't) have high intake temps you don't need the detonation resistance of 91 or 93, so 87 or 89 will be fine. Now if there is excessive carbon or other deposits in the engine they could cause a higher temp causing detonation and requiring a higher octane fuel. But if this is the case, usually a can or two of quality fuel system cleaner will fix this, I'd try Seafoam or Amsoil Performance Improver. Using higher octanes in a properly running NA engine though is a waste in most situations. The fuels actually don't contain really anymore energy. But if the computer for the engine is responsive enough it may be able to increase timing, fuel delivery or a few other things to make a couple more ponies MAYBE! And if any it won't really be worth the extra cost in my opinion. And just for reference where in the world did you find 96 octane?! That's getting pretty close to race gas level. I don't think there is any factory car on the road that needs over 93.

[clidefr0g]

I live in canada, vancouver island to be precise.

[ESG-642T]

Yep if the car isn't tuned for it.... As much as your mind wants to tell you its running better chances are its not. UNLESS your detonating for some odd reason and the higher octane takes care of that.

[skowvy]

Originally Posted by clidefr0g I live in canada, vancouver island to be precise.

Oh ok. haha I was gonna say I don't think I've seen anything over 93 at a normal pump here in the States.

[Trick Tuners]

What Octane should i run? - Trick Tuners Forums

[v6kid]

^The answer to end all^

While you are in the discussion.. How exactly do you know if you are having spark knock, without a sensor?

[Mr. Red Pony]

Originally Posted by v6kid ^The answer to end all^ While you are in the discussion.. How exactly do you know if you are having spark knock, without a sensor?

you can hear the detonation in mid-high RPMs.

[Trick Tuners]

Yup, you can hear it, but hearing it is a very bad thing!! You can also measure it on the dyno. Cars make the most power with a tiny bit of random detonation, but there is a fine line between peak power and reliability. As you add timing you will see the power levels, go up, taper off, then go down. When the power goes down you are in the detonation zone. The goal is to stop as soon as the power stops increasing. The other way is to pull the plugs. Guys have been tuning cars since before the days of local dyno shops. They race at the track, record ET, shut down, and view the plugs for signs of detonation. The plugs show many details of the combustion including the AFR.

[v606er]

Originally Posted by C MY 4D IMO 96 is way to much for a v6.

lol



Would it be enough for a v8?

[C MY 4D]

Originally Posted by v606er lol Would it be enough for a v8?

I assumed it was stock v6 but 96 is actually what I mix my gas to for the track. So yeah it's perfect for my v8.