91 octane on a n/a ze is a must?

[hgallegos915]

"We're at 4000ft average. You don't NEED premium up here, unless you're forced induction or have crazy high compression ratios like 12.0+."



as per a local website i got...

is there truth in this matter..? isnt that why we have a knock sensor for detonation?



I really am at 4000 ft. Any input?

[Mooneggs]

I've been wondering this for a while as well... I was always told to use 93 octane in my ze and I always have but I've wondered if I can use lower grades as well (with the gas prices skyrocketing)

anybody have a for sure answer on this?

[mdavis]

I'm at about 2400. The other day I accidentally put 87 in (87-89-91 in California). while temporarily using the K8 ECU w/ KL02 VAF (functioning ECU/check engine light codes). I noticed a huge loss in power -- read-out the EDU codes to see (knock sensor). Checked sensor wiring, then cleared the codes and drove a few times over just to make sure it kept coming back -- yep. After burning all the 87 and put some 91 in again -- instant fix. Power was back and the knock sensor code went away.

[ElectricEnergy]

I read somewhere that the ZE is designed to operate on the extreme edge of knocking at full throttle. It doesn't just use the knock sensor to stop the engine from blowing up when something goes wrong, it uses it to keep the timing advanced as far as it possibly can before it starts to knock and then stays right on that line. So it makes sense that using lower octane fuel would result in a loss of power.

Of course, I might be wrong about this, I only kind of vaguely remember seeing it somewhere.

[marcdh]

standard unleaded over here is 95 RON... maybe that's partially why it's so damn dear! Super/Premium is 98 RON.

And yea pretty sure your right about our cars using knock sensor for ECU controlled increased performance -

Knock control is used to allow the ignition timing to continually approach the point of detonation. This is the point where the engine will produce the most power, as well as the highest efficiency.

[V8KOMX3]

I normally use 91 octane or 93 whewn in florida but I used 87 in 2 fills before and had no problems and I used the 87 at 5600 elevation...

[fowljesse]

I use 89 sometimes. I believe my ECU retards the timing enough that it doesn't do any harm. It isn't as strong, though, and I lose about 3 MPG. I'm researching which is cheaper.

[Mnemonic]

ran 87 on accident and engine started running poorly, i ended up having to put some octane booster in.

[onlytrueromeo]

What about a DE? I'd imagine with the slightly lower compression that it wouldn't be required? Honestly, this might push me to buy a DE instead of a ZE if I hafta pay for ultra premium gas all the time

[onlytrueromeo]

Interesting IDEA!

What if you were to mix e85 with regular 87 octane gas - wouldnt this give you the octane boost, AND save you money? I'm borrowing this from performanceprobe.com

What if you were to mix e85 with regular 87 octane gas - wouldnt this give you the octane boost, AND save you money? I'm borrowing this from performanceprobe.com About E85: A Mazda 626 with a 2.5L engine(=Probe GT) should run on up to 40% E85 and 60% 95 Octane without modifications. It could get hard to start when it's cold .
To be able to run on only E85 you need a fuel heater (for start in cold climate....if you do) and some modifications of the fuel/ingition system.
The sheapest way is to replace the fuel pressure regulator to an adjustable one and increase the fuel pressure, since the engine needs about 20% more fuel when run on E85.
Another way is to install a trim chip adapted for E85, which extends the injection times. This will also give you more hp when you run on normal fuel.
The latest way, which I hear of this very morning is a add-on chip which you connect between the lambda sensor and fuel injection valves. My gess is that it simply extends the valve opening times (more fuel) according to the fuel mixture (free mixing). It's sold by a Swedish company named AutoFFV. The price for a V6 is about 720$ at todays dollar rate.

By the way, mixing a few percent of E85 in the fuel gave me som more power. I tested it on a Ford Mondeo 2.0i. On normal fuel it made the test 0-100km/h on 12 sec.
With approximately 25% E85 it manged the test on 11 sec.
Using E85 in old cars has it risks since it dissolves deposits in the tank and fule lines which can clogg your injection system. I fueled 25% E85 in My 2.5GT (unconverted) last week. 4 gallons later it choked and stopped![

Apparently we could substitute SOME e85 in, which is cheaper than regular gas. This quote says "and 93 octance" but I think it would work with 87 too, right? Since I will be doing a swap soon, I don't mind rippin out my hoses and whatnot, but I don't have the $$ to shell out for a full e85 conversion.

[fowljesse]

E85 sucks.
I don't know if it would be more economical, but the cheapest octane booster is Toluene. You can get it at paint stores. People use it with pump gas, instead of race gas, to save $$, while raising octane to around 120. Acetone boosts octane a little, too, and lowers the surface tension of the gasoline molecules, so it atomizes better, and burns more thoroughly, increasing mileage.

[onlytrueromeo]

Isn't toluene a rediculous solvent thats extremely toxic? Google says its about 25$ a gallon, how much do you sub in for an additive?

[Nd4SpdSe]

I've only done a few tanks of regular fuel, but when I do, fuel economy is horrible when I do.

[fowljesse]

Isn't toluene a rediculous solvent thats extremely toxic? Google says its about 25$ a gallon, how much do you sub in for an additive?

Unfortunately, I can't copy/ paste on this computer, but if you google "Toluene octane" there are really good articles about it. It seems that you can get it for $2.50/ gallon, and each gallon would raise octane by 2.
I'll have to look into it's ridiculousness, and toxicity.

[onlytrueromeo]

http://store.hamiltonmarine.com/browse.cfm/4,5722.htm" onclick="window.open(this.href);return false;

Thats about an average for the prices I've found online, maybe it's something different in the paint stores. I did find that article you were talking about, but also found a bunch of articles saying that toluene is a biohazard product, and some companies wouldnt ship it without a biohazard label.