Octane Fuel Question??

[pro151]

Bad natured post after I admitted making a mistake, shame,shame

You misunderstood my answer. I was simply answering his question about the difference.

I am wounded gravely that you would even think I was taking a cheap shot at you.

Oh the pain, the agony, the unending suffering of my tortured soul.............................

 

[Brake Weight]

High octane in a vehicle set up to run low octane is throwing money away. My DD has a turbo inline 4 and is programmed to run 91(US). To complicate matters, I advanced the timing 1.5 degrees and spray a water/meth (60/40 ratio) and it pulls very hard for a 1.8l. Night and day next to a stock one. To complicate matters further, a higher water ratio produces more power and more methanol produces a cooler burn. Anything over 50% methanol is not recommended, though. Some guys tinker with alcohol and H2O2, but that's more than I want to fool with. A 60/40 gallon will last about me three tanks of gas taking it easy. My piston tops look brand new and after a hard pull, the intake manifold will have condensation if it is hot and humid weather. It works well and I highly recommend a w/m set up for all turbo engines. EGTs, as well as intake temps will plummet, and the turbo will thank you.

 

[Watergate]

Approximately 2006 miles.

Is that figured with the RON+MON/2 standard?

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[Se7en]

High octane in a vehicle set up to run low octane is throwing money away. My DD has a turbo inline 4 and is programmed to run 91(US). To complicate matters, I advanced the timing 1.5 degrees and spray a water/meth (60/40 ratio) and it pulls very hard for a 1.8l. Night and day next to a stock one. To complicate matters further, a higher water ratio produces more power and more methanol produces a cooler burn. Anything over 50% methanol is not recommended, though. Some guys tinker with alcohol and H2O2, but that's more than I want to fool with. A 60/40 gallon will last about me three tanks of gas taking it easy. My piston tops look brand new and after a hard pull, the intake manifold will have condensation if it is hot and humid weather. It works well and I highly recommend a w/m set up for all turbo engines. EGTs, as well as intake temps will plummet, and the turbo will thank you.

The company that is doing the pcm tune is giving me a choice on shift firmness and octane choice...since I am paying I might as well go with high octane...? No point in getting a performance tune and run normal gas right ? I can afford the 40¢ difference per gallon at the pump.

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[KF7RUQ]

To put it in layman terms. The higher the octane level is, then more compression, and later ignition timing you can have. If you change your powertrain control module, or reprogram it, then your ignition timing will will be retarded for better performance.

The more that your new computer or program retards your timing, the higher octane level you need. This is because the fuel/air mixture can spontaneously ignite just under the pressure of being compressed, and a higher octane level prevents that.
.................

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Partially correct......

Higher compression does like more octane, but your timing statement is going in the wrong direction. It supposed to be Advanced, instead of Retarded.

Ignition timing is (BTC) Before Top Dead Center. "Free HP" comes from advancing that BTC number. It's an old "Trick."

Also, advancing the timing causes higher levels of NOX. Hippies say that is the cause of Acid Rain. (If that was or is still around.)

Retarding the timing is common or needed when Boost or Alcohol is involved.

I'm not wanting to start a fight, but just to get the OP's question correctly answered.

 

[Se7en]

Can i get a straight answer on this question.

Why would I NEED OR WANT to step up the octane if I am just getting a pcm tune ?

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[KF7RUQ]

Can i get a straight answer on this question.

Why would I NEED OR WANT to step up the octane if I am just getting a pcm tune ?

Here you go.....

On a programmer, when you choose a "Higher Octane," the programmer will download/provide a different Fuel MAP and Timing MAP. The different MAPS will require the different octane levels. But most engine management systems will retard the timing if "Detonation" is detected, anyways.....

Some people like the "Performance" and some like the increase in "Mileage" or MPG's, if you can keep your foot out of it....:laugh:

First Question: Why is there three options for fuel octane at gas stations?

Three different Octane choices are typically based engine needs and Personality flaws/insecurities. Like stated in other posts, Engine compression, Timing, Boost, and Temperature will determine the engine octane requirements.

Personality flaws equal someone "Feeling" that their car/truck runs better or faster on higher octane. That's kind of like saying that the car/truck gets 2 MPG more, with a good wax job.... :laugh:

Mid Octane fuel is just a way for the manufactures not to Waste their batch extras. They combine the "left-overs" and target the people that are too cheap to buy the high octane, but "Feel" that their car/truck needs something more than the Low Octane fuel.

Second Question: I am getting a Second PCM for my truck and its being tuned for harder shifting etc...How and why would i need to bump up my Octane?:w00t:

Why is answered above... How is based on what you vehicle is. Some of the older motors will let you adjust your "Base Timing." Others will be adjusted with a programmed "MAP."

Line Pressure increase, through programming is a good thing. (Harder Shifting) Typically two clutch packs are engaged at the same time, during a shift. Increased Line Pressure speeds up the transition and makes a "harder"/crisper shift. The bad part is..... it isn't as comfortable, makes you spill your coffee, or makes you smear your lipstick......:laugh:

note: i bought my truck used and it appears there is no rev limiter. it should be set at 3000-3500RPM but i am able to red line it in park or neutral so maybe my current pcm is tuned already but i am not sure how to check it? today i ran the truck till it was about to die and filled up with 91 Octane and wow my engine is very PEPPY.. Sorry about the silly questions but hey i have to ask and listen if i want to learn right?

3500 RPM is a safe limit for a Diesel, but a gas motor should be a few grand more. But this still depends on the type of engine and the internal(s) condition.

I don't know what else to say......but now, I have answered your questions. Take it for what it's worth......

Good luck with the new machine....

 

[Mudfoot]

He just gave you $40 worth of advice.

 

[KF7RUQ]

He just gave you $40 worth of advice.

So, I guess that the extra $39.98 is a tip.......:laugh:....

Thanks, but I thought that it was only $.02 worth.......:laugh:

 

[Watergate]

Partially correct......

Higher compression does like more octane, but your timing statement is going in the wrong direction. It supposed to be Advanced, instead of Retarded.

I'm not wanting to start a fight, but just to get the OP's question correctly answered.

I knew what I meant just not what I was saying. I did correct it later, and i hope that everybody gets what you and I are trying to say.

It's the next day and I have slept since then. You ever think one thing and say another?

Advance, not Retard.

I need a higher octane coffee.

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[KF7RUQ]

I knew what I meant just not what I was saying. I did correct it later, and i hope that everybody gets what you and I are trying to say.

I figured as much, after reading through the rest of the posts.

I guess that I should have read all of the posts, before I added my $.02.