Thanks. I'm just going to use 93 without making any other changes for now. Maybe future drop-in replacement turbo, then new tune.

 

Your tune might have had an estimated fuel delivery for anything above 140kpa eventhough it was only tuned up to that amount. I've only used MS for tuning before, which can somewhat do that.

 

In other words, advanced programming to acclimate to changes?

 

No matter how much octane if it is a petroleum based fuel with the same percentage of ethanol (up to 10% from the pump) it will have the same a/f with the same tune.

I haven't done a lot of fuel testing with cars but I've done years of fuel testing on race bikes. With bikes the a/f portion of the tune will not change from pump gas to c16 (116 octane). When using a fuel that is oxygenated that is a whole different ballgame though. Specific gravity plays a role in it but most petroleum based fuels will have close enough specific gravity that any variance in a/f will be small (not enough to actually notice a difference over the atmospheric differences between WOT pulls).

My 93 octane tune runs the same a/f when I run 110 octane fuel in it. The only difference is my 110 octane map has a higher boost pressure. Vac map and boost up to that point is exactly the same.

 

^Good to know, thanks.

 

OP, you'll be fine. as long as you dont increase the boost and the timing to much you'll be fine. The octane will not affect the A/F ratio unless you change the type of fuel like increasing the amount of ethanol. Ethanol has a different weight than gasoline so changing the mixture will affect the A/F.

 

Good information, I'll have to read over this a couple more times.

Indeed

I'm tuned already with osiris by SpecialtyZ, I couldn't adjust timing if I wanted to. From my new understandings I don't need to increase wg (increase boost) at all with 93 octane, nor should I....I'm not get another dynotune right now.

 

The way I've understood octane is "safety" not performance. You don't increase performance with octane (alone)- or change a fuels consistency... You simply increase a margin of safety to accommodate more aggressive tunes.


I'm a know nothing- but I've been learning about the same stuff as you are and frankly you can use 93 right now... But you'd just be wasting your money. The boys tuned it safely to 91... Save your money and use 91- even if you have 93 available in ny.

You're a stock block on a used kit- with minimal supporting mods. My suggestion is to stick with this for a bit. Enjoy it. You think you're broke now- blow an engine. Nothing forces your hand quite like 1 step too far.

 

Run 93 if you can. Nothing wrong with playing it safe. I use a splash of 103 octane at the track. I don't have to, but why not.

Fuel quality is highly variable depending on season and brand. Why risk your motor on a bad batch if you can prevent it.

 

I'm going to use my 91map with 93 octane fill ups in NY. Like I said, I'm not about to get another tune right now.

 

I will be in NY. Like you said, I'll play it safe.

 

I agree with the whole playing it safe thing- believe me... Up here the transition between 91-94 is prohibitive... Sort of.

I imagine your tuner was being "safe" too- you say you trust him. I mean- I can take my 99 dodge ram that says 86 and throw 91-93/4 in it all day long... There is no benefit. Just costs more.

In your situation what with boost and all that- yeah 93 is safer. But if you're tuned to 91 you should feel "safe" at 91.

Reminds me of the high angle environment- guys who aren't comfortable tend to want to safe everything quadra- redundantly...

If you pull the trigger and your engine blows up... I would be surprised if octane had anything to do with it. But down there if the price difference is pennies per gallon... Like djamps says it certainly won't hurt