Tuned for winter gas?
 

I think we already have winter gas here and as always I am scratching my had over differences in fuel and how it influences my tune. I found pretty interesting article on summer vs. winter fuel. It kind of flipped my notions on winter gas upside down. Higher 02 content, lower vapor pressure and higher octane add-ons at least on the paper should help our tunes. I was tunning my car sometime in spring and don't remember what fuel I was on. Have to talk to my tuner if he has date of the tune in his logs but my question is does it influence the tune and in what way? Should midwest people tune in the winter or summer for safer tune? Link to the article here:
http://zhome.com/ZCMnL/PICS/winterGas/winterGas.html

...non of the Tuners here has any opinion on that?

The answer is it depends. The car adds timing the colder it gets. Pull logs and monitor how she does in the winter and decide. There is no reason a competent tuner can't nail a tune that works for both hot and cold.

Not every map does that. My Stage 2 map from Infamous that I got about 3 years ago has the "Timing Compensation B (IAT)" table zeroed out completely.

So does mine. I meant "by default"
The table is there and can help cope with exactly what op is asking
In mine, timing is pulled when hot but none added for cold

That seems like a fairly safe approach.

what the hell are you guys talking about ? I am not asking about temperature variations. I am talking about different chemical composition of fuel! Map doesn't know that so it can't compensate for anything.It can react by pulling timing when knock is detected. Not exactly the best approach is it? It like tuning for 93, putting 91 in and hoping for the best. Again my question is: based on the assumption that winter gas is more knock resistant, should cars be tuned on summer fuel only?

In short no you should be fine, the octane rating is what should determine if detonation will occur. Ive logged my own car all four seasons as well as seen logs from countless others. If your not knocking on summer blend your shouldn't on winter either and vice versa.

thanks much, that's what I was hoping to hear :)

No offense op but we were trying to help and gave you the correct answer. Looks like you got frustrated because you had the wrong understanding of summer/winter gas.
If you want to be 10000% positive you should log because none of us can guarantee you anything.

Dude seriously!?!?!? I know you were trying to help but you were off topic since I didn't ask about lower temperatures you were reffering to. Where the hell in my post do you see me asking about lower temperatures? The only relevance is the fact that yeh, in winter it's colder...you won!!
I think I have pretty good understanding of winter vs. summer fuel. Do you? There is enough data out there suggesting that winter gas is more knock resistant just like E85 is, obviously not to such extend. I think it's a good enough reason to raise discussion on how healthy are summer tunes that are used in the winter. We could discuss further but then you will start on other irrelevant issues so what's the point. Also, I never asked about guarantees, you missed it again have you? I asked about opinion, I asked people that understand that subject better then anyone else >>TUNERS. Everything was good and this thread would be done after Infamous voiced his opinion if not for you irrelevant whining.

I would think that if winter gas were really more knock resistant, it would be reflected in its AKI #.

Temperature plays a more important role here. That is where you are wrong and that is why you thought myself and iNVAR were off-topic.

Octane rating is octane rating. If it didn't meet 91 or 93 it would not be labeled as such. Barring that article and all things being equal, under most circumstances there is no need for summer and winter maps. We cannot give you the ultimate answer. It depends on the tune and how your car runs!

However, just looking at gas you are not getting the complete picture.
You may run into other problems making the car not run right, such as overboost, TOO MUCH timing added in the winter.
Like iNVAR and I mentioned, it depends on what the tune is.
If that table that we are talking about is zeroed out, you're good.
But, just so you understand, there IS a table which ADDS timing the colder it gets and SUBSTRACTS timing the hotter it gets.
So if the car is tuned at the very edge of running safe and during the winter now the car adds timing, it CAN throw the car off to unsafe levels and it WILL knock.
So! What does your timing compensation table B (IAT) show?
You should know this since you tuned your car.
Instead of getting angry, you should offer some more background because so far you've come across as missing some crucial overall information and getting hung up on an article you read online.

And, again, just because we have now established and resolved the issue of winter vs summer gas, you should still datalog the car to make sure all is well.

None of the conversation was off-topic, there is no whining here, you are a newbie looking to learn so if you hope for future help, it may be best that you set aside that attitude and aggression. A little humbleness never killed anyone. An attitude will marginalize you here real quick.

Precisely. It would be rated as, as an example 93 during the winter and 91 during the summer. AKI is AKI, all things being equal.
OP has too much of a simplistic and narrow view of the issue.

LE: OP, if your concern is how the car will run during the summer then yes, it is more likely it will run bad if you tuned it in the winter.
It's a moot point asking now since we are in November. I say yes, definitely watch it next summer and see.
How has the car run during this year?
Two tunes are usually necessary if you want balls to the wall power during both summer and winter. You may run max on the threshold of knock during winter, likely you will have to back out during the summer. My original point, which you missed, was that under normal circumstances the car can cope with this.
You've run the car during one season already and are now asking about summer in November. You should have datalogged throughout.

You see, again this whole conversation is off topic hence my frustration. First of all I haven't tuned my car, it was tuned for me as stated in my OP when I refer to "my tuner". I am aware of issues that might arise from extreme temperatures, addressed this with my tuner, he mentioned exactly what you are talking about and basically told me that this is a non-issue. The car was tuned very conservatively, is being logged all the time and runs great. Can we finally put the temperature issue behind us please.

Going back to my OP I have asked very simple, very specific question about FUEL. You were the one who went off on assumptions ...did you even read my OP? Stop putting words in my mouth, read OP and trust me I will be very humble. After all this we are back to square one.

I agree that octane rating should be a good enough warrant not to even have this discussion but CALI gas has rating of 91 and supposedly is much worse to tune and has worse power gains compared to other 91 ???At least that's what I gathered from all the tuning threads. The fact is, chemical composition, vapor pressure, O2 content is different for winter gas. I think we all experience little bit lower milage on winter gas. It might be due to higher O2 concentration per volume of air in cold weather in which case tune would add fuel to compensate. Theory #2 - maybe winter gas is in fact more oxyganated hence ecu needs to run little bit richer mixture? I don't know, that's why I am here and that's what this whole thread is all about. Maybe octane rating falls within some tolerance and is a non issue on 99% of the cars but could be an issue on tightly tuned turbocharged cars. Maybe that's why Subaru map is so pathetic to compensate for all that. So who again has simplistic and narrow view of the issue. You think Octane rating is all there is and I am showing some article suggesting otherwise and I am the one who has simplistic and narrow view of the problem? It's hard to stay humble when someone fails so dramatically to comprehend basic logic and tells you that you are the one that is narrow minded, don't you think?
Last but not least I am sorry for raising this question in November. I shouldn't be so narrow minded. I should make a note to ask this question in he spring so it's more relevant. You are right, talking about differences in summer/winter fuel and how it affects tune should be restricted to spring time only.