Custom tune question

[Riceball1]

I have custom tunes on my Gryphon and love them (Thanks Bill) but I was wondering if you can just change the octane setting to run 93 octane on the 87 performance tune. Are there other things that need to be changed? Just wanted to see if there was a difference in performance.


Thanks
Bob

[Jackpine]

Originally Posted by Riceball1

I have custom tunes on my Gryphon and love them (Thanks Bill) but I was wondering if you can just change the octane setting to run 93 octane on the 87 performance tune. Are there other things that need to be changed? Just wanted to see if there was a difference in performance.


Thanks
Bob

Bob, your question is probably best answered by Bill, but I don't see how you change the octane setting in a tune. I don't recall that being a custom setting option. You COULD advance the spark timing on any of the tunes if you ran with higher octane, of course, but this would probably not give you the full benefit of using the more expensive stuff.

I'm 99% sure you need a specific, custom tune for 93 octane if you intend to use it. Bill can put that tune on any of the levels though.

- Jack

[Riceball1]

Originally Posted by JackandJanet

Bob, your question is probably best answered by Bill, but I don't see how you change the octane setting in a tune. I don't recall that being a custom setting option. You COULD advance the spark timing on any of the tunes if you ran with higher octane, of course, but this would probably not give you the full benefit of using the more expensive stuff.

I'm 99% sure you need a specific, custom tune for 93 octane if you intend to use it. Bill can put that tune on any of the levels though.

- Jack

yea I meant to say advance timing. I was just trying to see if that was an option now that gas is so cheap

Bob

[Jackpine]

Originally Posted by Riceball1

yea I meant to say advance timing. I was just trying to see if that was an option now that gas is so cheap

Bob

No worries, Bob.

But, you might consider this: I recently looked at the difference in price per gallon between 87 and 91 (which is what we have here in Tucson) and found it was 22 cents. Now, where I buy gas, I get 87 for $1.499, so the difference in price is roughly 16% to go to the premium stuff. To break even, I'd have to see an increase in MPG of 16% by using the higher priced blend, which for me would be about 1.94MPG (using 15MPG with 87 octane as a baseline).

Here's where my memory is fuzzy though. Back when 87 octane gas was near $4.00 per gallon, I never even looked at the price of 91. If it was still only 22 cents higher, it would only cost a bit over 5% more to use it and at that price spread, I'd only need to improve my MPGs by about 0.75MPG.

So, it's possible that if the cost of gas DOES go up again (and it probably will), we all might do better running hi octane tunes.

It's something to think about.

- Jack

[Corey Cohron RIP]

Don't do it...

The answer is that TECHNICALLY you can run 93 octane with an 87 calibration. However, you run the risk of detonation even with retarding the timing. Also, your 87 calibration was written with a particular timing curve. By backing off the timing of a 93 octane program, you are affecting the whole timing curve and will be sacrificing fuel economy.

Ask yourself, "Self, is it worth it? Am I feelin' lucky?"




Yay! I knew the answer!

[Northern Supercrew]

well...that didn't make me happy i'm doing the same thing...running 91 octane on my 87 perf tune...just cause wifee f'ed up and put that in, i raised the timing 2 adjustments and everything seems good, but.........i better put 87 back in or run the canned 93 tune i guess.

[Jackpine]

Originally Posted by Groovy Chick

Don't do it...

The answer is that TECHNICALLY you can run 93 octane with an 87 calibration. However, you run the risk of detonation even with retarding the timing. Also, your 87 calibration was written with a particular timing curve. By backing off the timing of a 93 octane program, you are affecting the whole timing curve and will be sacrificing fuel economy.

Ask yourself, "Self, is it worth it? Am I feelin' lucky?"




Yay! I knew the answer!

Corey, respectfully, I'm not sure you're right on this and I think we need an opinion from the Mad Doctor.

I believe you can ALWAYS run higher octane fuel in a low octane fueled vehicle. (OK to run 93 octane in an 87 octane tuned truck). And, since the octane is higher, you should be able to bump the timing a bit to at least recover most of what you would lose by using the higher octane fuel in a lower octane tuned vehicle.

The reverse is probably not true. I wouldn't try to stick 87 octane into a 93 octane tuned vehicle, because, as you say, you still run the risk of detonation under certain conditions (unless you backed the timing WAY off).

But, he won't get the full benefit from using high octane fuel unless he has a custom high octane tune - we agree on that - 100%.

- Jack

[Corey Cohron RIP]

(The Mad Doctor was standing over my shoulder while I typed the other post so I could verify I was right!) I think we're saying the same thing, Jack (and I would never be offended if you corrected me!). You can always use a higher octane fuel in a lower octane calibration (it would be a waste of money, but you could). The problem comes with the reverse. Using 87 octane fuel in a 93 octane tune can cause detonation unless you bump the timing. What I was saying is that due to the timing curve on the 93 map, you sacrifice fuel economy by messing with the timing manually.

Is that what you said, too?

Is that what I said before?

[Jackpine]

I think we're on the same page now, but he was asking about using 93 octane gas with an 87 octane tune.

Quote: "I was wondering if you can just change the octane setting to run 93 octane on the 87 performance tune."

I said yes, and he could probably bump the timing to gain a bit of power to offset the increased cost of fuel, but it would not be as good as a true custom tune.

You said, Quote: "The answer is that TECHNICALLY you can run 93 octane with an 87 calibration. However, you run the risk of detonation even with retarding the timing."

And here, I think is where we crossed ideas. But, I now believe you were thinking he should not put 87 octane gas into a vehicle that is tuned to run 93 octane (and that's why you mentioned "retarding the timing").

But, I understood you were saying not to put 93 octane gas into an 87 octane tuned vehicle, or damage could result. And, I was puzzled by your comment on retarding the timing. Also, I'm pretty sure Northern SuperCrew thought he should either replace his fuel tank contents with 87 octane (OK, but wasteful) or raise his tune to 93 - which would be bad, since he'd be burning 91 octane in a 93 octane tuned truck.

So, all is well, now that we are communicating again. Riceball and Northern SuperCrew are you with us now? It's OK, just not particularly efficient, to burn a higher octane gas in a vehicle tuned for 87. And, if you do it, you can advance the timing a bit. (The Edge/Gryphon manual even gives you guidelines here as I remember).

- Jack

[Northern Supercrew]

yep, clear as mud lol. my understanding is that you could run the highest octane in you area on the 93 canned tune..which happens to be 91 in my area. basically, no octane less than 91 on the 93 tune....but that's another rant i will burn the remaining 91 out of my tank and go back to 87 on the 87 perf tune again.