91 octane gas with a 93 octane tune?

[Mishri]

How many tuners here say it would be safe to run 91 octane gas using their e-mail 93 tune? I received an e-mail tune that is labeled 93 octane, I only have 91 octane gas in my area. I was told that it's fine to run 91 octane with that tune. What are your thoughts on this? I understand the 5.0 is supposed to pull timing automatically when different octane gas is used, but then some peoplel are blaming #8 piston problems on wrong octane gas used.

basically, my thoughts are, no, absolutely don't do it. I just want to see if other tuners would say yep, should be fine.

 

[2014_GT]

D-E-T-_-N-A-T-I-_-N. I'd like to buy a vowel.

 

[Lee's05GT]

Im no tuner but I would think that the car would run like shit if it had a 93 tune and your using 91 just my thoughts

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[JEWC_Motorsports]

I wouldnt do it on any car.

 

[Black 5.0]

"I was told that it's fine to run 91 octane with that tune."

By who? In my opinion, you don't run a 93 tune on anything less that 93. Especially the 5.0s. Your fooling with trouble by burning a fuel needing more heat to combust on a car set up with increased timing and a leaner A/F.

That being said, If all you can get is 91 and you insist on using a 93 tune, at least get a octane booster or a couple gallons of race fuel (unleaded). Don't run straight 91!!

 

[Lee's05GT]

Or....get a 91 octane tune

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[Wnt2gofst]

Then it is going to go

BOOOOOOOOOOOOOOOOOOOOOOOM.

 

[Rob72]

Don't do it!

 

[HELRAZR]

Not worth the risk

 

[Scott_0]

come on man! dont become a part of the #8 statistic, with a tune the timing is increased slightly as a means to make more power, if youre running 91 octane on a 93 octane tune you run the risk of the knock sensors not being able to pull enough timing to squash detonation. if anything Id run a 91 tune on 93 octane gas

 

[ixtlan]

I ran a 93 tune on 91 gas with no problems.
But I am at 4700 feet too.
With altitude the octane need is less.
I watched very closely for the detonation issue though.
Datalogs and all but never got any.
The math is for every 3000 ft you reduce your octane requirement by 1 to 2 ROM.
This is because the higher the altitude the less air there is to burn fuel.
The result is you run richer at altitude so the pcm reduces the fuel to keep the air/fuel ratio in range.
Be careful and datalog to verify.
You may need to retard the global timing to compensate also.

 

[2012GT]

Yea man, don't play with that. Steeda sent me an 87 and 93 tune. To be honest, I can't tell the difference. Both are as abrupt as hell. If i were in your shoes, I would call Gus at Steeda and have him send you a 91 and 87 tune with their CAI. Your car will turn into a beast. I have considered just running the 87 tune on my car due to it feeling just as strong as the 93.

 

[Mishri]

well basically what happened is I ordered parts+tune from a friend who runs his own performance business. I told him i needed a 91 tune, he got a 93 tune from bbr, I told him i couldn't use it, no 93 here. He is SCT certified, and works primarily on mustangs. He said he'd get me a new tune, then a few days later he sent me a text saying BBR said it would be fine to run 91 on their 93 tune. I am at about 3200' elevation.

 

[DIB5.0]

Lund told me it was ok to run 91 on a 93 as the car would pull timing if needed. I have not done this though.

 

[Deez-67]

Octane booster?

I've run 93 tune on 91 before didn't seem to hurt it at all. how much is 2 octane really?

 

[Mishri]

yep, with the elevation im at, the 2 octane difference, probably not a huge deal, and yeah, it's supposed to automatically pull timing if needed. but with the #8 issue it just has me wanting to avoid any problems.

 

[Scott_0]

this very thread and the thinking by some in it are where the #8 issues are cropping up from, aggressive 93 octane race tunes being run on 91 and sometimes prolly even lower octane because...................what is 2 octanes points really? its a huge fucking difference on a high compression motor with pistons made of glass and a #8 cylinder known to run hotter than the other 7, the dopes out there running race tunes on lower octane than the tune was built for with jacked up timing are the ones eating #8's

 

[2012GT]

Screw it man. Try it on E-85. I bet it's worth 75 hp

 

[Rob72]

One theory is that bank 2 knock sensor cannot pick up knock in #8 until major damage has occurred. Who is going to pay for that if that happens?

 

[DDTCM]

Not to be a dick but why in the hell would you even want to consider running a lower octane tune if it is tuned for 93,anxious? That would never even cross my mind.I would call and say,"Hey,I ordered a 91 tune and got a 93 tune,how soon can you have the correct tune sent to me"? End of fucking story,dont risk it brother.....is it really worth the risk?