2007 Tahoe octane?

[a_kraker99]

So I realize running higher octane doesn't make sense unless compression is higher and you are experiencing preignition, but I was e-mailing Justin from Blackbear and he told me that the lowest octane he tunes for the 2007+ 5.3 is 89 and that I should be running 89 even while it is stock.
The manual says 87 which Justin says is acceptable but not optimal. Has anyone else heard this? What octane are you running on your stock 5.3's?
I am inclined to believe him considering the fact that I am showing some knock retard under higher engine loads with 87 octane. I still had some KR with 89 but not as much. I had 0 KR while running e85.

 

[imi4tth3w]

just get the 93 oct tune from bb and don't worry about it anymore and enjoy all your new found power

use top tier gasoline (shell, exxon, google it) much better refined and better for your truck as well.

87 oct is fine for 99% of the world. its lack of basic maintenance that will kill an engine LONG before using lower octane fuel will. also, a bad batch of fuel can do some damage. stay away from little hole in the wall gas stations. like mentioned before, can't go wrong with top tier gasoline. i strictly use shell gas in all my vehicles.

 

[CHOO CHOO]

at least run 89. Is a few dollars really gonna hurt. you are gonna get better mpg's w/ 89 unless you are a lead foot. i run 93 or 91 if thats not available. hell its only 5-7 more dollars a tank. i think we can spare that for our vehicles.....

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[imi4tth3w]

at least run 89. Is a few dollars really gonna hurt. you are gonna get better mpg's w/ 89 unless you are a lead foot. i run 93 or 91 if thats not available. hell its only 5-7 more dollars a tank. i think we can spare that for our vehicles.....

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do you have an aftermarket tune to run higher octane fuel? if not your just wasting your money.

 

[CHOO CHOO]

do you have an aftermarket tune to run higher octane fuel? if not your just wasting your money.

bb tune. One set for 89 oct and one set for 91 oct. i just run 93 all the time because i never take it out of performance mode and sometimes i cant find a quality gas station that has 93

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[imi4tth3w]

bb tune. One set for 89 oct and one set for 91 oct. i just run 93 all the time because i never take it out of performance mode and sometimes i cant find a quality gas station that has 93

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i'm guessing you have autocal then?

and i agree if your going to get a tune, do the highest octane you have available. 93 is available everywhere here so thats what i went with. i can pull 15-16mpg on the highway easy when i had 35's and stock 3.73's with 10" of lift.

last 2 fill ups were 13.5 and 14 mpg on the current set up, 33's with 6" lift and thats almost all city. starting up and driving 1 mile to work and 1 mile back. 4 times a week. 93 oct is definitely worth it. i saw 19 and 20 mpg when i first got my tune back when i was stock.