Hey guys,
sure its been answered before, but I cant find it.
Im going from the 87 to 91 tune on my 3865. They sell 87, 89, and 93 by me. If I run my tank down to when light comes on with the remaining 4+/- gallons of 87 still in, then fill up the rest with 93, should I be ok with ping?
Also, for those of you with the same 87, 89, 93 ratings in your area, do you guys go half 89/half 93? or just go all 93?
I figure I will set the tune right after I fill up with 93 for the first time, about how long did you guys notice that its takes to see some results? A full tank? more? less?
Thanks for the help guys

 

I think you will be a okay.

 

I don't think it is that big of a deal. And I run 89 oct with the 91 tune all the time. There is a lot about this on the SC thread.

 

Thank you for your bussiness, We will be seeing you soon.


Your friendly neighborhood shop!

 

Huh? u run 89 on the 91 tune all the time? and you have no ping?
Well, thanks for your reply, but I will NOT be doing that.
Anyone else got any input? Ill search in the SC thread, but its so long, it takes forever to find what Im looking for.
thanks

 

i just put mine back on the 91 tune with 93 and havent had any problems with ping even with that little bit of of 89 fuel left in the tank

 

To the OP:
You will be fine if you run your tank down to at least a 1/4 tank and fill with 93. As far as trying to balance 89/93 to give you 91, although it would work just fine, I think it's going to be a royal PIA, plus I get enough better MPGs from using 93 octane over 91 to offset the cost difference. Just stick to 93 all the time.


As far as running 89 on the performance tune, you are probably pre-detonating especially on hills and quick starts. Have you ever pulled the data to see just how advanced the timing is with that performance tune? 89 octane fuel with that tune is just not a good idea and I would imagine long term engine effects would be similar to the guys who have run 87 on a stock engine long term. Most cylinder failures I have seen with the Hemi have been people running 87 in a stock truck. I think you are going to have the same issues over a long enough period of time running 89 on the performance tune...

 

we don't even have 93 round these parts. So 91 is my only option.

 

oe thats okay cause all you will have is the 91 perf tune like me....all we have is 93 so i have to run that but its okay with me cause of the offset like hammer mentioned....and redtruck you should switch that out man ya gonna hurt your red truck bad and your pocket when she blows....they say right in the user manual for the s/c run specific octane with specific tunes.....

 

Alright, thanks Hammer, thats the info I was looking for.