Running 91 Octane on a 93 Octane Tune

[Cornhusker91]

Hi, I have a 2007 300C SRT8 with the 93 octane cai performance tune. I'm about to make a long distance trip and am not 100% sure along the route I'm going to take is going to have 93 octane gas. Is it safe to run 91 octane with the 93 octane tune still active? I currently don't have the Diablo Sport tuner to change it to 91 octane or else that's what I would do. Any info on this subject would be greatly appreciated, especially for the 6.1L hemi.

[mikel]

yes, thats fine.

[Cornhusker91]

So it is safe to run 91. Will there be any possible problems I should be aware of? I've heard that I will possibly get knock from running 91 vs. 93 with the 93 tune?

[mikel]

no, running 91 with the 93 tune will lead to knock.

edited to correct myself.

[Cornhusker91]

O ok lol. So not trying to sound like a broken record, running 91 with the 93 cai tune is fine. The only thing I assume will be affected is that the horsepower will go down some, but the car should run just fine even at wot? Sorry just trying to make sure the car is safe to drive. I'll probably only put maybe 4 tanks of 91 thru it before being able to put 93 back thru it.

[Mike_Levy]

No. Mike, you have it backwards. Running 91 octane gas on the 93 octane tune will cause knock. Running 93 gas on the 91 tune will not.

Do not run 91 octane gas with the 93 octane tune on the car. If you must, keep the throttle position very low. WOT will knock and you will destroy the pistons.

[Cornhusker91]

So running 91 with 93 tune is a no no?

[mikel]

No. Mike, you have it backwards. Running 91 octane gas on the 93 octane tune will cause knock. Running 93 gas on the 91 tune will not.

Do not run 91 octane gas with the 93 octane tune on the car. If you must, keep the throttle position very low. WOT will knock and you will destroy the pistons.

I need a week off. What the hell...lol.

[Mike_Levy]

So running 91 with 93 tune is a no no?

Right. Cruising on the highway will be okay, but once you put the motor under high load, it'll knock like crazy.

[Cornhusker91]

Ok. I'll have to get a few 5 gallon gas cans to take 93 with me. Thank you both for your help!

[Excavator]

Wouldn't the knock sensors take care of that?

[mikel]

Wouldn't the knock sensors take care of that?

depends what you consider taking care of....it will keep it from blowing up, yes, but it will also pull way more timing than needed and cause a loss of power below stock, which kinda defeats the whole purpose of tuning

[Vader619]

Sorry to bounce off this question but is that the same for the 3.6l ? I have 2012 challenger?, I have a CAI and dual Gibson exhaust plus eibach lowered springs.. It's on 91 octane now Will bumpin it to 93 hurt it since it's not a hemi? Thanks guys and sorry very new to this as well..

[Nietoleo123]

What about 92 octane but on 93 caí tune b/c

[mikel]

What about 92 octane but on 93 caí tune b/c

best to log to see how it likes it, or stick with the 91 tune.