No **** that ****, every time one of these threads gets started up AGAIN, it ends up by the end of it turning into a, "I'm right, you're wrong, go **** yourself" type of deal. EVERYONE gets involved, calls each other names, etc. Before I would just post what was in an owners manual or in the FSM. On this topic I'll be a d!ck and tell everyone to go and figure it out for yourself.

 

Dang dude. Get an enema or something to relieve the stress.

 

Stress has nothing to do with it. It happens every time.

 

how bout we get back on track here guys... octane does matter do a google search and you'll find your answers. If stock always use what the manufactors recommend, and depending how much you mod it- really just with the timing of the engine and temps depends on how much more octane you need.

 

So basicaly if you got no mods stick with 87. And if you got mods go with 91? Like I got a custom cat back magnaflow exhuast, drop in k&n filter and a superchips tuner set to 91 performance, am I okay running 91 then?

 

There is a similar thread started in 2nd gen yesterday.

I'll repeat what I put in there... only three reasons you should run anything higher than what the manual states.

1. Cheaper (example: 89 octane out hear is 10% ethanol, tax breaks end up making it cheaper)
2. Hide a blown plenum gasket or similar problem (reduce ping, this is mostly for us 2nd gen guys with the 5.2L V8 or 5.9L V8, not you 4.7L V8 or 5.7L V8 3rd gen guys)
3. You have a programmer/tune that allows you to take advantage of the higher octane

The Hemi calls for 89 in the manual, put in 89. If the 4.7 calls for 87, use 87. No reason to run any higher unless you have a Hypertech, Superchips, SCT, or equivalent programmer/tune to take advantage of the higher octane rating. Factory is designed for the octane specified in the manual, going higher does absolutely nothing for you except for the previously mentioned reasons.

Biggquis, I hope the 3rd gen mods don't mind, but I am helping you out of this thread. You appear to have just popped in here to stir the pot. Lonestar may have been a little harsh, but he was on topic.

 

stock 4.7 87
mod 4.7 with 89 tune 89
mod 4.7 with 91 tune 91
stock 5.7 89
mod 5.7 with 91 tune 91

seems pretty straight forward to me

dirtydog maybe we can add this to the common problems/question sticky

 

I would agree with Marx, however it's NEVER a BAD IDEA to run a higher octane gas than the engine calls for. IT WILL NEVER DO ANYTHING NEGATIVE to your engine, but it may not do any better than the octane the engine is tuned for either.

Because the profit margin is higher in higher octane fuels, many gas/oil companies use better (more expensive) additive packages with the premium fuels. So over the long haul, engine life could theoretically be extended when using these fuels.

IF any engines documentation states: XX octane is ok, but XX octane is recommended. USE THE HIGHER OF THE TWO! UNLESS the engine has knock sensors built into it, like the 4.7 HO. The standard 4.7 & HEMI does NOT...

 

If you ever get into advance tuning and actually WATCH the PID you record and how they react with lower octanes versus higher, you will visually see the difference. If you can see the different and understand the mechanics of an engine then you can understand why higher octane can be better.

I did not learn all of this until recently even though I have built several engines in the past. But the tuning aspect is what I am learning and can now understand.

 

Nothing but 89 or higher for my 5.7 Ram and 300c, as the manufacturer recommends. I have put 87 in the truck on accident before and just follow it up with 93 at half tank.