DodgeTalk Forum banner

Which octane rating do you put in your HEMI?

Status
Not open for further replies.
1 - 20 of 33 Posts

·
cas66ragtop
Joined
·
17 Posts
Discussion Starter #1
I just recently bought my 2007 Ram HEMI. I was reading the owners manual, and in one place it suggests 87 octane gas is just fine, and in another place it suggests 89 octane. :huh: Which is it??

I have been "playing it safe" by using 87 on one fill up, and then the next time I fill up, I use 89 - and just keep alternating. I just dont want to do anything to hurt my engine. But I also dont want to buy 89 if I dont have to, as bad as the gas prices are now. :crazy:

What do you guys use?
 

·
Registered
Joined
·
23,005 Posts
I run 91, since I have SC on performance tune. But otherwise my truck has run on 89. Its recommended to run 89, but 87 will work fine.

KB
 

·
cas66ragtop
Joined
·
17 Posts
Discussion Starter #3
OOPS - i just saw that SCDAREN posted the same octane question only 8 hours before my post (shown on next page).

Damn do I feel schtoopid for not looking for responses to questions already asked by others!!! :WHT:
 

·
6.1 FTW
Joined
·
2,307 Posts
I use 93 now because of my mods, but I never had a single problem with 87. If you can run 87 and don't get pinging, knocking, or noticable power loss, then that is what you should run.
 

·
Speed Junky
Joined
·
48 Posts
HoustonHemi said:
I use 93 now because of my mods, but I never had a single problem with 87. If you can run 87 and don't get pinging, knocking, or noticable power loss, then that is what you should run.

I kinda figured the same thing, but since the manual calls for 89, I thought maybe there might be some inaudible knock or something.
 

·
Registered
Joined
·
256 Posts
I can't get 89 around here, so I use 87. Seems to work just fine.

I'll top off at Costco on 91 when I'm down there, since it's 15 cents cheaper there than the regular gas stations....but otherwise 87.
 

·
Got 2 Hemis
Joined
·
5,042 Posts
I use 89 most always. Every now and then I'll put half a tank of 93 in him. We don't have 91 here, so I figure that impromptu blend is close enough.
 

·
6.1 FTW
Joined
·
2,307 Posts
Running 91 or 93 in a regular Hemi without compression mods is not a good idea. The octane rating can be thought of simply as a measure of how slow the fuel burns. 87 burns quicker than 89 and so on. So all you want to do is run the lowest octane fuel that will not pre-ignite in your engine. The Hemi PCM will automatically retard timing based on knock sensors up to 9 degrees to prevent detonation. So if you use 87 you could be getting a very small performance hit but no detonation. If you run 91 or 93 in a stock Hemi you probably will just get a shatty performance because the fuel is not going to burn fast enough. At the very least it is a waste of money.
 

·
Speed Junky
Joined
·
48 Posts
HoustonHemi said:
Running 91 or 93 in a regular Hemi without compression mods is not a good idea. The octane rating can be thought of simply as a measure of how slow the fuel burns. 87 burns quicker than 89 and so on. So all you want to do is run the lowest octane fuel that will not pre-ignite in your engine. The Hemi PCM will automatically retard timing based on knock sensors up to 9 degrees to prevent detonation. So if you use 87 you could be getting a very small performance hit but no detonation. If you run 91 or 93 in a stock Hemi you probably will just get a shatty performance because the fuel is not going to burn fast enough. At the very least it is a waste of money.

I've played with octane and fuel in high performance applications a lot, and I can guarantee you there will be no noticable performance hit using 91 octane fuel. Yes it does technically "burn slower", but I would be willing to bet money that if you filled up the same truck with 89, ran some passes, and then put 91 in it and tried again, you wouldn't see a difference.

I run the 91 because it's the same price for me, and if I'm towing or just beating on my truck for the fun of it, I don't have to worry about any pre-ignition due to using less octane than is recommended. Spark knock does way more damage than it's tiny noise indicates, I can tell you that with absolute certainty :)
 

·
Registered
Joined
·
10 Posts
One of the reasons I bought a Superchips

With the Superchip tuner, I run 87 octane most of the time. Only if I had a reason to load the highest performance profile would I use a higher octane and tuner level.

Abomb
 

·
6.1 FTW
Joined
·
2,307 Posts
Fryguy302 said:
I've played with octane and fuel in high performance applications a lot, and I can guarantee you there will be no noticable performance hit using 91 octane fuel. Yes it does technically "burn slower", but I would be willing to bet money that if you filled up the same truck with 89, ran some passes, and then put 91 in it and tried again, you wouldn't see a difference.

I run the 91 because it's the same price for me, and if I'm towing or just beating on my truck for the fun of it, I don't have to worry about any pre-ignition due to using less octane than is recommended. Spark knock does way more damage than it's tiny noise indicates, I can tell you that with absolute certainty :)
Fair enough. I'm not rattling your cage. Rare situation to be able to get em same price though.
 

·
Speed Junky
Joined
·
48 Posts
HoustonHemi said:
Fair enough. I'm not rattling your cage. Rare situation to be able to get em same price though.
I totally agree, if I couldn't get it the same price, I wouldn't do it.

Around here (Michigan), 91 octane is kinda rare, most have 87,89,93/94. The gas station that has 91 for the same price as 87 is right near my work. I'd never put 93 in it unless I put timing in it somehow.
 

·
Registered
Joined
·
4,832 Posts
93 octane durring the week and 100 on the weekend when I go play. The gas station by me has 87/89/91/93/100/e85 at the pump. My hemi with the mods it has gets KR with with anything under 100, its not noticably knocking because the sensors pick it up and pull timing before you ever know its going on. If you hook up a scan tool you can monitor it though.

fryguy nice notch :gr_patrio
 

·
You've been Hijacked
Joined
·
14,749 Posts
87 because I'm using the superchips 87 tune for the winter.
 

·
Mopar Madman
Joined
·
135 Posts
93 year 'round.
 

·
Same Name, Different Game
Joined
·
9,640 Posts
My truck never gets anything below 89.
 

·
Registered
Joined
·
1,364 Posts
I've been using 87 since day one, no issues other than the up and down $.
 

·
Milkman
Joined
·
444 Posts
I run 93 all the time now since I got the SC programmer but before that I always ran 89. I quit driving my truck so much and started my V6 mustang. Only put 650 miles on it since September! So the price of 93 doesnt bother me so much anymore.
 
1 - 20 of 33 Posts
Status
Not open for further replies.
Top