91 or 94 Octane?

[kblake905]

My local Sunoco station has switched to a shell which has only 91 Octane, I have heard conflicting advice on which is best for my stock 04. Has anyone dyno'd their car with the 2 octanes to see if there is a performance difference?

 

[plumcrazy]

octane wont change the dyno number.

 

[plumcrazy]

look here:
http://forums.viperclub.org/rt-10-gts-discussions/619452-what-octane-stock-motor.html

http://forums.viperclub.org/srt10-s...630157-91-versus-93-octane-stock-gen-ivs.html

and search octane for a ton of other info

 

[JonB]

Your owners manual asks you to use 91 minimum.

If you have a Mopar PCM, or certain engine mods, 93 or higher is recommended. But the knock-sensors can deal with 91, but performance IS dialed back a bit under load in Mopar PCM.

 

[Crompton]

heard rumor that the 94 octane will eat the rubber fuel lines out do to the % of ethanol believe that is in the fuel.True or not i switched back to the 91 octane from shell.

 

[swexlin]

Our Sunocos here, offer both 91 and 93. I use 93 in both the SRT8 and the Viper. Can't hurt.

 

[rw99]

OK, I'm looking for an update to this burning (ha!) question. Now that another 1.5 years have past, has anyone dyno'ed their stock Gen IV with 93 or 94 octane fuel in the tank? Any difference from 91 octane?

Just curious...

Rich

 

[ViperGeorge]

As I understand it, using a higher octane than is required by the engine can in fact reduce horsepower. The reason, as it has been explained to me, is that higher octane gasoline burns slower. Higher octane fuel is more resistant to detonation (uncontrolled explosion of the fuel mixture due to pressure) but it burns more slowly than lower octane fuel. Your engine must be tuned to take advantage of the higher octane or you get no advantage. This could be BS but that is what I've been told.

 

[ACR steve]

Its more about the percent of ethanol today then octane. We test the ethanol content in the race cars fuel (very easy to do with a $15 kit) and it varies from supplier to supplier. Lower the percent the better and the more detergent the better for modern day injectors........ I am no expert but I do listen to them

 

[rw99]

For the love of God, would somebody please post a dyno sheet?

Hopefully another Californian, who's similarly locked into our state-specific brews. Thanks, guys...

 

[mjorgensen Woodhouse]

93 with 10% ethanol is still better than 91 without IMO, and I doubt that without a Mopar PCM you will see any real performance gains from 91-93/10%. If there is no detonation on 91 then the timing is already advanced as far as it will allow, going to 93 won't do a thing. The Mopar PCM will allow advance over stock to use with the better fuels, but even this will not benefit from even more octane if all is the same.

 

[mjorgensen Woodhouse]

No dyno sheets, but I know that in the import tuner world they offer California spec tunes for turbo cars and they are drastically reduced for the fuel you have. If you fall into that category as DC Performance will tell you the more octane the better!

For the love of God, would somebody please post a dyno sheet?

Hopefully another Californian, who's similarly locked into our state-specific brews. Thanks, guys...

 

[bluesrt]

so if i accidently put race 110 in my x car - it will make it a little crisper on the pipe? oh and it smells good.. no harm?

 

[redtanrt10]

For the love of God, would somebody please post a dyno sheet?

Hopefully another Californian, who's similarly locked into our state-specific brews. Thanks, guys...

RW, Mark J has a good post on this subject. Also, the effects if any would be extremely small. Maybe a couple of HP difference between 91 and 93 on a stock controller?? But, getting the exact read on a dyno is too hard at small increments, and, it's possible that doing back to backs on the dyno might show that the 91 has a few more HP due to atmospheric conditions or set up.

With the Mopar venom controller, that's a different story, if its not senseing 93 or better if will retard the timing. Dan at DC and others recommend mixing to 95 with the venom controller to make sure it gives all the power. Not sure how much 100 costs up your way,but I paid $9.99/gallon last Friday at a local station. ***** not to have 93 here in CA. Mike

 

[Mopar Steve]

so if i accidently put race 110 in my x car - it will make it a little crisper on the pipe? oh and it smells good.. no harm?

Race gas at 110 usually has lead in it. This will destroy your cats. BE VERY CAREFUL!

 

[bluesrt]

yes, but i have none in the x car- thanks for the warning...

 

[klamathpro]

More important than the 94 octane rating is the fact that Sonoco put 10% ethanol garbage in all their gasolines. In Michigan, Sonoco is one of the few that do this so I stay away from them. I don't know about other states or Canada for that matter, but in MI it's the law to post the 10% ethanol label on the pump and every Sonoco has it. That corn crap will knock your HP and MPGs down a bit. I noticed a 1 to 2 MPG difference when I dumped Sonoco.

 

[alpha85]

I have dyno sheets posted in general viper discussions. Search dyno day. My 08 after Belanger headers, exhaust, Mopar PCM on 91 octane (pure gas) dynoed 585rwhp, 565rwtq. After that I started running 93 octane (pure gas). I also started using Torco fuel additive 1.60z per gallon to get 95 octane. I took the car to a local dyno day event in February 2011 it dynoed 630rwhp 613rwtq. I was blown away. The temprature that day was around 52 to 55 degrees with a light mist. I think the combination of temp, Mopar PCM, and Torco are the main reasons for those numbers.