I am wondering? I believe that they recommend 93 octane for the SRT, might be all Challengers. What are the opinions on this?....Is it Hoyle that we must adhere to this and what is the result if we use a lower octane fuel; And could you just use a lower octane with an addative like +108 or such?:scratchhead:

The owners manual calls for 91 or higher octane. Actually, mine runs stronger on a mixture of 89 and 93 octane. I wouldn't go below 91 octane because it would probably cause detonation (spark knock). Under normal driving, the computer would pull timing to avoid damage to the engine, but at wide open throttle (open loop), you could do serious damage to the engine. This is for the SRT (6.1L)

Thanks for the reply Bonez.

A mix of 89, 93 huh?.....you mixing half and half to your tank?.
and do you think it would hurt to run say 89 plus the octane booster like +108?

I certianly do not want to ruin a brand new ride....I guess if you wanna play, you gotta pay in terms of the SRT

Assuming the MPG doesn't change, what it is the difference per mile between what is recommended and lower octane gas? $0.01 - $0.02?

Why would I spend all those extra $ to get a performance car and the cheap out for $0.02/mile?

I would just by a Honda to start with.

My opinion.

Oh - and back when I could not get (wasn't available) premium for my 428HO Pontiac, 108 octane boost did nothing for me except drain my wallet. A water/methanol injector did help.

SRT8 300 here in Canada, I have 122,000 miles on it and have run regular (87) with 10% ethonal (?) = 90 octane, all of the time no problems, 6.1 is bone stock.

Thanks guys...

Lucky....so your pretty much running at the recommended.

Waumo...Gas seems to jump daily in my neck of the woods and it is more than a few cents between the 2 ratings. But I do get your point.

how much is the 108+ booster.. I bet it's more expensive than just buying the right octane gas...

Waumo...Gas seems to jump daily in my neck of the woods and it is more than a few cents between the 2 ratings. But I do get your point.

I think there is about $0.20/gal between mid and premium. I'm averaging 17.2 MPG so therefore my numbers.
Also I don't drive but about 4-5K miles per year so it doesn't affect me much.
And yes the price fluctuates wildly from day to day here. Makes no sense.

Now if you look at insurance costs vs what you get out of it compared to gas =:fight:

[quote=waumo;404830]Assuming the MPG doesn't change, what it is the difference per mile between what is recommended and lower octane gas? $0.01 - $0.02?

Why would I spend all those extra $ to get a performance car and the cheap out for $0.02/mile?

I would just by a Honda to start with.

My opinion.

Totally agree with you. Spending up to 50k on a performance vehicle and then trying to save $200-$300 a yr and get less performance just makes no sense at all. These gas questions are on every performance car forum and I do not understand it

how much is the 108+ booster.. I bet it's more expensive than just buying the right octane gas...

I have not priced the stuff in years, but it didn't seem like alot considering the bottle did a tankful or so.

Of course gas was way cheaper then as well, you could get away with running the cheaper octane in the Charger, but had to run the lead additive as well.

I just at times think there are connections to reasons they do things....scratching each others backs...like repairing your own car anymore....the manufactureres force you to take them to dealers, because the dealers are the only one with the special tools and parts, yadda..


Thanks for the input.

I think there is about $0.20/gal between mid and premium. I'm averaging 17.2 MPG so therefore my numbers.
Also I don't drive but about 4-5K miles per year so it doesn't affect me much.
And yes the price fluctuates wildly from day to day here. Makes no sense.

Now if you look at insurance costs vs what you get out of it compared to gas =:fight:

Amen to that Waumo.

Thanks for the input
:)

I was just curious as I do not have my Chally yet and just wanted the opinions of those that already have theirs in terms of what they feed them for fuel...

We can close this thread.

I remember reading that if you have the Predator, you can edit your tune and pull some timing so that you can run 89 octane. Seems logical to me.

A couple of weeks ago i put in 3 gallons or Cam 2, 110 octang gas along with 10 gallons of 89 in my SRT to see how it would react. And it ran real good. Throttle responce was mint! seemed to pull harder in the midrange rpms. But i won't be doing again at 7:86 a gallon

I remember reading that if you have the Predator, you can edit your tune and pull some timing so that you can run 89 octane. Seems logical to me.


Sounds like your saying detune it to run 89 octane by tweaking the timing?....I don't want to lose power at the cost of wanting to save money in the tank.

Bottom line. it sounds as though the recommended is best....just have to cut back on cruising a bit.:thumbsup:

A couple of weeks ago i put in 3 gallons or Cam 2, 110 octang gas along with 10 gallons of 89 in my SRT to see how it would react. And it ran real good. Throttle responce was mint! seemed to pull harder in the midrange rpms. But i won't be doing again at 7:86 a gallon

Is that racing fuel?.....yeah I bet the car loved it....but your right...a bit too expensive for my wallet.

Is that racing fuel?.....yeah I bet the car loved it....but your right...a bit too expensive for my wallet.

Yea, Cam 2 is a Racing fuel from Sunoco. It comes in 99 and 110 Octang
Great stuff for your Vintage muscle car or Bike on a track day. The smell from the exhaust it awsome!! Ahhhhhhhhhhh purple fuel.... its the best!!!

That race gas wouldn't happen to be leaded would it?... Bad stuff...
And so you all know 89+93 is just plain old 91.

Although I don't have the SRT, 91 octane is still recommended (max perf & milage) on the 'stick versions of the 5.7.

The differance is price between the grades runs about .10 - .12 / gallon, so its less than $2 differance on the fill ups.

Not even worth the consideration when the tab is $46 - $48, trivial amount in perspective of what I'm spending at fill up time.

Do your car the favor only use premium!

Thanks for the reply Bonez.

A mix of 89, 93 huh?.....you mixing half and half to your tank?.
and do you think it would hurt to run say 89 plus the octane booster like +108?

I certianly do not want to ruin a brand new ride....I guess if you wanna play, you gotta pay in terms of the SRT

I start out with a full tank of 93 octane and when I get down to about a half a tank, I fill back up with 89 octane. Then when I get down to about a half a tank again, I fill up with 93 octane and so on. I figure that at no time am I running too much under 91 octane. I don't do this to save any money! Like mentioned above, the difference between the two octanes is nill when looking at the whole picture. I only do this because the car runs so much better on approximately 91 octane. Funny thing is, my Magnum RT seems to like this mixing too! I'm not sure about the octane booster, but I would worry about any lead being in it. Lead will kill your cats! BTW I can really tell when I am on mostly 93 octane, the car just doesn't feel as strong as when it is on about 91 octane. I am not really seering any difference in mileage either, not that it really matters! LOL Oh, we don't have any access to "real" 91 octane around here.

I have a 6sp R/T Classic and I run about 91 octane all the time. The dealer put in pure 87 but I didn't run it very long before I put some 93 in with the 87. I ran pure 93 for one tank but didn't notice any difference, she was still young then so I didn't run it very hard. The fuel gauge is real accurate for me so I just put in 2/3 93 plus 1/3 87 every time I fill up. The price difference between 87 and 93 per gal is .32. I thus save an average of .11 per gallon and will thus save $60 this year. If I didn't feel like doing it I wouldn't since that isn't anything to speak of. But I don't mind and with a stock tune, 91 is perfect. Now... with some mods, I will run 93 the whole time and be :) while I am filling up!

As a side note, I saw Turbo Blue at a gas dock at the Lake that was selling at $6.999 per gal for 110 octane. Ouch! That gas is for supercharged boats which NEED as much octane as they can get! I think all gas sold has to be unleaded now, whether for cars or boats.

I suppose if your car is a daily driver to get back and forth to work and all, and its an auto, i dont think a tank full of 89 is gonna do any harm at all. Its not like your gunnin it all the time.....are ya's???:browsmiley:

You all should feel lucky to have the choice. We can only get 90 octane up here. I would pay $7+ a gallon if I could get better gas. I don't drive it enough to make it really hurt the wallet. I hate the fact that I have to run this crap we have up here. I would never dump any of that octane boost crap in my tank. I do have a water/meth injection kit but I want to figure a way to mount it that can be pulled easily for dealer trips. After a little while I would like to talk to some of the performance vendors on here about the best route to take for major upgrades keeping in mind that 90 octane is the best I can get. I would like to get the car in the 550-600 crank hp range but I want it to be safe on the motor.

You all should feel lucky to have the choice. We can only get 90 octane up here. I would pay $7+ a gallon if I could get better gas. I don't drive it enough to make it really hurt the wallet. I hate the fact that I have to run this crap we have up here. I would never dump any of that octane boost crap in my tank. I do have a water/meth injection kit but I want to figure a way to mount it that can be pulled easily for dealer trips. After a little while I would like to talk to some of the performance vendors on here about the best route to take for major upgrades keeping in mind that 90 octane is the best I can get. I would like to get the car in the 550-600 crank hp range but I want it to be safe on the motor.
Is there any way for you to get 110 racing gas? How about fuel for gas engined planes? If they are using unleaded fuel now it has to be at least 100 octane and you could use it in the Challenger! I used to use it in my 70 Vette along with 93 octane auto gas to get the octane up!

I wouldnt use "octane booster" in new cars....heard on various other forums(ford, pontiac, etc) that it can cause problems in late-model(comp-controlled) cars, confusing the computer & fouling plugs(or worse)....may just be b.s., but I'd stick with the proper fuel for the car, and if u cant get 91(like here in ny), then go with the 93....."wanna play, gotta pay":icon_razz:

i had a great drive last weekend in the viper but i was in a isolated area...the one exxon station i was counting on was down so i had to stop in Fouke , Arkansas...All they had was diesel and 87 octane.. i thought i had just killed my engine but the 87 ran fine .. really no difference from 93

i had some fellow viper owners tell me this....


the higher the octane, the slower the burn and that it why it can be compressed more before detonation. So higher octane does not make more power, it actually makes less, but you can put more air/fuel in the cylinder before detonation. Therefore that is why you do make more power in a high compression or boosted engine.

also....After attending a few of the Viper Tech sessions around here, I learned that the best performance you can get out of your engine is to use the lowest possible octane rating that does not make your engine ping under load. So if your engine does not ping using 89 octane, you are getting more performance than if you had 93 octane in your tank. It cracks me up to go to this one 76 gas station around here, that has a 100 octane pump, with a price of $6.10 per gallon, and see all kinds of guys filling up their Mustangs, or Harleys. They think more is better. I explain to them that they are actually de-tuning their cars by buying the expensive gas.

i had a great drive last weekend in the viper but i was in a isolated area...the one exxon station i was counting on was down so i had to stop in Fouke , Arkansas...All they had was diesel and 87 octane.. i thought i had just killed my engine but the 87 ran fine .. really no difference from 93

i had some fellow viper owners tell me this....


the higher the octane, the slower the burn and that it why it can be compressed more before detonation. So higher octane does not make more power, it actually makes less, but you can put more air/fuel in the cylinder before detonation. Therefore that is why you do make more power in a high compression or boosted engine.

also....After attending a few of the Viper Tech sessions around here, I learned that the best performance you can get out of your engine is to use the lowest possible octane rating that does not make your engine ping under load. So if your engine does not ping using 89 octane, you are getting more performance than if you had 93 octane in your tank. It cracks me up to go to this one 76 gas station around here, that has a 100 octane pump, with a price of $6.10 per gallon, and see all kinds of guys filling up their Mustangs, or Harleys. They think more is better. I explain to them that they are actually de-tuning their cars by buying the expensive gas.


It seems to make sense to me, plus, I have heard the same thing before! That has to be why mine runs stronger on 91 octane, as opposed to 93 octane.

i had a great drive last weekend in the viper but i was in a isolated area...the one exxon station i was counting on was down so i had to stop in Fouke , Arkansas...All they had was diesel and 87 octane.. i thought i had just killed my engine but the 87 ran fine .. really no difference from 93

i had some fellow viper owners tell me this....


the higher the octane, the slower the burn and that it why it can be compressed more before detonation. So higher octane does not make more power, it actually makes less, but you can put more air/fuel in the cylinder before detonation. Therefore that is why you do make more power in a high compression or boosted engine.

also....After attending a few of the Viper Tech sessions around here, I learned that the best performance you can get out of your engine is to use the lowest possible octane rating that does not make your engine ping under load. So if your engine does not ping using 89 octane, you are getting more performance than if you had 93 octane in your tank. It cracks me up to go to this one 76 gas station around here, that has a 100 octane pump, with a price of $6.10 per gallon, and see all kinds of guys filling up their Mustangs, or Harleys. They think more is better. I explain to them that they are actually de-tuning their cars by buying the expensive gas.

I agree with you as well. The problem is that these new cars don't ping it seems. They just retard their timing which is hard to detect. I don't use 91 fuel with my 91 tune just in case the tune is slightly off base. I use 94 fuel with my 91 tune so there should be no timing retard. Does that sound logical? I would never use 100 or higher octane. It seems faster using 94 octane. I have no proof though.

Hello, I live in France and I have a Srt8, the fuel is 95 or 98. Are the adjustments of the diablosport are compatible without risk? I do not know if my question is comprehensible, I am taking of all answers. thanks in advance.

Hello, I live in France and I have a Srt8, the fuel is 95 or 98. Are the adjustments of the diablosport are compatible without risk? I do not know if my question is comprehensible, I am taking of all answers. thanks in advance.
First of all check your octane rating system. I think they are different between USA and Europe. Your 98 might be our 93 or 91 and your 95 might be our 89. When you find out how they compare then the correct diablosport tune level could be picked. Does Diablo have instructions for using in Europe??? Have fun and have a nice run on the Autobahn for me and my car!

First of all check your octane rating system. I think they are different between USA and Europe. Your 98 might be our 93 or 91 and your 95 might be our 89. When you find out how they compare then the correct diablosport tune level could be picked. Does Diablo have instructions for using in Europe??? Have fun and have a nice run on the Autobahn for me and my car!

Gasoline pumps typically post octane numbers as an average of two different values. Often you may see the octane rating quoted as (R+M)/2. One value is the research octane number (RON), which is determined with a test engine running at a low speed of 600 rpm. The other value is the motor octane number (MON), which is determined with a test engine running at a higher speed of 900 rpm.

In Europe and most other countries, the "headline" octane rating shown on the pump is the RON. But, in the United States and Canada, and some other countries, the headline number is the average of the RON and the MON - (which usually produces a lower "overall" octane number.)

The ideal thing would be to have an indicator when the engine (computer) is retarding the timing due to the knock sensor input. Then you could actually tell what octane was needed.

I drove (still do some) a pre-computer control car with 10.75:1 compression.
I learned that today's 93 octane fuel is just barely adequate under good conditions. When the outside air temp is above 80F it is not adequate.

I have trouble believing 93 octane is too much for the 10.3:1 6.1 Hemi but I have no way to prove that.

I did some (R+M)/2 calculations to see how much STP Octane Booster would be required (using 91 octane pump gas) for the Diablo Predator 93 Octane CAI tune as we can't get anything higher than 91 octane pump gas in Utah.

The STP Octane Booster (which has one of the best ratings on a quick google search) recommends one bottle for each tank of gas. My (R+M)/2 calculations indicated that 4 bottles of STP Octane Booster would be required for each tank of 91 octane gas to boost it up to 93 octane gas equivalent.

Obvisouly my wallet would suffer from buying that much octane booster and it is my understanding that octane booster actually hurts performance. I have never tried using that much octane booster (with a tank of gas) to try to prove or disprove this claim (which I doubt I could feel the difference anyway).

As my calculations indicate, most octane boosters are a waste of money and as such I have gone back to the Diablo Predator 91 Octane CAI tune using only 91 octane pump gas.

First of all check your octane rating system. I think they are different between USA and Europe. Your 98 might be our 93 or 91 and your 95 might be our 89. When you find out how they compare then the correct diablosport tune level could be picked. Does Diablo have instructions for using in Europe??? Have fun and have a nice run on the Autobahn for me and my car!

Thank you for your answer, I will get information and try to find an answer concerning the comparison between the US and European fuel. :google:

I do not have yet of Diablosport, I do not know what is recommended. I await an answer on the forum before buying this equipment.

I promise to you to accelerate on French Autobahn by howling your name and making a smile to the radar, I am still in Canadian license plate.:rocker:

Torco Race Fuels for octane booster, not STP that stuff is junk, Torcoracefuels.com