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Here in the Bay Area there isn't 93 octane, only 91. To get better performance should I use octane boost ie, Royal Purple, or go to a local 76 and put a few gallons of 100 octane every fill up? Last time I checked the 100 octane was seven something a gallon. Or just stick to 91 octane? By the way, all stock 392 motor.
 

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Best thing would be to log for Knock Retard and see what the situation is on the available fuel. Different brands will yield different amounts of Knock Retard.
In my 09 SRT I had to add 2 gallons 100 for every 3 gallons of 93 BP in hot weather to eliminate ST KNK. In cold weather 93 BP was OK.
 

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While I don't know that much about the Bay area and their octane available... Here in Denver, the most common premium gas is 91 octane due to our high altitude so octane 93 isn't needed for regular driving. I think there are only two gas stations in the Denver metro that offers 93 octanes.
 

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Off the shelf octane boosters don't work. The only octane booster I've used that worked was Torco but that has a downside as well.
 

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Here in the Bay Area there isn't 93 octane, only 91. To get better performance should I use octane boost ie, Royal Purple, or go to a local 76 and put a few gallons of 100 octane every fill up? Last time I checked the 100 octane was seven something a gallon. Or just stick to 91 octane? By the way, all stock 392 motor.
The 392 will do just fine on 91 and only on the really hot days will you see it pull some timing. Focus less on boosting the Octane and just make sure you get Ethanol free if you can. Ethanol was designed for economy and has less energy per burn cycle than pure gasoline. I have two stations in town that sell ethanol free 91 that I fill up on regularly. It is not the most ideal situation since I would prefer to have 93+, but it is what it is. If you start looking for boosters and adding that to every tank, that will get expensive fast. You would probably be looking at at least $6-$8 per bottle per fillup. Depending on how you drive, that will not be cheap. Back 10 years ago I had a 2003 Grand Prix Turbo project and since I had didn't have crap for tuning where I was stationed, I had a ton of KR. Every tank I had to fill up with Torco which was like $8 per can. Since the only thing you can do with a project like that is pedal to the floor type driving, I was filling up every few days. That got expensive enough that I gave up on the project and went a different direction.

There is a product called VP Racing Madditive Octanium Booster that raises the level by at least 8 points. Not 8 decimal points like other boosters, I am talking 8 real points. As in 91 becomes 99 octane. Only one caveat to that is that it is a lead substitute which means it will eff up your O2 sensors and Cat. I ran it a few times, but since I got a new motor put in I will not touch that stuff again. I should have known better, but I was trying to maximize my power in this crappy 5600 DA that I live in.

In either case, just put 91 in it and drive it. It will pull a small bit of timing in the warm months, but you will never know the difference because you can't put the power down anyway. Just find some ethanol free 91 and enjoy the car. If you get a wild hair for a cruise, then pick up some 100 from a local store. Be prepared to pay upwards of $10 a gallon for that mess though.
 

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I wonder if anyone has done dyno runs with premium gas and regular gas with octane boost to see what the "at the wheels" power difference is?
 

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If it's stock 91 is all you need.
 

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I wonder if anyone has done dyno runs with premium gas and regular gas with octane boost to see what the "at the wheels" power difference is?
I only dynode with 91 on a AWDYNO JET with 1 mods of cai only and that was 368 hp to the wheels on my 07 srt8 jeep. On the racing calculator that was 472 hp to the crank and 420 hp was stock . With my unleaded vp109 and 91 50/50 gas mix which made 98 octane and on the racing calculator it was 510 hp at the crank with no changes to the tune for the higher octane. The dyno guy wanted to re dyno with the gas mix but I didn't want to keep switching tunes back and forth. The best times in the 1/8 mile was 8.16 on 91 octane and 7.95 with 98 octane on the same tune. With 91 the tune would hold 23 to 24 degrees and with 98 it would hold 26 degrees as that was all the tune had in it. I remember a guy back east had all vp109 and that was 105 octane and he put 30 degrees in his tune and it only held 26 so I guess that was the it for the 6.1. I hope this helped. The race wt was 5190 lbs. On my 2012 srt8 jeep bone stock the stock hp was 470 hp with stock timing and tune with no mods the racing calculator said 485 hp at the crank with 98 octane with the times I got in the 1/8 mile and the race wt was 5492 lbs.
 

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Mix E -85.
To many changes to fuel sys to use E85. I did use some Sunoco E15 which is unleaded nascar gas 98 octane with 91 and it was about as good as my vp109 gas mix. You can use E15 in cars built after 2006.
 

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Thanks Jim,

but I was curious about the power difference between premium fuel (91 or 93) and cheap fuel mixed with octane booster (mixed to 91 or 93) is on a dyno (no changes to tune). Even though both fuels would have same octane levels, I am guessing their BTU content would be different. But then again, ethanol content between the 2 fuels would need to be the same.

Where is our resident Ph D in ethanology?
 

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I only dynode with 91 on a AWDYNO JET with 1 mods of cai only and that was 368 hp to the wheels on my 07 srt8 jeep. On the racing calculator that was 472 hp to the crank and 420 hp was stock . With my unleaded vp109 and 91 50/50 gas mix which made 98 octane and on the racing calculator it was 510 hp at the crank with no changes to the tune for the higher octane. The dyno guy wanted to re dyno with the gas mix but I didn't want to keep switching tunes back and forth. The best times in the 1/8 mile was 8.16 on 91 octane and 7.95 with 98 octane on the same tune. With 91 the tune would hold 23 to 24 degrees and with 98 it would hold 26 degrees as that was all the tune had in it. I remember a guy back east had all vp109 and that was 105 octane and he put 30 degrees in his tune and it only held 26 so I guess that was the it for the 6.1. I hope this helped. The race wt was 5190 lbs. On my 2012 srt8 jeep bone stock the stock hp was 470 hp with stock timing and tune with no mods the racing calculator said 485 hp at the crank with 98 octane with the times I got in the 1/8 mile and the race wt was 5492 lbs.
Jim,

I am sure you are a nice guy, but these numbers just don't add up. I can see why you got the 1/8th since you were AWD, but there is no way your HP numbers could have been where you say without some type of forced induction. A CAI doesn't add horsepower and changing the fuel will only make the motor run more efficient in its stock form. Neither of those "mods" are power adders. You can increase the timing and injector cycles to try and add more fuel to the mix, but the motor is only going to pull in X amount of air to burn due to its overall design. The 6.1 litre was around 10.3:1 compression which is less than the 6.4 litre which is what makes them prime for forced induction. I just can't see how you were making 510 at the crank which is about 10 more than a larger displaced 6.4 litre at a higher stock compression. You have to add more air AND fuel to make more power. You can't just richen up the mix and hope for more power. That is what the diesel ******s do to roll coal and why diesel is the new RICE burners. All they do is throw more fuel at it until black smoke and then throw a bigger turbo at it, AKA more air. Then dump more fuel and on and on. There has to be some key element here that is missing to say a stock 2007 Jeep SRT8 was making 510+ at the crank. The 6.4 litre was a bit underrated and has been clocked in at about 500 to the crank, but that is because people were putting down nearly 430 to the wheels on most dynos in negative DA.

You have to remember that correction factors are used to correct observed numbers. They are not to take factory rated horsepower and add on what you think. Factory rating is at ideal conditions and that is what the motor is making within ~10%. If we took ~15% drivetrain loss on your 2007 Jeep that puts it right at 423 hp which is what it is rated at stock. Even if we say that the 6.1 litre was underrated and gave you 20% that puts you at 441hp stock. Those numers make sense. I am not sure how you are getting over 500+ with a stock 6.1 litre Hemi. I don't think you are using the calculator in the manner for which it is intended. I am open to debate so if there are key elements that I am missing then I would be happy to see your evidence.
 

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Jim,

I am sure you are a nice guy, but these numbers just don't add up. I can see why you got the 1/8th since you were AWD, but there is no way your HP numbers could have been where you say without some type of forced induction. A CAI doesn't add horsepower and changing the fuel will only make the motor run more efficient in its stock form. Neither of those "mods" are power adders. You can increase the timing and injector cycles to try and add more fuel to the mix, but the motor is only going to pull in X amount of air to burn due to its overall design. The 6.1 litre was around 10.3:1 compression which is less than the 6.4 litre which is what makes them prime for forced induction. I just can't see how you were making 510 at the crank which is about 10 more than a larger displaced 6.4 litre at a higher stock compression. You have to add more air AND fuel to make more power. You can't just richen up the mix and hope for more power. That is what the diesel ******s do to roll coal and why diesel is the new RICE burners. All they do is throw more fuel at it until black smoke and then throw a bigger turbo at it, AKA more air. Then dump more fuel and on and on. There has to be some key element here that is missing to say a stock 2007 Jeep SRT8 was making 510+ at the crank. The 6.4 litre was a bit underrated and has been clocked in at about 500 to the crank, but that is because people were putting down nearly 430 to the wheels on most dynos in negative DA.

You have to remember that correction factors are used to correct observed numbers. They are not to take factory rated horsepower and add on what you think. Factory rating is at ideal conditions and that is what the motor is making within ~10%. If we took ~15% drivetrain loss on your 2007 Jeep that puts it right at 423 hp which is what it is rated at stock. Even if we say that the 6.1 litre was underrated and gave you 20% that puts you at 441hp stock. Those numers make sense. I am not sure how you are getting over 500+ with a stock 6.1 litre Hemi. I don't think you are using the calculator in the manner for which it is intended. I am open to debate so if there are key elements that I am missing then I would be happy to see your evidence.
I told you guys the numbers were from a calculator. The only number that were real were the dyno numbers of 368 to the wheels. To get the rest of the numbers on the calculator all they wanted was the ET and total race wt. I never corrected any of the numbers.
 

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Thanks Jim,

but I was curious about the power difference between premium fuel (91 or 93) and cheap fuel mixed with octane booster (mixed to 91 or 93) is on a dyno (no changes to tune). Even though both fuels would have same octane levels, I am guessing their BTU content would be different. But then again, ethanol content between the 2 fuels would need to be the same.

Where is our resident Ph D in ethanology?
We had guys in our group using octane booster with no help at all with mods listed. They really picked up using vp109 and 91 and there mods were cai, exhaust and tunes by johan and jerseyboy. In ca 91 gas has only 1.8% oxygen and eastern 91 and 93 has 3.8% oxygen.
 

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Hey Canative,,

if you want to run a test drive out to Sunol Super stop on adrade rd off of 680, they have 91,93,98,100, and 104 octane at the pump they also have torco race fuels inside in 5 gallon cans if you want to try 112,116 or 118 octane.

I have ran the 98 octane as a test once, but without a track to give at least some semblance of consistent traction we are still at the mercy of deserted backroads with varying surfaces to try to establish a consistent baseline for each of the fuel grades.
 

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Could not find VP109 but there is an MS109. I take it they add E85 because it states it's oxygenated?

https://vpracingfuels.com/product/motorsport-109-ms109/
VP109 is MS109 and there is MS109E ( ETHANOL) MS109E is designed for the same applications as Motorsport 109, offering the same substantial power increases and protection against detonation. Oxygenated with ethanol, MS109E can be used in all 50 states, including those that restrict the use of MTBE in fuels. The 2 best gas I have mixed with 91 is MS109 ( 105 octane ) and Sunoco E15 (98 octane ) as the have the most oxygen with 6.3% and 5.6%.
 

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To many changes to fuel sys to use E85. I did use some Sunoco E15 which is unleaded nascar gas 98 octane with 91 and it was about as good as my vp109 gas mix. You can use E15 in cars built after 2006.

Mix meaning EXACTLY like you said and did and the results seemed positive correct?
 
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