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Discussion Starter · #1 ·
I mixed in half of tank of unleaded 100 octane race gas ($8/gal) with pump gas 91 and, man oh man, the car really liked it! In talking with the Dodge guys down at Mopars At the Strip, they acknowledged what many of us thought, that there is significant built-in "protection" for the engine to run on pump gas. But with higher octane those "protections" go away and you get things like more timing and more boost. Give it a try and let the rest of us know what you all think.

Be careful and make sure it's unleaded! Do not run any leaded fuel as it will kill your car within seconds.
 

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Discussion Starter · #3 ·
where do you get 100 octane?
It depends on where you live. Here in Utah, several places have it right at the pump. Other places won't allow you to pump it directly into the car but make you put in gas containers. Check with your nearest drag strip. They should sell it there and/or be able to tell you where you can get it locally. Also, check with local car clubs. They will most likely know where to get it.
 

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A final octane of 93-94 will allow the car to run at MBT (mean best torque) on the spark curve; it does use the wideband lambda that you see on the AFR gauge. Past MBT, higher octane does not provide much; SRT tells me the benefit of going from 91 to 93 octane is GREATER than what you'd see going from 93 to 100. With the obvious caveat: stock tune.


Rich
 

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Discussion Starter · #7 ·
Can't you just buy 93 octane gas where you live? Using 100 octane for a car tuned to run on less usually provides no benefit.
No, 91 is the max available at the pump in Utah with the exception of a few stations that offer 100 Unleaded. But that costs $8/gal. So, no one is going to run race gas all the time but mixing in a little for an occasional romp can be a lot of fun. You're correct that if the engine was tuned to run on a max of 93 octane, going higher is of no real benefit. However, you have to know that a lot of gas is inconsistent at best and the computer is constantly making adjustments to protect the engine by such things a pulling timing. Mixing in a little race fuel (I tried half and half as in the title of this thread) from time to time can bump up the octane, help stabilize the fuel and let your engine run like it was meant to. I'm not going to do a one to one mixture anymore but I'll probably drop a gallon or two in with a new tank of gas every now and then.

As to being tuned to run on no higher than 93, the Dodge Boys who were at Mopars at the Strip said that, yes, the sensors are designed to adjust engine parameters to safely run 91/93 octane with great results but, in the absence of knock, the computer will open up and give you even more. In other words, the computer is capable of sensing and using higher octane race gas. That is why the guy in Texas ran a 10.43 with only drag radials and race gas.
 

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A final octane of 93-94 will allow the car to run at MBT (mean best torque) on the spark curve; it does use the wideband lambda that you see on the AFR gauge. Past MBT, higher octane does not provide much; SRT tells me the benefit of going from 91 to 93 octane is GREATER than what you'd see going from 93 to 100. With the obvious caveat: stock tune.


Rich
Are you saying that the stock O2 sensors are wideband?
 

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Are you saying that the stock O2 sensors are wideband?
I know for a fact that there's a wideband. I do not know for sure whether the traditional narrow band sensors are also utilized, but I'd be VERY surprised if they weren't, given exhaust monitoring requirements.
 

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FYI, but it was confirmed that the guy in Texas who ran the 10.43 was also using nitrous oxide.
Who confirmed that?! Others have shown pictures they took, underhood, and he'd have to have the first invisible nitrous setup I've heard of. People have asserted he used nitrous, but have not talked to the car's owner/driver, nor seen anything to show he did, --have you?
 

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Who confirmed that?! Others have shown pictures they took, underhood, and he'd have to have the first invisible nitrous setup I've heard of. People have asserted he used nitrous, but have not talked to the car's owner/driver, nor seen anything to show he did, --have you?

Perhaps best to contact member " buddyg" . I believe he will be able to confirm that indeed nitrous was used.
 

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Every time I ran at the track I used 93 octane , except one time it was 85 degrees and humid , so we decided to add some 100 octane to the 93 octane ( less than 50/50 ) for a test ! I didn't notice a difference , and if anything it made me a tad slower! Just my 2 cents! Not sure how humidity plays into the mix , I know Vegas has virtually no humidity and I am far from an expert on this matter , so I am not sure how that would come into effect there! As far as the 10.48 run , it was stated that he used VP109 ! I would be curious to know if the Hellcat engine/ computer could sense and retune to adjust to such a large octane gap !
 

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Are you saying that the stock O2 sensors are wideband?
I know for a fact that there's a wideband. I do not know for sure whether the traditional narrow band sensors are also utilized, but I'd be VERY surprised if they weren't, given exhaust monitoring requirements.
upstream = wide band
downstream = narrow band
 

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where do you get 100 octane?
In Las Vegas it is sold under Rockett Brand Racing Fuels. It comes in 5 gallon containers. I also run the leaded 112 in my BB El Camino. Both work great with a noticeable difference than the 91 crap at the pumps.
 
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