Ran Half and Half!

Discussion in 'SRT Hellcat General Discussions' started by MoparPhil, Mar 30, 2015.

  1. MoparPhil

    MoparPhil Gold Member

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    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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  2. huggytree

    huggytree Gold Member

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    where do you get 100 octane?
     
  3. MoparPhil

    MoparPhil Gold Member

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    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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  4. hellcat1

    hellcat1 Gold Member

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    So you seen a.higher boost pressure using that gas??
     
  5. rw99

    rw99 Silver Member

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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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  6. Mopar707

    Mopar707 Silver Member

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    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.
     
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  7. MoparPhil

    MoparPhil Gold Member

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    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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  8. DrBuick

    DrBuick Gold Member

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    Eh wolf in slinger

    I will be going E85
     
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  9. hellcat1

    hellcat1 Gold Member

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    So what about running 93 octane and putting a bottle of octane booster in
     
  10. DrBuick

    DrBuick Gold Member

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    I don't see 4 tenths off fuel alone. I stand corrected called Duttweiler and sad very possible
     
    Last edited: Mar 30, 2015
  11. Hellcat Jack

    Hellcat Jack Silver Member

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    The guy in Texas ran 10.43 with help from nitrous not high octane gas.
     
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  12. SRT_HC_707

    SRT_HC_707 SRT_HC_707 Staff Member

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  13. SRT_HC_707

    SRT_HC_707 SRT_HC_707 Staff Member

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    Are you saying that the stock O2 sensors are wideband?
     
  14. rw99

    rw99 Silver Member

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    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.
     
  15. hellcatrules

    hellcatrules Hellcat Member

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    FYI, but it was confirmed that the guy in Texas who ran the 10.43 was also using nitrous oxide.
     

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