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Given a choice, I can't imagine why anyone would even conceive of running 91 octane over 93 for any reason. The 93 octane will allow more spark advance which should allow a more aggressive tune and more HP. Conversely, the lower octane could retard the spark advance due to knock sensors pulling timing. I'd rather have higher octane and not need it, than lose power due to timing being pulled..
 

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I'm not sure where you are, but the Sam's Club near me in FL has 93 octane (not a top tier gas though). The weird thing is that Walmart, that's the same corporate owners, only has 91. I know Costco gas is top tier, but I'm not sure what their octane rating is, or if there's one near you. Even if you have to go out of your way to get decent gas it may pay off in your time slip.
If you're not familiar with the top tier gas subject: https://en.wikipedia.org/wiki/Top_Tier_Detergent_Gasoline
 
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The costco by me has 93 and I think 87 (or 89 I don't recall). My experience with costco fuel is it tends to coat the spark plugs in a reddish color (posted a pic of it a while back) which to me suggest they use some type of octane booster additive like MMT. Again, this is just my suspicion. On my challenger I switched to shell exclusively about a year ago and just had the plugs off when doing a cam swap and there is no signs of reddish coating...just grey-ish tan.
 

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Up here in Colorado, 91 is all we can get with our altitude. No reason to run anything but 93 closer to sea level.
 

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As suggested, if you can get 93, especially in a top tier fuel, that's what I'd use. It's super easy to find 93 here, but I doubt the generic convenience stores and Sam's Club have top tier fuels. We have a company here called Go Gas and they have non-alcohol 93, but I can't determine they are a top tier fuel seller. I called their corporate office and couldn't get a straight answer. I use Shell and BP.
 

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91 vs 93 seems to be a regional or state thing. Calif appears to be 91 octane, other than racing gas. I'm in Illinois and 93 octane is the only premium grade by me. Costco is TopTier and is either 87 or 93.

Costco adds its own additives to make their gasoline TopTier.
https://www.neiwpcc.org/tanks2013/p...DEF/Fuel+Additives_Hurlocker_2013_Tuesday.pdf

This shows some AAA gasoline tests & TopTier is cleaner than non-TopTier.

The above shows differences between the TopTier gasolines they tested, too bad they don't state which brands they are. I try to rotate between Costco & the major TopTier brands in an effort to balance out those findings.
 

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Any thoughts on any difference using 91 vs: 93 octane in Drag racing
It depends what you’re tuned for. But using 91 will not hurt anything on your stock engine. The pcm will make whatever minor adjustments are needed to keep the engine safe. If you have a choice , and you’re running a 392(higher compression) then I would always pick the higher octane as there’s less of a chance for detonation. If you’re drag racing at a track , adding some race fuel isn’t a bad idea either. You won’t gain much performance(without tuning), but you’ll be less likely to have knock.


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2020 Dodge Challenger Hellraisin Scat Pack
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Any thoughts on any difference using 91 vs: 93 octane in Drag racing
From my 2018 Hellcat owners manual, which also covers the 6.4l SRT engine in the Scat Pack:
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6.4L Engine

Do not use E-85 flex fuel or ethanol blends greater than 15% in this engine.

This engine is designed to meet all emission regulations, provide optimal fuel economy and performance when using high-quality unleaded “Premium” gasoline having a posted octane number of 91 as specified by the (R+M)/2 method. The use of 91 or higher octane “Premium” gasoline is required for in this engine.
---------------------------------------------------

Thus on surface 91 should be ok. However, an engine's octane requirements can increase over time and 93 octane buys one a bit of margin against the engine controller having to dial back timing to avoid detonation.

If 93 is available and is unleaded -- although I'm a bit concerned about a 93 that apparently gets its octane boost via MMT and Dodge is against any fuel additives like MMT -- you might consider running 93.

Be aware that being 93 and being I suspect priced at a premium (no pun...) the fuel might not be that fresh. In this regard then it could be no better than 91...

Check if the track has a racing fuel station/pump on site. While if it has the octane rating will be much higher 100 or higher you can use this mixed with whatever you have in the fuel tank which should bring the octane rating up to 93 or even higher. Be sure the racing fuel is unleaded! If the choice is run 91 or something higher arrived at by mixing leaded racing fuel with 91 run 91.

Be sure you show up at the track with fresh engine oil in the engine.
 

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While on the subject of fuel, you'll also want to keep the amount of fuel present in the tank to a low level to reduce added weight!
 

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Does anyone have a good way to FIND it? There are some websites, but they are not terribly accurate.


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Does anyone have a good way to FIND it? There are some websites, but they are not terribly accurate.


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I would recommend Shell VPOWER 93. If you do some looking on the LX forums, Charger ******, our forums, etc - you will find that this is the resounding answer for 392 owners.
 

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While on the subject of fuel, you'll also want to keep the amount of fuel present in the tank to a low level to reduce added weight!
On the street my Hellcat ran out of gas with the fuel level just below 1/4 tank.

Given gasoline weights around 6lbs per gallon I don't think a half a tank (9 gallons, 56lbs) is going to keep you off the podium. And you sure ain't going to get there if the fuel pump sucks air coming off the line.
 

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While on the subject of fuel, you'll also want to keep the amount of fuel present in the tank to a low level to reduce added weight!
I've seen stuff posted about leaning out and other problems at the track when running low on fuel so not sure that's a good idea any more.


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Now, if only I could find ethanol free...
 

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On the street my Hellcat ran out of gas with the fuel level just below 1/4 tank.

Given gasoline weights around 6lbs per gallon I don't think a half a tank (9 gallons, 56lbs) is going to keep you off the podium. And you sure ain't going to get there if the fuel pump sucks air coming off the line.
Agreed. I meant don't go with to much like over 1/2 a tank. If weight doesn't matter, what's the deal with rear seat delete? I've read every 100 lbs. eats up 10 HP. A lot of people probably should go on a diet if they want to go faster and keep the seat.
 

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Agreed. I meant don't go with to much like over 1/2 a tank. If weight doesn't matter, what's the deal with rear seat delete? I've read every 100 lbs. eats up 10 HP. A lot of people probably should go on a diet if they want to go faster and keep the seat.
While weight matters there are places one can save weight and places one can not. Drill lightening holes in the drive shaft if you don't believe me.

Running a hard launching car's gas tank level too low due to concern for a few pounds of weight is risky unless the fuel tank/fuel system is designed to ensure the fuel pump will not suck air at the low fuel level.
 
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