What octane should I run

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MOPARMAGA

MOPARMAGA

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I'm about a week out from putting my 471 back on the Dyno after nearly a year of being apart and doing a few more things for the betterment of it. My compression

(WAS) at 11.6:1 and I was running 108, I was running a fairly small camshaft 260-264 @.050 .
(NOW )
the cam is still small, just a little bigger 264-268 @.050 & the compression ratio is 12.8:1.
I'll be running the car at 1000 feet elevation & the dynamic compression is 9.5:1 if that matters.
Anyways I just need a safe octane number.
Thank you.
 
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Demonracer said:
Minimum 108, I'd run 116 and read the plugs.
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Okay, I can get 108 leaded at the pump down the road. They also sell drums of other race gas octane ratings so I'll check out their prices.
Thank you
 
RustyRatRod said:
That'll run on pump premium, but it's a trick for sure. I'd stick with 110 or even 112. Better safe than sorry.
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Yeah, this is a drag car. It won't be running 92 pump lol, it will run on it for sure but I'm not going to risk it.
 
MOPARMAGA said:
But the 110 or 112 yeah. I gotta call up the money grabbers and check out there 55 gallon drums. Knowing rat bastid we'll use it up in a week on the Dyno lol
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Give him a kick in the shin for me.
 
Hysteric said:
Try that. Local Carb Maker and Tuner since passed who knew his stuff said he could run 240 psi on 87 octane.
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I believe it, the guys at Hughes sure don't mind saying 93 pump and 12.5 compression is easy.
Now my 1st couple pulls on my engine before rebuild I used my own formula with 3 gallons of 92 pump and a gallon of toluene. It didn't mind it at 11.6 cr.
That just gave me a sinus infection lol
 
MOPARMAGA said:
I believe it, the guys at Hughes sure don't mind saying 93 pump and 12.5 compression is easy.
Now my 1st couple pulls on my engine before rebuild I used my own formula with 3 gallons of 92 pump and a gallon of toluene. It didn't mind it at 11.6 cr.
That just gave me a sinus infection lol
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Try it and see, read plugs and go easy with the tune so sneak up on it. There's more to detonation than just octane, same guy said he'd managed 21-1 compression on pump fuel BUT this guy was in his own league.
 
Hysteric said:
Try it and see, read plugs and go easy with the tune so sneak up on it. There's more to detonation than just octane, same guy said he'd managed 21-1 compression on pump fuel BUT this guy was in his own league.
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I've definitely got a new learning curve to figure out now, since this will be my 1st tunnel ram deal ported with 2- 850s, if this was a street car I'd go all in on tuning it for pump gas and surely the plugs will tell the tale.
 
I rarely post on threads about spark plugs, motor oil, or fuel/octane……. So I’ll keep it brief.

I’d use what you can get locally that’s the equivalent to VP C12, or Sunoco Standard(if neither of those are available).
 
110 is what id run. Anything above 110 is wasting money in my opinion. I was at 13:1 with much bigger cam in my 499 low deck before making it a 528 with 14.5:1. When it was a 499, I put 112 in it from 110 to see if it would make any difference and it made zero.
 
71Demon528 said:
110 is what id run. Anything above 110 is wasting money in my opinion. I was at 13:1 with much bigger cam in my 499 low deck before making it a 528 with 14.5:1. When it was a 499, I put 112 in it from 110 to see if it would make any difference and it made zero.
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Cool
 
Strip only or street/strip? In my area we can get e85 quite a few places and your combo would be good for it. I realize it’s a carb change but at the pump it’s half the price of 91 and way cheaper than race gas. But you should be just fine on 110.
 
TT5.9mag said:
Strip only or street/strip? In my area we can get e85 quite a few places and your combo would be good for it. I realize it’s a carb change but at the pump it’s half the price of 91 and way cheaper than race gas. But you should be just fine on 110.
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Strip only.
 
PRH said:
I rarely post on threads about spark plugs, motor oil, or fuel/octane……. So I’ll keep it brief.

I’d use what you can get locally that’s the equivalent to VP C12, or Sunoco Standard(if neither of those are available).
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Thanks for posting!
 
I'd start with a five gallon can of your pump 108, make a couple short dyno pulls, and see what you get. If you don't like what you see, 112.
 
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