Octane requirement?

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L31MaxExpress

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Another advantage is as we go up in octane the additive packages are mo’ better. One reason mid grade cost only 5 cents more 30 years ago was it had the same additive package as regular. Today it has mo’ better additives, and of course costs more.

The problem is the new EPA sulphur rules. Higher octane gas has less sulphur so refineries are blending it into low octane fuels to reduce sulphur, and in the process making mid grade and premium more scarce, thereby raising the price.
Agreed on the additives. Most of the cheap gas lacks Top Tier additives and prone to carbon buildup.

My old 350 was pretty clean running top tier fuels. Most of these engines have big flakey deposits on the pistons. The dished pistons tend to get a ton of crusty carbon buildup compared to flat tops because of the lack of quench effect aiding in proper combustion. Because of the pistons texture it tends to build a little on it but mine was much cleaner than most. I need to get a picture of the pistons on my 383 from my bore scope. But the smooth finished flat top pistons are nearly spotless in it.

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This is just a random typical used short block off google images. Way more buildup on this one. My engine was also sludge free running synthetic oil. I have pulled dozens of dished piston small blocks apart that look just like this one.
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L31MaxExpress

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Flat tops in my 383, still clean. Top tier fuel doing its thing. Little bit of oil getting pulled through the pcv baffling and into the intake through the PCV valve though and ended up as a drop on top of the piston. Might explain the small grey puff of smoke on startup I sometimes get from the thing. Might try a baffled grommet to see if it will cut down on it. What I was saying earlier about how flat tops with good quench have a cleaner burn. Flat tops, good quench and aluminum heads are key to how I am running 11:1 compression with a small cam on pump gas.

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L31MaxExpress

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They're only that clean cuz you rip on it all the time.
I really don't! It has enough power that I really don't need to. I will get on it a bit from time to time just to feel all those bald eagles but who doesn't. If I run it over 3,000-3,500 rpm now I am in one heck of a hurry. With the ~2,800 rpm converter unlocked accelerating I can sit in the 2,500-3,000 rpm range through the gears and it gets rolling quickly. By the time its at the WOT 1-2 shift I am almost at the speed limit on most of the in-town highways. With the engine cranking 6,000 rpm in 1st, I get 58 mph out of 1st with the current peg leg 3.73 rear. It always wants to nuke that tire though.
 
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L31MaxExpress

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I cannot keep the rear wheel wells and the underside of the body behind the tires clean. That was laying into it from a 15-20 mph roll the other day, spun the right rear close to 100 ft judging by the black mark. 383 loves its premium fuel if I do much of that though. I am going to spray those inner wheel houses and about 1" of the lower body with rubberized under coat, should help hide any rubber or road tar that might deposit itself there. I really feel the 3.73s will work well in this combination vs the 5.13s I had with the 350. Might throw a Powertrax in the 3.73 open 10.5 and call it good.

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Supercharged111

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You and your sea level air, you just love to gloat don't you? My trucks get pretty rowdy in MI at 700' elevation. The dually would blow donuts if I let it, it hits like being punched in the back. Hard. Even barks tires with a trailer hooked up.
 

L31MaxExpress

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You and your sea level air, you just love to gloat don't you? My trucks get pretty rowdy in MI at 700' elevation. The dually would blow donuts if I let it, it hits like being punched in the back. Hard. Even barks tires with a trailer hooked up.
I dunno it was like 3,600 DA when I lit them up like that and my IATs were in the 140-150°F range. Like 660' elevation here but it was hot as hades.

Now you are gloating on a dually. A little off topic, but I have really considered building my van into one for added stability and the beefier look. If I could figure out a decent looking rear dually fender setup I would have a dually too. I hate the trailer fender look with its trapezoid wheel arch in place of the OEM round wheel openings. I really like what one guy did with his Ford, but I am kind of against welding my rear door up to graft dually fenders on it. I literally think it would look better with 37-38 Chevy truck rear fenders on it that have a round wheel opening and a teardrop on the back.

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If I do a dually conversion, would probably use these fenders over the crappy looking ones made for the van. Atleast they would look better than the $1250 trailer fenders. The company that makes them also builds very nice looking bedside replacements that are widened to put semi wheels on later model trucks and made the van ones that cost about the same look like an cheesy after thought.

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L31MaxExpress

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I don’t even know what’s going on in this thread anymore. All I wanted was to know what gas to run . ‍♂️
Whatever your vehicle runs best on. That question is about like asking someone how they want their steak, eggs or toast cooked. Everyone is going to have their own opinion and what works for them.
 
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