Just out of curiosity- what kind of chemical are they getting 400 octane fuel?
Given how fuel blends, to make 10gallons of 93 octane into 10.25 gallons of 100 octane, that additional .25 gallons needs to be 400 octane.
This is a linear octane blend, which isn't 100% correct, but when we are talking a tiny part of one to a massive part of another, it works quite well.
There's no way 2.5% of the fuel can add 7 actual points in octane.
Same can be said of "Boostane".
MMT aka Methylcyclopentadienyl manganese tricarbonyl in Boostane.
In reply to fatallightning :
While that is an octane adder compound, I really question if it's capable of raising the octane in those amounts at the rate being recommended.
In reply to alfadriver :
What little I know of octane ratings, is that anti detonation qualities are not always linear with the additives used, and the way the chemicals interact with each other also plays a large role.
People used to make super high octane fuel by mixing pump leaded with pump unleaded, which ended up having a higher detonation resistance combined than either one had individually.
There was a LOT of money poured into the field about 80-90 years ago, as detonation resistance meant more power available from forced induction aircraft engines, which was a real priority at the time. A lot of this is freely available info nowadays (seems that detonation resistant fuel is no longer a matter of national security 
) and some of the things they learned are really interesting, including how some fuels fared differently in "severe" (usually air cooled) and "mild" (usually water cooled) engines, or under lean/economical mixes and fuel power fuel enrichment. Which is where fuels were given ratings like 115/145, or 100/130.
Triptane, IIRC, was rated at 270. This was also before octane numbers were standardized, so a lot of these numbers are kind of like SAE Gross horsepower.
Some chat from your pals at GRM on fuel additives right here.
Here's just about every conversation we've had with Technical Specialist Zachary Santner over at Sunoco. Hopefully there's a few items on this list that should help:
• What separates a race fuel from a street fuel?
• The science of high-octane fuel
• Buying and storing race fuel
• What happens to gasoline as it ages?
• Ethanol or not for your gasoline?
• More oxygen for more power?
• Why not methanol?
• Picking the proper gas regarding lead and oxygen
• Narrowing the fuel field
• 91 vs. 93 octane
• Fueling your boosted engine
• What fuel to feed a rotary engine?
• Lawn and garden equipment needs the proper fuel, too
• What is vapor pressure of gasoline and why should you care?
• What is specific gravity of gasoline and why should you care?
• Adding additives to your fuel. | Yes or no?
• What's really in that fuel additive?
• Antioxidants, fuel stabilizers, and you
• Winter fuels for wintertime
• Fuels for a post-apocalyptic world
• Need help selecting a fuel? Call the experts.
• Gas station basics that aren’t that basic
And our conversations from Classic Motorsports, too:
• What is race gas?
• Which race fuel is right for you?
• Buying and storing race fuel
• The right fuel in the fall might help your engine start in the spring
• Fuels for storage: good, better, best
• How much octane is enough for my classic?
• 93-octane not enough? Solutions exist.
• Picking the proper gas
• How to choose a quality gas station
• Why is there ethanol in our gasoline?
• Why not avgas in your car?
• Water is great for your plants, not so much for your fuel system
In reply to Pete. (l33t FS) :
Even so, adding just 2.5% of the fuel to gain 7 points would be incredibly non-linear. That's what I'm questioning.
Or less for other additives.
Whereas when there's a label on a full barrel of fuel, you have the idea that whoever made it did test it. I'd much rather get a fully blended fuel than hope that some additive is that non-linear.
In reply to alfadriver :
As a friend in the oil biz once said, Why are you playing chemist?
In reply to alfadriver :
It does take less TEL than that to make a change that large, given that 4-6cc/gallon is considered to be an extreme amount. But this specific claim does seem spurious.
I do kind of agree with "Why you playing chemist?". And I don't happen to have a Waukesha test engine kicking around to see if I made a beneficial change or was just pointlessly dumping stuff in the tank.
heh. Pointlessly
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