if there is much point in trying to explain this to someone who says Childress doesn't know what he is talking about :rofl: - but here goes...
Ethanol has an octane of 115. Gasoline, high test, is aroung 92-93. Higher octane means you can operate at higher compression ratios which gives you a more effficient burn and greater power. Now, I doubt if the car owners went to higher compression ratios but they probably did move up the spark advance - you can do this with higher octane fuel (the 15% ethanol will raise the octane a bit and enable you to move the spark timing forward a bit). This in itself, can produce more efficient combustion and greater power output.
... this is really no news to people who have a little knowledge of internal combustion engines and fuels used in them. Years ago, before Nitrous became so popular in drag racing they had two major categories of cars: Gas fueled cars and what they called 'Fuelies' ... which before nitro meant alcohol. Alcohol allowed the racers to use GMC blowers (superchargers) to boost compression - wildly. You could not do that with low octane gasoline (even the leaded gas of that era). Consequently it was recognized that it wouldn't be fair to make a guy running gas to have to compete with a car powered with alcohol and 'blown'.
here is some more
'bullshit' on getting more power out of a given displacement engine using ethanol with turbo-charging - if you're interested:
http://www.ethanolboost.com/EBS_summary_2-10-09.pdf"Our engine technology is called Direct Injection (DI) Alcohol Boosting, and is used with turbocharged gasoline engines. It involves on-demand injection of an alcohol containing fluid, such as an ethanol or methanol-water mixture similar to windshield cleaner) or E85, into the engine. This on-demand direct injection allows operation of a given size gasoline engine at much greater power and at higher compression ratio. This makes it possible for automakers to use much smaller and more efficient engines to achieve the same or better performance as today’s engines."