No this is completely backwards - although in practice the nitro engine produces more power, as per your experience . Gasoline has a much higher SPECIFIC thermal energy (BTU/lb of fuel) than the other mixtures when based on the volume of the fuel itself. Nitromethane and methanol produce more power SOLELY BECAUSE they burn so much more of it. Gasoline has more than TWICE the amount of energy per unit as methanol, but produces 20% more "work" in the engine by burning 2.5 times the amount of fuel. In the example above the 355 SBC burns 2.89 lbs of gas to produce 53,176 BTU while the combustion of 7.11 lbs of methanol produces 67,545 BTU and nitromethane burns 25.8 lbs to generate 125,412 BTU. By corrolary, we could expect to burn 3.5 lbs of gas to generate 67,545 BTU of the methanol and 6.89 lbs of gas to generate the 125,412 BTU of the nitromethane example.

This stands to reason. The chemical breakdown of the fuel into CO2 and H2O is what releases the energy. Gasoline has more chemical bonds to break down per molecule, thus releasing significantly more energy per complete combustion cycle. FWIW diesel fuel has significantly more power per unit mass than gasoline due to the even longer carbon chains.

As always, the balancing act is in burning the sufficient amount of gas to make the amount of power we need. Of course this requires a somewhat larger engine because we need to pump more air in the same amount of time. After this we have many other considerations including port timing, compression ratios, induction method (preferably a rotary drum as mentioned by Renegade above).

Here is the problem. None of the gasoline engines on the market really maximize the power available to them. On the nitro side the new YS 1.70cdi may be the (current) pinnacle of efficiency, having both supercharged induction and electronic ignition to control the start of combustion. The YS engine becomes more fuel efficient with the EI. This proves (to me) that there is quite a bit of efficiency to be gained with a few improvements.

LCHeliover built a Pentathlon and now a Black Magic and converted his piped OS 1.60 to gasoline. He noted a similar RPM value as on the nitro version (around 7850 on an APC 18.1x10) but it now has an extremely reliable idle and the EI should completely eliminate deadsticks. He notes the power isn't quite up to the YS 1.70 levels however.

I have to wonder how an OS 2.10AX (theoretical engine, wishful thinking!) would work converted to gasoline/EI. The 1.60FX seems to work sufficiently, especially on the smaller/lighter/streamlined older planes. For instance the OS 1.60 would be a gross excess of power on my 11 year old Zimpro Viper 2m, but would be barely enough for a new Black Magic V3 or other large, draggy, modern pattern plane.

I am not confident we could easily convert a 4-stroke engine to gasoline the way the OS 2-stroke engine can be converted without running into preignition issues, and we know the YS diaphragms and gaskets won't play nicely with petroleum-based compounds.

I have to admit the thought of burning 15 gallons of gas at $3.75 (including oil, etc) vice burning the 22 or so gallons at ~$27/gallon for 30% heli fuel for the same number of flights is HIGHLY interesting. Who wouldn't want to save $500+ dollars on the fuel bill in a season?