I have about 200 old R/C Modeler magazines and I bet 25% of them have Clarence Lee answering the same question. The answer is always the same. No there is not a practical substitution for Nitro Methane. Some time back I believe Sig did have some success replacing it with Nitro Ethane. If acetone worked that would be great. That's a lot easier to obtain. If there is a practical replacement, let me know. I will go back to making my own fuel.