Being an old time 2c guy and getting a lot of help in another thread about 4c engines this makes me think of some other questions, but here's what I've learned...

- .56 4c makes a good replacement for a .40 2c
- .56 4c is great but still doesn't make as much HP as a .40 2c
- .70 4c is recomended if you really need the same power as the .40 2c

So do we really need all that power? Personally I hardly ever go vertical and fly 95% of the time between 1/3 and 2/3 throttle. On sport planes or aerobatic planes (not full on pattern or 3D) what manuvers require all the .70 4c power? What I'm trying to decide is if I really need to replace all the .40 2c power with identical 4c power (.70 4c) or if I can go with less (.56 4c). 2 plane example: Tower Fun-51 - flying now, Midwest Sukhio - building. Basic to lower-mid level aerobatics. Rolls, loops, knife edge, hammer head, flat turns (don't know if there's a better name for flat turn). Nothing serious. Let me know your opinion.

thanks,
Mike