ORIGINAL: Don M.
I have a MVVS 26cc which is where the EVO 26cc came from. It is a very easy starting engine and runs like a champ but by the time you add the ignition system and battery it is a lot more than 2 ozs. heavier than a Saito 180. Mine weighs 42 ozs. without exhaust and 60 ozs. with the header & tuned pipe. Now you can use a Pitts type muffler and save some weight but although I have never run mine without a pipe I understand that a muffler lowers the power output considerable.
I have mine in a 13 lb. Balsa Nova 120 and performance is OK but in order to be really spectacular I would need to shed 2 lbs. I also have an OS 160 glow which is about equal to the Saito 180 and it is a 1 lb. lighter than the MVVS and will turn the same prop 500 more rpm's than the MVVS. Take the tuned pipe off the MVVS and the difference would be even greater. As I said the MVVS is a great little engine but unless you just have to save the fuel $$$'s the Saito 180 or OS 160 would be the way to go.
I am looking for a plane with an all up weight ( including engine and pipe ) of 10 - 11 lbs. Then I think the little gasser would be impressive.
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No one should expect a gas engine to come close to the high power and light weight of an equivalently sized glow engine under 35cc's. It probably won't happen in our lifetimes.
In many applications, the difference in power and weight is unimportant, but not so with 3D flying. Fortunately, for that type of flying, I pull out my little electric powered models and have a ball. That's more my speed, these days.