Originally posted by John B
The os 70 is a great engine , have not owned one ,but, everyone I have seen is a great runner. Myself, I have a habit of overpowering, if I was going with the wieght of the 70 I would install the saito .91 instead.
Good point John!
I was just messing around with choices of power for the Kyosho P-51D ARF I'm assembling right now. It requires an inverted engine mounting, so I wanted to run a four-cycle in it. I bought a new O.S. .70 Surpass II. I brought a pile of engines over to my scale and started comparing them. The O.S. .70 weighs ONE FULL OUNCE MORE than my Saito .91! (Both ready-to-run with mufflers attached.)
There was some debate in this thread about the merits of the .70 Surpass vs. the Saito .72. The comparison should be between the .70 Surpass and the Saito .91 or Saito 100!
Anyway, sometimes the extra weight is not a bad thing. I have The World Models Super Frontier Senior (a SIG Senior copy). It doesn't need much horsepower to fly. It came out pretty tail-heavy and I had to stick a bunch of lead all over the firewall and engine mount and use a heavy hub to get the balance right with a Saito .56. Later on, I picked up a new Saito .65 cheap. This engine is a lot heavier than the .56 but only makes a fraction more horsepower. It was the perfect solution for the Frontier Senior. It's extra mass even makes it a little smoother.
I'll hang on to my O.S. .70 until I build something that needs some nose weight.
Happy New Year!