This is to add a little more observations to the subject. I can compare two basically equivalent engines, a Saito 80 and an MDS 68. One is mounted in a Phaeton II and the other in a Hog Bipe. When tuned for flight, they both turn a 12-6 propeller approximately 12,600 rpm. The idle is set at 2,500 rpm for both. They will both idle a little slower but this is slow enough and gives dependable prompt transition. (Of course the Saito sounds much lower since there is ½ as many power strokes.)

They both start easily. The MDS can be choked by putting a finger on the intake. This won’t work on the Saito since the intake is at the rear and the cowl is in the way. However a finger over the exhaust port of the muffler works just fine. The needle valve adjustment on the Saito is further from the prop but similar locations can be had for many glow engines. The Saito has a deeper throaty sound while the MDS is more of a scream, but neither is exceptionally loud. The Saito costs $224, and the MDS $99.95. The Saito weighs 19 ounces, the MDS weighs 18.2 ounces.


Both engines turn the propeller with authority and have more than enough power to fly the airplane. As far as dependability, since the MDS is relatively new, I will consider my experience with other engines. In the last six years I have built nine R/C models with power plants ranging from a Norvell 0.61 to the Saito 80. They have included five 2-stroke, three 4-stroke engines and a diesel. During that time I have experienced several “flame outs” with each type. In every case the cause was either a fuel delivery problem or a mistuned engine. In other words I was the cause of them all. If a mechanically sound properly adjusted engine has a suitable supply of fuel, it will continue to run as long as you ask it to.

Each type engine is slightly better in some areas than another, but it is apparent to me that there is no significant technical reason to prefer one over the other. The choice really comes down to personal preference and passion.