Basil:

The K&B model number 6550 is a ringed engine, weight is 17 ounces. I fly them with 12x8 3 blade MAS props.

http://www.modelengine.com/price.htm

Look also at the 61 "Twister" on special for $100 - but that one is an ABC design. Number 6170.

Here are the specs for the three K&B .61 models:

http://www.modelengine.com/aero/aircraft.htm

I have some 6550 engines, an 8360, a couple 4011s, these are all ringed, and have given excellent service. And I have no objection to the ABC engines, I just don't have any from K&B.

But you said earlier that you had already bought the Super Tigre, so I suppose it's a moot point. Unless you are going to buy another engine.

Bill.