Here is what my note book says I got:

6x3.5 Cox 14,200

7x3 MAS 3,500-12,500

7x4 MAS 10,000

On a different "55":

7x4 MAS 3,500-9,900

7x3 MAS 3,500 - 11,100 Then with a 3" piece of exhaust tubing I got 3,200 - 11,200

8x3 MAS 2,500 -9,000

8x4 MAS 2,500 -8,000

Likes about 12" of exhaust tubing on the bigger props.

Runs about 20+ min on one oz. on the larger props.

Treven