ORIGINAL: turbo.gst
I know that the rpm claims by Fox don't sound like much difference between the Eagle IV 60 & 74, but it is very noticeable in flight. I run 11 x 10, 12 x 8, or 13 x 6 on my 74's. I love the way the planes fly with the extra power not really any speed difference, but easy long verticals and constant speed. I have both the ring and ABC versions of each. Get ready for a fairly long break-in process, but you will be rewarded with a real jewel. I have tried just about every type of break-in I have read about. To me, the heat cycling is the key. I use short runs with complete cool down in-between runs. When I put it in the air, I'm pretty easy with it for the first gallon ( not alot of high G's or extended verticals). I have had people offer to pay me to break-in their engines, I just tell them to furnish the fuel and I'll do it for a friend. I love to see people excited about the way their engines run!
I have SuperTigres (Italian made), so long break-in is nothing new. I relish the idea of supporting a US company making a US made product. It really bugs me that my Fox .40 ate its piston and liner not once, but TWICE. It sounded like it was gonna run like a ragged squirrel until the prop stopped dead at 9000rpm and the propnut came loose and the prop fell off. Locked it up solid... I miss it even though I only ran it on the test stand. Sad.
It didnt squeak like my K&B's though.