Hello

I have a 55 AX on a 3D Profile. I am running wildcat 15% Nitro with 18% castor syn blend. The engine has about 1 hour of runtime, starts wonderfully, never run lean, idles great and makes GOBS of power with an APC 12.25 -3.75. I am also running a MACS pipe.

The problem that I am having is that the midrange is nonexistant. I have a good transition to full throttle, but there is a deadband which is I guess is the best way to describe it.

Any suggestions ??

We'd suggest that the midrange is a problem because you have a too-high top-end RPM. The prop sounds a bit small. Check the peak RPM on the ground and see what you have. You may need to bring the RPM down a bit.

Now, it's normal for the midrange to have a "flat" spot, where you see little RPM change when you move the stick, but you should still be able to move the stick from low to high without much engine problems.

I have also run the APC 13-4W and a XOAR 13-4 Same thing for each one. A little research from some others running this is suggesting just put the stock muffler back on.

The deadrand is REALLY big almost to the point I was thinking it was a throttle rigging issue. But checked it and it's linier.

I will try a bigger prop and tach it this time and get back to you here. Might be a day or two though.