ORIGINAL: gabrielg74
cporres,
I also live in a city at 4,000ft asl and I am using a Saito 100 in my Excelleron.
The saito 100 is marginal for an Intermediate pattern at this altitude, I've tried it at a contest at 4,500ft and it definitely lacked power, but then the Saito is a lot less powerful than a YS110, so I would think that a YS110 would be perfect at 4,000ft, unless you intend to do 3D.
I've also heard a YS110 is more powerful than a YS120, although I haven't tested this myself.
Gabriel
I'm just starting to trim a JR Explorer which is very similar to the Excelleron 90. It has a YS 120NC. The plane is not over powered but the 120NC probably isn't much different from the YS110 in output. The main problem is weight. The Explorer has retracts which shifts the CG back some. The plane was modified by moving the tank to the front of the cockpit area. The servos and receiver were shifted to the rear. The 1100 mAh battery was relocated behind the wing. While the CG is in the middle of the recommended range for the Excelleron (no instructions came with the plane so I'm using a downloaded copy of the Excelleron instructions), the plane flies nose-heavy.
Allan