An experimental aircraft pilot reported a NMAC while approaching the final approach course at a non-towered airport. The pilot took evasive action then proceeded with an uneventful landing.

Narrative

Personal flight to 2G8 from the east; descending from 4500' MSL over terrain. Made first call on listed CTAF of 122.8 10 miles east. Made another at 5 miles. Made one for final on runway 30 and established on a visual approach to the airport; surrounded by rising terrain. Looking throughout; particularly at left traffic and then at field; it looked like there might be more activity than normal. I knew there was an event at the field but had not hear activity.Then in my 2 o clock position about 50 feet higher and 100-200 feet away a single-engine aircraft was turning right base to final. It had more speed than me and the rising terrain was closer on the left side so I instinctually made an immediate right 180 to keep terrain away as well as keep the plane in sight without the wing blocking. I do not believe the other aircraft saw me. We proceeded to regroup and then turn back to the airport; landing in a left traffic pattern without incident. Upon landing; I checked NOTAMs and the radio frequency for the field had been changed from the listed CTAF in order to accommodate the event activity [frequency] XXX.X for event. The traffic pattern direction had not been changed. Upon departure; we used the correct frequency; and heard (and made) calls without issue.1. This is a reminder to check NOTAMs like your life depends on it. I had been in only a week earlier with no one around and had assumed it would be the same. In 8 years of flying here; I have never heard anyone else in the pattern for this field but this highlights the need to check NOTAMs for every airport no matter what. 2. I regret my instinctual decision to turn right (into) the traffic vs. left (away). We did not need to make a 180; the rising terrain was not that bad and in retrospect. We could have simply jogged away to the left while keeping the plane in sight.