thanks for the input i just thought cause the ggl needed high test gas to work properly that the high octane would help it. u just saved me $1.72/litre. thanks! what kind of rpms and what prop size were u using. i was thinking of building a spacewalker 2 for this engine. and want something easy to fly with power to do big loops and stuff like that. not over powered, but not a slouch i had a 25cc homey that i hoped up, but it went bang! cause the plate i used to stuff the case didnt have enough clearence. apparently engines dont like pieces of aluminum