EV's

you need to take into account the way you trained your Infernape if you constantly fight pkmn with high sp attack of course Infernape will have a higher sp attack. but it cant make the best use of it as most of its attacks are physical so best bet is to give it an Adamant Nature and give it tonnes of Attack EVs.

Good Moveset

Flare Blitz
Swords Dance
Close Combat
Earthquake