JAL
Member
The STC for gravity fed 150hp Io-320 to run Mogas only consists of of paperwork and placards, with no modifications made to the engine. The 160hp version requires using 91 or better Mogas but otherwise the same.
So the engine runs mogas no problems although Peterson's (STC holder) suggest you run a tank of 100LL once and awhile to keep some lead on the valves but is not a requirement of the STC.
The STC gets a little more complicated for engines using a fuel pump as its the fuel delivery system needs to be changed (fuel pumps mainly) I think because Mogas is more prone to vapor lock so a different type of pump is recommended.
So if you were designing a IO-320 installation you can make it Mogas compatible quite easily by designing the fuel delivery system to be in line with the STC.
So the engine runs mogas no problems although Peterson's (STC holder) suggest you run a tank of 100LL once and awhile to keep some lead on the valves but is not a requirement of the STC.
The STC gets a little more complicated for engines using a fuel pump as its the fuel delivery system needs to be changed (fuel pumps mainly) I think because Mogas is more prone to vapor lock so a different type of pump is recommended.
So if you were designing a IO-320 installation you can make it Mogas compatible quite easily by designing the fuel delivery system to be in line with the STC.