Turns out there is laminar air flow in the combustion chamber and the propane line goes and "T's" into one of the fuel injectors on the opposite side of the temperature probe.

IE, when you pump gobs of propane into the engine during startup, one side of the engine is getting hotter than the other during startup and you are not reading the correct temperature.

This can distort the EGV such that the turbine wheel will rub.

Some engine manufacturers pipe the propane line into an even number of fuel tubes so you get uniform heat during startup.

In fact, I found out recently that you can pipe propane to your fuel line and run the engine on propane through all the injectors, obviously this would not be manufacturer recommended.

I have not been using a solenoid on the propane lines for years. All my jetcat engines were started up this same way, and never not even one time did I ever see a rub or a problem with jetcat. This seems to me to be a problem of uneven heating in artes engines.

I did not ask specifically, but I believe jetcat is using an even number of propane lines T'd into the fuel lines, or separate lines completely into the comb. chamber.