Hello,

I'm building an airplane that will use the OS FS 155 four stroke engine. Because I'm at the part of the build where I need to install the firewall, I would like to know the dimensions of the OS engine mount that will go with this engine & which engine mount part number is compatible with this engine.

From the OS website, I was able to find the dimensions of the engine's mounting lugs.

I think OS part number 71904200 is the right mount for the OS FS 155 four stroke engine. Is that correct? If so, what is the distance from the back of the mount (where it will contact the firewall) to the first pair of engine bolt holes?

thanks,
Greg

According to OS, the distance between the firewall and the center of the rearmost engine mounting hole is 56mm.

Thank you, that's what I needed for the length.

Can you confirm; Is 71904200 the correct engine mount part number for this engine?

The mounting holes for the FSa-155 are as you described. I think the mount should work.