RE: Great Planes Extra 330L
I'm not sure of the exact distance between caps but the width of the engine is 10.04" The caps most likely add about 1" to the total as they are at a downward angle. This engine fits in the Extra cowl with plenty of space to spare. The GT-80 and the DLE-111 are almost exactly the same widths, BTW.
Hope this helps.
Bliksem