As @TurkeyOnRye suggested, an enclosure is pretty much a necessity for high-temperature prints, however, there is another option that I’ve used successfully for PolyCarbonate on an open printer.
In Cura, there is an option for Draft Shield. I enable the shield and set it to be built 5mm from the part. It builds a wall around the part to trap warm air against the part edges and to force drafts up and over the part. It doesn’t work 100% of the time but I"ve had very few failures with it.
It is not available in Cura by default. You have to enable it via the Preferences mene / Configure Cura / Settings then search for “draft” and enable all the options. Now it will be available for use in the Print Settings menu on the right.
If you’re using something other than Cura, you’ll have to find the equivalent yourself or consult someone else as Cura is the only slicer I generally use.