Over pressurized antifreeze tank

[Unilevers]

you split a piston from excessive timing and the bottom plate on the piston fell out, or you scored a liner, or you cracked the head so bad its into the crankcase.

Is the puff out the fill tube once per rotation or just constant? can you cut out cylinders and the puff goes away?

Having a blown head gasket will not make your blowby look like that - yes it looks like its pressurizing but that wont fill your crankcase with blowby.

my ass that program is stock power and has safe timing. Should pull it and have someone look at it.