If the fire gets thru the suit it will melt most synthetics faster than cotton so I'm told. Nomex is used by the majority of pro racers and the military has used it for some time for certain garments. Keep in mind that the suit is designed to protect you for a fairly short time-which should be enough to get away from a fire.
------------------
Grandpa's toys-modded suspensions and a few other tweaks
'89 CRX Si-SCCA ITA #99
'99 Prelude=a sweet song
'03 Dodge Dakota Club Cab V8-Patriot Blue gonna tow