Originally Posted By: GMorg
I would modify Shannow's comment a little by suggesting that HMW PIB may maintain droplets as opposed to vaporization. As a result, the evaporating fuel may not displace as much air.
Could be right, I was playing off memory when the stuff was discussed ages ago, and I was pulling it out of STP with acetone.
It was tested in aircraft to try to prevent a blevvie formation on a crash, so maybe the thickening up under high shear is the effective mechanism.