According to the Youtube, he went 55, so I assume the suction increases and pulls more fumes into the intake, the faster it goes. I'm sure if one added a little heat to the fuel, it would produce even more fumes.
2008 F-250 4X4 Lariat V-10
2002 Airstream Classic 30' w/SO #2074
2007 Kubota 900 RTV
1996 Ford Bronco
2007 Lincoln LT