The susceptibility to vapourisation within the fuel system depends a lot on its design, so it will be engine- and airframe-dependent.
One can’t compare cars with planes.
With an aux pump mounted low you have to be very unlucky to get vapor lock. With EFI (rotax 912 is) it’s pretty much impossible due to high amount of recirculation of fuel.
Fresh mogas is worse than old mogas in this respect. Also using winter fuel in the summer is not a good idea.
Fresh mogas is worse than old mogas in this respect.
Why?
Because vapor pressure is one monitored parameter. Winter and summer fuel have different vapor pressure. The way it is done is to mix in the correct amount of lighter hydrocarbons before shipping it out to the pumps. Fresh mogas has the correct vapor pressure, but when stored in a ventilated tank, the lighter components evaporates fast, the heavier takes much longer time.
On a Jodel DR1050 with an O200 engine, gravity feed with low mounted electric pump on, I’ve had vapour lock on opening throttle full to take off, Revs rise, level off at about 1600, then engine dies, could be quickly restarted, but taxi only. Mogas in tank within temperature limits, but heat from engine getting to gascolator when sitting into wind. Definitely vapour lock, as gascolator blew out froth when drained immediately after.
