|
|
I have been told that running 1/2 auto gas is good. Is this true? I tried using Mobil 93 octane for half of the tank and everything seems to run fine.
Lorn- I've been burning 93 octane auto in my normally-aspirated 8.5:1 CR IO-320
for six years with good results. Octane isn't the problem. The real potential problem with gasoline is vapor
pressure. Gasoline is formulated for Winter and Summer vapor pressures. Winter is the
higher, to aid engine starting under cold conditions. The vapor pressure for
Summer formula is very nearly as low as that of 100LL and I've never
experienced a low fuel pressure problem in hot Summer or Fall weather. I have, however, gotten a low fuel pressure alarm (set for 14 psi on my
injected engine) when running Winter formula on a hot Spring day. I'm
certain that it was due to incipient vaporization on the low pressure
(inlet) side of my engine-driven fuel pump. Fortunately, turning on the
electric boost pump, which is located just ahead of the engine-driven pump,
restored normal pressure. I had to leave it on for awhile. I've experienced this just a couple of times, after takeoff and at higher
altitudes (taking a tank of warm gasoline to the lower pressure of high
altitudes results in the same condition).
When do refiners switch from Winter to Summer formula and when are their
stations tanks clear of Winter formula? I don't know, but I've only
experienced the problem during April and May.
I noticed or think that I noticed that the fuel caps are harder to take off. It is almost as if the large rubber washers were expanding. Is this my imagination?
The newer fuel cap washers (light pink color) are rated for gasoline,
however, you should still remove and wipe them with silicon lube at least
once a year for long life and smooth operation.
How about some other comments and thoughts on using auto gasoline. Is it as safe as using aircraft fuel?
It can't be too hazardous, about 1/3 of all small piston airplanes are now
using it and the FAA issues STC s for it on certified aircraft.
Bill Rumburg
N403WR (Sonic bOOm)
|
|