My Vmax has the Factory 5 gallon wing tanks installed. This afternoon I decided to do a usable fuel quantity test. Knowing that my pickups are installed thru the side of the tank in the rear inboard corner vs thru the bottom I was  curious to see how much usable fuel I really have.

I filled both tanks, elevated the tail til a protractor placed on the upper longeron read -5deg then opened the right hand tank valve and gascolator drain and waited....... after the right tank had emptied as much as it could (I noted approx. .75" of fuel still in the bottom) I closed its valve and Taxiied the plane (on the left tank) to the gas pump. When I refifilled the right tank, the pump indicated 5.3 gallons!

So now I have questions...... How much does a factory 5 gallon tank actually hold? These arent the slanted 6 gallon tanks, they are 5 gallon. I think for safeties sake I will still call it 4gal usable but still i was shocked to see that 5.3 number.

Chris

Chris,
The 5 gallon poly fuel tanks swell after they have had fuel in them. I don't recall what the original dimensions of the tanks. I want to say that mine grew 1/4 - 3/8 of an inch.

Kgrenier,
Good point, I wonder how much extra capacity it adds. Mine hsve had fuel in them since 1998.

Chris