Any guidance on how much fuel to have when you arrive at the track? I would imagine the handling would be influenced by the weight in the front.

 

I prefer to drive with a full tank in the front.

 

Just fill 'er up before arriving and don't worry about it. A full tank should get you through 4 sessions. If you want to obsess about minimizing weight, you could always run low and refill after every single session, but that would be pretty silly.

I haven't really found fuel level to be a significant factor in my handling or lap times. And even if it were, so what... this is just DE.

 

Full tank man - don't worry, it doesn't stay full for very long

 

Yup, it's just a DE, so don't worry about trying to run a lighter load. I've run some of my best lap times with a nearly full tank. In practice sessions for a race, I try to fill the tank up. Having to refule after every session is just needless work.

 

Also, the fuel guage tends to jump around on the track. Sometimes my light comes on when I still have 1/4 tank. Now that I know, it isn't a big deal. However, having the light come on is an unnecessary distraction.

 

OK, but how about oversteer v. understeer characteristics in a full tank v. 1/4 tank

 

The car will tend to understeer more with less fuel. It is noticable.

 

+1

 

This is one major reason why 911 race cars have in cockpit adjustable front bars, you can adjust the handling as the fuel weight is lightened.

 

+2. If you want to see just how dramatic of a difference it makes, empty up your tank and go to AX. It'll feel like you're driving a FWD car.

 

There is also the notion of a half full tank having the most amount of slosh providing one with a dead-blow hammer effect. Cars with rear mounted tanks are most effected like that of a 1985 C4 Corvette I once had. Later years C4 vettes had a mid tank baffle installed that helped the tail-wag syndrome. Probably not that much of an issue with a 911, however.

 

I start each day with a full tank, also. My reasoning has nothing to do with handling, however - I don't want to spend $7 per gallon for race fuel!!

 

I think this is what I had at VIR. I was coming out of Oak Tree and was in my normal oversteer mode and when I put the gas pedal to the floor the tach just "bounced" at around 4,500 and didn't go anywhere. That was as good as a lift and I spun. Went back out and the same thing happened at Roller Coaster, but no spin. I though the clutch was slipping. I went back in and told some buddies what happened and at the same time they asked, "how much gas do you have?" The answer was less than about an 1/8....fuel light was probably about to come on.

I didn't have this problem w/ RA-1, but w/ Hoosiers my DL-1 is recording up to 1.5 g spikes on some turns, so from now on I start on full and fill again once I get close to 1/4.

 

Interesting - I have found that a full tank increases lap times. The difference between a quarter tank (enough for one session) and a full tank is probably and extra 75 lbs.