Fuel loads
Instructor
Joined: Jul 2002
Posts: 174
Likes: 1
From: Johannesburg, South Africa
After every practice session we drain the tank completely dry. The details are then entered into a spread sheet to establish exact consumption per lap. Safety car laps at 50% on full speed consumption and in-out laps at 70%.
I know that I get stavation at 2lt left in tank so I run a 5lt minimun level. If you do this diligently you will find that you have the minimum of fuel to drain from the tank. (We use a dry-break system to minimise any fire risk.)
Important: I have found that 10kg's of weight equals 0.1 of a second per lap. This, on a lap where your average speed is 120km/h is 3 metres per lap. On a ten lap race it amounts to 30 metres. Quite a substantial amount!
I know that I get stavation at 2lt left in tank so I run a 5lt minimun level. If you do this diligently you will find that you have the minimum of fuel to drain from the tank. (We use a dry-break system to minimise any fire risk.)
Important: I have found that 10kg's of weight equals 0.1 of a second per lap. This, on a lap where your average speed is 120km/h is 3 metres per lap. On a ten lap race it amounts to 30 metres. Quite a substantial amount!
Burning Brakes
Joined: May 2003
Posts: 1,158
Likes: 60
From: Living in a cardboard box, but a nice one.
Running out of gas during a race sucks. Big time.
Der Professor was once racing an SSC car (SCCA "Showroom Stock C") at Nelson Ledges...with 3 laps to go, was beating all the other SSC cars AND all the other SSB (faster class) cars, along with a raft of other stuff..."over-all lead", BSD and all of that stuff. Coming out of the Carousel...cough...bang...wheeze. Nada...zip...squandool power...I'm out of freakin gas, dammit. After about 5 seconds, fuel pick-up starts working, but the lead SSB car is getting close, and I really wanted to keep him behind me 'cuz he was a dick and I wanted to "pee on his fire hydrant". Next time thru the Carousel, it started coughing even earlier. SSB car gets by me just before the Kink. CRAPwich. Held on to 2nd overall, but it ruined my afternoon, and necessitated extra cactus juice in the blender.
Fuel is good ballast. It's actually usable ballast. Like the airplane guys say "The only time you have too much fuel is when you're on fire".
I manage my fuel load. On Le Plastique Pig, I pump out before qualifying, leave just enough to get on & off the scales, and weigh-in. Fuel load is then adjusted (car weight depends on "which wheels", "which bodywork", ballast plates, etc.) so that I'll make weight by 3-5 lbs. post-qualifying/post race. On the Red Sled, since I know they never weigh us post-race, I just make sure I don't run out (which I've done in that car, too...). In the production-based crap, I just weigh and take an educated SWAG.
And...of course...if I'm using "leaded gas"......
Der Professor was once racing an SSC car (SCCA "Showroom Stock C") at Nelson Ledges...with 3 laps to go, was beating all the other SSC cars AND all the other SSB (faster class) cars, along with a raft of other stuff..."over-all lead", BSD and all of that stuff. Coming out of the Carousel...cough...bang...wheeze. Nada...zip...squandool power...I'm out of freakin gas, dammit. After about 5 seconds, fuel pick-up starts working, but the lead SSB car is getting close, and I really wanted to keep him behind me 'cuz he was a dick and I wanted to "pee on his fire hydrant". Next time thru the Carousel, it started coughing even earlier. SSB car gets by me just before the Kink. CRAPwich. Held on to 2nd overall, but it ruined my afternoon, and necessitated extra cactus juice in the blender.
Fuel is good ballast. It's actually usable ballast. Like the airplane guys say "The only time you have too much fuel is when you're on fire".
I manage my fuel load. On Le Plastique Pig, I pump out before qualifying, leave just enough to get on & off the scales, and weigh-in. Fuel load is then adjusted (car weight depends on "which wheels", "which bodywork", ballast plates, etc.) so that I'll make weight by 3-5 lbs. post-qualifying/post race. On the Red Sled, since I know they never weigh us post-race, I just make sure I don't run out (which I've done in that car, too...). In the production-based crap, I just weigh and take an educated SWAG.
And...of course...if I'm using "leaded gas"......
Team Owner
Joined: Jul 2006
Posts: 21,267
Likes: 6,020
I have a question regarding fuel load. In theory, less fuel = less weight, = lower lap times. But in my GT3, (it's was corner balanced at 1/2 tank of fuel), I tend to have faster laps from a full tank to 3/4 of a tank full rather than a lower fuel load. Could this be because the car handles better with more weight on the nose considering it's *** heavy?
Race Director
Joined: Aug 2002
Posts: 17,643
Likes: 8
From: Phoenix, Az
Yes less weight does equal faster however some times balast in certain locations on the car improves overall balance and then makes the car faster. Fuel as ballast is ok at the club level, but at the pro level if adding weight makes the car faster it means you to need adjust the set-up as the weight is band-aiding a problem. Of course the pro will set-up a car for a specifc fuel load and consider how a fuel load change impacts that balance through out the run.
Personally I have never drained the tank to get fuel consumption, However it does make sense if you are running lots of enduro's. It can be very important to know what you fuel burn rate is to plan fuel stratagy. For example my 944 with is 17.4 gallon tank with rull 90 mintues with out stopping at most tracks. 2hrs? Well that is a tougher guess. Maybe maybe not and who want so get it wrong?
Personally I have never drained the tank to get fuel consumption, However it does make sense if you are running lots of enduro's. It can be very important to know what you fuel burn rate is to plan fuel stratagy. For example my 944 with is 17.4 gallon tank with rull 90 mintues with out stopping at most tracks. 2hrs? Well that is a tougher guess. Maybe maybe not and who want so get it wrong?
Burning Brakes
Joined: May 2003
Posts: 1,158
Likes: 60
From: Living in a cardboard box, but a nice one.
Race Director
Joined: Aug 2002
Posts: 17,643
Likes: 8
From: Phoenix, Az
My point was that any weight over minimum that might make the car faster is a "band-aid" to some set-up issue or inherient car problem.
My class min weight is 2600lbs. I ballast to 2625 or so most times over the scales with 30lbs of ballast. Why? I don't want to worry about being DQ'ed if the scales are a bit off. Ideally I would weight me and the car to 2601 lbs with no fuel and then always be ok, but given my weight can change(5lbs during the year) I find it easier to just put in a little extra margin to allow for that and bad scales. I could drain fuel and run the car over the scales each day to calibrate, but that is too much work. Since my ballast is in 10lbs weights I am considering pulling 10lbs of that. I figure 15lbs should be enough as compared to 25lbs.
