PDA

View Full Version : Running with a full fuel tank.



wepsbee
10-09-2009, 07:57 AM
Possibly a dumb question but I have to ask anyway. Is it better to run with the least amount of fuel the car needs for the race to lighten the rear end for ratation or is it better to have the weight for traction in the rear. This is a FWD car.

Andy Bettencourt
10-09-2009, 08:19 AM
Dan,

I would think it depends on the design of the tank. If it's in a bad spot (high) or allows for a lot of slosh (upsetting the car) then you may not want that much gas. Problem is that you have to usually start with that problem or finish with that problem.

Best solution is a nice baffled fuel cell. I run the stock tank and try and finish within 5-15lbs from minimum weight. A cell allows you to size it perfectly, eliminate slosh and put it in decent spot for weight distribution.

billf
10-09-2009, 10:17 AM
Handling aside for the moment, my next thought is the amount of flammables carried. I'd like to limit the amount to what is needed for the event, and ballast the rest as needed for the scales.

Just another approach.

Good racing.

Bill:024:

wepsbee
10-09-2009, 10:31 AM
Dan,

I would think it depends on the design of the tank. If it's in a bad spot (high) or allows for a lot of slosh (upsetting the car) then you may not want that much gas. Problem is that you have to usually start with that problem or finish with that problem.

Best solution is a nice baffled fuel cell. I run the stock tank and try and finish within 5-15lbs from minimum weight. A cell allows you to size it perfectly, eliminate slosh and put it in decent spot for weight distribution.
My tank seems to be low in the frame but I think sloshing is an issue. I know all 3 EGT's racing in our region have a fuel starvation problem when the level is between 1/4 and 1/2. This problem shows up on severe turns like T3 at NHMS. I do not know if turns like the ones in the Boot at WGI are severe enough to cause this problem. Overall however I get the feeling less fuel/less weight would be the way to go. Learn the new rotation characteristics of the rear. I assume we would need to change the rear strut settings.As far as a cell is concerned at one of our recent Anual Tech Inspections we were told to keep the stock tank rather than a cell due to the better safety mounting low in the frame?

wepsbee
10-09-2009, 10:34 AM
Handling aside for the moment, my next thought is the amount of flammables carried. I'd like to limit the amount to what is needed for the event, and ballast the rest as needed for the scales.

Just another approach.

Good racing.

Bill:024:
That is a great thought. An issue that never entered my mind. Thanks

JLawton
10-09-2009, 12:47 PM
If you ran a full tank would you be able to hit the minimum weight? If not, I would run as little as possible. If you run ballast I would think you would get better weight distribution with the fuel towards the back than you would with ballast in the foot well.

I also don't think at this point you would notice much handling differences of 8-10 gallons of fuel.

wepsbee
10-09-2009, 01:09 PM
If you ran a full tank would you be able to hit the minimum weight? If not, I would run as little as possible. If you run ballast I would think you would get better weight distribution with the fuel towards the back than you would with ballast in the foot well.

I also don't think at this point you would notice much handling differences of 8-10 gallons of fuel.
I do not think I can get to minimum, the last time I checked I was 150 over!!!! With 3/4 plus fuel load. We are working on the weight issue a little at a time. Got some good ideas at LRP and will work on them this winter. I was trying to always start with a full tank for consistency. The handling difference is what I am trying to figure out. If none then less weight would be better.

wepsbee
10-09-2009, 01:10 PM
I do not think I can get to minimum, the last time I checked I was 150 over!!!! With 3/4 plus fuel load. We are working on the weight issue a little at a time. Got some good ideas at LRP and will work on them this winter. I was trying to always start with a full tank for consistency. The handling difference is what I am trying to figure out. If none then less weight would be better.
According to M. Kessler this car is probably classed wrong comparing the power to actual weight.

Andy Bettencourt
10-09-2009, 01:29 PM
According to M. Kessler this car is probably classed wrong comparing the power to actual weight.

Actual weight maybe, but POTENTIAL weight, no. 2325 is your minimum?. If you pulled the stock tank and replaced it with a small cell, you could probably eliminate about 50lbs (less gas needed). Go to some lightweight wheels and tires and I bet you could save another 30lbs. Mins are also based on 180lbs for driver. Most of us have some work to do in that department too.

wepsbee
10-09-2009, 01:35 PM
Actual weight maybe, but POTENTIAL weight, no. 2325 is your minimum?. If you pulled the stock tank and replaced it with a small cell, you could probably eliminate about 50lbs (less gas needed). Go to some lightweight wheels and tires and I bet you could save another 30lbs. Mins are also based on 180lbs for driver. Most of us have some work to do in that department too.
I am using Tracklites at I think 9-10 lbs. The fuel cell sounds really good. The last issue is a no brainer!!!!! We will keep at it though as we are seeing year to year improvements but the desire to get it done now is strong when we watch to rest of the pack in front.

JLawton
10-10-2009, 07:42 AM
You need to work on the car weight. 150 is a lot. I run with the bare minimum in fuel I only need a bout 2gls at the end to make weight. I run no ballast........... Of course, I am under 180lbs so that makes a difference! ;)

924Guy
10-10-2009, 08:08 AM
Tank location makes a big difference too... in the '24, our tank sits square over the rear axle. Fuel weight goes solely on that rear axle. As a result, the car is actually very sensitive to fuel load, once we get it critically tuned. We'll typically burn 2.5 gal of fuel in a race at our home track; over those 14 miles, the car will go from a mild push to a mild loose condition. Bigger races exaggerate the condition, of course.

Then you get to decide how you wish to set the car up - for the beginning or the end of the race? :)