Visit The Dirt Forum for More Information

Author Topic:   fuel cell placement?
JT54
Dirt Maniac

Total posts: 183
posted December 02, 2005 02:52 PM  
I was wondering what the best location is for a fuel cell ,or at least what peoples opinions are ....I have my 32 gallon fuel cell mounted as close to the rear end as possible but I have seen them mounted farther back...I think my rear weight pecentage is suffering by where I have it placed now....I can move it about 6 inches back without much trouble but I dont know how much that will affect my rear #....also I have noticed a trend of using a tall narrow rectangular cell that can be moved from side to side ....what are people using and where are they placed and why????thanks..JT

Todd83C
Dirt Full Roller

Total posts: 75
posted December 02, 2005 03:37 PM  
While i am no pro at this but i would think you would want it as far back as possible to get the rear %. It is also just my thought that you would want the cell just about centered on the center line of the chassis. Just as you would to bring your car up to weight.

Todd83C
Dirt Full Roller

Total posts: 75
posted December 02, 2005 03:42 PM  
Also try to get it as high as possiable. Just think of it as adding ballast. This would provide more overturning mass and would in turn produce more side bite.

JT54
Dirt Maniac

Total posts: 183
posted December 02, 2005 04:22 PM  
I have it all the way up to the deck ....I have been wondering if I moved it all the way back if that might have a pendulum affect on the car ,making it loose and keeping it loose .....right now the car is fairly tight on entry and pretty easy to drive.....anyone ealse have input?

JT54
Dirt Maniac

Total posts: 183
posted December 03, 2005 01:10 PM  
anyone have more input on this ?

dirtrace54
Dirt Freak

Total posts: 220
posted December 03, 2005 10:44 PM  
the pendulum effect is correct but in a mod, you dont see it happen often. one big thing to keep from having sloshing wieght, makes sure there is some foam or baffles in the fuel cell to get the fuel from sloshing around. my opinion would be to put it at the back and as far to the right as possible. alot of people debate with the right mounting, b ut this also decreases some of th ependulum effect and also helps tighten the car as fuel burns by increasing the amount of wedge because the RR wieght slowly decreases.

Hope this helps. Just some opinions being throw around

wfoondirt
Dirt Forum Champ
Total posts: 530
posted December 04, 2005 10:09 AM  
Mounting the fuel cell to the right will cause a DECREASE in crossweight as fuel burns off.

dirtrace54
Dirt Freak

Total posts: 220
posted December 04, 2005 10:50 AM  
the cross would increase since the RR is loosing wieght. the cross is measured of the LR and the RF. if the opposite corners were getting lighter then the cross percentage would increase

JT54
Dirt Maniac

Total posts: 183
posted December 04, 2005 12:38 PM  
thanks for the input ...I think you are right about increasing cross with cell on the right...at least that is what the scale # say.....I have been thinking a taller rectangular cell would help control fuel slosh by keeping it confined to a more narrow area .....what are some opinions on this?

tilley88
Dirt Forum Champ
Total posts: 885
posted December 04, 2005 01:01 PM  
As fuel burns off, the corner the fuel cell sits in will rise, which in effect will cause that corner and it's diagonal partner's cross to increase. Acts just like a weight jack.

Mark Wakefeld
Dirt Roller

Total posts: 21
posted December 04, 2005 01:41 PM  
Actually cross doesnt increase.

only left side which is still fine

your not jacking wt you are merely burning wt off the rr,lr and rear.

If you set a 20lb wt on your rr, both rr and lr increase, remove it and the opposite occurs.


wfoondirt
Dirt Forum Champ
Total posts: 530
posted December 05, 2005 09:14 AM  
You've got something odd on your car if adding 20 lbs on the rr corner doesn't change your crossweight.

dirtrace54
Dirt Freak

Total posts: 220
posted December 05, 2005 02:03 PM  
put a piece of lead on the right rear tire...if the lr increases the same amount.....your scales are screwed up......

now if you add it to a fuel cell that off set to the right.....both will increase....BUT the right will increase more than the left....and if the rr adds 20 lbs to the scale and the lr only adds 15.......you cross (LR+RF) just decreased if all other numbers stay the same

leapinlizard
Dirt Freak

Total posts: 430
posted December 05, 2005 02:10 PM  
cross weight can only be changed with Weight Jacks.

Adding weight on the RR would decrease Left side, increase Right side, and increase Rear weight but would not affect the cross.

Adding ballast on a corner changes side and rear but cannot take from another corner like weight jacks.

wfoondirt
Dirt Forum Champ
Total posts: 530
posted December 05, 2005 02:16 PM  
It can when it changes the ride height of a corner.

leapinlizard
Dirt Freak

Total posts: 430
posted December 05, 2005 02:45 PM  
When you tighten the RR screw jack, the RR goes down and the LF goes up, the LR goes up and so the RF.

By adding ballast to the RR, the LR also goes down. Negating the affect's of jacking weight.

Or at least the way I'm seeing it.

wfoondirt
Dirt Forum Champ
Total posts: 530
posted December 05, 2005 03:00 PM  
Try it next time you have your car on the scales.

Or do a search on here. This exact discussion has been on here a few times.

Limited Mod 57
Dirt Forum Racer

Total posts: 87
posted December 05, 2005 03:32 PM  
I do have to wonder though... On Speed this past weekend they were showing WOO Late Model races. I noticed, as each Late Model passed by, the cell was set about as far left as possible.

Yet a number of you are saying "place it on the right".

Why the discrepancy between the two groups?

tilley88
Dirt Forum Champ
Total posts: 885
posted December 05, 2005 08:35 PM  
Putting a piece of lead on the RR tire does'nt have the same effect as putting it on the chassis when scaling a car. Putting weight on the chassis at any corner will drop that corner and all others. If it is fuel, then when that fuel burns off, that corner will rise, jacking weight into that diagonal. It's minimal at best, unless you run a large cell and burn off a ton of fuel. I don't know about the rest of you, but I only burn 6-7 gallons a nite.

dirtrace54
Dirt Freak

Total posts: 220
posted December 05, 2005 08:44 PM  
6 or 7 gallons X 6lbs.....thats 36 to 42 pounds you burn a nite

guess we all see it a different way

for the way i set up cars, i guess the way i see things works for me.

but explain this, if you have to have weight jackers, or spacers to change the cross, how can you do it in a car that doesnt have them and can only use moving of weight?

dirtrace54
Dirt Freak

Total posts: 220
posted December 05, 2005 08:48 PM  
the late models running it to the left.....good point......we run ours to the left on the late model......but unless we run a sanctioned track, were trying to keep the car as light as possible

the mods we always have a weight rule and ussualy are always addin lead to make weight....so we play with the fuel cell more

fastow
Dirt Maniac

Total posts: 175
posted December 05, 2005 09:50 PM  
Heres a thought as a car is running around the track where exactly is the fuel be lost the fuel in the cell is being pushed back and to the right so as you burning fuel it would be like losing the fuel out of the left front corner of the cell. think about it if you burn 7 gallon of fuel @ 7lbs per gallon = 49 lbs on the scales in the shop its going to be different than when your running around the track it would be like taking 50 lbs out of the left front corner of the cell.

2nd2none
Dirt Forum Champ
Total posts: 764
posted December 06, 2005 01:36 AM  
having the cell mounted all the way over on the LEFT side will INCREASE LR weight as fuel burns off and will also DECREASE rear percent. This is why you see the cell always mounted to the left. As the race goes on and fuel is being burnt you are losing rear percent AKA losing forward bite BUT at the same time gaining LR weight INCREASING forward bite.

As for the original question it all depends. A newer car that is built well will benefit from the cell being over on the left side and mounted high. I say it depends because some of the older cars are built so heavy with a high left side percent already that having the cell all the way over to the left will cause too much of left side percent

[This message has been edited by 2nd2none (edited December 06, 2005).]

[This message has been edited by 2nd2none (edited December 06, 2005).]

JT54
Dirt Maniac

Total posts: 183
posted December 06, 2005 10:17 AM  
Interesting debate you have going on here guys ....right now my cell is centered in the chassis and can only be moved rearward 6 inches or so....to get my rear # right I have to add about 60 lb. lead and then my car is heavy .....so I think I already know the answer to my own ?....move the cell back and loose the weght...right?....I realy just wanted to see where other people actualy had theres mounted.....my car is fast right now but I want to loose weight anyway I can to try to get a little faster ....JT

tilley88
Dirt Forum Champ
Total posts: 885
posted December 06, 2005 10:43 AM  
I would'nt worry about the car being heavy, as long as it is'nt excessive. I've seen 2800 lbs mods take the checkers over 2500 lb cars. Get your numbers where you want 'em and feel comfortable driving. If the car is already fast, make small changes, and not too many at the same time. Move that fuel cell back 6", but make sure you have good protection behind it. Sounds like you're pretty close.

tilley88
Dirt Forum Champ
Total posts: 885
posted December 06, 2005 10:50 AM  
dirtrace54, Sorry I missed your point, but it is a good one. A mod with no adjustable spacers or jackers? Sounds like a street stock. I guess you would have to move your weight left to right, and up and down without any adjustments. But can you use non-adjustable spring spacers(trimmed to height), lowering blocks, or coil-over eliminators?

Mark Wakefeld
Dirt Roller

Total posts: 21
posted December 06, 2005 06:36 PM  
If you have no screw jacks you adjust cross with spring rates and or spring heights,period.

I allready did this on my scales before I posted what I posted. And what I posted is simple fact.

nothing wrong with my scales its very simple.

wt jacks remove wt from a corner and add it to another, ballast does not.

PEwaste
Dirt Full Roller

Total posts: 54
posted December 06, 2005 08:58 PM  
So you are saying if I hang a 25 pound chunk of lead to the left rear corner of the car I will not add lr weight?

On heavy tracks we normally add weight to the left rear, and then when it dry's off we move it up and over to the right.

dirtrace54
Dirt Freak

Total posts: 220
posted December 06, 2005 09:12 PM  
lol....im gonna say if i take 25 pounds off the LR and put it up on the LF.....i just moved weight without touching a weight jack.....

JT54
Dirt Maniac

Total posts: 183
posted December 15, 2005 02:24 PM  
tear drop or rectangular which is best and why?

Back to the Archives