Everyone is making valid points.

Jonny, yes, the polar moment will increase by moving the cell into the spare tire well. I agree with SnowTrooper though in regards to the CG not being affected. Also remember that a cell is going to be lighter than the factory assembly, so while you're moving 12-15 gallons of fuel about 10-12 inches to the rear, you're reducing the total mass of the unit. So to wrap up the polar moment issue, I tink Audi UK, Champion, Stasis and Istook would have gone a different route if they were really losing by moving the cell to the spare tire location.

There are a couple options out there for ready-made well cells. ATL and Fuel Safe both make them. ATL has two off-the-shelf models in an 8 and 12 gallon capacity. By the time you option them out with a surge tank, etc... it's an easy $1400, probably more. The well cells are a polycarbonate and are not legal to run in SCCA/NASA as-is because they don't have a metal enclosure. For U.S. model S4's, the lower part of the spare tire well has to be enclosed with a steel plate, then after the fuel cell is in place, it must be enclosed on the top via a steel plate... then a firewall must be constructed between the trunk area and the passenger area to pass tech. After all that fab work is done, the total bill will be north of 2k. If you wanted to go on the cheap and just slap a cell back there and not mind the interior of the car smelling like race gas, I suppose you could do it for around 1500. Good luck passing tech at anywhere other than the drag strip.

I haven't made my final decision on what route I'll be going, but the factory fuel tank does meet NASA/SCCA standards because of its DOT crash rating.

 

I do not know the cost, but I think the fuel cell is over $1,000.

But if you can do better.... I would love to have you build a trunk firewall for me. I am also looking for a body shop that is inexpensive - I can pay cash if needed.

 

vlms4@yahoo.com

i know of a killer body shop that will take very good care of you, the owner also happens to have a fabrication shop cpapable of building whatever you need.

 

how about you just shut up

 

you say that it can be done, so do it. you CLAIM that you can do it, show us....

 

welding aluminum and building a nice balanced and baffled tank is not that hard, i have dont them before. reading a rule book or 2 and building it to a certain spec is not hard. it is done everyday Eric. as of now my car is driven on the street, it has to pass smog. it will not pass smog in WA or CA with a cell. so if you want to contract me to build one for you then great. if you want to run your mouth for no reason then just STFU.

btw- how much is a entry level steadycam, i have been intrested in getting better shots on foot.

 

<center><img src="http://pictureposter.audiworld.com/1510/mvc-250f.jpg"></center><p>There are also several more reasons for installing a fuel cell. When we installed the cells in our Grand am Cup cars, we put them just back of the rear axle....if anything, it helps move the weight rearward, which you need in the front engined cars, and help offset the engine and part of the transmission that stick out in front of the front axle. We slightly offset the tank to the right to counter the drivers weight on the left.

By cutting out the spare tire well, we were able to put the cells as low or lower than the stock fuel tank.

Another feature, and very important, is that with two or three pickups inside the cell, we could get almost every drop of fuel out during a race...important when you are endurance racing, which you can't do while cornering left and right with the stock tank...you always starve for fuel at some point when you still have a fair amount left.

Other factors include our double dry break, which allowed us to refuel 20 gallons in about 45 seconds.

The picture shown is before we went to the double dry break system on both of our car.

 

wish you posted around here more Don.

 

<center><img src="http://pictureposter.audiworld.com/1510/img_4060.jpg"></center><p>We are now racing the TT Quattro. We have one car now, and I am building a second car that should be ready in two weeks