My plans are to be running E85, and have the case tank situated behind the passenger seat, where the boxes used to be. I was hoping to be able to fit a 5 gallon fuel cell there, possibly 8 gallon.
I plan on mostly AutoX, and slowly moving to SCCA.

What size do you suggest, and what type? I've seen plastic and a metal.

Do I want the street race version?

My hopes are to save some weight by dropping the stock gas tank.

This is going to be full race prepared. Not streetable.

Thank you for any advice!

 

Check rules first. Make sure you can move the fuel tank that far in the rule set you want to run in. The next issue is a metal bulkhead that will be required between the cell and driver's compartment.

The stock tank hardly weighs anything, any SCCA legal cell will weigh more than the stock tank.

 

Alright.
Not saying you're wrong, but I was wondering.

Why does the SCCA fuel cell weigh more? Going from a much larger tank, to a smaller 5 gallon?

As for the metal bulk head, what do you mean by this? A thick piece of metal between me and the fuel cell? What if I had a metal box surrounding the tank?

My goal was to move more mass towards the center of the car. I wanted to put the tank behind the passenger seat to try and counter my personal weight in the driver's seat. I'm guessing the batter will weigh more though. So, maybe I should put the battery behind the passenger? I've also been considering the Micro batteries. They are super small, and take little to no space. I've also considered push start.... LoL.

Thank you for the advice. This is a few year long process. Everything is being redone, so I am in no rush.

 

You might be able to lose some weight since you are going to such a small cell. The stock tank is made of really thin metal and only held in by thin straps. An SCCA legal cell will have an inner bladder, then an outer can to protect it.

The metal bulkhead is just what you are thinking, something that seperates the cell from you. A lot of this stuff is from road racing when it comes to cell rules, you need to make sure just what SCCA expects when you decide to toss your stock tank.

You might get away with a cheap/light cell if you are only running auto-x and the class doesn't require a cell in any way. Rules rules rules. And don't skimp on holding stuff down in the car just because you're only stomping cones. I've witnessed 2 cars roll at auto-x's. One VW Rabbit GTI and one Omni GLH, the Rabbit driver was almost clocked by his own battery when the only thing that kept it from hitting him was the ground cable. Be glad you drive a low car that is hard to make fall over.

 

Hahahah! That would scare the *%$( out of me.

I planned on welding most stuff to the body. I'd like to make sure everything is super secure.

I guess I need to look at the rules. I guess if I don't fit SCCA, i'll have to stick to autoX and just have fun.

I appreciate all the input. So many plans for the car.

In terms of AutoX, do you suggest a metal fuel cell? Or, something like this?

JEGS Performance Products 15500 JEGS Circle Track Fuel Cells

I see some have foam, some don't. Any suggestions?

I want smaller, but if I have to, I'll do 8 gallon.

 

You'll have to check the current rules for SCCA auto-x. I haven't seriously run an auto-x since about 1990. Ran some borrowed cars since then but no rule book studying since I built an E prepared Rabbit.

It used to be if the class didn't REQUIRE a cell you could use just about anything you wanted. If that is still the case;cheap and light!

 

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Awesome.

Thanks again for the help and advice.

 

One thing to remember is that some of the bladders do not like E85, so make sure you check that before buying one!

 

I'm confused by your use of terms autox/SCCA... since SCCA holds autocross events. I assume you mean road racing.
Road racing rules are probably more strict than autocross, so if you really plan on a dual purpose car then build to those standards.
Regardless, I would get foam in the tank. The larger tank required for road racing with create more slosh during autocross, unless you plan to run it full, in which case there won't be much weight advantage.
As for location, I plan to put the battery behind the passenger seat. And put the tank close to it's original location, right behind the diff. Reason being I don't want the thing that is changing weight on one side of the car. I would rather that weight be centered.
Good luck!

 

Thanks Abeomid, I will be checking to make sure the fuel cell is compatible with E85.

Travis,
I guess my view of AutoX is slightly slower, usually topping at 50-60, maybe 70 in longer tracks, but more focused on tight turns. SCCA has always been a more high speed, wider turns. Also way more strict.

At my local autox, the rules are too strict. They make sure you don't have anything loose, and then you go. But I've never gotten into very competitive classes.

I think I will end up with the battery behind the passenger and the gas behind me. 5 gallons doesn't weigh too much, and I doubt I'll use more then 5.

 

The Sports Car Club of America - Home You can download...for free...all of the rules for every kind of event that the SCCA sanctions. Also, in my experience, autox events that are not sanctioned by the SCCA still use all of the SCCA rules and regs especially those concerning safety.

I used to autox a race prepared Mustang in C Prepared. I eventually installed a 5 gallon cell in the car because I was having fuel starvation issues. Interestingly enough it did not save any weight over the stock tank and the rules required it to be placed in same location as the stock tank - behind the axle. Also, the SCCA specifies the height a fuel cell has to off of the ground at 6 inches. A stock gas tank is not spec'd in this way. In my installation, the fuel cell had to mounted two inches higher than the stock gas tank

As far as placement in the car - I believe an alternate gas tank has to be within 12" of the OE tank. In some cars, like a Miata, this allows a cell to be in the passenger compartment. But in an RX7 I am not sure you can pull this off legally. Check the rules to be sure.

Finally, not all club racing classes in the SCCA or NASA require fuel cells. For example SCCA Improved Touring does not require fuel cells. Where a fuel cell is required, the cell has to meet FIA certification and has nothing in common with the cheap circle track/drag race fuel cells you see in Summit or Jegs.

 

Thanks Mustanghammer.
I was looking through the rules yesterday and noticed the FIA rule requirement. I'm going to see if I can find one that meets those requirements.

 

Too funny! I was looking at placing a fuel tank in the jump seat location as well! My first thought was to just use a tank from a more modern car like a mid-90's Mercedes C-Class (tank's under rear seat) or an E30 BMW (same location) but both are just a little too wide to fit in that location. I've also considered an MR-2 tank due to it's shape but I can't get any specs on it.

If these don't work out, I'll be mig-welding an aluminum tank to fit the jumpseat section and utilize two OEM fuel pick-ups on either side of the driveshaft which should eliminate the need for a surge tank (both pickups will have baffles)

The risky route would be to take the C-Class tank (A Poly-plastic) and use a Devcon product to cut and taylor-fit the tank to the jumpseat section. Decisions, decisions...

OH! And yes, I'm doing this not only for weight distribution, I'm doing this because of the ground-effect package I plan to incorporate.
~Mike

 

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Look up the ATL and Race Cell fuel cells they have.

 

I ran a EP Datsun 510 in SCCA Solo2/ProSolo and was using a plastic 5 gal Boat tank. No starvation problems till it was dry. I could run it down to 1/2gal with no problems.

But it's only legal in Solo2 (autoX). 10 to 15 bucks. Has a fuel gauge on top of it. Held down by two 1x1/8 alumimum straps (tank has cut outs for straps molded into them.

I flatened the spare tire area and mounted it there. I think it would work for the fb. Then just make a bulkhead (box cover) over it.

This will not work for Road racing in SCCA or NASA. But till your ready for that. it works perfect!