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Fuel Cell Frame Design


SuperDave

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Hey folks!

We at HounDawg Racing are making huge progress building our next race car. Someday in the next four years, we hope to actually see some of you on the track!

While I finish up the roll cage and work on paint and body, I'm planning my fuel cell installation and I have some questions about design for the frame.

I see many examples where you folks have built nice frames that protect the underside of the cell--and there's no doubt that the more protection you have the better. But I don't see anywhere in the GCR or ITCS that mandates any kind of frame for the fuel cell other than the steel casing. You have to keep the bottom of the cell six inches off the pavememt--I assume your frame can hang down lower than that. So unless I'm missing something, as far as the rules go, I have the option of building a big strong frame nestled around the bottom, buying a kit like the RCI-7412A kit (looks like 1 inch by 1/8 inch steel strips that wrap 4 sides in two places), or (not that I'd want to do it) just letting the bare steel case hang down unprotected.

Apart from the rules, what are the design considerations for a safe fuel cell frame? First, I'd guess you want to cradle it firmly in place. Second, you'd want to protect it in case both your rear wheels fall off so the pavement doesn't dig into the cell. Third, the frame can provide some impact/crush protection.

Finally, have any of you running enduros with really big cells had any problems with ground clearance? Some of the 22 gallon cells I see can be pretty tall/deep. I saw an (old circle track) RCI cell, and if I installed it in my 240Z with the top flange sitting on top of my rear deck, it would hang down below the rockers. So if my rockers were 5-inches above the pavement, my cell would have to be raised 1 1/2-to-2 inches to meet the 6-inch minimum. That doesn't seem insurmountable--I guess you just build the frame and cover accordingly, but it seems like there'd be a better way.

Dave

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"Panchovillia" <sp> and "Ctompkins" have some great photos their installs. My vintage Z race car has a "Well Cell" in the spare tire well which is another option. See my gallery.

I am a little surprized that you need a 22 gallon cell. Most racecars have 8 to 12 gallon cells, unless you are looking to run enduro's exclusively.

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I am a little surprized that you need a 22 gallon cell. Most racecars have 8 to 12 gallon cells, unless you are looking to run enduro's exclusively.

I don't know anyone who runs enduros exclusively. If you run an enduro only occassionally, what are you suggesting...take out your 12 gallon cell and put in your 22 gallon cell for the enduro? I'd think that if there's a CHANCE you will run an enduro, you install the 22 gallon cell in the first place. Then for your sprints you just fill it with 8-12 gallons of gas. That's why I'm looking at a 22 gallon fuel cell.

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Hey SD, You know, we just don't see enduros on the west coast. No one I know runs such a large tank. Most Vintage events out here are sprint races, so 8 gallons works fine.

It seems what ever you do, your penalized....22 gallon tank is heavier than an eight, and you are limited on where you can put the tank to balance out the weight in the car. An eight gallon tank would not make it for an enduro. So...what to do???

Are you building the car for enduros or sprints? most guys I know build purpose built cars. An enduro is built for longitivity and reliability, and not super high HP. Sprints are built a little more "high strung".

What are you building?

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most guys I know...

What are you building?

Guess I ain't most guys.

I'm sure you're exactly right that the champions in the sprints have purpose-built sprint cars and the champions in the enduros have purpose-built enduro cars.

But you know what...here's a shocking revelation...it isn't always about being the champion!

I've been around the track enough to know that, given the amount of money I'm spending, I have no chance of winning any races. One of the Atlanta Region board members, who works at my place, told me there was a guy last year who spent $10,000 on one race weekend.

My initial aim is a Solo I hillclimb event--I do have a shot at winning there. But I want to be able to do other things without having to rebuild the car.

My goal is to field a car that is reasonably safe, doesn't oil down the track (or at least doesn't make the corner workers say "here HE comes again"), is reliable enough to finish, and isn't embarassingly slow. I am not an engineer and I am not a Nissan specialist. I am doing virtually all of the work myself. I may be a back-marker. But I'll be a back marker with enough money left in my pocket to buy you a beer after the race! And if I roll my precious Z up into a little ball, I'll be able to walk away with a smile on my face and a zero-balance on my credit card!

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Quick enough to wizz off the guys spending big bucks, good looking enough to be proud of, but affordable enough to keep the hobby a fun thing to do!

Gosh, I would just die if Rons car was ever injured! Don't know if I could take a car like that on the track? I would worry too much about the marbles bouncing of his hood!

Thumbs up Super Dave.

Hey, Ron where & when is your next event?

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Dave! Whoa!!

We are off on the wrong foot. You can and will do what ever you want to do...All I am doing is expressing what I see here and having a calm discussion....This is supposed to be fun!! You asked for Ideas, I tried to give you a few...remember I dont have all the details of what you are trying to accomplish...I am trying to understand where your head is at...

From one back marker to another :) have fun!!

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Chino, I am having the same problem....I am a little too concerned about running my Z right off the bat...As a matter of fact I am buying a well sorted C Production Roadster to run for my rookie year.

I just can't bear the thought of balling up my Z....too much time, effort and $$$ into that project.

As for my Z, well it will be in Sports Car International Magazine in the next two weeks or so. Sport Compact Car in about April or May and at Motorsport's show in late April.

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NP SD,

Let's find a way to make you fast where you want to run and beat a few of those guys with way too much $$$.

I would suggest calling the guys at ATL directly. They were awesome when I called them and made me a great deal on my cell directly from the factory....Be sure to get a cell with a surge tank as they make a really big difference.

There is nothing better than passing a Porsche that has to be worth $100k+ in a rusty ol' Datsun. :D

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  • 6 months later...

I have built Z racers with 22 and 15 gallon ATL cells.

The 22 gallon tank had about a 1 1/2" offset into the carand had 1 1/2' x 1/8" straps with stand offs welded to ends. The basic frame at the floor area was 1" steel box tube. At the bottom of the cell I made it the way Greg Pickett did in his Trans-Am Vette. It was 1/8" x 1" angle iron with a 20(?) gage plate covering the bottom of the angle iron frame. To connect the upper and lower frames I used 3/8" round bar stock bent with a 5" radius. Long sides had ends to the lower corners with radius bend centered on upper frame. Short sides were reversed with radius bends centered on lower frame.

All in all cheap and easy to make.

The 15 gallon install was more "show" and made from 1 x1" and 1 x 2" aluminum and was a bolt in (and rivit in) type of install. I will attach a photo, sorry I can't find my old car photos of the 22 gallon.

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Here's what I did. My understanding of the SCCA GCR not make me belive a "Frame" was needed. I am using a Fuel Safe 15 gal cell. I removed the spare tire tub with a spot weld cutter. I then cut out additional floor pan area wher needed. I then made a 0.090 steel filler panel that fit into the old spare tire hole. This kind of looked like a big "Pac Man" and made the round hole square. I also tried to offset the cell as far to the right side of the car as possible. I fabricted 1" x 1" 0.090 angle iron steel and welded it along the longitudal sides of the fuel cell opening. These pieces are welded to the floor pan of the Z and the classis front and rear crossmember stampings Uunder side of floor pan). The angle pieces also serve as a doubler for the fuel cell can side mounting holes. I also made some 2" wide 0.090 steel bottom support straps that fit onder the fuel cell can. Overall, this mounting method should meet the SCCA GCR, and does not add too much weight to he car. I tested the strength with my 240 lb arse standing on the floor, and was very satisfied with the result!

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  • 4 weeks later...

I'm building an EProd using an ATL 12 gallon cell. The support frame is simply some 1" square tubing welded between the car's frame under the trunk area that has been removed. See pictures Here.

I am going to bend some 1.5" roll-bar tubing that will hang down and get welded to the vehicle frame. This will protect the cell from a rear impact. I'm also going to weld some braces from the tubing forward at a 45 degree angle to the vehicle frame. This will help keep the rear bar from collapsing.

With the larger cells I have seen guys mount then higher in the trunk area. That's about all you can do to get the ground clearance. It does raise the center of gravity a bit though.

Good luck.

Rick

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Your role cage looks very strong! To bad you couldn't make mine! I think I am going to do my fuel cell frame about the same as yours, but with aluminium. I also am going to put the fuel pump and regulator in back next to the cell, and I still need to figure out where to position the battery back there. I think I'm just gonig to make on big frame, put some aluminium or light sheet metal around it to form a box drop in the cell on one side and put the pump and reg on the otherside above the battery. I want to make a seperate little compartmet to divied fuel and battery!!LOL that could get bad real fast!LOL thanks again!

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Hey SD, You know, we just don't see enduros on the west coast. No one I know runs such a large tank. Most Vintage events out here are sprint races, so 8 gallons works fine.

I realize this is an old post, but I just wanted to throw in my $.02. I have an 8 gallon cell, only do sprint races, and it's not large enough. Well there's BARELY enough fuel for a 1/2 hr session depending on the track. Part of my problem is the fuel pick-ups, I don't have a surge tank or enternal box to pick up every last drop, but after a session it has less than an inch in the bottom. In my club there are a few events which are 40 minutes and this being my first year, I've had to duck out early and just take the novice sign off (at least 1/2 the leader's laps).

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  • 2 weeks later...

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