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PostPosted: January 1, 2018, 1:03 pm 
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Location: Austin, TX
I'm still toying around with fuel tank ideas for my build and the latest is a scuttle mounted tank. There are a few reasons I like it and only one that I don't and that isn't even that bad.

So the pros-
1. Gets fuel tank out of the "kill zone" in the back of the car where it is pretty vulnerable if I get rear ended.
2. Opens up a ton(relatively speaking) of room for storage in the back of the car.
3. Moves the weight of the fuel more central to the car.
4. Makes use of a giant dead space
5. Reduces fuel line and wiring runs

Con-
1. Moves the CG of the car up some. On my car design it would move the fuel weight up by only about 2" though

So am I nuts for thinking about this? Is there something I'm missing? I just don't see many if any people going this route for the tank. I feel like I'm missing something obvious that makes this a terrible idea.


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PostPosted: January 1, 2018, 1:41 pm 
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From what I've seen and what I'm planning with my build that's where I'm putting my battery and almost all of my wiring.
If that's not an issue in your build I suppose it could work. I would probably want a firewall of some sort between me and the fuel tank.


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PostPosted: January 1, 2018, 1:48 pm 
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Seems to me that there is room at the end of the passenger foot well for stuff. I think that some have put their battery down there, but if you want to put a fuel cell there (with appropriate safety measures of course) that might be a place to consider.

I know what you mean about not wanting to put a fuel cell at the rear of a small car, I've wrapped mine in 1" square tubes (same stuff I used to build the frame) in hopes of some protection in case of a rear-ender.

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PostPosted: January 1, 2018, 1:49 pm 
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Sounds to me like you might be adding a major fire hazard. Any thing leaked or spilled could be bad.

I have thought about saddle tanks behind the rear fire wall (seat back) on either side of the drive shaft. Comments appreciated.


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PostPosted: January 1, 2018, 1:52 pm 
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vroom wrote:
Sounds to me like you might be adding a major fire hazard. Any thing leaked or spilled could be bad. .


Certainly you'd want to put a firewall between the passenger's compartment and the fuel cell, and the fill hose going outside of the passenger's compartment. But at least one of the Lalo's have their fuel tank in the pontoons next to the passenger's feet. And I believe that the original Mk1 had it there too.

Of course, now we have to ponder what happens with a side impact....

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PostPosted: January 1, 2018, 3:39 pm 
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Joined: February 23, 2017, 12:45 pm
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Location: Austin, TX
I don't think I was clear on location. Here's a little diagram. The red rectangle is the more typical fuel tank spot I was first going to do. The green rectangle is the new scuttle mount idea. The tank would be over the trans, middle of the car.

Attachment:
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Untitled.png [ 129.98 KiB | Viewed 3412 times ]


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PostPosted: January 1, 2018, 3:47 pm 
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The Reventlow Scarabs did this in preparation for their big win at Riverside in October of '58! They outfitted two of their three cars with cowl mounted saddle tanks for extended range. Here you see Jim Travers of TRACO with his foot on the tank just ahead of the cockpit! Another tank sits on the ground right in front of the car.


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scarablongrangetankCapture.PNG [ 307.51 KiB | Viewed 3409 times ]

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Last edited by ngpmike on January 1, 2018, 3:56 pm, edited 2 times in total.
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PostPosted: January 1, 2018, 3:51 pm 
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It has been done. Check bonjo's build.
However, I think it will have to be a fairly small tank. I still think that the best solution would be a "cheese slice" like fuel cell that you'd be sitting/leaning on (they use them in Formula Fords), but I recall them to be pricey and still smallish.

viewtopic.php?f=35&t=2027&hilit=bonjo2&start=15

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PostPosted: January 1, 2018, 3:53 pm 
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First, everything is a compromise. We've noted here over the years that these cars aren't exactly what you'd want if you get into an accident with them. If you're looking for an "it's all good no downside" kinda thing, it probably won't happen.

Having said that... That's a lot of weight (5 pounds per gallon) mounted as high as you can mount it. It would slosh around, meaning a moving bit of weight as high as you can mount it? I assume that you'd put the fuel filler outside of the passenger compartment (in front of the windshield) too which adds a bit of complication.

Your design would certainly be safer in a side impact than my suggestion, or a rear-ender in your scenario.

I recall, back in the day, some Indy 500 cars would have an auxiliary fuel tank in front of the driver. Eddie Sachs had 8 fuel tanks in his vehicle in his 1964 accident.

G'03

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PostPosted: January 1, 2018, 5:03 pm 
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I have mixed feelings on that location. Regardless what the car is used for, I agree that a liquid-tight firewall must go between it and the passenger compartment. It's still at modern-car bumper height, though less likely to get hit than at the rear. Having fuel, or worse, the fumes, that close to all the electrics, well...

If the car is used on-track and you're looking to win, moving the CG forward and upward are both bad. OTOH if it's a cruiser it doesn't matter.

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PostPosted: January 2, 2018, 1:38 am 
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The VW Beetles put their fuel tanks over your feet. Some pre-WWII cars had the tanks up by the windshield to gravity feed to the carburetor.


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PostPosted: January 2, 2018, 2:18 pm 
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WWII vintage jeeps had the tank under the drivers seat! :shock:

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PostPosted: January 2, 2018, 3:34 pm 
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So the trick here is figure out an easy way to separate the tank from the passenger compartment in case of a spill or worse. That could be kind of difficult. Hadn't thought of the kind of natural separation the tank has in the back from me in the middle.

I did think of another down side and that is the fuel tank will be exposed to engine bay heat. Summer heat here in Texas will mean it will easily see 200 degree air washing over it.


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PostPosted: January 2, 2018, 3:56 pm 
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Joined: June 5, 2016, 7:03 am
Posts: 230
Location: ontario
banzairx7 wrote:
I'm still toying around with fuel tank ideas for my build and the latest is a scuttle mounted tank. There are a few reasons I like it and only one that I don't and that isn't even that bad.

So the pros-
1. Gets fuel tank out of the "kill zone" in the back of the car where it is pretty vulnerable if I get rear ended.
2. Opens up a ton(relatively speaking) of room for storage in the back of the car.
3. Moves the weight of the fuel more central to the car.
4. Makes use of a giant dead space
5. Reduces fuel line and wiring runs

Con-
1. Moves the CG of the car up some. On my car design it would move the fuel weight up by only about 2" though

So am I nuts for thinking about this? Is there something I'm missing? I just don't see many if any people going this route for the tank. I feel like I'm missing something obvious that makes this a terrible idea.


I don't think you are nuts,
Tanks have been set in the front, even behind the scuttle for a long time. However relatively speaking there is one situation in which I would prefer to have my fuel tank in the rear: that is if an engine fire was going to start under the hood while underway. My own tank is in the front, between the front wheels because my engine is in the back. On my first build with the engine in the front there was never any question for me where my tank was going to be (in the back). Nothing is perfect. With the engine behind the scuttle you may want to make sure your firewall is meaningful. You may even want to look at racing car fuel tanks for good measure. Good luck.


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PostPosted: January 2, 2018, 7:10 pm 
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banzairx7 wrote:
I did think of another down side and that is the fuel tank will be exposed to engine bay heat. Summer heat here in Texas will mean it will easily see 200 degree air washing over it.


It might not be that big of a deal. DeTomaso Panteras had the fuel tank in the engine compartment on the driver's side, snuggled up against the exhaust manifold.


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