Lets install a fuel tank

[jo proffi]

how about just welding a bit of angle to the outside the frame and bolting through that?
You want to bolt the tank fairly snug and you want the weight to be carried across its whole surface, not just 6x 10mm bolt heads, which is what it will end up being once the foam compresses.
Jo

 

[COL]

how about just welding a bit of angle to the outside the frame and bolting through that?
You want to bolt the tank fairly snug and you want the weight to be carried across its whole surface, not just 6x 10mm bolt heads, which is what it will end up being once the foam compresses.
Jo

Can you change the bolts to the type with a counter sunk head Bowie? All you would need to do is counter sink the holes you already have. The put the foam around the frame going over the top of the bolts.

I would also put some foam under the straps so that the tank is a snug fit.

 

[REN TIN TIN]

The foam used as a spacer won't last very long before it compresses (or wears away, or disolves from the petrol) and you have the tank sitting on the bolt heads.
The bolt heads will then eventually abrade their way into the tank and you'll have a fuel leak.
With the leak being on the bottom of the tank and the weight of the petrol pushing, it won't need to be a big hole to be a big problem.

 

[85Fuego]

how about just welding a bit of angle to the outside the frame and bolting through that?
You want to bolt the tank fairly snug and you want the weight to be carried across its whole surface, not just 6x 10mm bolt heads, which is what it will end up being once the foam compresses.
Jo

This ^^^

 

[Bowie]

Yeah fair point all. Yes I can easily now weld tabs to the outside of the right angle.. probably should have thought of that at first.. ..

The frame is made of 3mm material, I can counter sink them a little, but the bolt heads wouldn't really sit flush... I think the solution above is what I should do..

And yes I have foam protecting the aluminium straps currently. It all ties in pretty snuggly which is good

You can see now I'm experimenting with where the fuel line is going to go. It's annoying there is so many bouncy bits one needs to consider. I want to make it as straight as possible because, well I like the idea of my overpowered pump having to do as little as possible. Once it gets past the rear frame rail, it can run across the floor, along the front rail where the OE line was.

I may end up going into the cabin here, then back under the floor. It is a nice shortcut to avoid a bunch of corners.. Just have to think about sealing the line away from the driver, perhaps just a half circle tube welded onto the existing sheet floor allowing it to submarine. Maybe I keep it above the floor and run it along the passenger rail, then simply get a section of flat bar, weld it to the floor and sides making a triangle.. Hmmmm.

 

[schlitzaugen]

Nah. Countersink all the way will work even it the bolts' cones will project below the steel. But even then, I would still not leave the tank sitting on a steel frame.

What I suggest is you countersink the bolts (or not) and use a piece of plywood of the same thickness as the bolt heads to sit the tank on. If you don't want to countersink you'll just have to make some cut outs for the heads in the plywood. 6mm plywood should do it.

 

[Bowie]

Ah yeah, just make a bed within the structure, yeah that's a neat way to do it too.

 

[Greenpeace]

This is the 30L alloy marine tank I fitted in my Reliant. The 6mm aluminium plates bolt to 4 body mounting points and the tank is suspended through these plates by four 3/8" bolts. There are 2 pieces of 3mm thick aluminium angle that run across the bottom of the tank to support it ,(the same as the two that run across the top). The bottom two have rubber strips on them. The pipe that runs off to the right bottom of the photo runs to an external marine breather above the taillight.

No it's not a race car so doesn't have to meet certain regulations but it has been in situ for 7 years on the rough as guts roads around here and hasn't moved so much as a bee's d#ck.

This tank sits entirely between the chassis rails, the original sat against the left hand mudguard .
There was about 1.5mm of fibreglass between the petrol tank and some muppets bull bar.

 

[Bustamif]

Bowie is struggling to follow the race regulations and keep within a budget however the end result is not really suited to a car that is intended for going fast around race track corners. It is way too high and will make the rear end feel very unstable with a full tank of fuel in a light car.
With all due respect, modifications on a track car should be cost effective but they should also improve performance. There has to be a way of getting a lower C of G or the only advantage gained will be a tank spotlessly clean inside.
It will probably roll onto its roof before those bolts have enough miles to chafe through the tank.

 

[Greenpeace]

Bowie is struggling to follow the race regulations and keep within a budget however the end result is not really suited to a car that is intended for going fast around race track corners. It is way too high and will make the rear end feel very unstable with a full tank of fuel in a light car.
With all due respect, modifications on a track car should be cost effective but they should also improve performance. There has to be a way of getting a lower C of G or the only advantage gained will be a tank spotlessly clean inside.
It will probably roll onto its roof before those bolts have enough miles to chafe through the tank.

Mmm that's the main reason why I positioned the Reliant's down low between the chassis rails. A delta 3 wheeler needs all the help it can get.
The positioning being safer from an impact perspective was just an added bonus.
The poly race seats are also mounted much lower than the originals and anything from the belt line up was lightened as much as practicable. 0.4mm thick aluminium boot and bonnet, 3mm thick lexan windows etc.

With Bowie's tank only being 30L we are talking 21kg of fuel mass plus whatever the tank weighs. Of course ideally it would be better mounted lower down but in reality wouldn't the effect on COG would be similar to that if two different drivers varied by 20 odd kg in weight?

 

[Bustamif]

Mmm that's the main reason why I positioned the Reliant's down low between the chassis rails. A delta 3 wheeler needs all the help it can get.
The positioning being safer from an impact perspective was just an added bonus.
The poly race seats are also mounted much lower than the originals and anything from the belt line up was lightened as much as practicable. 0.4mm thick aluminium boot and bonnet, 3mm thick lexan windows etc.

With Bowie's tank only being 30L we are talking 21kg of fuel mass plus whatever the tank weighs. Of course ideally it would be better mounted lower down but in reality wouldn't the effect on COG would be similar to that if two different drivers varied by 20 odd kg in weight?

Remember fuel moves around and gathers momentum side to side and forward back even with foam filled tanks and baffles. Also remember that although Bowies car will not have huge grip and big G forces from super soft tyres or ground effects, the 21 kg could be up to 40 kg plus.
Corner weights frequently make a bigger difference to handling than wheel alignment. Most successful race cars will be corner weighted down to less than 1/2 kg variation side to side with the driver in, helmet on, fuel and oil. It makes a huge difference to stability when braking and turning.
Any advantage with a race car, especially cheap solutions are well worth the engineering effort.

 

[Greenpeace]

Remember fuel moves around and gathers momentum side to side and forward back even with foam filled tanks and baffles. Also remember that although Bowies car will not have huge grip and big G forces from super soft tyres or ground effects, the 21 kg could be up to 40 kg plus.
Corner weights frequently make a bigger difference to handling than wheel alignment. Most successful race cars will be corner weighted down to less than 1/2 kg variation side to side with the driver in, helmet on, fuel and oil. It makes a huge difference to stability when braking and turning.
Any advantage with a race car, especially cheap solutions are well worth the engineering effort.

No doubt in an ideal world a 7.5L tank at each wheel that depleted at the same rate would be a perfect solution.

I'm not sure what the standard tank volume is but I'll guess at 45L. I'm thinking 30L in a foam filled cell mounted directly over the rear axle wouldn't be any more detrimental to the handling characteristics than the (albeit lower mounted) 45L (non foamed filled) stock tank would be sploshing around and acting like a pendulum behind the rear axle?

In Bowie's case maybe two flatter 15L tanks with non return valves spaced evenly either side of the boot hump may have been a bit better? Not sure if the current regs permit 2 tanks however? Or maybe one long, thin, low tank walled off in the middle with seperate outlets for each half? These/this would have to be custom made, so a lot more $$$ than the off the shelf fuel cell he is currently fitting.

A tank either side over the rear wheels seemed to work OK in the old Cooper S's.

 

[schlitzaugen]

The best setup for that car would be two flat tanks placed in the depressions left by the rear seat (i.e. just in front of that hump) but I think we're overengineering the car. I doubt the car can pull more than .5g in the corners or .6g under braking so not sure if the exercise is warranted. I think it's just a keep it simple, have fun car.

 

[Greenpeace]

The best setup for that car would be two flat tanks placed in the depressions left by the rear seat (i.e. just in front of that hump) but I think we're overengineering the car. I doubt the car can pull more than .5g in the corners or .6g under braking so not sure if the exercise is warranted. I think it's just a keep it simple, have fun car.

Not sure if the fuel tanks would be allowed in the driver's compartment unless they were somehow firewalled off?
I think Bowie will have to put something in place to isolate his current tank from the passenger compartment?

 

[Bustamif]

Tanks on different sides of the car have not proved successful in circuit racing as transfer pumps and systems are usually too heavy, don't work fast enough and usually fail. Although those systems were tried in the 1960's The positioning would not be compliant with the current motor racing safety regs.
I can only speak on what I have been involved in during real world race track testing of systems that comply with the safety regs, for works racing teams, with real results measured accurately by team engineers.

 

[schlitzaugen]

Not sure if the fuel tanks would be allowed in the driver's compartment unless they were somehow firewalled off?
I think Bowie will have to put something in place to isolate his current tank from the passenger compartment?

Probably not, but ideal does not mean allowed.

Regarding fuel transfer, it is very easy to have a pipe at the bottom of the tanks to connect across. No need for pumping, they would equalise by gravity.

 

[Bowie]

It is always a series of compromises.

The OE tank is 11 gallons, ~41L, and the thing that started this was as the tank is vented out of the cap, I was getting black flagged as when ever I turned left, fuel would piss out the side. I ended up having to keep the tank 1/4 full, so maybe only 10, 15L anyway, and when it was that low, it would stall and shudder in corners.

I suppose I could have just tapped a line into the filler neg to create a vent line, and then change the cap arrangement to close it. Or, I probably should have just installed a bloody facet 12v elec pump low in the engine bay, along with a 1L surge tank and called it a day, but here I am!

It would have been easier to install the tank low and tight against the beam, but I was fouling the 500mm rule and didn't want splurge on nomex or aluminum honeycomb as the rule requires.

And yep, fuel tanks need to be protected by a secondary barrier away from the cabin, so moving it as close the back of seat supports (which will be platted in sheet metal) was as far forward as I could go without making to much of a fuss in the cabin wall structure and it's over the beam anyway now so cool.

I suppose Ideally one would organize something next to the driver, in the middle of the axles, as low as the floor and as wide as allowed. But then I'd be making a secondary structure to separate that compartment etc etc, and I need to put a cage in before I get too stupid.

Finally in regards to Geeee's, when it was last rego'd she actually measured 1.1 under brakes on the 165 road tyres And for what it's worth, with mobile phone sensor apps it was managing 0.6-0.8 in some corners, So yeah at worst / best case we are dealing with ~50kg positioned in the middle of the rear beam. I had thought the trade off in moving it over to the beam would negate the detriment as it increased in height, buuuuut I confess I didn't check that. I might look up that math and see just what I've done.

Measuring roughly the center-line of each tank, I have raised the weight ~450mm from the OE position.

I probably can cut in the beam housing to lower it a little then just box around it, but I'd want the suspension in to confirm that movement, and it's all in pieces as I save for the coil over modifications to the Koni's

But what have I done? It dam well shouldn't leak out of the fuel cap now, and confident I can run with a lower fuel level and it won't stall out going around corners + it will have strong solid supply from 5k rpm

We will settle on this as the Mark1, and I can continue to learn from my mistakes and short comings here on in

Now to look up that math..

 

[Bowie]

#Edit.

The weight is now ~450mm higher then the OE, but has moved forward, ~420mm, now on top of the beam

 

[Bustamif]

When you are at a track, check what other people have done with their tanks, I would be surprised if you cant strike up a conversation with some smart people who could have some spare material, offcuts of Nomex, Kevlar, honeycomb aluminium etc. I have scavenged heaps of free carbon fibre and even titanium over the years, you don't know until you ask and most people in racing are happy to help on projects such as yours.
Version 2 may be easier to achieve than you think.
Many big teams upgrade heaps of stuff in the off season and you would be astonished at what goes in the skip bin.

 

[Greenpeace]

Regarding fuel transfer, it is very easy to have a pipe at the bottom of the tanks to connect across. No need for pumping, they would equalise by gravity.

That's all my Mini has.