Fuel tank location

[heemoth]

Hi there, long time lingerer, first time poster!

I have a Sonic 7 kit which is still yet to be put on the road, it is an older style MEV kit. I bought it as "95%" finished kit (I did not buy the kit new - it was part built, yes I know - not a great idea - I have found that out the hard way!) so obviously I have a long way to go before it's IVA ready.... 

I have a question that relates to the fuel tank location. At the moment the fuel tank is located behind the passenger seat, but I notice that a lot of the newer kits have the fuel tank located at the front.

I was reading the IVA manual which seems to expressly prohibit having the fuel tank in the passenger area.... before I go and weld a load of structure into the chassis to support the tank (the previous owner thought that bolting directly onto the floor plate would be sufficient  ) will I be OK having the tank in the "passenger compartment"?

I guess if I do it would need to make a cover for it, how well sealed will the cover need to be? I'm wondering whether it might be better to re-locate it to the front - although annoyingly the hole for the fuel filler has already been cut in the side bodywork.... but repairing that might be easier than making a cover, depending how well sealed in needs to be.

Thanks in advance,

James Ward

[andybaird]

Hi James

Welcome to the forum

When I built my sonic I made a fiber glass three sided cover for the fuel tank behind the passenger seat.
It sat against the bulk head, side panel & floor. I have put a rubber u shaped edging on the edges that are in contact with the car but it is not sealed in any way.

If you go to the Sonic7 section in the form and look at my build thread (Andy's Sonic7) you can see a photo of the black cover.
My build Thread is on page 4 of the sonic7 section & the photo is on page 4 of my build thread about half way down,

Hope this helps
Andy

[buildityourself]

Hi James,

Great to hear there is another Sonic7 in progress somewhere. How long have you had it? Got any pics to share?

The main reason to move the tank is to get better weight distribution. Being mid engined most weight is at the rear. I used to have an Mk1 MR2 and that car was very light at the front at higher speeds. With the tank 7 battery at the front I've not noticed any lightness in the Sonic7 yet.

IVA don't like the tank in the compartment anymore so it would be checked closely so the cover would need to be well constructed and vented correctly. You could always use/cover the old filler hole as an intake duct for the engine bay as it will need extra cooling. I don't have any extra cooling currently and am seeing air intake temps of up to 45 deg C in October. 

Stuart.

PS Check out the Sonic7 facebook group.

[heemoth]

thanks for the replies guys, really appreciate it. Some pics enclosed. I’ve had it for a few years now, just trying to work through all the issues for the IVA but the project has languished this year, mostly because I’m at a point where I need to relocate the fuel tank and rewire the car, neither of which are appealing because it means removing all the body panels and under trays to do it properly. I need to grasp the nettle and get it done!

[buildityourself]

I remember that one coming up for sale. Are the side panels painted or a gel finish?

[heemoth]

The original gel was orange, it has been repainted in red.

[mawdo81]

I have mine up front, a disadvantage of that is that the tank does get warmed by the hot air coming out of the rad, so you have warmer fuel, so less dense which is not as good as nice cold fuel...I have heat shielding to limit the heat transfer but it doesn't eliminate it.

Also the weight balance of the car does shift full to empty...there's a reason race cars often have the fuel tank at or near the CoG...keeping the balance the same at all fuel levels.  Its not massive, but it is a consideration.

One of the main reasons I put it up front was to make use of the behind the seats storage space, and whilst there is lots, accessing is v hard due to the limited space between the seats & between the seats & roll bar/style hoop. I have now made the passenger seat tip forwards using mechanisms from a Fiat Multipla and it's much more useable now. If I had my time again, and the (hopefully soon to be released) Equilibrium hinges, I'd have a really hard think if I wanted to use the front space for luggage or fuel.

A big part of your decision is what you want to use the car for and what you want from it...

[buildityourself]

Nov 7, 2022 8:25:52 GMT mawdo81 said:

One of the main reasons I put it up front was to make use of the behind the seats storage space, and whilst there is lots, accessing is v hard due to the limited space between the seats & between the seats & roll bar/style hoop. I have now made the passenger seat tip forwards using mechanisms from a Fiat Multipla and it's much more useable now. 

We also thought the space behind the seats would be perfect for storing helmets whilst at shows. Only when we fitted the harnesses did we realise that this was a flawed idea. There is a lot of space but with little access. How do you tip the seat with the harness in place?

[heemoth]

Thanks for the replies. I was checking it out in the garage and it looks like the fuel tank I have would fit in the space ahead of the bulkhead but currently the radiator is there - but looks like I could cut off the brackets off the chassis, turn them 180 and weld them back on so the rad sits right at the front. The only thing I need to check is that the rad will fit in the new position width wise as the space is narrower at the front due to the tapering shape of the body. I will have a look at the weekend and try and get some pics. I also considered the heating effect of the rad and wondered whether I could make a scoop between tank and rad and have a vent above in the “bonnet” I have some mesh left over from the vent at the rear that I made for the engine bay so that would match nicely. I had started to make a bracket for the tank in the behind the passenger seat position but hopefully I can adapt it to the front position.

Those who have the tank in the front, do you have the filler directly on the tank underneath the bonnet panel or have you got a remote filler cut into the side body with a connecting tube?

Have to say I’m not concerned about having any storage space at all, just want to get it on the road!

[buildityourself]

[wishful4444]

Good day heemoth

I have a Sonic with the petrol tank in the front. There is no external filler. To fill the tank the bonnet is lifted off and the tank filled directly.
I do not find it a problem or inconvenient.

[kiwicanfly]

Nov 7, 2022 8:25:52 GMT mawdo81 said:

and the (hopefully soon to be released) Equilibrium hinges,

Tell us more.

[mawdo81]

Nov 13, 2022 23:14:59 GMT kiwicanfly said:

Nov 7, 2022 8:25:52 GMT mawdo81 said:

and the (hopefully soon to be released) Equilibrium hinges,

Tell us more.

equilibrium have designed a set of front and rear hinges to allow access to the bonnet/engine without completely removing the cover.  They are a work of art, but are taking a number of iterations to fettle the action...I've told Mike my money is waiting...so fingers crossed!

[mawdo81]

Nov 7, 2022 19:18:06 GMT buildityourself said:

Nov 7, 2022 8:25:52 GMT mawdo81 said:

One of the main reasons I put it up front was to make use of the behind the seats storage space, and whilst there is lots, accessing is v hard due to the limited space between the seats & between the seats & roll bar/style hoop. I have now made the passenger seat tip forwards using mechanisms from a Fiat Multipla and it's much more useable now. 

We also thought the space behind the seats would be perfect for storing helmets whilst at shows. Only when we fitted the harnesses did we realise that this was a flawed idea. There is a lot of space but with little access. How do you tip the seat with the harness in place?

I only tip the passenger seat, the drivers is fixed, but that gives sufficient opening for it not to be an issue.  I keep more of the harness adjustment at the passenger chest adjusters than at the harness mount adjusters and so by opening the buckle and loosening the chest adjusters the seat flips forwards.  Most of the time I only have to undo the passenger buckle and that gives sufficient extra opening for 5L plastic jerry can, tool wrap, shopping etc.

Never used the space for helmets.

[perthwa]

This is what it was going to look like - completely sealed etc..



Here is my 2 bobs worth. I made a 3mm fire wall. then found a fuel tank.  A mate supplied a steel tank from a kit supplied from a Subaru conversion Factory 818.

this photo shows the open ended fuel tank ( I had to reduce its length) inside the fuel tank cover  attached to the fire wall. It removes in one section.



I had to add a box section  above the unit as the fuel pump section was bigger than I predicted.. measure once etc.. and also need access insitu... The box attatches with rivnuts and is rubber sealed.

added a fuel cap from a motor bike. 


Here is the top of the fuel tank. Sealed up the sensor hole and made up a ring attachment unit to suit Focus sender unit etc.







Hopefully both sealed properly.
these are the brackets I attached to the front of the tank that fit over my support rails that I welded to the frame.  see the first photo where the brackets are in place. 


This bit makes the tank end feed into the passenger compartment walls that I have made. again - see first photo for claity.

the fuel lines and the fuel breather and main fuel filler pipe all go through this opening.