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[patsmx5]

I've probably got 100 hours of doing fiberglass work on boats. So I know how to do it. But that's all limited to glassing over fiberglass or wood. I'd like to propose two ideas and hear what yall have to think about them, or how you'd do it, etc.

First, I want to build a big fiberglass tank that will fit below the carpeted area in my trunk, where the spare tire presently resides. This will be for water injection, not fuel. The tank will ideally be shaped such that it fits the goofy contoured shape of the lower area of the trunk perfectly. That way I get maximal volume of my tank. (I realize most don't want/need a big tank, but I do, preferably a 5 gallon+ size tank) And the top will be flat such that the carpet in the trunk will lay right over it, and nobody will ever know it's there and it won't take up any trunk space (trunk space in a miata is already pathetic). Filler cap will be flush mounted to the top so I can simply pull the carpet back to fill the tank.

I'm thinking that it would be best to make the tank in such a way that it's got 1/4" to1/2" of clearance between it and the trunk at all points. Then I can use some weather stripping or something to support the tank, and when the car flexes/bends/etc the tank has some wiggle room. That way it doesn't crack, or bind up, or make noise from binding when I hit bumps, etc.

So, I'm thinking I'll take an old blanket or something and fold it over till it's 1/2" thick, and then lay that down into the trunk area. That will take the needed 1/2" off of all the dimensions of the tank. Then I'll need to put something over that that can be fiber glassed over and won't let the glass penetrate through it.

Here I'm not so sure what to use. I've heard/read that aluminum foil works good. Also heard wax paper works, though I could see that being a pain the ass for some reason. Any suggestions?

I'd also like to build a void in the lowest area of the tank for the pump to be mounted. That way it's the lowest point in the system, and doesn't have to pick up the water, no air lock, and all that. I'm thinking I'll just build a cardboard box that's 6"x6"x8" or something that's big enough that the pump will easily fit in. Then tape that cardboard box to the trunk, wrap it with foil or something, and glass over it when I'm glassing over everything else. Then when I remove the tank and pop the cardboard box out, I'll have a cavity to mount the pump and I can simply drill a hole in the tank right there to feed water to the pump.

The top of the tank will need to be flat. I'm thinking put a big sheet of plywood on some saw-horses, wrap it with something to keep the glass from sticking too it, and lay a sheet down. Then I can cut it to shape to fit the top of the tank, and then glass the two halves together. While I'm cutting the top, I could also cut some pieces to glass inside the tank to minimize sloshing.

Sound good? Any suggestions on how to do it? I also wanna build something else out of fiberglass. I'll post that when I get done typing it up.

[92CXyD]

Is tank for fuel?

If is this vehicle required to pass regulations for ever racing body you will be involved?

Most regulations  require some kind of inner liner to keep from spilling fuel all over the place catch on when in a wreck.

Maybe research fuel cell building techniques and or have a custom fuel cell made for your application. I see advertisements in the GRM magazine about custom fuel tanks all the time.

If cost is a concern I would research on building fuel cells then see what kind requirements are needed to pass regulations for your intended use.

[patsmx5]

Is tank for fuel?

If is this vehicle required to pass regulations for ever racing body you will be involved?

Most regulations  require some kind of inner liner to keep from spilling fuel all over the place catch on when in a wreck.

Maybe research fuel cell building techniques and or have a custom fuel cell made for your application. I see advertisements in the GRM magazine about custom fuel tanks all the time.

If cost is a concern I would research on building fuel cells then see what kind requirements are needed to pass regulations for your intended use.

Whoops. Tank is for holding water for water injection. I edited my original post. This will just be a street car. I won't be racing it anywhere where they'll be checking stuff.

[92CXyD]

Cool  ;D

[patsmx5]

Second part

I also wanna build a fiberglass funnel looking thing. Basically it will be a funnel that has an oval on one end (to hook to the oval opening of the miata bumper) and a rectangular exit to hook to my first heat exchanger. The purpose if this is to direct air flow through the heat exchangers and to maximize the pressure differential across the heat exchangers as to maximize cooling potential at all times. The goofey shaped thing will help increase pressure in front of the heat exchangers. Called Bernoulli's equation. You smoothly slow the air down and it compresses.

Anyways, I'm thinking I'll build a big block of foam, sand it with a rasp and sand paper till it's the right shape, then wrap it in something and glass over it, then pop it off of the mold and whalah.

So how would I make a big foam thingy that's like 3'x2'x1'? Lots of triple expanding foam?

Terrible pic of what the funnel thing will look like.

[92CXyD]

Reminds me of how bathtubs are made but with a vacumn pump. ;D

[ratcityrex]

Go to the hardwaye store and ask for a dock flote. Like the ones you put under floting docks on lakes. I think they are 14"x24"x96"


I use to sell them at my lumber yard I use to work at. Or you could go to home depot and ask them if they carry anything/order anything. You could always get a 2"x48"x96" sheet of the pink stryofoam and cut it down and glue it together and start shaping it to the size you need.


Just my .02

[90boostdaccord]

speaker box fabric works good for custom fit stuff, i don't know if that is what you are looking for, i always glassed right to the shit

[Henry]

I tried pink foam insulation and it was a pain to cut as it liked to break in chunks when cut. I still have a pretty big section in my garage I may try again to build a tank for my bike.

[t_cel_t]

make a heated wire knife

piece of nickle chromium wire and a battery charger

[ratcityrex]

I tried pink foam insulation and it was a pain to cut as it liked to break in chunks when cut. I still have a pretty big section in my garage I may try again to build a tank for my bike.

I always used a wood coping (i think thats how its spelled)saw, and then finished with a file

[txdohczc]

if the big foam block idea is not what your trying to do just lay some tin foil in the trunk then get some of that foam shit that you mix together (i think marine stores carry it) pour it in, then wait for it to cure then remove it sand it down some then fiberglass over it with tin foil on it and voi la you have exactly what your looking for that would probably be the easiest beside what ratcity said

[ratcityrex]

just lay some tin foil in the trunk

to hook to the oval opening of the miata bumper and a rectangular exit to hook to my first heat exchanger.

IN the trunk would be great if thats where he was working 

Hes kinda working on the other end of his car.

[patsmx5]

if the big foam block idea is not what your trying to do just lay some tin foil in the trunk then get some of that foam shit that you mix together (i think marine stores carry it) pour it in, then wait for it to cure then remove it sand it down some then fiberglass over it with tin foil on it and voi la you have exactly what your looking for that would probably be the easiest beside what ratcity said

You know, this makes me realize a potential problem... If I did what you're saying, I don't think I could get the big foam piece out because the opening to the trunk isn't that big. That said. I'm not sure if I do this the tank will be removable.  :somb: Gonna go pull some measurements. Might have to make this a spec smaller, or one side square so it's narrow enough one way to go in.

[caged]

In my opinion it will be to large and flat. You need it like a surge tank, if the pump picks up air it will cavitate for about 4 seconds and if your setup is tuned with the injection it is bad news. I run a 5L container and it is plenty large enough and lasts 2 weeks+ in  my daily that runs no intercooler and sees boost alot.

[patsmx5]

In my opinion it will be to large and flat. You need it like a surge tank, if the pump picks up air it will cavitate for about 4 seconds and if your setup is tuned with the injection it is bad news. I run a 5L container and it is plenty large enough and lasts 2 weeks+ in  my daily that runs no intercooler and sees boost alot.

Yeah, I see your point. For you, that 5L tank is plenty. But I want something bigger. If mine holds 30-40L that would be great. It will be baffled to keep sloshing down, and the pickup for the pump will be the lowest point in the tank, plus the inlet of the pump will be lower than the outlet of the tank, so even if it got sloshed around sucked air, it will self prime.

You say you can use 5L in two weeks. 5 liters from a 40L tank, mine's still about full. Sloshing or not, it won't pickup air or run out. Part of the reason I want the big tank is because I don't want to have to worry about the WI tank running out. Like you said, you tune for it and run out and your fucked. This is my daily driver. I want it to be as fool proof, low maintenance, and trouble free as possible.

[dvst8r]

Just run safety foam in the tank. That way it will not slosh. Also 40L is ~ 90 lbs. That is a fair bit of weight to haul around.

[patsmx5]

Just run safety foam in the tank. That way it will not slosh. Also 40L is ~ 90 lbs. That is a fair bit of weight to haul around.

Hmm. Might have to get some of that. But it will be baffled too. 40L is just a number out of my ass. No idea what it will really be. I can always make it smaller if it turns out it's gonna be huge.

[dvst8r]

Just so everyone knows what I am talking about when I say foam. http://store.summitracing.com/egnsearch.asp?N=400379+301310+115&autoview=sku

[caged]

Yeah, I see your point. For you, that 5L tank is plenty. But I want something bigger. If mine holds 30-40L that would be great. It will be baffled to keep sloshing down, and the pickup for the pump will be the lowest point in the tank, plus the inlet of the pump will be lower than the outlet of the tank, so even if it got sloshed around sucked air, it will self prime.

You say you can use 5L in two weeks. 5 liters from a 40L tank, mine's still about full. Sloshing or not, it won't pickup air or run out. Part of the reason I want the big tank is because I don't want to have to worry about the WI tank running out. Like you said, you tune for it and run out and your fucked. This is my daily driver. I want it to be as fool proof, low maintenance, and trouble free as possible.
[/quote]

I was going to use a 20L plastic container untill I got one and filled it up and felt the weight, I suggest you do the same with a 40L one. If you plan on using the car as a track car you will have handling issues with all that weight over the back wheels IMO. Dont forget to put an external vent on top of the tank.

[MTZ]

get a smaller tank and fill it up more tada ur problems are solved lazy mofo

[patsmx5]

Yeah, I don't track it so I'm not worried about that. I may one day buy a high speed valve and setup MegaSquirt to do X% water injection at all times, so that's part of the reason I want a big tank. This car could use 100lbs siting over the rear wheels actually. From what I've read I may have to coat the inside of the tank with something. Dunno what yet though.

[txdohczc]

[

just lay some tin foil in the trunk

to hook to the oval opening of the miata bumper and a rectangular exit to hook to my first heat exchanger.

IN the trunk would be great if thats where he was working 

Hes kinda working on the other end of his car.

you were half right. i was refering to the first part where he wants to make a water injection tank in his trunk to go underneath the carpeting

[Conceptz-X]

Rig a float switch(bilge pump) to a light, then when you shit is low you know about it.  Also your not hauling around too much extra water weight.

[SgtB]

I rigged my low fluid alarm to the secondary map switch on my EMS. It automatically went back to the low boost map when I ran out. I split the signal to my scramble boost input on my EBC too, to cut pressure. On the AEM you can use the NO2 window switch input.