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Here's an easy to make surge tank


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I came up with this over the past few weeks working on my little Honda and wishing I was working on my Z. My Z, and I'm sure many others, has been a fuel-system challenge since day one - day one of installing a fuel-injection-system, that is. I haven't really been pleased with the different things I've tried, such as a Holley fuel pickup system for f.i. (which I managed to mangle installing and didn't know until it left my high and dry), and the good old "To heck with it, I'll just keep plenty of fuel in her" technique. I couldn't find a 280 tank the right year that didn't have a couple gallons of water in it, nor did I want to weld a sump onto a fuel tank. Weld on a fuel tank = scary to me, and also they look funny. What I needed was a surge tank, as suggested by Mike Knell in his book. Welding one up was beyond my meager skills, nor could I find a container that was both the right size and heavy enough to tap into.

 

Finally I have the answer, and that answer is: a receiver-dryer. In particular, a Honda Civic receiver-dryer, but I'm sure any would work. Behold its beauty:

 

IMG_00191.JPG

 

Here's the thing: receiver-dryers have to be heavy walled because they're located just downstream of the compressor and see quite high pressures - in a '93 Civic like mine, up to 360 psi, as opposed to an accumulator which sees much lower pressures and thus has thinner walls - too thin to tap. As the picture shows, there's plenty of meat both top and bottom for tapping fittings into. Note that the receiver/dryer is 6.5" long, so with the barbed fittings about 8" overall. Probably holds a quart or so.

 

The only caveat is that there's some guts in there, including a "bag/filter" of desiccant and a tube which passes from the center pickup at the top through the dessicant. The "bag" is visible in the picture but the tube is not. The guts came out through one of those teeny little (1/2") holes. I drilled all the necessary holes in the thing first and managed to tangle the bag while punching the bottom hole, ripping it to shreds. Much hilarity ensued with hundreds of little balls - the desiccant itself - zooming out the hole at high velocity toward my face. Needle-nosed pliers ripped the remains of the bag/filter out the bottom, and the tube followed shortly after via grunting and cursing. Then I just used a normal tap to thread it.

 

I'm as we speak designing a bracket that will hold all three of my cylindrical fuel-handling devices and their filters together, as per this sketch:

 

SurgeTank.jpg

 

Convenient, eh? The whole thing is going in back between the tank and the moustache bar, perhaps configured so that the whole thing can be swung down intact for filter/pump replacement.

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Jonas, I used a program called "Vellum" on a Mac. I did some 3d drafting for a living "back in the day", I like to freshen up my skills once in a while.

 

'55, I don't expect capacity will be a problem - the near "0" pressure on the low pressure side guarantees that the pump flows at its' max capacity, so a relatively small pump can handle the job nicely. To tell you the truth, I'm more concerned about packaging than capacity right now!

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Jeffer, last night I was going to sleep and I was thinking "That guy's idea is really simple, why didn't I think of that?" I was pondering how to strap a capped pipe under the car, making a mental picture of it, when it occurred to me: you better not drive onto a military base with your car! They're going to be thinking "terrorist"!:eek:

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question. would reversing the pump location work better?

 

high pressure pump filling the res before the lower pressure pump can deplete it? that would always allow it to supply the car with fuel in the worst case scenario, no?

 

any excess fuel will be pushed back to the tank.

 

it seems like having the high pressure pump suck fuel off the low pressure pump through a reservoir instead of in-line with just a straight connection spells trouble =/

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You need the high pressure pump to feed the fuel injection.

 

Exactly,it cant work any other way.All will work fine as long as the low pressure pump supplies the volume necessary.Low pressure does not mean low volume,and high pressure does not mean high volume.In other words just cause the high is feeding off the low doesnt mean the high requires more volume,its just capable of more pressure that the FI needs.

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when it occurred to me: you better not drive onto a military base with your car! They're going to be thinking "terrorist"!:eek:

lol actually when i was buying the parts at the hardware store a few guys gave me the "wtf are you making" look and the "am i going to see this on the news?" look lol my friend thought i was making a bomb also. and actually my surge tank is mounted in front of the radiator crossmember. i took a piec of aluminum and bent it around it and then its bolted to where my horn used to be i have a picture around somewhere if your interested its been on my car for a week now and its working fine

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lol actually when i was buying the parts at the hardware store a few guys gave me the "wtf are you making" look and the "am i going to see this on the news?" look lol my friend thought i was making a bomb also. and actually my surge tank is mounted in front of the radiator crossmember. i took a piec of aluminum and bent it around it and then its bolted to where my horn used to be i have a picture around somewhere if your interested its been on my car for a week now and its working fine

You might want to think about moving it behind the core support.

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lol actually when i was buying the parts at the hardware store a few guys gave me the "wtf are you making" look and the "am i going to see this on the news?" look lol my friend thought i was making a bomb also. and actually my surge tank is mounted in front of the radiator crossmember. i took a piec of aluminum and bent it around it and then its bolted to where my horn used to be i have a picture around somewhere if your interested its been on my car for a week now and its working fine

 

Its great when I go to the hardware store and I tell them what I am doing and they just give me a confused look and go on to help an easier customer.

 

I don't know how safe i would feel with it in front of the radiator in a collision, but I suppose it might drop the fuel temp a little. Then again i don't have a front bumper to absorb an impact.

 

 

 

Kevin

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i have a crash shut off switch in line from a ford so if it crashes the fuel pump is turned off. and honestly gas is pretty hard to ignite in a liquid state. i know its a risk to an extent but the tube is so thick im pretty sure it could take a pounding i know the bracket would break first and'or the lines would get cut but they would get cut behind the core support also

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You need the high pressure pump to feed the fuel injection.

 

 

well, i was under the impression that they were both capable of providing enough fuel to the injectors on their own, except that one was LOWER pressure than the other one, thus making it the "low pressure" pump.

 

but if it's actually below the standard required pressure that the injectors need to provide enough fuel, than what's stopping the "high pressure" pump from sucking the resevoir dry?

 

would one who tries to make this end up buying a low pressure high flow pump, and a high pressure "lower" flow pump?, so that the pressure is adequate, and the resevoir is always full?

 

or is there some other trick to this thing? it's easy to look at it and say "cool, i'll make that". I'm just trying to understand the ins and outs, and the benefits of this setup, as I have one of those canisters laying around.

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