Fuel Cell or tank mod?

greg75vette

The Traffic Baron
Joined
Jun 9, 2009
Messages
704
Location
Lindenhurst, LI, NY
Hey guys, yet another question. I thought I had this all figured out, until my cars configuration could have possibly screwed me over. As you know, I'm swapping in an LS1 that will be kept as EFI. I plan on running braided SS hose from the tank/pump to the fuel rail, keeping the current evap system, and either having an internal return or using a C5 filter/regulator externally. As far as I see it, here are my choices:

-Modify the tank with a sump: I've seen a thread on here with some beautiful welding by TT himself, but seems rather involved and since I can't weld, labor would be expensive. Then isn't there aeration potential with fuel sloshing?

-Modify the tank to hold an Fbody pump: This is what I was going to run with. It is cost effective and I don't have to worry about aeration due to the pump/sending units design. The pump will first lift fuel to a 'bowl' integral to the assembly, then pump out of the tank from there. This also opens me up to the Fbody aftermarket, so when the call for big power comes, I some more options. Vetteworks sells a little kit to adapt the pump to an early C3 tank (pre '74). However, I spoke to Dan of Vetteworks and he felt it may still work in '75 to '77 tanks (which is mine) as long as the liner is removed. All that is needed is about a 6" square of flat space to mount his kit (which is really some plates, but handy plates). When I dropped my tank a few weeks ago I noticed that I don't have such room due to the '75 to '77 ginormous sending unit/filler neck assembly on top of the tank. I have not spoken to Dan about this yet, so we may be able to find a solution to this. I could also by a new pre '75 tank and then modify from there, but I'll also need a new sending unit which would eat up the prime advantage to using an fbody in tank fuel pump: cost. Here's the source of the kit I speak of: Vetteworks.

-Buying a fuel cell with a sump: I figured if I had to buy a new tank to get the above to work, why not just get a new tank to fit my needs right off the bat? However, that's a whole new bag of issues with possible fitment problems like mounting and filler neck and whole locations. I don't ever plan on running a spare, so I do have some room to drop the tank a bit. I can also get a cell with foam to at least help eliminate aeration of the fuel.

-Using the current pick up with an external pump: This is by far the cheapest, but not convinced it's a good idea, especially if I'm looking to increase power any time soon. I've heard of some guys just welding on AN fittings to the old pick up lines ( or buying adapters) and hooking it up to external pumps. I think this would be alright at stock power, but once any more fuel is needed, I'll be facing one of the above options anyway. Also, there may be aeration issues and the in-tank filter sock may not be able to withstand the differential pressure across it (not reinforced on the inside) since it was not designed with EFI pressures in mind.

So who is running what? Anyone feel that one is better than the other, more practical than the other? I'm not looking to spend crazy money, but I don't want to throw it away at poor solutions either.
 
Been running a L98/LT1 style induction on my '72 with the stock tank and lines for some 15 years now....only issue is when tank gets lo....like less than 2 gal in it, and I take a hard right turn, the pickup is sucking air, and will kill the engine....so it is effectively a 16 gallon tank.....not a issue really...

I use a frame mounted cheepy pump from AZ, mounted just below the tank bottom outlet, yours maybe have the pipe/sending unit mounted up top, I dunno....

I just wrapped the pump in some radiator hose, and hose clamped to the frame nice and neat lines to filter and OEM hard lines....used stock return line to pass side top of tank....
 
Have you had any WOT issues? What kind of power are you running now? I figure that set up would be fine for the stock LS1, but once I move up to more power, I'll be held back by and then have to use one of the other wonderful solutions.
 
Have you had any WOT issues? What kind of power are you running now? I figure that set up would be fine for the stock LS1, but once I move up to more power, I'll be held back by and then have to use one of the other wonderful solutions.

I have read that stock lines are good to 500? hp, on the feed side, I know I can drop pressure down to ~30 lbs without running engine, and FP running....

had my share of troubles, but line size/fuel pump.. is not one of them....

Since taking out the spare, I am thinking of a rather large 'sump....maybe about ten gallons....
 
I am running a stock tank and sending unit with a Warbro 255. I haven't had any issue, but I never let the tank drop below 1/2. I am thinking that a larger custom tank is in my future though.

Didn't 82 Vette's use a pump in tank? Why not use an 82 sender with a diff pump?

Also I remember seeing a company that makes an efi baffled tank for our Vette's, but I think it was like $800. Way to much for me to spend.
 
Have you checked out Tanks Inc? I'm planning an EFI install for next year and came across their website with this in tank fuel pump. Made note of it as one of my options:

http://www.tanksinc.com/index.cfm/p...category_id=61/home_id=61/mode=prod/prd84.htm

DC

I like it, but I think it's in the same boat as the Fbody pump mod in terms of room. You see, I would have to cut my tank since my sender is integral to the filler neck and a completely different shape. But it does seem like a good option for an earlier tank. The tanks they listed were also on the cheap from what I've seen.
 
I am running a stock tank and sending unit with a Warbro 255. I haven't had any issue, but I never let the tank drop below 1/2. I am thinking that a larger custom tank is in my future though.

Didn't 82 Vette's use a pump in tank? Why not use an 82 sender with a diff pump?

Also I remember seeing a company that makes an efi baffled tank for our Vette's, but I think it was like $800. Way to much for me to spend.

I believe that is what a lot of the guys use for their tank that do LSx swaps into these cars. My concern is power later on. I'll have to see what some of the higher powered set ups are using.

The 82 tanks are different than mine, so I would probably have to convert to that tank in order to make it work and still have to modify the set up just to feed the stock LS1. I'll keep that on the back burner though and look into it a little more.
 
Hi,

There are a number of external EFI pumps that flow about 43GPH which will support about 500HP. Flow thru the stock 3/8 line is less than 3 ft/sec at 43GPH. Easily within good practice limits. Bigger pumps with more flow will only recirculate the fuel through the regulator if you are not making the horsepower to use the fuel flow.

Grampy
 
I never thought of doing a velocity calc. I've just been nervous using the stock pick up because of future fuel demands I am still not sure what to do about fuel sloshing. I guess what I can so is just something like this for now and after I do my engine mods (years from now), I could always go custom tank.

I honestly thought more of you guys would have more feedback on fuel cells. Regardless, I appreciate what you guys have given so far in feedback.
 
Both the stock fuel pump and an exteral high pressure EFI pump draw fuel through the pick-up sock. There is no significant pressure difference between the two pump types on the suction side so the pick-up should be OK. With a rear mounted pump getting sufficient pressure to a rail mounted regulator should not be an issue as most pumps supply more than the typical 45psi needed even allowing for line losses at the max flow rate. The regulator return line needs to be the same size as the supply line. Recirc flow is about the same as supply flow at idle. The stock tank/ pick-up should work ( that's what I plan to use) for an EFI install as long as you heed Gene's caution about low fuel levels.

Grampy
 
At first, I didn't understand you, but now I got it. Looks like I mispoke about the in-tank filter sock. You're right, there won't be a significant difference betweeen suction pressure, however, what I meant to say (and failed) is that I'm worried the increased flow with crush the sock because it may not be able to handle a larger flow, thus creating a restriction, larger pressure difference, then crush. The pump won't create the differential pressure, per se, the sock will. But in all honesty, I bet that's just over thinking it waaaay too much. That happens to be my specialty; ask my boss. So since the return line should be about the same size, then I probably can't use the stock return line then. Not all that bad really.
 
Good point. Just by observation, the net free area of the screen should be many times that of the pick-up tube so the delta p across the screen should be small.

I still plan on using stock pieces.

Grampy
 
Agreed, but it is not really reinforced and I don't think there will be even flow across all parts of the screen. I think the section directly across from the start of the pick up tube will have the bulk of the flow. However, I think it's all small potatoes. If it crushes, destroys itself and enters the pump, then I'll figure out a solution, haha.

If I have some time during lunch tomorrow, I'll see if I can do some little calculations of sonic velocity and pressure drop across the tube tomorrow. Can't hurt right?
 
So since the return line should be about the same size, then I probably can't use the stock return line then. Not all that bad really.

If you use the Camaro pump setup, the picture shows an outlet line that returns fuel directly back into the pump with the claim that there is a regulator on that return. The fuel (to the rail) is supplied from a T fitting in the line. Not sure how this is plumbed but it looks like they are trying to make a non return system. I think that will cause problems.

So, if you are going to use a return system, why can't you use your stock return line?
 
Have you looked at the documentation for the selected pump? They will have minimum fuel line sizes specified - any smaller and your warranty will be voided. All the calculations have been done for you already. The only calc you need to do is figure out what HP you want to generate, then you pick your pump.
 
BBShark, From what I understand the Fbody pump system is self regulating if you hook it up as shown. No need for an external regulator. However, my comments about using the stock return line, I meant the stock '75 return on on my sending unit. I believe it's a 1/4" and the pick up is a 3/8" line. However, if the '75 return line is too small, I could just attach an AN fitting to the sending unit and be done with it.

Z-man, all the documentation that I've seen for any of these pumps is what Summit has supplied. I haven't looked too much further because I haven't really had the time for the fuel system. Honestly though, I didn't think they would list the recommended ( or required) fuel line sizes, so I will definitely look up more info. on the specific pumps.
 
Wow, talk about mixed feelings. I just looked over the two manufactures I was considering and what a difference. I looked at Aeromotive first. They don't really have a pump that I would consider right for me. The A1000 seems like overkill but the 700 HP EFI doesn't look like it would be enough (let alone their price is nearly identical). I also checked out Walboro. The site is terrible and couldn't find a thing on there 255lph inline fuel pump.

The aeromotive pump looks like it would require a sumped tank or at the very least a modified pick up (stock pick up is apparently too small). Not sure what other manufacturers are any good.
 
Hey Greg,

I have a 75 also and have been following your thread, thought it might be a winter project for me. Did you settle on a pump/fuel delivery design that you were happy with or are you still in the research mode?

Bill
 
Wish I wasn't, but still in research mode. I like the idea of a fuel cell, but there doesn't seem to be one that fits the body pocket well and is large enough. I know of one guy modifying his '76 to fit one (cut the back trunk wall), but I'm not confident this is a safe way to go. If I can't find a proper fuel cell to fit without cutting the body, I'm considering going with 3 options:
-Just hook up an inline pump to the current sending unit. Cheapest, but worried about pump reliability and would most likely need to redo this come bigger power later on.

-Hook up an in-tank pump with the old sending unit. This could be done with the existing lines or run some larger ones out of the tank. Not really sure how or what fitting to use if I ran new lines out of the tank.
-Run an intermediate "sump tank" as I call it like fellow member Z-man has. In his profile, he has a link to his site where he details it out. I had some questions about it, but he hasn't written back. I might spin off of his like using a small 1 gal fuel cell as the intermediate tank instead of welding a small tank up like Z-man (I can't weld). But it seems expensive and complicated for my way.

I'm currently ( keep in mind that can and has changed hourly) leaning towards the second option with new lines running out of the tank. I figure The design hurdle here is how do I route the lines from the pump and out of the tank. I believe I can cut out the old lines on the sending unit, drill a new hole and install a fitting that will have threads, or barbs/bungs, on both sides. But what these fittings are, I'm not sure.

My big issue now is trying to determine how deep down the rabbit hole do I want to go. Do I do the quick and easy, but at the possible expense of reliability on the pump and potentially have to rip it out and change it when more power is built or dp I go by a serious racing fuel cell like Fuel Safe or ATL as well as 'future-proof' the system and don't screw around? I feel I'll be somewhere in the middle, but where I'm not sure.
I wish I could help you out better. Hey if you find a solution, let me know, haha.
 
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