Long slow MS3X build starting soon

[TheSilverBuick]

I drew up this diagram on how my fuel systems are plumbed.

The surge tank should remained topped off and airless unless the gas tank is getting low and air is being pumped in. I actually do not know what happens under WOT as the EFI pump and engine consumption starts to exceed the lift pump's ability. What I suspect happens is a vacuum starts being generated in the surge canister, which I expect the first thing to happen is it draws the fuel from the return line back into the surge canister then eventually sucks air from the tank. I also suspect the lift pump starts flowing a bit more as the vacuum starts to build in the surge canister until it sucks air from the return line. Given my pump flow calc's, I assume my setup has never actually pulled air to the surge canister, only perhaps has drawn fuel from the return line because I am rarely at high rpm WOT for more than a few seconds at a time, 13-15 seconds is about it. Also, the lift pumps in my Skylark and I used in the Thunderbird were the stock mechanical pumps attached to the block. The Firebird will have a universal 3/8th electric lift pump.

[BlueCuda340]

Where is your surge tank located?

[TheSilverBuick]

Attached to the firewall next to the brake booster. I will admit there are more graceful setups than mine.

I've contemplated setting it up back by the gas tank itself and have an electric lift pump do a loop to it then just make sure the EFI pump is lower than the surge tank.

[BlueCuda340]

You had me going on the surge tank setup, until I started thinking of where I would put it lol.

To get back on topic(lol right) I got my jimstim board built this weekend. Pretty easy really, I feel much better jumping into the ecu now. Next step, purchase ecu.

[TheSilverBuick]

I know, packaging is a bitch hence the advantage is to have a sump or proper baffles in the gas tank. Realistically the surge tank does not have to be that large, I'd say with a sufficient lift pump something simple like a 1" diameter 3" tall would suffice if you can squeeze all the fittings on to it. A piece of 1" box aluminum tubing 3" long would probably work good and if I could weld aluminum I would probably consider that route. I suppose I could try it with 1" steel box tubing. Just something to separate the air out and buy sometime while the pickup is uncovered.

[Matt Cramer]

You had me going on the surge tank setup, until I started thinking of where I would put it lol.

Mine is ahead of the rear axle, attached to the floor where the back seat mounts. Works for an early narrow A-body; shouldn't be trouble for a '68 either.

[BlueCuda340]

Mine has those pesky mufflers back there. I need to wiegh my options. The car won't see any attention until I have the ECU built and working on the bench. When I take it down it tends to be down to long so I am trying to do things in pieces.

[milner351]

I'm not familiar with either stock fuel tank you guys are working with, but I wonder how hard it would be to add a baffle of some sort to our old stock tanks, attached to the pick up assembly that is already removable? In the same theory as the oem EFI pump "modules" could we come up with some sort of "tank inside the tank" that surrounds the old OEM fuel pick up. As simple as a can with one end open around the pick up so when accelerating or cornering, the can would hold fuel around the pick up.

[TheSilverBuick]

You can always plumb in a lift pump and install the surge tank with the carb'd system if you want to take small steps that don't down the car for a long period. Just have your Holly Blue pump pull from the bottom and the regulator return line capped off. Probably could use the Holley Blue pump as the lift pump (if it's rear mounted it'd be even easier) and cap the return to the gas tank as well and it should just pressure up the surge tank with the rest of the carb's fuel system and work just fine installed that way. Then just install an EFI pump between the surge tank and EFI system and plumb the return lines from the surge tank in. Or do it all at once with the EFI upgrade

[TheSilverBuick]

I'm not familiar with either stock fuel tank you guys are working with, but I wonder how hard it would be to add a baffle of some sort to our old stock tanks, attached to the pick up assembly that is already removable? In the same theory as the oem EFI pump "modules" could we come up with some sort of "tank inside the tank" that surrounds the old OEM fuel pick up. As simple as a can with one end open around the pick up so when accelerating or cornering, the can would hold fuel around the pick up.

That's what Aeromotive sells now where you drill the big hole in the tank and drop a whole canister module with fuel pump, etc in it. There is certainly more than one way to skin this cat. Sump and baffles, canister intank fuel pump modules and external surge tanks are the common ones.

[BKBridges]

My fuel system currently is a holley blue that pulls from the stock sender. I don't have any delivery issues with an approximate 450-500HP. Say I added fuel injection and an external walboro pump and made a provision for a return how would this change? I plan on going to a sumped tank anyways but just wondering.

Blue Cuda 340,
It would work about the same way provided that your in line fuel pump is mounted at or below the bottom of the tank. In an A body that's usually right under the passenger seat location. Some vehicles may require a surge tank due to poor OEM tank design, but the A body seems to pull from the tank nicely at low fuel levels. The large sock filter on the pickup has something to do with that I think. At any rate, adding a return to the sender unit or getting a repop from Mancini or someone with the 3/8 pickup and return in it makes the in-line approach pretty simple on the Mope. Not so sure re: Falcon. I used to run in-tank pump set-ups, but older cars don't have the cool panicky flashing light warning at 3/4 tank level to remind you to keep your pump cool. Without that, old habits keep you running until the pump is uncovered and overheated. Never had any delivery issues until the pump gave it up though. In-line pumps are designed to be air cooled (and internally gas cooled too in most cases) so if you run low/out of gas they don't get hammered near as badly as an in-tank pump does. If you cant mount your pump down low, youll need a lifter pump and surge tank set-up. Also IMO don't run pre-filters before the pump other than the pick up sock filter, but always run the pick-up sock filter! Make sure the sock is firmly attached to the pickup tube. Ive seen em slip up the tube (chevy repop) and block off all flow to the pump..
Heres some pics of the in tank set-up that was in my Barracuda for a few years (15K miles) before it overheated.. I cannot recommend this set-up...

[TheSilverBuick]

You had me going on the surge tank setup, until I started thinking of where I would put it lol.

To get back on topic(lol right) I got my jimstim board built this weekend. Pretty easy really, I feel much better jumping into the ecu now. Next step, purchase ecu.

You've inspired me to try something different. When I made my first two surge canisters (favorites of Home Land Security) I did not own a welder. And it seems now that I do own a welder I am still incapable of making a sealed container, so I blobbed some acid core solder on there afterwards to seal it up. I used 1" box tubing and steel tubing. The hoses are just mocked up right there.




The exhaust system is what kept me from mounting it back at the gas tank, so I have the generic universal fuel pump at the rear of the car and the new surge tank on the fender well right above where the stock fuel lines come up on the frame and mounted the high pressure pump on the firewall (wouldn't likely fit on a V engine).

[BlueCuda340]

I always pictured something much larger than that. Very cool.

[TheSilverBuick]

I will find out if it really works when that small. I think the key to this setup working is the lift pump being sufficient to feed the engine as there is not much volume to it, unlike my pipe tank that holds about a quart hence the 8 to 10 minutes of WOT before I would run into trouble. I don't expect that issue with the 6 cylinder naturally aspirated.

[NewEnglandRaceFan]

I drew up this diagram on how my fuel systems are plumbed.

The surge tank should remained topped off and airless unless the gas tank is getting low and air is being pumped in. I actually do not know what happens under WOT as the EFI pump and engine consumption starts to exceed the lift pump's ability. What I suspect happens is a vacuum starts being generated in the surge canister, which I expect the first thing to happen is it draws the fuel from the return line back into the surge canister then eventually sucks air from the tank. I also suspect the lift pump starts flowing a bit more as the vacuum starts to build in the surge canister until it sucks air from the return line. Given my pump flow calc's, I assume my setup has never actually pulled air to the surge canister, only perhaps has drawn fuel from the return line because I am rarely at high rpm WOT for more than a few seconds at a time, 13-15 seconds is about it. Also, the lift pumps in my Skylark and I used in the Thunderbird were the stock mechanical pumps attached to the block. The Firebird will have a universal 3/8th electric lift pump.


[ATTACH=CONFIG]28470[/ATTACH]

how big is your surge tank 0.5 gallon, 1 gallon? nevermind, next few post cleared that up..