Hey guys. Trying to help a buddy out. I know fuel injection but carbs are still pretty new to me. A buddy of mine has a 355 with trick flow heads, cam, and a pro systems blow through carb on it. He's running an 88mm turbo at around 9 PSI. Car was on the dyno and made about 536 rwhp before it ran out of fuel.

The fuel system currently is a single walbro 255 pump in the tank and an aeromotive return style reg. I think the feed line is a 10AN and the return is an 8AN, however the line to the carb is only a 6AN. He's pushing his luck with the single 255 pump but I know the lines need some changing too. My question is what is the BEST way to run a fuel system that will supply his needs? He bought a magnafuel 300 external return style pump, but I don't know if this can be used in conjunction with the in tank 255 or not. Also, what type os fuel pressure do you normally see on a boosted carb set up?

I am thinking the best way to do it is to pull out the in tank walbro and just run an aluminum 1/2 inch hardline to the bottom of the tank for the pickup and then have a braided line go to the magnafuel external pump as the only pump in the system. I'm just not sure what size lines to run or how to do it on a carb set up. Anyone that has done it or has experience please chime in!

Well simple solution is if 1 pump wasnt enough, run dual walbro in tanks...but its harder to fit that in a 3rd gen tank compared to a 4th gen tank. Some guys have done it in a 3rd gen tho. Thats probably the easiest solution.

Else you will have to add external inline pumps but I never liked those and dont know of anyone running one that works well. OR sump the stock tank and put a big A1000 or big weldon pump in there. Depending on the hp requirements ofcourse

Were trying to stay away from dual in tanks for the reason that they are a PITA to fit and I don't know how I feel with all the rubber hose and clamps in the tank. The external magnafuel pump he bought is similiar to an aeromotive A1000 but do you NEED a sumped tank for those to work? Or could we just run a pickup to the bottom of the tank and then have a braided line go to the pump? He must have called 10 different shops and we cannot find one place that wants to sump a tank so were kind of out of luck on that route.

Also I'm sure the -6 line at the carb feed is causing a restriction.

JMO on this, you should be sumping and getting an A1000 or other large pump. 88mm is a hell of a lot of turbo and should be good for 1200hp plus if everything else is up to par. Two Walbros may be enough depending on how much he's leaning on it at low pressure. Another option may be the new Aeromotive 340 in tank pump but I haven't see anyone run one. I'm very curious tbh as it may be my next purchase for the fuel system.

The 88mm is a little on the large size for his set up honestly. The bottom end is just an eagle non forged bottom end so it will not support the true potential of the turbo. We have a spare tank but I don't trust myself sumping a tank and niether does he and we can't find anyone to do it. That would be our first option if we could though.

Any info on what size lines needed for a feed and return line on a carbed set up? I know I've heard the return line should be larger due to the low pressure needs of a carb. I really just want a solid proven set up with all the details so we can finalize his fuel system and not have to worry about it anymore.

damn fuel system

-10 an feed from the tank a 100 michron filter then to the pump then to a 10 m michron fuel filter.then to the fuel pressure regulator........you may ba able to get away with -8an for a return line.......go to the aeromotive site.....they have recommendations as to what you should run

and yes the 88m is pretty big for his combo imo........im running a t76 and its plenty

Eric? LOL

I have a T76 as well on my LSx combo and I'm sure I'll never need anything bigger.

So now that the lines are figured out I guess all we really need to do is figure out how we're going to set the pump/pumps themselves up. Too bad we can't find someone to sump the tank.....def seems like the best route. Maybe we will try the dual in tank pumps if all else fails. Thanks so far for the help all!

if you have another tank and know exactly where you want the sump let me know....

We do actually have a pretty nice spare tank that he was going to use as the sumped tank and then swap it in afterwards. Never really thought about where to put it though lol. I'm guessing right in the middle on the back of the tank? I'm pretty sure he has the sump kit as well with the peice to weld to the tank and all.

If you could help us out I'm sure my freind would greatly appreciate it and throw you some bucks too.

im in mass......i could mig weld the sump where you want it........then it would be presure tested so i could make sure it did not leak.......it would have to be left with me though of course. prolly be 50.00 or so to do it

That would be AWESOME! If you can, PM me a phone number or address or something to get in contact and we can set up a day. My freind said possibly next weekend or I guess I could always bring it up during the week since I'm free. Then you can just let us know when your all set with it.

pm sent. eventually i will be sumping the new tank ive had for 6 yrs in storage but for now im runnin a bulkhead fitting in my tank

Im using a bulkhead fitting on my stock tank, I also drilled and tapped for the return line. Never even had to drop the tank. I run an a1000, -10 feed and return. Also running a blow thru Carb, previous setup was a 383sbc w 76mm pt76gts. New setup will be an 88 mm 402ci lq9 also blow thru. Fuels system should keep up with 800 rwhp hopefully.

I always heard the a1000 was good to 800 whp and no more. Definately let us know how your's does.

Will do! My cousin made 780 rwhp with an a1000 blow thru Carb twin Turbo 408 lsx without any issues, and he was running -8 feed and return. It should be fine I hope.

What type of bulkhead fittings are you guys using that don't leak?

I used epoxy to ensure a seal from the get go and it hasn't leaked a drop in over 3years.

a proper washer and clean hole should seal...

WRT the pump, it will feed more power worth in a carbed setup then FI...

since the car already has in intank pump check out areomotives new 340lph pump its 169 bucks, and at carb presure levels it flows 400+ lph

Lots of places don't like to sump used tanks. Has he considered buying a new tank to have that sumped? They won't have a problem with a new tank.

Let us know how the mig works out. The only two people I know that weld them only use TIG because they say it is the only way to get a clean weld with the contaminated steel.

white devil.............i did not get your number off my phone before my son was playing with it....if you stiull want it sumped call me tomorrow or wednesday so we can make arrangements to get it done for you. i apologize for not getting back to you sooner........its been a little crazy here

No problem. After all, you are doing us a favor. I will ask my freind when he'll be free and then give you a call.

My buddy has that bosche single that has been modded to flow 340lph in his LSX 6.0 el camino. Its a nice pump setup, i didnt know he had one. It should be good to 700whp easily on normal voltage and more on a hot wire kit. I've heard 600whp was possible on a 255 walbro on high voltage.

im going to use one of these new pumps on my tt iroc, at 20 psi of fuel presure under boost it will flow 380lph,and im going to do dual intanks on my turbo v6 car with e-85

How long has the 340lph pumps been out? Any reliability data on them? Who makes them for Aeromotive? They do look interesting.

EDIT: On second thought. After looking at the curve for the pump it is only OK and not great. The flow vs. pressure drops off way faster than a Walbro pump. That is fine for NA engines, but not good for forced induction. Looking at stock fuel pressures (43 PSI) and 15 PSI of boost gives a total pressure of 58 PSI which comes out to a flow of 285 lph on the curve.

poor to typical forced induction engine: (285)*.264*5.8*.8/.57 = 612 FWHP
typical to excellent forced induction engine: (285)*.264*5.8*.8/.48 = 727 FWHP

can't have been out long... the tests that I've found on line don't look any better than a standard 255lph walbro like the GS340...

Just tried .023 wire last night on a stock tank.
just cleaned both surfaces with 3M coarse cookie prior to welding.
Pressure testing found slight moisture in one small area. (Not enough penetration).
Went over that small 1/4 inch area again and all was good!

im looking at a blow thru setup, not sure where to start. any suggestions?
85 trans am

355 flat top
049- aluminum botwties/ matching intake
doug herbert c6k +114, 585/600 lift 245/255 @50 solid roller

700r4 auto, 3.23s