87bob

I have an 89 which was in a flood, I am looking to make a Driver/ Track car out of it. Since the guy I bought it from was smart enough to pull the gas pump and dry the tank it's in good shape. Since it is all apart I need to do something about a pump sender combo. I don't need anthing to exotic but while I'm working on it I have the option to make changes, my plan is to run a 6.2L 2500 truck engine. I would like to run a return line so I don't have to mess with a special regulator set up. Have any of you guys that have done the LS swap added the return to tank that the LS style motors need or have you just bought the adapter kit with the single feed line and special regulator? Thanks in advance.

ThickLizzyVetteswerv

I believe the C4 does use a return line.

https://www.corvetteforum.com/forums...fuel-line.html

87bob

Thank you for the info!

s346k

my 89 has a return line back to the tank.

Krusty84

My '84 is setup with a Walbro 255 in the oem sending unit, oem LS 58 psi filter/regulator located on the passenger side frame rail near the rear of the wheel well. Dead headed after the filter/regulator to the fuel rail. 520 ish crank hp, 450 ish wheel hp, ~80% inj duty w/ 43lb ls3 injectors. No issues for over 6 years now.

Phobos84

I did a -8AN feed and a -6AN return for my LS swap. I'm using a Walbro 450 in tank pump and an Areoquip regulator under the hood. I'm also using a flex sensor on the return line. E85 is why I went so big on everything. But it all works well.

I modified a factory C4 fuel sending unit. I just used bulkhead connectors and fittings. I had to weld some tubing to make the return line on the sender big enough but not a big deal.

s346k

im hoping to use my factory 89 hanger and feed/return lines. walbro 525 will be here monday. i'm expecting 490/480 whp/wtq and hope the pump will support it on ethanol. also curious how well the holley hydramat is going to work out.

Phobos84

That pump is a bit big for that power level even with E85 but it will work. The 450 LPH pumps will support over 700 hp on ethanol. I wouldn't use the factory fuel lines. Braided PTFE hose kits are so cheap anymore it doesn't make sense to use the factory stuff. That and they are really going to choke off that pump. Also I'm not 100% sure on your year but I'm going to assume you have some rubber in that factory fuel system. I never use rubber or aluminum in any fuel system that I plan on running with E85. I've had too much stuff rot over the years. I had a Fram fuel filter disintegrate from E85 and blow bits of rubber and other debris into my injectors. So if you're going to play with ethanol you need to build the entire fuel system. Now everything in my car is E85 compatible.

s346k

i don't think the fuel line will be a restriction. same size line on my 18 camaro that used the same engine. the lines are steel as far as im going with them. walbros rating for the 525 is 700 on ethanol na. never used their stuff so im not familiar with ratings. my absolute minimum power output is 490. also as pressure goes up, supported hp goes down. i'm looking at 62 lb minimum, 70 if i can get away with it. originally had plans of doing hci with this engine but i don't see a single 525 supporting that much power on ethanol.

Phobos84

The power rating for the 525 pump is 900 hp+ NA. The 450 is 750 hp NA.

See the rating for the 525 pump here
https://walbrofuelpumps.com/walbro-f...ve-tcd470.html

As far as the fuel line I use this chart

https://help.summitracing.com/knowle...SR-04879/en-us

So for 500 hp the common recommendation is 1/2" feed line or -8AN especially if you're running E85.

It's your ride. Do what you want. But if you're here for advice from people who have done this swap. Then I'm saying the factory fuel line is too small.

s346k

to be fair i popped in here to comment on the 89 return fuel line. i had an lsx swap c4 11 years ago. this is a gen v swap but same principles apply to fuel supply. i'll keep it all in mind.