Here goes the so called screw up.It pertains to my fuel system.I bought all my stuff with the thinking that no one made an intank pump that could support my combo.I sumped the tank,a new tank a that,bought the pump and all the hardware(lines,fittings,etc)Modifyed my fuel rails.And now here I am not wanting to spend money on a custom Exhaust system,too dam much trouble.

So here is the kicker,I call Walbro,intank pump maker.They now make an intank that will support my combo.Supports up to around 650hp crank ponies.The name of the pump is the GSS340M.I asked the rep to just give me a flow figure off the chart at 50psi,he told me it flowed 67gph at this pressure,that is awsome for an intank.Im pissed.Im selling my fuel system,and the tank if anyone wants it.Fuel sytem was never used.All SX stuff.If I even run into a problem that I will need more fuel,Ill just run a KB boost a pump.This is much cheaper that what I was planning.

But there is something else.The rep I talked too,said somthing about line size that goes against all I ve heard.Run the stock lines,he said.I was like what.He told me big lines with EFI is a waste.It made sense since when I got my regulater from SX and looked into the feed holes,10AN at that,and you see the little hole the fuel travels through to get to the other side and to the rails his statement makes sense.Why the hell run 10AN when the dam hole it travels threw before the rails is about 4AN or less.Im gonna run 6AN to the rails and 6AN back and thats it,it will support my combo and then some.Boy these lessons are expensive. Anyone agree?I think I went overboard here.Just want to let everyone know,if you are planning the same thing.I cant believe they now make an intank to support such levels,the pump is only $110 plus the installation kit,$10.Anyone interested let me know.

Anyone interested in my SX stuff,email me.Thanks for hearing out my blunders.

 

I've got the Walbro GSS307 intank pump (pump curve at http://www.eecs.tufts.edu/~askulte/ttt/pumpspecs.jpg), which shows 70 gph @ 50 psi. This is a drop-in in tank pump (picked up for $75 from some Sy/Ty guy that does monthly gp's), and I've been very happy with it so far. I think I'll need to upgrade the fuel system eventually, but until I hit about 700 hp, I think I'll be alright (unless I see fuel pressure dropping at WOT). The reason for the super big lines is that the inline pumps really don't work too well under suction, and the cavitation will kill the pump in short order. The pressure side of it isn't as crucial, and small diameters just increase flow loss. The factory lines are 3/8" feed (-6AN) and 5/16" return. Shouldn't the regulator be mounted after the injectors in the flow loop? The small metering hole should be enough for the return, but could limit full flow if you're feeding the rail through the regulator. All the fpr does is pinch the return line and raise pressure before it (in the fuel rail). If there was no fpr, the rail pressure would be basically the backpressure in the return line. Does this make sense?

I agree - the sumped fuel system is overkill, but its something you'll never have to worry about ever. I have no idea what you want for the fuel system, but I might be interested if its "affordable" (hah!) See ya!

Andris

 

Custom exhausts suck on our cars so I can see wher you are coming from. I know mine is going to be a tight fit with the muffler on there. I am hoping it holds up okay though.



Good luck with your new pump bro.

------------------
-86 IROC
Vortech stuffed EFI 406 in progress
-=ICON Motorsports=-
Cluelessness: There are no stupid questions, but there are a lot of inquisitive idiots.

 

Guido, is your return line next to your feed line? There is a chance the returning fuel can cause aeration around the fuel feed line and starve the system! You should have the return on the top of the tank in efi applications. Just an FYI, dude.

------------------
Old: 1989 Formula, 383", DFI, built 700R4, TFS heads, Mini-Ram, Vortech S-trim 15 psi, 3.70 gears
Best ET: 10.796 @ 125.8 mph

New: 1989 T/A, 400" CNC Bow-Tie Tall-Deck, Accel Pro-Ram, DFI, AFR heads, HRC T76 Turbo, NOS 150-hp dry kit, TH400 w/GV overdrive, 12-bolt w/3.70 gears, 8-pt. S&W rollbar, Spohn suspension, 18" wheels, Baer brakes
Best ET: Spring 2001

Employed at:
Hahn Racecraft
Accel EMIC/DFI Tuning
Turbosystems & Custom EFI

Member of Midwest F-Body Association www.mfba.org

 

ASKULTE,Walbro said the GSS340M is hotter than GSS307,so thats why Im going with it.I should have done this sooner.If I run into any problems I ll run the Boost a Pump.The GSS340M runs higher runs the same gph per hour as the Gss307 but thats where the GSS307 maxes out is at 50psi,after that the gph drops,this is Walbro told me.The Gss340M,after 50 psi increases gph,I didnt get a flow chart but this is what Im told.And Walbro is comming out with an even more powerful pump in the comming months for the 5.0 guys first.About the way the SX FP regulater mounts,it has the feed going right threw it and the return ou the bottom.So you cant mount it after the rails.Go figure,if you were to look at the inside of the regulater you would laugh,any regulater from any company of this type is the same,so why the big lines and such a small feed to the rails?I was told it doesnt matter with EFI because of the high presssures.

 

PROCHARGED89Z,
That walbro pump is one mean little pump. It'll easily take your car into the low 11's. The 340 is the same pump as the 307 with a different pressure spring. The 307 falls off sub with pressuress over 60 psi. I ran a single 307 into the low 11's in a 3600# GN a few have gone high tens. The fuel lines on the thrid gen won't be a problem until you are in the very low 10's even high 9's. They are relatively short and bend free and will flow more than the G-body Regals which rountinely run high 9's low 10's without problems.
Chris Lyons

 

since your on the topic i have a few questions. I need a intank pump since i'am spraying 100-150 shot wet. I currently have all stock fuel but my 24#svo on my 350. I have gone 12.7@111 so witch pump should i get the walbro 255gph? I run about 50 psi, is my car going to run rich with the knew pump when the nitrous is not on? Should i go for the larger walbro pump? thanks for your help

 

The line size can be important. A freind of mine raced a car that had 1 inch fuel line(overkill i know but intimidating). My freind was driving a 10 second fire hawk and got beat so bad it was not even funny. you know the feeling when the guy next to you pulls the front tires going into 2nd. This was on the street. the guy had a narrowed 9 inch rear with some fat et streets on the rear. The car was a 97 stock bodied formula. I guess it goes to show you size does matter no mater what she says.

------------------
90 iroc l98
last season best corected 13.62 @102
mods
full exhaust, AFPR, pulley, jet stage 1 chip, billet servo, 52mm throttle body and a few other little things.

 

D*mn...He was a 10 sec car and he got beat?

------------------
1989 IROC-Z 5.7L

 

hey darren, shoot me an email and we will talk about the tank and stuff. i might be interested.

and for who wants to know: i do believe with the proper injectors (dont know if this figure was for n/a or blown cars, makes a difference) our fuel lines support up to 700hp then you need to up the fuel line size because the lines wont flow enough fuel (volume here) to get to the injectors. you will know when you have hit your limit. you will see fuel pressure steadily fall as rpm goes up.

 

omar he did not just get beat he got crushed. I would have to say that the formula he raced was an 8 second car. i guess when you have that much power you need 1 inch fuel line. I doubt my fuel lines would support 700 hp. i would say when you pass 600 hp it is time to upgrade the fuel lines. The simple reason for this is you have a very expensive engine when you have more than 600 hp and why not protect it as much as possible. 600 hp will put you in the 10 second bracket. that is fast and it is time to get really serious with every thing then. I mean you had to change every thing else to get that much power to the ground reliably. why not make sure that your pistons don't develop holes.

------------------
90 iroc l98
last season best corected 13.62 @102
mods
full exhaust, AFPR, pulley, jet stage 1 chip, billet servo, 52mm throttle body and a few other little things.

 

Hey Dan, I didnt put it in the top of the tank because the returning fuel would be pouring into the tank and causign aeration.

Think about the physics of it. You have fuel dropping from the top of a tank, through open space and then into a liquid. Its going to bubble and churn.
or the alternative is that you have it returning UNDER the surface of the liquid with much less of a chance of aeration.

I talked with a few people who have done fuel systems like mine on 4th gens and that was the biggest thing they said. Dont put it in the top. Put it in the bottom.

------------------
-86 IROC
Vortech stuffed EFI 406 in progress
-=ICON Motorsports=-
Cluelessness: There are no stupid questions, but there are a lot of inquisitive idiots.

 

no offense, but i do feel that is a bad idea. if it is such a bad idea....then why does factory fuel lines return at the top? plus, having it return on the bottom i think would be forcing too much pressure in the return line because the fuel is going back into it, but at the placement of the line fuel can be flowing into it.

just my .02

 

Hmm good point.

Counterpoint. Look at how fuel cells are designed. They have two ports next to each other.

I may be wrong on THIS point but I think that the return line goes down into the tank a bit before its cut off. Again, I could be wrong but I think that is how it is...

Im not worried about it. It held good fuel pressure when I had it started it yesterday but remains to be seen at WOT.

 

I think as long as the return is away from the feed you wont have any problems

 

That is exactly my point! With fuel dropping in from the top, the aeration is farther from your feed line than when the return line is right next to it! We have seen this problem with our 9-second turbocharged Mustang. It has been apparent in other applications as well. The fuel cells you see have always been originally designed for much lower pressure carbureted systems... Good luck in whatever you guys decide.

------------------
Old: 1989 Formula, 383", DFI, built 700R4, TFS heads, Mini-Ram, Vortech S-trim 15 psi, 3.70 gears
Best ET: 10.796 @ 125.8 mph

New: 1989 T/A, 400" CNC Bow-Tie Tall-Deck, Accel Pro-Ram, DFI, AFR heads, HRC T76 Turbo, NOS 150-hp dry kit, TH400 w/GV overdrive, 12-bolt w/3.70 gears, 8-pt. S&W rollbar, Spohn suspension, 18" wheels, Baer brakes
Best ET: Spring 2001

Employed at:
Hahn Racecraft
Accel EMIC/DFI Tuning
Turbosystems & Custom EFI

Member of Midwest F-Body Association www.mfba.org