When do I need bigger fuel lines?

[turbo minivan]

it hasnt been much work at all actualy! or money either. maby 30$ total!

[TFMech]

Really it is just like anything else on our cars. The whole system needs to be matched. If you have a 3/8 or 1/2 inch feed line and a monster pump then you will need need to have a bigger regulater and a return line because the pump will have to much volume and the pressure will be to high. The fuel system is the only place where bigger is better holds true. You can run a 2inch fuel line if you want as long as you have to pump to pressureize it up and a return to return it. The engine will run the same. You just have to make sure if you make one part bigger you make it all bigger or you will run into all sorts of stupid problems.

I have always thought that the guys that want to skimp on there fuel system and say stuff like I can go 12s with my 5/16s fuel line or my car made 450HP with the stock fuel system....yeah right..... like it is a big thing or something. No one ever won a prize for be the first guy to make 500HP on the stock fuel system. They never won one for running 10 seconds the stock fuel line. They just spent more money when they found out it would only run 11.50 makein 250HP I have always thought it better to spend the couple hours and the couple hun cash to buy the fuel cell, lines, pump, and upgradeing the fuel rail. Then to burn up a motor while your looking for limit of your fuel system. They Pay $300 for a cheap turbo, $125 for a valve job but wont spend $150 for a good fuel pump or $35 for fuel line .....I just dont get it. I guess I learned with the first valve I ever burt to not skimp on the fuel supply system. Sorry had to rant for a second.

The only things to remember on fuel systems is that bigger is always better as long as it all matches in size and flow.

[wallace]

For my application I believe that the 5/16" feed line is acceptable. I am going to replace the stock pump with a Walbro. So my question is who has actually installed a 255 Walbro using stock line and had problems regulating pressure. Based on this thread so far two people had problems. If the return needs to be modified what needs to be done at the tank end to get the 3/8" return line connected?

[turbovanman]

Quote:

Originally Posted by wallace For my application I believe that the 5/16" feed line is acceptable. I am going to replace the stock pump with a Walbro. So my question is who has actually installed a 255 Walbro using stock line and had problems regulating pressure. Based on this thread so far two people had problems. If the return needs to be modified what needs to be done at the tank end to get the 3/8" return line connected?

3/8 is larger than 5/16 so that would be overkill for the return line. As for problems, out of 1000's that haven't, one or two have. I have used an AFPR, stock fuel rail and lines, and lowered the pressure to 30 psi easily.

[wallace]

Yeah, I think I'll just stick the pump in with the factory lines and if I have a problem I'll go and get a pre-bent factory supply line from my favorite parts house.....the junkyard! Then I'll have the same supply and return. Thanks for the info. Is the Walbro swap a pain in the '90 Caravan? My machinist is killing me, I'm still waiting on bore size to order pistons....its been 3 weeks.

[turbovanman]

If 90 has the same pump hanger as my 89, slight mods needed but pretty simple,

[Timmay2]

Even with a high HP car and stock lines alot of fuel is returned to the tank.

using a general guideline,

1/4" System 30-50 PSI 250 gal/hour

1/4" lines can flow 4.1 gallons per minute.

So if you have a 12 second car ( i have no idea how much HP that is), youre lines can push .8 gallons of fuel through in that time.

Does a 12 second run really consume nearly a gallon of fuel? What HP level is that anyways?

And this is a minimum at 50 psi idle.

Toss in the boost and the increased Fuel pressure while actually driving...

Someone else do the math...

[Timmay2]

Quote:

Originally Posted by turbo minivan in the case of one failing, the pressure and fuel supply shouldnt go bad (unless racing) cause if one shut down, it would basicly go back to stock, with one pump. right? maby not? they will be running on 2 sets of stock supply and return lines and be Y'd at the rail, so basicly 2 totaly seperate units working together. i dont know, maby not? what do people think of this?

Two seperate units working together is a great way to maintain fuel pressure to ensure it doesnt drop. Done all the time.

[Dean Stillie]

My race car has a 1 gallon fuel cell and its not quite empty after a pass and that is driving to the staging lanes burnout and driving back it has 3/8 lines. I ran 11.05@127 with the stock 5/16ths line and tank.

[Timmay2]

Quote:

Originally Posted by Dean Stillie My race car has a 1 gallon fuel cell and its not quite empty after a pass and that is driving to the staging lanes burnout and driving back it has 3/8 lines. I ran 11.05@127 with the stock 5/16ths line and tank.

When you were at 11.05 was that what, about 380whp ?? Whats your current times and HP level to be using nearly a gallon each run.

more info the better to piece together this puzzle!

[Dean Stillie]

Quote:

Originally Posted by Timmay2 When you were at 11.05 was that what, about 380whp ?? Whats your current times and HP level to be using nearly a gallon each run. more info the better to piece together this puzzle!

Not sure car has never been dyno'd weight was about 2400lbs then .
Now the car is about 2250 and has run a best of 10.64@135

[turbo minivan]

Quote:

Originally Posted by Dean Stillie Not sure car has never been dyno'd weight was about 2400lbs then . Now the car is about 2250 and has run a best of 10.64@135

DAMB!!

[turbo minivan]

would it be ok to run my second pump idea through 1 set of stock lines? would the stock lines handle 2 pumps pushing around 170 gph each? im just worried about the return line not being able to return all that exess fuel.
?????

[W.P._TurboCars]

are the original lines on lets say... a Rampage the same as that of an 87 turbo-charger?

[John B]

I have the idea of using two fuel filters in parallel to reduce the filter pressure drop. Good idea or waste of time and money?