I'm going to need to run -8 (1/2") fuel line for my BBC. Can you just snake hardline along the frame rail? I know with brake lines you HAVE to (atleast what I've heard) pull the body.

How do you big motor guys feed the beasts?

[RANT] Why are some people, in between all the great people on this Forum, such ******. I had a guy offer to sell some Hooker side pipes, then try to tell me shipping would be $200, and finally say, I'm just going to sell them locally. Why do they even bother to offer them for sale, get someones hopes up, and then pull that. [/RANT]

 

ddn,
Unless you pull and modify the outlet at the tank (i think) your wasting your time. ......redvetracr

 

Take a look at Merlin522.

I guess it was series 17 where he displayed the fuel system.
He ran the lines through the frame rail.
Check it out, its worth it.

 

Merlin only ran the garden hoses through the frame to go over the wheels, in case something breaks it won't cut a fuel line.

Pure insanity.

Monty, 427HotRod, gkull, big engine guys, where are you?

 

I'm interested in this, too.. I need to run some high pressure feed lines for FI, and would prefer a metal line over a rubber line for asthetic reasons...
-Jason

 

blue72: Actually you bring up a good point. I wouldn't mind running a braided stainless/rubber line at all, but I've read that there is actually a measurable amount of friction with rubber hose as compared to hardline, and it shouldn't be used for long runs.

Is there any truth to it?

 

Well I just ripped out the rusty old metal line and ran the -8 allong the frame in the same place. It was a little tough getting the clamps on with the body in the way but I got it. I also used a piece of -6 sipped over the stock pickup but thats only 6" or so to the filter so it should be OK

 

I removed the tank and silver brazed 2 new outlets to the lowest portion of the tank then install twin fuel filters and 2 holley blue pumps. I then used 1/2 inch id stainless line all the way to the front where it feeds a holley 4 port regulater. The stainless line is in 2 pieces with a compression fitting.

 

Originally I wanted to use solid lines, but we talked at great length about the subject with an engineer here at Boeing. First, it is practically impossible to bend solid line - especially at 5/8". Maybe be easier with 1/2 but the angles can't be too severe. Another lesson learned was that these solid lines can break also. They can crack or get scratched & have all kinds of issues. Their tensile strength is far greater, but they aren't flexible & that can be a problem. This engineer also convinced us that this line is incredibly strong. I can't remember the numbers, but the burst pressure it would take to rupture it was incredibly high. Just make sure you get an aircraft quality line. There are many differences in how the lines are constructed. I am sold on flexible lines. Also, they are cheaper to replace should there be any rubbing. Just mount it with lots of rubber around the actual line & you will be safeguarded against rubbing. The comments above about running it through the frame are accurate - this is in case we break something in the rear (can't imagine that happening :) ). I have heard of a dude that ran the line through the whole frame, but he actually dissasembled the entire frame. Too much work for most folks. Lots of good pics on my site if you are interested..


[Modified by Merlin522, 6:16 PM 1/21/2002]

 

P.S. We are using a regulator that will turn off boost & kill the pumps if the line senses a 5psi drop. This is a good plan for those with monster blocks & pumps. In my case, it is critical. 5/8" line with dual huge fuel pumps could lead to complete decimation if they kept pumping into a fire - especially if it happened with a 50+ gallon tank sitting right there!! Something to look into. Very cheap insurance if you ask me. That way if you rupture a line or have a leak, there is no chance of your car ending in a fiery inferno...

 

Nick Scavo and Chuck Samuels of NMCA/NSCA/NMRA fame get by with a single -10 feed line with a -08 return line, and they make around 2000hp with their turbo setups, so you can be pretty sure that it will be good enough for you too.

 

Actually Monty, not to disagree but to augment that point - the size of the lines really isn't that critical to power - as you mentioned. You just need enough diameter to squeeze enough fuel though. The large size of the line is really for cooling. Yes, I could get 2,000HP out of a 1/2" line, but could I drive that on the street every day or sit in traffic? This is where a large size line on the street is far more critical. I would hazard a guess that the 2,000HP vehicles you speak of are not daily drivers. The faster you can get the fuel in & out of the system, the more it will cool & this is critical for a high power application - especially when trying to drive a 1,000+ HP vehicle around the street for extended periods of time. Cooling that gas mixture also ultimately provides more power as well. Again, not to argue, just want to offer something that I've learned along my quest for world domination. :)
Big fuel lines aid in cooling. The bigger the better.

 

When I put fuel injection in my vehicle, I ran two 3/8" aluminum lines back. I just ran them along where the old lines were where I could, then pushed them up over the fram next to the body by the back wheels and down to the tank. Then I attched them to the old fuel line using wire ties. I ran my wires along the same place.

The aluminum tubing is cheap, you can get it at any good hardware store, and it is very easy to bend and work up over the wheelwell. I thought of using copper, but the aluminum is so much easier to work that I decided to use it instead. Then, you can just put rubber line from the end of the hose to your pump or tank. I have a pump back at the tank. Take off your right rear wheel and have someone help you work the tube up over the frame there. After you get it secured, spray paint it with some flat black paint and it looks fine.

The line coming out of the bottom of the tank on mine is about 3/8", the line back into the top of the tank is about 1/4", but for a return line it seems to work fine.

If you put your pump back at the tank, you should have no problem flowing enough fuel for a big block through 3/8" lines. It doesn't look as impressive though :) I still have a lot of fuel flowing back to the tank on mine -- my engine isn't particularly hot though (only runs up to about 5500 RPM, mild cam - similar to comp cams 274H, stock exhaust). Good luck.

 

John73bb, you're running throttle body injection, right? If your setup is similar to stock TBI setups, you're only running about 15psi in those lines. Sure, aluminum lines will work fine at that pressure... but for multipoint injection you need to pump about 50 psi through the feed line, maybe more depending upon the pump used. Will aluminum lines handle that pressure?
-Jason

 

I don't see why not. The lines for A/C are aluminum, a little thicker and I don't know about the alloy, but A/C runs up to 250-300 psi. I guess an easy way to check would be to get a section, crimp one end, and put 120 psi of air pressure on it. I would be very surprised if it wouldn't hold several times the 50 psi that you need.

I had the Holley system on mine before, and ran it to about 20psi. The GM system I am setting up now will run at 11 psi.

 

Dave,

Why do you have to run #8? In my Vette 468ci/LS7 the stock 3/8" line worked fine and I used the supplied 5/16" line as my return line. Why make it more difficult on yourself.

Unless your running somekind of mega dollar pump 3/8" line will work fine.

In reference to line size, the bigger the pump the bigger the line has to be, I have a Paxton 300 pump in my Camaro that requires as Monty said a #10 feed with a #8 return line. To run a 3/8" line into such a pump would cause it to run dry. Also, the return line is what is keeping the fuel cool, because it's allowing the fuel to be in constant flow, not sitting there deadheading.

Just throwing my .02 in...

 

Wouldn't a car running EFI and 50+ psi get by with a smaller diameter fuel line since you'll get more flow at higher pressure? I wouldn't think a mechanical pump could get the same flow out of a stock 3/8 line.

-Joe

 

Even with the higher pressure, the volume may not be enough depending on the engine's requirements.

 

Good questions.

On my car, the main line was rusted out when I got it. I put my pump on and immediately had fuel running on the floor when I turned on the key. So, I ran a 3/8" line from the pump at the tank to the engine for the feed line and used the original return line. I found, however, that I was getting too much pressure on the return line, so I replaced it also. I guess that at the pressures I was running, the return line could not handle what the pump could shove down but the engine could not use. With the 3/8" line, my return line pressure (at the exit point of the throttle body pressure regulator) is less than about 3 psi now, and was around 8-10 psi with the original line.

Long story short, yes at higher pressures with the same size line, you will get more fuel flow. That reminds me of my old mercedes. It ran over 60 psi and had a very small (about 1/4") line for its 4.5L engine.

 

the 580 HP L-88 from chevy used a 3/8 line,just make sure the tank pickup is that large also. i have fed 800 +HP blower engines with 1/2" line


[Modified by clem zahrobsky, 3:24 PM 1/22/2002]