additional fuel line - copper ok?

[pupjoint]

recently plumbed my car for FI, used copper as that's easiest and quickest to buy, i did read somewhere it is not the best choice. Aluminium and SS would be better way to go.

anyone using copper and have issues?

[Martin S.]

I wouldn't do it just because my local hardware store sells al tubing for cheap.

[Peter]

I used copper for years and no problems..
don't worry too much about it

[hotrodsurplus]

recently plumbed my car for FI, used copper as that's easiest and quickest to buy, i did read somewhere it is not the best choice.

I do not think copper is the best choice but it is not the worst either. Copper work hardens fairly easily and can fatigue (crack). That said, I have friends who use it in hot rods and never have problems. The key is in the installation. Support it very well at as many points as you can and keep it as short as possible where it enters/exits the pan and the engine compartment. Use soft rubber hose to accommodate the engine movement.

Aluminium and SS would be better way to go.

Aluminum: definitely not a better way to go*. Stainless: maybe.

I know aluminum frequently gets used in fuel systems but you have to be exceedingly careful with it. *Aluminum is very rigid and work hardens at an alarming rate making bicycle frames made from it very harsh feeling and crack prone. You have to support it to a very great degree on a pan and I would not consider using it on a very vibration-intensive application like an engine. Yes, the OEMs use aluminum fuel lines but they also invest millions of dollars in engineers to design the mounting points among other things. This is one area where I do have experience with a cracked fuel line. Luckily it was a return line but it failed nonetheless. And it failed within a year.

Stainless is very strong but is considerably harder to form than zinc-plated steel line. You can't easily form a double-flare end with most stainless grades either. I avoid it in applications where I intend to run JIC/AN hardware. I know you can form a 37-degree flare with all SS tubing to use JIC/AN but I would rather make inverted-flare ends and use IF to JIC/AN adapters. That way if a component fails far from home you can temporarily repair the system with production or universal parts and replace the IF/JIC-AN adapters with regular barbed fittings and use plain rubber hose.

I know that sounds like a real pain in the ass but it is nothing compared to the pain you will feel 150 miles from home and a part for which you can't find an exact replacement fails. Then all that work you invested earlier pays off.

I prefer zinc- or copper-plated steel line first, copper a relatively distant second, and aluminum in a pinch.

[JS]

recently plumbed my car for FI, used copper as that's easiest and quickest to buy, i did read somewhere it is not the best choice.

I do not think copper is the best choice but it is not the worst either. Copper work hardens fairly easily and can fatigue (crack). That said, I have friends who use it in hot rods and never have problems. The key is in the installation. Support it very well at as many points as you can and keep it as short as possible where it enters/exits the pan and the engine compartment. Use soft rubber hose to accommodate the engine movement.

I have the same experience but as you say, probably not the optimal choice.

[cameron shorey]

recently plumbed my car for FI, used copper as that's easiest and quickest to buy, i did read somewhere it is not the best choice. Aluminium and SS would be better way to go.

anyone using copper and have issues?

Do NOT use aluminium. Aluminium has a low melting point of 600C (approx 1200F). If your car catches fire the aluminium will melt quickly.
Aluminium does not like to flex either, so your tubing will have to be supported very well. Work hardens easily, and cracks.
If you are planning to take your car to a race track, check the race authority's rule book. They will specify what material they require you to use. Usually steel or stainless steel.

Edit for clarity.

[hotrodsurplus]

Wikipedia isn't the most credible source in the world but it at least offers enough general information that you can use as a springboard to learn more. Here's a paragraph from its Fatigue Limit entry:

"Ferrous alloys and titanium alloys[2] have a distinct limit, an amplitude below which there appears to be no number of cycles that will cause failure. Other structural metals such as aluminium and copper, do not have a distinct limit and will eventually fail even from small stress amplitudes. In these cases, a number of cycles (usually 107) is chosen to represent the fatigue life of the material."

In other words, if you maintain an amplitude less than steel/stainless steel's fatigue limit those materials will last indefinitely. On the other hand, copper and aluminum will eventually fail regardless of amplitude. It might take forever and a day to reach those fatigue limits but the salient question is...are you willing to gamble?

http://en.wikipedia.org/wiki/Fatigue_limit

As an old bike-builder guy I once knew would harp when people chose frame materials, steel is for real.

[Rich_h]

here some more advice that may help
http://cal-look.no/lounge/index.php/topic,19726.0.html
 

rich

[69Stu]

I have used Cunifer (Copper Nickel Alloy) for many years without any issues.
To work with it's harder than copper, but not as hard a steel or stainless steel.

The first one that came up on a Google search.
http://www.cunifer.com/

[pupjoint]

thanks guys. i went to the shops around my area, funnily nobody has any SS tubing for sale??? 

things just wont be available when you look for them....

will seee what i can order online

[hotrodsurplus]

thanks guys. i went to the shops around my area, funnily nobody has any SS tubing for sale??? 

Out of curiosity, why does it have to be copper, aluminum, or stainless? Why not steel? It's available everywhere auto parts are sold. It's the same stuff as brake line. If you get the stuff with the dark green cladding you can bend it by hand.

Steel bundy tubing will last for decades. Stainless is largely hype.