Water Tubes (pipes)

[Pete K.]

While I don't have a GT40 (yet), I do have a midengined car that needs new water tubes (pipes) between the engine and the radiator.

I've been brainstorming to come up with ideas...

pvc - nope, won't hold the heat
copper - easy to work with (brazing)
stainless steel - bit expensive, heavy
aluminum - looks like a good bet
rubber hose - could work but would need to be protected
steel (exhaust tubing) - no thank you
SS Braided line, AN fittings - $$$$$$

Thoughts?

Thanks.

 

[Alain Vanhollebeke]

Pete,

when I was working on my Manta, my plan was to use aluminized exhaust tubing for the cooling hoses.

It is cheap, and available at any muffler shop.

Plain steel was my #2 choice.

Do not use plastic. I really wouldn't trust my cooling system to plastic, with temps constantly around 200 degrees and over 10 psi of pressure.

Make sure and clamp the lines to the frame, DON'T weld them to it. The lines will expand/contract as they heat up & cool.

Put a bead, on the end of the tubes so that your clamps can't slide off. This should be easy to have done at the muffler shop if you get the tubing there.

Also here is a tip I got from Kennedy Engineering. They have done alot of 914 porsche V8 conversions,so I think they may have a good point on this.

Put a restrictor at or close to the entrance of the radiator. A washer with a 3/4" hole is what they use for a chevy V8 powered car.
This restriction is supposed to make the waterpump "pressurize" the tube going into the radiator so that really hot coolant won't "flash" into steam before itenters the radiator,,where it can condense. This should help to prevent air bubbles from forming in the cooling system.

Oh,
the nasty sticky stuff on your A/C hoses at the box is called "A/C tape".
This is to keep condensation from forming and dripping into the cockpit & onto your feet. You can buy it by the roll at any auto parts supplier. Use it to cover any exposed metel (suction side) A/C system tubing in the cockpit area.

 

[Guest]

Pete K

On the originals I've seen 2 different materials aluminum and stainless steel.

Another thing to consider is diameter as this affects volumn and velocity of flow. All I've seen as far as diameter is 1-3/4".

I'm using 6061 T6 straight tubing to run through the tunnel and high dollar urethane(?) elbows to make the bends at the ends. You can get 6061 bent but it is in the "0" hardness condition. Got my tubing from boeing surplus, pretty expensive otherwise, probably as much as stainless.

Aluminum is light only problem is it conducts heat quite a bit. Tunnel needs to be well insulated or it will act as a heater.

Stainless is heavier but opposite to aluminum conducts heat less than even mild steel.

If you wanted stainless I would use 204 stainless with an .049 wall x 1-3/4"dia. Stainless Works (exhaust OH) sells .065 wall for $6.50 cents a ft. Burns Stainless (exhaust CA) sells .049 for $7.18 per ft. they also sell 6061 for $6.31 per ft.

If cost was a prime consideration, mild steel might be a choice, especially if access to replace the tubing wasn't difficult, which might not be so on a GT40.

Case in point the Acura NSX uses mild steel tubing to transfer coolant although it is cadmium plated. You could paint mild steel to make it last. POR comes to mind here.

 

[Pete K.]

Thanks everyone!

Looking like stainless might be the way to go ... or aluminized steel.

 

[Mark Worthington]

Aluminum will be significantly less expensive and lighter than SS. As for heat conduction in the tunnel, it will be proportional to the contact area between the tubing and the aluminum the tunnel is made of. If you have a round pipe sitting on a flat floorpan, there isn't much contact area.

[ November 26, 2002: Message edited by: Mark Worthington ]

 

[Jim Glickenhaus]

In my P4 the water and oil flow through the chassis tubes. In the MK-IV the tubes are alum.

 

[Hershal Byrd]

My tubes are aluminium. I individually wraped each tube with Pipe protection tape. It keeps the pipes from making any noise from chafing or something else rubbing on it. The tape also insulates as well. You can buy this tape at most hardware stores.
The tape looks like exra thick electrical tape.

Hersh

 

[Jim Rosenthal]

You might also look at fiberglass tubes. There are filament-wound, heat-resistant fiberglass tubes which are made for the purpose of carrying exhaust gases and hot water on boats. The smallest size I have seen in West Marine's catalog is 1.5"- a ten foot length is $90.00. It is made by Centek Industries, and may be available smaller. The largest size they show is 6"- maybe a bit large for GT40 or similar plumbing...
Another alternative- there is an exhaust hose for (again) marine applications which is wire-reinforced, won't crush or pant, and is specifically designed for marine hot water/exhaust gas applications. It comes in
1/2" to 4", or larger, and is very tough as well. MOst marine stores sell it either by the foot or in long runs up to dozens of feet.
I have had very good luck with both of these materials in marine exhaust applications; hot seawater is far more corrosive than hot fresh water and antifreeze, and they hold up fine. The fiberglass tubing, incidentally, can be cut and glassed back together to make changes in direction, etc. It can also be glassed to fiberglass structures to hold it in place.