Coolant hard lines

I need to run coolant lines from the front of the RX7 to the rear through the passenger compartment. 1" OD Stainless braided hose is very expensive for this job. 6061 T6 aluminum tubing is much more reasonable.

Any reason why I shouldn't use 6061 for the majority of the lines beyond flex lines right off the engine?

It's more expensive than steel tubing?

Many OEMs use steel for coolant tubes. Others use aluminum of various species. It'll be fine.

Steel is heavier and a span of 15-16' adds up. 1" od x .93" id 6061 is pretty darn light.

I ran 24 feet of aluminum tubing with no issues. Coolant is 180 only degrees.

I used a muffler tubing bender, no creaks, no cracks, no issues.

Dan

why not use copper? you can get all the bends, you can fix it with eases or add in fitting latter if needed.

No reason not to use aluminum. I'd suggest 1 1/4", though. Another option is thinwall stainless, it's light as a feather but that stuff can get pricey.

All right, here's a question that's been burning a hole in my tiny little brain for a while: does anybody know if using different metals in a coolant system (specifically, copper tubes, brass tank, aluminum head, cast iron block) is copacetic? My thought was to just do it and see what happens. I mean, heater cores are usually copper, right? The rest is pretty standard aside from the brass lines. To be clear, what I was over thinking was weather there would be cavitation, or what not due to incompatibility of metal types.

I wonder if aluminum dissipates heat too well for this application? Or maybe it's a good thing?

Bridgeport 13b. Computer controlled electric water pump. Disapating heat too fast doesn't exist. If its too cool the pump slows. Too hot and it pumps more. Computer also runs the fan 2300cfm fan.

Regarding electrolysis, google "sacrificial anode"

porsche uses aluminum tube on all the rear/mid engine cars to get coolant and heat to the radiators and heater box, so i see no reason at all not to use it.

Used Al on a FSAE car back in the day. No problems.

Just make sure theres no flexing of the hardlines.

wheelsmithy wrote: All right, here's a question that's been burning a hole in my tiny little brain for a while: does anybody know if using different metals in a coolant system (specifically, copper tubes, brass tank, aluminum head, cast iron block) is copacetic? My thought was to just do it and see what happens. I mean, heater cores are usually copper, right? The rest is pretty standard aside from the brass lines. To be clear, what I was over thinking was weather there would be cavitation, or what not due to incompatibility of metal types.

Chemistry of the antifreeze keeps things happy.

DaveEstey wrote: Bridgeport 13b. Computer controlled electric water pump. Disapating heat too fast doesn't exist. If its too cool the pump slows. Too hot and it pumps more. Computer also runs the fan 2300cfm fan.

Then I vote aluminum with fins Tigged on. If you need me to do the Tiggin hit me up.

Practically all race cars that have the motor and heat exchanger at opposite ends use AL tubing. You need to roll a bead on each end, and secure the tube in rubber-lined P-clamps. Easy-peasy.

DaveEstey wrote: Bridgeport 13b. Computer controlled electric water pump. Disapating heat too fast doesn't exist. If its too cool the pump slows. Too hot and it pumps more. Computer also runs the fan 2300cfm fan.

Depending on what you are doing, that may not be enough fan. 1600cfm is almost adequate when the radiator is in the front of the car where it can get good airflow. Rear mounted radiators are more difficult to get air through them.

I don't know what my fans are rated at, my best SWAG is 4000cfm, and I stopped having cooling problems, but I still get kinda too close for comfort sometimes. I prefer to see temps stay below 200 which is asking a lot. You can feel the power going away when it gets over that.

That's why some days I wish I had a piston engine that didn't care if it was running at 230-240 degrees. That's maybe 30% more delta-T from the radiator to ambient air.

Where would someone find 1 1/2 inch aluminum tube for something like this?

In reply to bgkast:

One option:

http://www.onlinemetals.com/merchant.cfm?id=72&step=2&top_cat=60

http://www.onlinemetals.com/merchant.cfm?id=946&step=2&top_cat=60

Just use copper pipe, M tubing will suffice. You can flare the ends a little so the hose doesn't pull off. All the different metals don't matter. Think back to the days when cars had cast iron blocks, aluminum heads and copper radiators.

I get stuff from Online Metals all the time, great service but they can get a little pricey. It's worth checking out McMaster-Carr too.

Aluminum:

http://www.mcmaster.com/#standard-aluminum-alloy-6061-tubing/=qiy4gy

Stainless:

http://www.mcmaster.com/#standard-stainless-steel-tubing/=qiy54q

When you run the tubing be real careful not to have any loops that can trap air, that's bad news. If it's unavoidable be sure to put a bleed screw there.

In reply to Knurled: Good points. If I need to get creative I can. Dual radiators off side scoops? No problem. Hillclimb rules don't dictate how much cooling I run.

McMaster is cheaper than I thought it would be.

If you use a bit of rubber hose between dissimilar metals, it should act as a dielectric union.

Aluminum coolant lines are common, even on some factory vehicles.

You might want to insulate the line to keep it from heating the cabin though.

Regarding the use of copper pipe in for vehicle cooling systems, I remember reading somewhere that copper work hardens and gets brittle when exposed to vibration. This is why it isn't used much for car plumbing. I think I read it in one of Carroll Smith's books. Can anyone confirm this?

Conduit is a good option for price and availability, too, if the added weight isn't a big deal.