Cmon budding engineers give me input please!

[coomo]

The 911 reborn build is progressing to the point where I have to sort oil lines.Ive mounted the thermostat, and the aluminium tube has arrived the fabricate the oil lines.
Im using all original fittings.Now at the point to mock up stat and lines.However the conical fittings are steel.The lines are ally.Suggestions on how to attach.The fitting is a tight interference fit into the slightly flared pipe.Or do I get some hose fittings made in aluminium?

[chrisbalich]

Could you sweat the fitting to the pipe with silver solder?
The flow points for silver solder are significantly higher than the oil temp will be. (Even during catastrophic failure)

Caveat: Using heat to loosen the fittings at a later date would be risky.

[pampadori]

could you not source steel to use instead?

[jpnovak]

Get some aluminum fittings to match your aluminum tubing, or get some bronze tubing to match your steel fittings. You can braze the steel fitting to the bronze tubing.

While Al and Steel can be TIG brazed, ultimately the galvanic corrosion will crank the joint.

Maybe a modern adhesive could work. I would be concerned about long term heat exposure would weaken the bond.

Use Al to get your tubes bent in the correct shape and then have them duplicated in a different material.

[2jmotorsports]

I would be concerned about the difference in thermal expansion between the two materials. Aluminum expands more than steel does and considering its a pressurized application operating within a large range in temperature I think it would crack and leak eventually.

[Dpmulvan]

Originally Posted by jpnovak

Get some aluminum fittings to match your aluminum tubing, or get some bronze tubing to match your steel fittings. You can braze the steel fitting to the bronze tubing.

While Al and Steel can be TIG brazed, ultimately the galvanic corrosion will crank the joint.

Maybe a modern adhesive could work. I would be concerned about long term heat exposure would weaken the bond.

Use Al to get your tubes bent in the correct shape and then have them duplicated in a different material.

+1 aluminum and steel don’t mix, there’s some modern adhesives that would work, or you could have the steel aluminized then weld. whatever your choice the aluminum has to be insulted from the steel or it will corrode.
I assume you chose aluminum because of price ??

[3rd_gear_Ted]

The OEM thread bonded pieces including the tubing sleeve are all steel for a reason. The tubing will grow @ a different overall rate, but the mechanical bond around the tubing will not be impacted by the heat cuz there all the same material.
Let me know where I'm wrong with this logic?

[targa72e]

Not a budding engineer but, late model 911's (996/997) have fittings and castings that are glued together. The fitting and the housing are both Aluminum. Over time (20 years) these have shown to be a weak point. Upgrade is to pin the fittings so they cant blow out and cause instant failure (just slow leak) other option is to have fittings welded to casting. My 996 turbo still has glued fittings and no leaks. If you have the fittings made in aluminum I would weld. If you keep the steel you might try a pin and glue approach. Luckily the lines on the scavenge side of the engine are low pressure so might work. Since pressure is low and fittings are pinned a failure would result in leak vs blow out.

john

[dannobee]

You can't use a swagelok union between the two pieces? That would be the most reliable connection between a steel tube and an aluminum tube.