I was originally thinking about using 1/2" aluminum hard lines to makethe bulk of the rx-7 oil cooler lines I will be installing with the turbo. Iwill be adding some flexible hose for vibration and movement isolation betweenthe moving engine and stationary cooler. I have made a turbo oil drain line outof the same stuff and looks/fits very well.

Has anyone on here run aluminum oil cooler lines? I have found some negativeopinions about using aluminum due to fatigue cracks failures over time, but Iam planning to support the hard lines to limit movement. We used aluminum hardlines on Army helicopters for much higher pressure hydraulics so it should workin our applications as well.

 

It's fine on the chassis (assuming elevated and protected from any likely impact damage by structure). Aluminum shouldn't be used on the engine itself. I'd recommend changing your oil drain line to either flexible or steel/SS. It will crack. Remember that in the Army you were working with turbine engines, not piston engines -- and even then I'd wager that there weren't any aluminum lines on the engines themselves, only in the airframe. The only aluminum hard lines I've ever seen on aircraft piston engines are fuel primer lines. They are extremely small diameter with vibration loops bent in and only contain a limited amount of fluid. Other than that . . . flex or steel or SS.

At the end that connects to engine's flex lines, make sure you use AN fittings and try to support the AN fittings rather than the aluminum hard line at that end.

FAA has some great publications on this. I've posted some of these, but you're better off just going to faa.gov to avoid broken links.

 

Why? whats wrong with rubber, elastomer, or SS lines? Seems you are adding complexity really. There is no need for the hard line and you will have to add a flexible section...If the rubber/elastomer/SS has a weakness, then it will sitll inherently be there as you will have to use it for the flexible section.

 

Good point Hornet, turbines run much smoother, I didn't think about that. I already had myself convinced to use steel lines, but figuired I would post to see if there has been any experience over here in turbo miata world using aluminum. At least I have an aluminum template to use for the steel drain line fab!

The main reason for running hard lines coming off the turbo is for long life in the immediate high temp area. For the oil cooler lines I prefer hard lines since I can make it look much cleaner and will never have to worry about a steel line degrading like a rubber or rubber lines SS braided line can. My engine compartment is also getting crowded and it seemed like I could route hard lines with sharper bend radius through the spots I need to without worrying about rubbing.

We did a real nice oil cooler and remote filter installation on my brother's FFR roadster where I did 90% of the lines in hard SS lines. It looked sharp. That was back when I worked for Swagelok and had access to all the great tools they have and pretty much all the free SS tubing I needed.

How long do the braided SS oil drain lines last on track driven cars? Is life extended at all by running a reflective thermal sleeve over the oil drain line?

 

Get some good PTFE braided line (e.g., goodridge 811) and never worry about fatigue or degradation. Most quality PTFE lines have a 500deg f temp rating (melting point for PTFE is somewhere north of 620deg) so exhaust heat isn't a huge concern. Unlike the rubber lines, the PTFE won't harden with heat cycles.

Pegasus will make them for you, albeit for a price. https://www.pegasusautoracing.com/gr...pID=PLUMANFLEX

-Zach

 

The chassis still vibrates. Oil is critical. One cracked line and you risk losing an engine.

IMO, aluminum hardlines have no place on a car.

 

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