This seems to be a recent trend. I'm noticing people using pneumatic push to connect fittings and nylon hose similar to what people also use with water injection, for their vacuum lines. Has anyone in here done this? They seem to be rated awfully low, even for the metal fittings at 240° F, for wastegate placement.

 

From my experience with these, they are guaranteed to leak after a few months becuse the plastic line shrinks at the O-ring. Replacing the plastic lines, or making them overlong and cutting off the last half inch, is a regular maintenance item.

I would not use them on a rotary, which is critically sensitive to unfiltered air. I'd certainly not use them anywhere near a turbocharger.

 

Stick with known reliable solutions.

 

You can buy PTFE tubing which is much more tolerant of high heat. I've used it on turbo rotaries and turbo V8s with push-connect and compression fittings. Good stainless compression fittings like Parker or Swagelok are quick and easy to remove and relatively inexpensive. They're also rated for WAY more pressure than a silicone hose and barb.
That said, I've seen plenty of nylon line and fittings fail from heat. I wouldnt use that anywhere near a turbo but usually does okay on blow off valves.

 

Good info, thanks. I've always used AN fittings and line for vacuum whenever possible. It's definitely overkill but we always did it with our racecars back in the day, I guess I'm stuck in the past. Expensive, but worth the hassle imo.

 

They are usually used on vacuum applications around the intake. I wouldn't run them because of the low temperature resistance. If anything run -an lines to the critical components like the wastegate lines.