Wastegate hose size
 

When I first set up the turbo system I chose to use Teflon lined braided stainless hose and AN fittings to plumb the wastegate. The wastegate came with 3/16" hose barb fittings so I got -3 hose. -3 is supposed to be 3/16" but as it turns out it's only .14"id. Recently I had some issues with the wastegate, which led me to disassemble it. It was then I noticed how much play there is in the valve guide in the wastegate. This got me thinking that with such a small diameter hose to the gate, what is the percentage of loss through the guide?
Would there be any benefit in going to -4 hose which has a .19"id (much closer to 3/16" and nearly twice the area as -3)?

-3 is pretty tried and true. I would stick with it.

I use 1/4" (6mm) silicone hose on my wastegate (from signal to solenoid & solenoid to wastegate)

I've seen "online" where some people have had issues with simple hose to the wastegate.

I chose stainless braided because I viewed it as the most robust.

Because I have little direct experience with performance turbo setups, I frequently go overboard with details like this.

I used -6AN when I did my wastegate and never had any issues to indicate it was too big. Used it for 11 years on wastegate spring and with a manual boost controller.

Just make sure to use swivel fittings so any vibration or whipping of the hose does not unscrew the -AN fittings over time- common mistake with -AN fittings.

IDK about regular rubber hoses, but silicone looks just as good as day one (about decade ago when installed). I don't like how the braided metal part warms up and stays warm (or HOT depending on the location). My SS braided turbo oil hoses (specially the return one) were cooked after a couple of years of use, I have since replaced all SS braided hoses (fuel and oil) to nylon braided, much better on the hose temps issue that I was experiencing (no changes on fluid temps)

Hmmm, I have plenty of -6 hose and fittings, might do this. Is not that I have issues with silicone, at this point, I would like to make things aesthetically better. On the boost controller solenoid, I am guessing you used a 1/8 npt to -6AN adapter?

The AQP rubber lined hoses are good to 300degF, which is likely exceeded in close proximity to a turbine housing, manifold, or maybe downpipe.
The PTFE lined stainless hose is rated for 450degF and should handle anything besides direct contact. Silicone hose has a similar temp rating, but pushed to the limit has no supporting structure like the braided stainless outer covering on the stainless hose to hold it together. If you look, you can find pictures of the silicone hose ruptured.
That said, I know there are a lot of people using silicone tubing with no problems at all.

I'm entertaining the thought of making hard lines to the wastegate. If I can make it so it will be serviced easily, I could use 1/4" ni-copp brake line and AN flare fittings. I would have to mount the boost control solenoid on the engine.

There maybe something wrong with me...

Dual TiAL MVR 44 Wastegates.

https://cimg6.ibsrv.net/gimg/www.rx7...8a4092ca17.jpg

I use -3AN SST braided hose for the water and 1/4 silicone hose for boost. Routed away from heat source.
No issues for over 7 years other than re-tightening of -AN nuts once.


https://cimg9.ibsrv.net/gimg/www.rx7...cf6ffc9e82.jpg


https://cimg8.ibsrv.net/gimg/www.rx7...8aff1daf05.jpg

Hoses partially assembled.

Correct, I used -6AN to whatever thread my Hallman Pro RX MBC used as the bottom nipple and then "machined" the check ball seat into the -AN adapter fitting (its part of the nipple on Hallman).

I've always used 4an for vacuum lines.