Turbo Oil Inlet Thread not NPT?

[NWade]

Hi All,

Now that my turbo is installed on the engine, I'm trying to hook up the various hoses. I had no problems installing the new mini-sump on the bottom of the turbo and attaching an NPT-to-AN fitting on that machined component. However, I've run into a problem trying to run the line from the spin-on oil filter to the turbo:

The Assembly Instructions say to use a 1/4" NPT to -4 AN fitting on the top port of the turbo (for the oil inlet). They even specify its Summit Racing part # SUM-220447 (see page 56 of the current Assembly Manual).

But the NPT fittings that I've tried are all difficult to get threaded into the port (I've tried 3, to make sure it wasn't a bad fitting). When I do get a thread to start, it locks up after about 1/4 turn. I used a wrench to try to gently turn the fitting (in case it was a bit of contamination on the threads or something) - and it quickly cross-threaded and screwed up the fitting.

I checked the "side" ports on the turbo and found that the same NPT fittings thread easily into those ports. So its obvious that my turbo does not utilize NPT threads on the oil inlet port.

I've fired off an email to Sonex Tech Support. But in the meantime, has anyone else run into this? If so, what fitting size/type did you use?

Pics of my turbo are here:
https://flic.kr/p/Wezczx
https://flic.kr/p/WbapNs
https://flic.kr/p/V174Ap
https://flic.kr/p/Wezc2t
https://flic.kr/p/UXeQm1

Thanks,

--Noel
Sonex #1339

[NWade]

Quick update:

Issue resolved. Per the Sonex support team, the correct part to use in the Turbo Oil Inlet is "592047ERL". That part is included with the AeroVee Turbo kit, too. The current Assembly Manual incorrectly says to use an NPT fitting on the oil inlet. I believe Sonex is going to correct this instruction step in a future version of the Assembly Manual.

--Noel