In the process of my build. For feeding my GT35R coolant I chose the usual feed and dump. The feed 90 degree nipple coming off the upper water pump housing, and the dump is the lower nipple just above the heater hose.

I pulled the nipples out and tapped the holes. I tapped them with 1/8 NPT and planned to run -6 AN lines for each. My concern is that the 1/8 NPT is too small. Granted, the tap went right in the hole after pulling the nipples, so the original hole size is around 1/8 NPT plus the thickness of the nipple. The NPT to AN fittings are a little thicker, than the nipples, but not much.

The feed would be easy to drill out and tap with 1/4 NPT as there is plenty of metal there. However, the lower has the external post that the hole sits on, and 1/8th is as big as she goes without welding on a fitting.

My concern is coolant starving my turbo. Not sure if the difference is negladgeable, so I wanted to get your thoughts...

Thanks all.

 

Weld on a proper A/N bung.

Do it right do it once.

 

Damn it... I knew you would say that. Thanks buddy

 

My thoughts are that 'negladgeable' is not a word in the English dictionary

 

I make my own words!!!!

 

I thought the feed was the lower port by the heater core fitting?

And you have plenty of room to drill and tap to 1/4 NPT down there. Just get the EXACT size drill bit for the pilot and you'll be just fine.



EDIT: Can't get my computer to cooperate with me and I can't link the photo correctly. Just click on it and you can see that 1/4 fits just fine

 

Excellent. Thank you!