Tapping The Block – Part 1
One major part of turbo charging an SR20DE is creating an oil return path for the oil that is exiting the turbo. This process can be nerve-racking since many people opt to drill a hole in the block for the oil return. Some people choose to run the return right into the oil pan, but I have heard varying opinions on doing that so I choose to stick with the tried and true method of tapping the block.
The process of tapping the block is not overly complicated, it just requires great care as a mistake here can put you in a bad place!
Drilling and tapping the block requires a few tools:
- Drill
- 23/32 drill bit
- 1/2″ NPT tap
22/32 is the final size the hole will need to be before you can tap it using the 1/2″ NPT tap. It is recommended that you use smaller drill bits to start and progressivly build up to the 22/32 bit. This will reduce the likleyhood that the block will be damaged during the drilling process.
Connecting the oil drain from your turbo to the hole in the block will vary by application. I have an oil return flange on my turbo that gives me a -10 AN threaded outlet. I speced-out the needed fittings from AN Plumbing. In this case I used a -10 AN fitting on the turbo side and a -10 AN to 1/2″ NPT 45* fitting on the block side. Once again I will be using the Koul Tools product to assemble the lines, since they worked very well with my -6 AN lines.
In part two of this series, I will detail the process I used to drill and tap my engine block.