mine is post turbo and going to move it is it a 1/8 bit and tap both the 1/8 size or what?

 

1/8 in pipe thread is a size R drill bit. I used to know the size in inches but I forget now.

 

the size is a 11/32 drill bit

 

Technically you should use a size R as 11/32 is not exactly there, but it's close enough

 

the size R is just a tad bit smaller right

 

.325"-.343" -- because of the taper, there is some leeway in drill size. I've seen everything from Q to R to 21/64" to 11/32" mentioned. As you go up in size the threads will be less tight and you'll have to turn the fitting deeper into the hole to seal it.

http://www.carbidedepot.com/formulas-tap-pipe.htm

Here is a chart that lists all the drill sizes in decimals:

http://www.auto-ware.com/techref/drillsizes.htm

 

21/64 some guys use 5/16.

 

so one of those bits then the 1/8 tap?

 

yes, 1/8" NPT.

And this is very important - dont run the tap in too far (3/4 of the tap maximum) if you go past that your fitting will be loose in the manifold and you dont want that.

 

whys that the tap shaped like a cone??