i'm gonna be tapping the compressor cover on my turbo to 1/8 NPT i was just wondering what drill bit size to use to do this? i borrowed the tap from someone and they did'nt have the drill bit that came with the kit.

 

you use a 21/64th drill bit. the tap is tapered so make sure not to thread it too deep!

 

troof. it is a 21/64th.

 

thanks guys

 

Huh?? I think I'm being stupid, but most through taps are tapered, and bottom taps aren't. But if you're drilling all the way through it shouldn't matter which tap you use, but you'd want to run a through tap, allthe way through to get an accurate size

Please correct me if I'm wrong

 

depends on the tap being used. i cant count how many times i have seen people try to tap something.....oil pan, compressor housing, whatever else. they run the tap through too far, and go to thread in whatever fitting it is that they are using but they went too far with the tapered tap and the fitting would not properly tighten.

moral of the story is take your time and be careful. its a lot easier to run the tap half way through...pull it out and see if its enough...and insert the tap back in if needed than it is to "repair" something after you blasted a hole through it thats too big for your fitting.

 

Just curious, could this be from using a regular tap vs an NPT tap?

 

i think i see where you are getting switched up clayton, normal taps have a tapered start. a NPT (national pipe tapered) like bspt (which i think is british standard pipe tapered) has a smaller diameter at the bottom and continues to get bigger in diameter as you go. NPT fittings are the same way they are tapered like the tap. thats how they seal. like joe said if you burry the thing it bottoms out and doesnt seal. it is designed to seal on the threads.

 

also its not like you will fond a 6mm x 1.0 npt......the NPT designates it is a pipe thread. on the same note there is no 1/4 x 20 npt. there is a whole pipe chart somewhere i cant remember where it is, the 1/8th NPT is 1/8 x 27 and 1/8 bspt is 1/8 x 28

man im confusing myself. he hee

 

What kind of a tap would you use to put in intercooler piping? Any pics?

 

Why tap the cover?

 

To put a fitting for the wastegate/boost controller.

 

intercooler piping is too thin IMO. if the comp housing is not an option, i drill a hole and weld a bung onto the pipe. gives the fitting a lot more meat to grab onto.



"Why tap the cover? "

its easier than welding to a charge pipe as it is thick enough to drill and tap. if you can help it you do not want to us a vacuum source (aka intake manifold / vacuum manifold) for your boost reference on your wastegate.

 

Just did this on my setup today actually. Good info. Question answered

 

An 'R' bit is the proper bit, I have a few letter index bits but not a full set lol

http://www.newmantools.com/tapdrill.htm

I have a bunch of starrett quick referance cards in my tool boxes, those come in handy if you're ever around them. Swipe them and put them all over lol

 

Hi...Turbo charged....In regards to tapping the comp cover, I just talked with the guys from bullseye and they told me not to tap the cover but pickup the boost signal from the intake mani, not to start a **** storm but why the difference in opinion....Thanks

 

well........ 99.9% of us use Tial wastegates. tial strongly suggests not to run vacuum to their wastegates. that is one of the main reasons.


the other way to look at it, is if you have say a 7psi spring, and you want the wastegate to open at 7psi manifold pressure....... its a little more "exact" if your supplying its signal from the manifold. however if there is a boost controller in the equation that kind of goes out the window.

that and they probably dont want to tell you to drill holes in your turbo just incase you screw it up LOL

 

I always tap the housings or the IC endtank depending on the setup. 1/8npt or sometimes 1/4npt. I would hate to run all that extra line/hose from the IM. While tapping use some wd40 or cutting oil for cleaner tapping.

 

this is true last year i ran my pressure source off the back of the intake manifold and my boost controller was all ****ed up it would make the boost jump around

 

Will this help you boost more or just to be more accurate?

 

accurate and consistent.

 

PPossible more boost to?