So this is the second turbo now that I had this issue with. When I bought my first turbo it didn't come with the tapped vacuum source on the compressor housing. Therefore I drilled the flat spot right before the compressor outlet and tapped a 1/8" npt hose barb. Once I got everything hooked up my wastegate would not open. I checked the source from the turbo and boom no vacuum or boost. As a fix I just ran my vacuum line to the intake manifold and everything worked I just had an issue in cold weather with the wastegate not opening fast enough. About a year later I built my motor and bought another turbo and tapped it again the exact same way and again no readings! Im not sure if there's a trick to this but I've watched so many videos and I cant find the issue.

 

May not have found the issue as to why but, you've certainly found a solution: use the intake manifold! Done and done.

 

what he said...... never use the tap off the turbo......ALWAYS use a vacuum line from the intake manifold

 

Exactamondo.. I'm just waiting for EGAJohn to show the standard Turbosmart image of the compressor housing being used as a vacuum source.

 

That's what I've always done but every company I talk to says to always pull from the turbo. I guess I'll just stick to what I know works!

 

I know is not recommended by many on here, but you should still get a signal out of the compressor housing. Guys have had issues with it being a reliable source, but it’s odd the issue your having. Not getting any signal at all from that port just doesn’t make any sense.

I know I pull my source from my compressor housing. When I pulled it from my intake manifold after the TB, I was getting bad compressor surging at part throttle/heavy accel. I switched it back to the housing and I haven’t had any more issues.

 

To hopefully add a bit more insight on this issue.. Is there any way the turbo itself could have any bearing on whether or not the compressor housing tap would be effective or not? I myself have used the housings in the past with no difficulty noted. On the recent Garrett, it had no housing tap at all so I was forced to head to the IM. Now, I've had difficulty before with the IM source but now, I do not.
So.. Could turbo specs and performance play any part on the housing source?

 

ths less efficient your intercooler is the more drastic the difference is. If your intercooler is not efficient enough for the boost you are going to run you will see resistance on the hot side of the intercooler which will show a higher boost pressure than what is actually hitting the intake which causes the wastegate to prematurely open. This will cause a pretty big performance loss, especially on cars running lower boost levels since the wastegate prematurely opening will cause the turbo to not spool up as fast. If you have a intercooler that has zero resistance you won’t really have a issue. Put if you want your wastegate to open at a consistent pressure.......ALWAYS use the the intake manifold as a reference point. There is a reason every performance shop uses the intake manifold as the reference point. If your only running 5-6 psi who cares , your not making much power anyway and probably won’t notice the difference

 

Oohh, good call! I didn't think about the IC. I hadn't had morning coffee yet either. Lol!

 

some of us just naturally wake up bright