My compressor housing didnt come with a tapped line for the WG signal. is it alright that i just tap the signal on the piping that comes out instantly from the compressor outlet?

thanks

 

That will work. You could just tap the comp housing if you wanted also

-Jacob

 

well i wanted to but its all bolted up nicely there with the oil lines in and all , i just that i wouldnt want to mess with it...

no negative effect on doin this?

 

Nope, none at all, just be sure the fitting your using (im assuming its just a brass barbbed fitting or something like it) is nice and snug and doesnt leak

-Jacob

 

That's fine.

As long as the wastegate is tapped anywhere from the compressor housing all the way to the intake manifold on the engine, it'll "work".
The closer to the turbo the WG line is tapped, the quicker the WG will react.
The closer to the engine the WG line is tapped, the slower the WG will react.
Now, keep in mind that "quicker WG" = "slower boost", since the WG is opening faster.
There is a slight worry about heat and the vacuum line, but if you're not running insane amounts of boost, this is not that big of a deal...
closer to turbo = hotter the vacuum line
closer to engine = cooler the vacuum line

Details are from "Maximum Boost" by Corky Bell...


-Ted

 

im just goin to run 10 psi to 15 psi max....or more specific 1 bar....

so how does it mean that

closer to turbo = hotter the vacuum line?

i mean is it because the placement of the line being routed or is it some other meaning?

 

The compressor outlet lets out heated Charge air but is compressed to a higher ratio, then the intake charge is then cooled and condensed due to this cooling and the compressed charge lets say right at the turbo it is 11psi and after the intercooler it is 9psi. it still contains the same amount of air molucues but is not condeced made denser by cooling. So now instead of having 11 psi of charge air actuating your WG spring if you tap it at the compressor outlet. You would have 9psi of charge air actuating your wg spring.

so in short
Closer to turbo more PSI and Hotter air
Closer to engine Post intercooler Less PSI and cooler air.
so because your WG is most likely like 10psi spring or something the more psi it has the quicker it will react.
I think you should Buy and Read "Maximum Boost" by Corky Bell.... awsome book will greatly steepen your learning curve.

 

thanks jeff

 

So if my wastegate vacuum source is tapped after the throttle body, I should run about 2-3 punds less boost because the wastegate will react slower? Am I understanding this right? I called up HKS directly and they told me it wouldn't make any difference between the two locations. Hmmmmm....

 

thru my understanding u will run 2-3 pounds more not less.....cause it takes longer for the wastegate to get the boost signal......

 

Run the WG vacuum line closer to the engine, the more boost it'll run.

To give you a real-world example...
We had an FC with a H-trim hybrid (Kouki turbo) that could only muster 2.5psi of boost due to the ported WG and smallish exhaust (2.5" main pipe).
This was using the stock WG vacuum location right off the compressor housing.
Moving the WG vacuum line onto the intake manifold after the TB, we got approximately 6psi of base boost.
That was a 3.5psi increase of boost.

Interestingly enough, the A'PEXi AVC-R could not raise the boost over 11psi no matter the WG vacuum line position.
The base boost was raised, but the boost controller could not raise it the same amount.


-Ted

 

what intercooler were you running?? it's possible that there was a significant pressure drop across the i/c.

did you hook it up before or after the tb?

 

I am running a Greddy VSPL
I also have mine hooked right up to the compressor housing becaus I have a 14.7 PSI spring my in Greddy WG and I want it to Open sooner so that I don't go much above that.