wastegate vac lines

[ernhrdt34]

i have a 95 TSI and i have noticed that the vac line from the wastegate is tapped directly to the BOV line. i noticed that there is a nipple located on the bottem of my turbo that has been capped. it looks like the previous owner bypassed the factory wastegate selonoid. im just wondering if directly tieing into the BOV is a good thing or is there a better way to hook up the wastegate vac lines?

 

[MrBoxx]

Your suspicions are correct. A quick search here finds that teeing off the BOV for ANYTHING is a bad idea, for numerous reasons. Ideally, for any sort of boost control, you want to get the most direct source of boost, which in this case is a nipple on the compressor housing, or lower intercooler pipe. You might find that it's best if you replace the entire BOV hose with a brand new one, and using the compressor nipple for your boost source.

 

[ernhrdt34]

i did replace the Bov line and connected the wastegate to the nipple on the intake pipe which is where it seems to have been originally. but now the boost peaks at 25 psi where it peaked at 12 psi when tapped off the BOV. is that a bad thing? should i try connecting the wastegate to the compressor nipple at the bottom of the turbo directly?

 

[Mr Peepers]

Don't do anymore pulls until you connect it from the nipple on the turbo to the wategate actuator. The nipple on the intake pipe is not a pressure source, it was just part of the plumbing for the stock BCS. You are basically running unlimited/open boost which can turn out VERY badly.

 

[MrBoxx]

should i try connecting the wastegate to the compressor nipple at the bottom of the turbo directly?

This is what I implied you should do. I apologize if I didn't explain it well enough in my post.

 

[ernhrdt34]

yeah thats better im back to 12 psi. You guys were a lot of help! its hard finding a book that has good diagrams or descriptions on how to get things right. at least theres a place to get some answers.
is there any way to squeeze a bit more boost out of the stock turbo?

 

[Mr Peepers]

Get a MBC and set it to ~15 psi, and a turboback or catback exhaust to get the most out of that boost. Your t25 will be close to maxed out by then.

A logger would be a very good idea for safety's sake when you start turning up the boost past stock.

 

[ernhrdt34]

I already have a tanabe cat back exhaust but not a MBC. by adding a MBC can raise the boost levels higer than a direct connection between the turbo and wastegate?

 

[MrBoxx]

Yes. The MBC delays the boost signal from reaching the wastegate actuator, allowing boost to rise. Currently, you're just running off the wastegate spring pressure, 11-12psi usually.