Hey everybody, I've been diagnosing a problem with my turbos and got tired of trying to decipher that nasty turbo digram, so I cleaned it up a bit and edited it. I thought some of the other people on here might find this useful and a bit easier to see what's going on. Feel free to edit it more, it's still a work in progress, and if anyone wants a PSD for it, PM me and I'll send it to you.

Also, I've got it on tinypic for now, if someone can host it somewhere better, that would be great.

 

Also, are the arrows I put in the wastegate and precontrol lines pointing the right way? I know they connect to the output of the primary turbo, but is it boost in those lines or some kind of bernoulli effect vacuum?

 

Also, does anyone know what this section connects to?

 

downpipe?

 

I don't think it could be the downpipe, since that should connect just above it (where those three black exhaust arrows are)

Could it be an exhaust port off the engine? (But wouldn't that be round?)

 

I think there is just a metal plate that goes over that.

 

That's kind of odd, isn't it? What would that have been for?

 

thats correct.

 

Do either of you guys know what that chamber connects to? If it's exhaust, it might not be a bad spot for an external wastegate!

 

no need for an external WG...that would be silly

 

There is no need for an external wastegate when there is allready one built in to the system. I f im not mistaken the cover is for the turbo precontrol valve. I dont know what you are trying to get to with this post besides showing a decent schematic.

 

An external wastegate would be handy for supplementing the stock wastegate which isn't quite big enough with a free-flowing exhaust, but that's beside the point.

Mostly, I worked on that schematic to get an understanding for the twin control system, and I figured that I might as well share it. -and while working on it, I ran across some stuff that I didn't understand, so I'm getting help figuring it out. Everything on that diagram makes sense to me now except for that blocked off port. Just seems kind of odd and pointless.

Anyways, I've got a slightly more cleaned up version of this diagram that I'll post soon. Hopefully other people will find it useful too.

 

Great work dude. Your diagram is ALOT easier to read than the original. Can't wait for the new one.

 

A search brought me to this thread and it will be great in helping me diagnose my problem. I have a non-sequential setup (permanent). About a 2 months ago I noticed boost not kicking until late in the RPM band. I haven't messed with anything, so I'm guessing its got to be an issue with the primary turbo. I still get boost up to 10-11 lbs but it comes in later in the RPM band than what I'm used to. I basically have no low end kick now. My car idles the same and runs fine, just no low end.

Specifically, I'm thinking it could be something with the restricter pill line. I had considered putting in the manual boost control valve, but up until now I was fine with the stock pill giving me 11 lbs of boost. I havent' checked the lines were the pills sit for problems yet, but do you guys think my boost issue with the primary turbo could be with the pills or a line popping off or something else?

BTW, just for confirmation. If I were to install a manual boost control for my setup, it would go in place of the "Boost Pill" in the diagram above, correct?

-KPM

 

My suspicion would be that you have a wastegate that's not closing all the way, or a boost leak.

If you've checked for boost leaks and ruled them out, a leaky wastegate would result in the following:

At low rpms, most of the exhaust flows out the wastegate, resulting in insufficient flow to spin up your turbos. (in a non-sequential setup, your precontrol and turbo control actuators are most likely wired open, so it's not really a primary vs. secondary issue since both turbos get exhaust pressure all the time).

At higher rpms, you have sufficient exhaust flow to overcome your leaky wastegate and spin up the turbos.

That's my guess. Like I said earlier, eliminate all chances of a boost leak first, and then look into this as a possibility. (FWIW, I ended up soaking my wastegate valve rod in repeated applications of WD-40 and my low rpm boost builds up much better now, presumably due to the wastegate closing properly/easier- if you do this, wait for the WD-40 to dry before you drive the car!)

 

Final Diagram:


This image is public domain, feel free to copy, edit, etc. Please post edits back in this thread though.

 

awesome, thank you!

 

You're welcome! I'm glad someone else found it useful too.

Here's the original, for anyone who might want it: