Turbo anatomy [Archive] - SaabCentral Forums

: Turbo anatomy


ctrlz
30-04-04, 11:52 PM
I finally took a look under the hood to see what the plumbing actually looks like. The pictures are of a 2003 Vector with the 2.0T.

First, the general layout. Fresh air enters through the filter at the left, passes through the turbo in the upper left, goes under the engine to the intercooler up front, then enters the intake manifold through the big black hose coming from lower right to lower center.

ctrlz
01-05-04, 12:18 AM
I took the aluminum shroud off the exhaust outlet for clarity. It's held by two bolts and one mounting boss. Remove the bolts and slide up. You don't NEED to take it off, I just did so for the pictures.

Doesn't show too well at this size, but good enough.
1 - intake
2- turbo
3 - turbo bearing with banjo fittings for oil cooling
4 - exhaust outlet with internal wastegate
5 - exhaust downpipe, oxygen sensor to right of "5"
6 - crankcase vent line
7 - wastegate actuator

ctrlz
01-05-04, 12:43 AM
Here's the actuator plumbing.

1 - "signal" = turbo outlet pressure

Black rectangular device is the boost control solenoid. I have it slightly off its mount.

2 - actuator inlet hose
3 - vent back to intake

The basic location choices for a manual boost control valve (MBCV) would be:

Line 1 --> MBCV ---> Line 2 --> actuator
This option allows for full manual control. No solenoid in the circuit.

OR

Line 1 --> solenoid --> line 2 --> MBCV --> actuator
In this situation the solenoid can still send pressure to open the wastegate, but the speed of the wastegate response will be delayed by the MBCV.

M4Gunner
01-05-04, 01:58 AM
ctrlz.. i think i should know your first name before i propose! I LOVE YOU!! lol, no but really GREAT post. one of the most useful yet. good work, yet again.. honey! :wink:

CallipNCSUsaab
01-05-04, 01:52 PM
yeah, this is appreciated by all... I will let gunner marry you though :)

Damn Stereo
01-05-04, 01:58 PM
ctrlz.. i think i should know your first name before i propose! I LOVE YOU!! lol, no but really GREAT post. one of the most useful yet. good work, yet again.. honey! :wink:

Here at SaabCentral we do not discriminate against race, gender and in this case, sexual orientation.

LinearSLT
01-05-04, 02:35 PM
Here at SaabCentral we do not discriminate against race, gender and in this case, sexual orientation.


By sexual orientation are you refering to Saab lovers ? :wink:
I'm sure Saab loving is banned in a few states still....unless you are married.

mbodo
01-05-04, 03:31 PM
I just noticed on my own, and on ctrlz's pictures, the paint marker dots lining up the hoses and hose clamps.

Moving any of these should signal any mechanic with decent vision that someone has gotten their meathooks into this device.

Oddly enough, someone HAS already gotten their meathooks under my hood, as a few of the paint dots already don't line up.

M4Gunner
01-05-04, 07:49 PM
I just noticed on my own, and on ctrlz's pictures, the paint marker dots lining up the hoses and hose clamps.

Moving any of these should signal any mechanic with decent vision that someone has gotten their meathooks into this device.

Oddly enough, someone HAS already gotten their meathooks under my hood, as a few of the paint dots already don't line up.

ahh.. good spot sherlock! (that probably sounded very sarcastic, but it wasnt) that will be good to know.

ctrlz
01-05-04, 10:03 PM
I just noticed on my own, and on ctrlz's pictures, the paint marker dots lining up the hoses and hose clamps.

Moving any of these should signal any mechanic with decent vision that someone has gotten their meathooks into this device.

Oddly enough, someone HAS already gotten their meathooks under my hood, as a few of the paint dots already don't line up.

The dots don't all line up, and I haven't touched them. Even if you moved hoses around, a yellow paint "marker" can probably be had for a few bucks at your local hobby store. A couple years ago Tamiya was making them.

Incidentally, my numbered photo may be somewhat misleading. I did it at 12:30 AM.

I labelled "2" as the turbo. The turbo actually is 2,3 and 4. 4 is the turbine housing. This contains the turbine and the wastegate. The turbine is attached to a shaft that passes through the bearing (3) and connects to an impeller in the compressor housing (2).

One thing I'm still trying to find is if the boost control solenoid is ever used in emergency situations to decrease power. If the TCS, for example, senses wheel slip, it activates the anti-lock braking AND cuts power. Since we have electronic throttles, it may simply back off the throttle. But it might also use the boost solenoid to quickly open the wastegate. Seems like something that would make sense, I just haven't been able to find if that's what really happens. We seem to have a few automotive design professionals lurking about, so feel free to chime in.

As for the marriage proposals... I'm already married with two (young) kids, which explains why I work on my car at midnight :D

M4Gunner
02-05-04, 03:28 AM
lol, ive only got one...and he took his first steps today!!

ctrlz
02-05-04, 09:12 PM
Been thinking some more about the plumbing.

Another option is to cut line 1 and insert the MBCV before the solenoid. This may actually be the best option. The pressure signal will still be delayed on its way to opening the wastegate. The main advantage of this position is that when the solenoid closes, the vent line from the actuator back to the intake will be WIDE OPEN, allowing the wastegate to slam shut as quickly as possible.

If you cut hose 2 and insert the valve, as I first suggested, you are still at the mercy of the bleed rate of the MBCV to get the wastegate closed.

pjku79
03-05-04, 12:20 PM
crtlz, where are these pictures posted?

ctrlz
03-05-04, 04:10 PM
crtlz, where are these pictures posted?
First few posts of the thread. They are sub 60K jpg's, so not that great. I'm at my 1 MB limit for pix on Saabcentral, and will need to start linking to an external server to post more pictures. I'm in the market for bright ideas in that department. I had to delete pix from earlier posts to make room for these.

If for some reason you can't see my numbered pictures in the posts, PM me and I'll e-mail you.