924Board.org

[peterld]

In piecing a motor together (after some years apart) I have a canundrum! On the underside of the 931/932 inlet manifold is a large take-off pipe c@ 20mm facing downwards. Where does this go to? I don't have any hoses left, and surely this wasn't vented to the atmosphere before?
I have searched Haynes and Turbo manual but haven't found anything conclusive. What have I missed?
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80/81 932/8 ROW

[Smoothie]

It connects to the turbo recirculation valve.
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"..it's made in Germany. You know the Germans always make good stuff."


'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

[Grenadiers]

There should be a hard to find short hose connecting that port to a metal vacuum line to a small hard to find rubber elbow which connects to the recirculating valve. If your Aussie friends can't help you out, I should have that metal line with the upper hard rubber hose attached, that I can send to you.
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'83 944 Track car.
'88 924S Track car.
'89 944 Turbo
2004 Winnebago Vectra monster RV
2012 Jeep Wrangler
2014 Kia Soul
2001 Ford F350 powerstroke

[Carrera RSR]

And if the metal pipe from the recirculating valve wasn't put back before you installed the water pump, cam belt and cam belt cover it'll all need to come off again. Ask me how I know this!!!
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252

[peterld]

Boys, Boys.....thank you for your speedy replies. It all makes sense now.

Turns out my canundrum has just got bigger, but then it's my doing entirely. Here is the full story:

Some years ago in talking to Dan (Ideola) about hybrid turbos, I decided to go that way and had a shop in USA put together exactly such a thing.
This is what it comprises:
Hot side = 931 (thus utilising odd 3 bolt flange)
Intermediate = 951 (thus giving capability of additional water cooling)
Cold side = 951 (a bloody monster)

Now this all bolts up in the same place as 931 utilising existing wastegate, exhaust, etc. though with FMIC, core measuring 250x260x60 situated in front of water radiator, both lines running down RHS of car.

The intermediate on the 951 is very similar to the 931 with the addition of extra threaded drillings for water fittings, and as I have just discovered, an extra drilling on the inside of the intermediate (facing the engine block).
The oil feed line fits to the top of the intermediate just as it does on the 931, while the oil drain-back to the sump fits to the bottom of the intermediate, just as it does on the 931. On the outside of the intermediate, facing the body frame rail are two drilled, threaded openings, one above the other. These I presumed were water inlet/outlet, however while lying on my back under the car staring to the heavens for inspiration, I noticed a third similarly sized inlet? on the block side.

By now you are shaking your heads thinking what a d...head, and you're right. How did I not see the third inlet/outlet? while all this was apart and why put the motor in the car with this matter unresolved.

Well after now 8 years off the road, impatience got the better of me, and I assumed I would be able to organise the water lines better while the motor was 'insitu', or at worst, plug the inlet/outlet and run it just like a 931 (oil only) until I could sort the issue. Honestly never saw the third (inboard) inlet. Doh! And then noticed the vacuum line off the bottom of the inlet manifold! Doh!

Incidentally, have the short metal line with short hose which obviously goes to original 931 turbo, on another spare block (albeit in dreadful condition).

So here is my question. Why did the manifold vacuum go to the cold side of the 931, when the 951 had no such provision. Does it primarily actuate the spring?
Obviously I'm in need of a few lessons in 'Turbo 101".

And if anyone has, or access to, a 951 - what is the orientation of those inlets/outlets.

Thanks for all your replies Guys, much appreciated.
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80/81 932/8 ROW

[peterld]

And given that I'm now running a 951 turbo, do you envisage any problems with simply plugging the under-inlet manifold vacuum line?
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80/81 932/8 ROW

[Smoothie]

[peterld]

Thank you Mr. Smoothie...........as always, informative advice.
Cheers.
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80/81 932/8 ROW